IMPROVEMENTS IN THE CONSTRUCTION. OF ARMATURES FOR DYNAMO ELECTRIC MACHINES
Year: 1885

page_text: Electric Machines.
I, FRANK WYNNE of 4, Carteret Street in the City of Westminster, in the
County of Middlesex Civil Engineer do hereby declare the nature of my invention
for IMPROVEMENTS IN THE CONSTRUCTION. OF ARMATURES FOR DYNAMO ELECTRIC
MACHINES to be as follows:—
My Invention relates to that class of armatures for dynamo electric machines
(generators and motors) known as disc or ring type, of which the well known
"Brush" and "Schuckert" armatures are examples.
Amongst other plans of constructing the said armatures a ribbon or band of iron
is wound spirally on itself into the form of a short cylinder and this ribbon or band
of iron has hitherto been taken of the full breadth of the core, round which the
armature bobbins are wound.
;
'
This, besides causing mechanical difficulties on account of the stiffness due to the
breadth of the bands is also very imperfect as regards ventilation and cooling inas-
much as the so-called "Foucault" currents as well as the less understood magnetic
currents generated in the core of the revolving armature have a very wide range.
It has also in this class of armature been proposed to employ laminated cheek
pieces between which to wind the wire coils of the armature, which laminated
cheek pieces were formed of thin iron plates inserted between the layers or folds of
the band iron coil.
The thin iron plates constituting the laminated cheek pieces being made in one
metallic piece transversely to the direction of motion of the armature, that is to
say of such a length that they extend in one piece from one side of the armature to
the other so that the respective ends of the said thin iron plates just clear the
respective pole pieces of the field magnets, when the armature is in place and is
revolved so that there is a continuity of the metal of the said thin iron pieces
extending in one unbroken plane from one side of the armature to the other or
nearly, of the full extent of the space between the respective poles of the field
magnets.
The range of the "Foucault" or magnetic currents due to these extended
unbroken metallic plates is a very serious drawback to the efficiency of the machine
and causes considerable loss by heating.
My Invention has for its object to so construct armatures of this type that
the before mentioned objections are removed or in a great measure removed, by

page_text: providing means whereby the ribbon or band iron can be readily wound, the range
of the "Foucault" and magnetic current considerably reduced, and an effective
ventilation obtained. In order to avoid the difficulty due to the employment of a
wide strip of ribbon or band iron to form the armature, I build the core of the said
armature up of two strips of a width which combined side by side will form an
armature ring of the requisite width. These strips may be wound upon or
supported by a foundation or supporting ring suitably connected to the hub in any
convenient way. In order to form the laminated cheek pieces for the wire coils of
the armature, I do not use thin iron pieces, which are continuous from side to side
of the armature, but I employ U shaped pieces, which I prefer to refer to herein-
after as "gap" pieces of thin soft sheet iron, which are so shaped & placed and
held between the coils or "laps" of the ribbon or band iron core of the armature
that the said gap pieces do not form a continuous metallic surface from side to side
of the said armature. These gap pieces are arranged radially in groups, one part of
which in the circumferential line of the winding of the iron strips, projecting
beyond the sides of the strips about the thickness of the layers of wire of the
coils to be wound on the armature so that each group of the said gap pieces forins
one side of the pockets in which each coil of the armature is wound.
pieces may be held in place by the coils thus wound on the armature ring.
The gap
The two cylinders formed by the strips of iron band, are electrically & mag-
netically, suitably & sufficiently separated from each other as also are preferably
the "gap" pieces and the laps of each of the iron strips forming each cylinder,
either by a space or by pieces of insulating material. In some cases the scale on the
iron will be sufficient to sufficiently electrically or magnetically separate the parts.
The arrangement described of the two narrow strips, allows a free passage to be
arranged radially between the two cylinders so that the core, as it revolves, will
act as a fan sucking in the air through such interstices as may be and are generally
left in or between the coils and ejecting it at the periphery. This space may be
occupied by insulating material, but it will be understood that it may be without
such material or be occupied only partially by it, so as to leave the air passage
aforesaid.
I sometimes insert an annular disc between the two parts of the core, the outer
edge of the disc being formed with ear-pieces, which are alternately bent first over
one cylinder and then over the other, around the core; and they may also be bent
alternately under and over the last lap of the strips. The inner edge of the said.
annular disc may be suitably arranged and be bent over and under the first layers
or windings of the strip of each cylinder. This arrangement may be used in the
inner edge only or the outer edge only or both in combination. A slight modi-
fication is sometimes used wherein two such annular discs are used, one for each
cylinder. Such annular disc fitting closely to or being fastened to the foundation
ring before mentioned, acts like a backbone to consolidate and support the whole :
in many cases I sometimes corrugate such disc or discs, the effect of this corrugation
being to stiffen the whole ring laterally and also to provide suitable radial air spaces
in the centre of the ring, but this may also be effected by radial bars attached to
centre plate, the corrugations, when made, extending preferably radially from the
inner to the outer circumference of the ring. I also further extend the outer
periphery of the said disc or discs into ear pieces so as to make use of them as
supports for the sides of the wire bobbin of the armature where these extend above
& beyond the core proper. Inasmuch as the spaces between the coil of wire when
wound on the armature are wedge shaped, it is convenient to make the lengths of
the pieces of sheet iron forming the "gap" pieces of variable length, small toward
the centre of the armature core and larger towards the periphery of the said core
so as to fill up the wedge shaped space and form cheeks for the said coils. In any
case for the purpose of ventilation, it would be convenient & beneficial to leave
spaces for the entrance and circulation of the air and these spaces may be left
between the adjoining ends of the "gap" pieces and between each gap piece and
the adjacent layers of the convolutions of the strips forming the core. Although

page_text: I have described only two cylinders formed of coiled narrow strips placed parallel
to each other it will be evident that a cylinder or cylinders of coiled or circularly
arranged strips may be employed between the other two, in the case of a wide
armature this might be beneficial. Inasmuch as the largest production of "Foucault"
and magnetic currents the generation of which it is wished to avoid, arises where a
continuous metallic transverse sheet of metal reaches all but across the space
between the pole pieces of the field magnets, when the armature is revolved, this
can be in great measure avoided by the use of the divided or electrically or
mechanically disconnected "gap" pieces, hereinbefore described. It may be con-
venient more especially in the smaller classes of machines to wind the core in the
ordinary way of a single spirally coiled strip forming one cylinder with the "gap"
picces arranged back to back and electrically or magnetically separated or insulated
from one another so as to avoid metallic continuity across the armature, and the
interstices between the projecting cheeks of these " gap pieces, may be further
filled in, if required, with pieces of metal, which are held in place by plugs of wood
or other suitable non-conducting material.
33
"
The "gap" pieces formed with parts bent back on themselves form a convenient
way of fitting up the interstices between the cheeks of consecutive "gap" pieces,
in place of the method of filling up, hereinbefore mentioned.
Ventilation between the laps of the core may also be secured by whipping,
winding or otherwise securing the strip iron with a narrow slip string, wire or
ribbon of suitable material either insulating or insulated, such as cotton tape in
such a way that a spiral of the whipping material is formed, round the strip iron
with a spiral of exposed slip iron between..
-
By this means narrow interstices of about the thickness of the whipping material
are left between the strip of band iron so wound and the interposed plate or "gap"
piece & through and into this space the air can enter and circulate.
11
1
FRANK WYNNE,
COMPLETE SPECIFICATION.
Improvements in the Construction of Armatures for Dynamo
Electric Machines.
I, FRANK WYNNE of 4 Carteret Street Queen Anne's Gate, Westminster, in the
County of Middlesex, Civil Engineer do hereby declare the nature of my invention
for IMPROVEMENTS IN THE CONSTRUCTION OF ARMATURES FOR DYNAMO ELECTRIC
MACHINES, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
My Invention relates to that class of armatures for dynamo electric machines
(generators or motors) known as disc or ring type, of which the well known
"Brush" & "Schuckert" armatures are examples. Amongst other plans of con-
d

page_text: "
structing the said armatures a ribbon or band of iron is wound spirally on itself,
into the form of a short cylinder and this ribbon or band of iron has hitherto been
taken of the full breadth of the core, round which the armature coils are wound..
This, besides causing mechanical difficulties on account of the stiffness due to the.
breadth of the bands is also very imperfect, as regards ventilation and cooling,
inasmuch as the so-called Foucault" currents as well as the less understood
magnetic currents generated in the core of the revolving armature have a very
wide range. It has also in this class of armatures been proposed to employ
laminated cheek pieces between which to wind the wire coils of the armature,
which laminated cheek pieces were formed of thin iron plates inserted between the
layers or folds of the band iron coil.
The thin iron plates constituting the laminated cheek pieces being made in one
metallic piece transversely to the direction of motion of the armatures, that is to
say of such a length that they extend in one piece from one side of the armature
to the other so that the respective ends of the said thin iron plates just clear the
respective pole pieces of the field magnets when the armature is in place and is
revolved so that there is a continuity of the metal of the said thin iron pieces
extending in one unbroken plane from one side of the armature to the other or
nearly of the full extent of the space between the respective poles of the field
magnets.
"
The range of the " * Foucault or magnetic currents due to these extended
unbroken metallic plates is a very serious drawback to the efficiency of the machine
and causes considerable loss by heating.
My Invention has for its object to so construct armatures of this type that
the before mentioned objections are removed or in a great measure removed by
providing means, whereby the ribbon or band iron can be readily wound, the
range or amplitude of the "Foucault" and magnetic currents is considerably
reduced and an effective ventilation obtained. In order to avoid the difficulties
due to the employment of a wide strip of ribbon or band iron to form the armature
core I build the core of the said armature up to two strips of a width which
combined side by side will form an armature ring of the requisite width as shewn
in section in Fig. 5 of the accompanying drawing. These strips "b" may be wound
upon or supported by a foundation or supporting ring "B" suitably connected to
the hub in any convenient way. In order to form the laminated cheek pieces for
the wire coils of the armature I do not use thin iron pieces which are continuous
from side to side of the armature, but employ "gap" pieces of thin soft sheet
iron A (shewn in various forms in Figs. 1. 2. 3) which are so shaped and placed
and held between the coils or "laps of the ribbon or band iron core of the armature
that the said gap pieces do not form a continuous metallic surface from side to
side of the said armature. These gap pieces are arranged radially in groups as
shewn in Fig. 4, with the part a in the circumferential liue of the winding of
the iron strip "b," the parts "a" projecting beyond the sides of the strips about
the thickness of the layers of wire of the coils to be wound on the armature so
that each group of the said gap pieces forms one side of the pockets on which
each coil of the armature is wound. The gap pieces may be held in place by the
coils thus wound on the armature ring. The said Fig. 4 shows two portions of an
armature ring the portion at X being a section and the portion at Y being a side
elevation before the coils of wire are wound thereon.
"
The two cylinders formed by the strips of iron band "b" are electrically and
magnetically, suitably & sufficiently separated from each other as also are, pre-
ferably, the gap pieces and the laps of each of the iron strips forming each cylinder
In some cases
either by a space or by the pieces of insulating material, "d. d."
the scale on the iron will be sufficient to sufficiently electrically or magnetically
separate the parts.
Fig. 5 is a transverse section of an armature ring before the wire coils are
wound thereon shewing this separation or insulation of the parts. The arrange-
ment described of the two narrow strips allows a free passage to be arranged
J

page_text: radially between the two cylinders as at "c" Figures 5 and 6, so that the core as
it revolves will act as a fan sucking in the air through such interstices as may be
and are generally left in or between the coils and ejecting it at the periphery. In
the drawing the space is represented as being occupied by insulating material but
it will be understood that it may be without such material or be occupied only
partially by it so as to leave the air passage aforesaid.
In Fig. 5" represents an annullar disc inserted between the two parts of the
core, the outer edge of the said disc being formed with ear pieces "e" which are
alternately bent first over one cylinder and then over the other, around the core
and alternately under and over the last lap of the strips "b" as shewn in the
portion Y of Figure 4. The inner edge of the said annular disc may be similarly
arranged and be bent over and under the first layers or windings of the strips "6"
of each cylinder. This arrangement may be used in the inner edge only or the
outer edge only or both in combination. Fig. 6 shews a slight modification
wherein two such annular discs are used one for each cylinder, such annular disc
fitting closely to or being fastened to the foundation ring "B" before mentioned
acts like a back bone to consolidate and support the whole and in many cases
I prefer to corrugate such disc or discs as is shewn at Fig. 3 of the accompanying
drawings, the effect of this corrugation being to stiffen the whole ring laterally
and also to provide suitable radial air spaces in the centre of the ring, the corru-
gations extending preferably radially from the inner to the outer circumference of
the ring. I also, as shewn in Figs. 1. 2 & 3 of accompanying drawings further
extend outer periphery of the said disc or discs into ear pieces "K, K," so as to
make use of them as supports for the sides of the wire bobbin of the armature
where these extend above and beyond the core proper. Fig. 4 shews "gap" pieces
used with the armature core shewn in these figures. Inasmuch as the spaces
between the coils of wire when wound on the armature are wedge shaped, it is
convenient to make the lengths of the pieces of sheet iron forming the gap pieces
of variable length small toward the centre of the armature core and larger towards
the periphery of the said core, so as to fill up the wedge shaped space and form
cheeks for the said coils. In any case for the purpose of ventilation it would be
convenient and beneficial to leave spaces for the entrance and circulation of the air
and these spaces may be left between the adjoining ends of the "gap" pieces and
between each gap piece and the adjacent layers of the convolutions of the strip
forming the core. Although I have shewn only two cylinders formed of coiled
narrow strips placed parallel to each other it will be evident that a cylinder or
cylinders of coiled or circularly arranged strips may be employed between the other
two, in the case of a wide armature this might be beneficial. Inasmuch as the
largest production of Foucault" and "magnetic" currents, the generation of
which it is wished to avoid, arises where a continuous metallic transverse sheet of
metal reaches all but across the space between the pole pieces of the field magnets,
when the armature is revolved and as this can be in great measure avoided by the
use of the divided or electrically or mechanically disconnected " gap pieces,
hereinbefore described, it may be convenient, more especially in the smaller classes
of machines, to wind the core in the ordinary way of a single spirally coiled strip
forming one cylinder, with the "gap" pieces arranged back to back and electrically
or magnetically separated or insulated from one another so as to avoid metallic
continuity across the armature. Such an arrangement is shewn in transverse
section in Fig. 7, in which the "gap" pieces are shewn held in between a single
band which is the whole breadth of the armature core. The "gap" pieces shewn
in this arrangement are like those shewn in Fig. 1, and the interstices between the
projecting cheeks a² of these "
gap" pieces may be further filled in, if required,
with pieces of metal "g" which are held in place by plugs of wood or other
suitable non-conducting material as at "k" Fig. 8.
33
The gap pieces shewn in Figs. 4 & 5 are those shown in Fig. 2 and those shewn
in Fig. 6 are those shewn in Fig. 3, the said "gap" pieces formed as shewn in
Figs. 3 & 5 with parts bent back on themselves, form a convenient way of filling

page_text: up the interstices between the cheeks of consecutive "gap" pieces in place of the
method of filling up shewn in Fig. 7.
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
.
1st Forming the cores of armatures for dynamo electric machines of two strips
separated from each other by a space or by insulating material or both including or
not, another strip or other strips situated between the said two.
2nd Forming the cores of armatures for dynamo electrical machines of two
strips separated from each other by a space or by an insulating material or both
(including or not another strip or other strips situated between the said two) the
winding of the cores thus formed being separated by "gap" pieces, which form
the cheeks for the wire coils and are not electrically or magnetically continuous
from side to side of the armature.
3rd In constructing the cores of armatures of dynamo electrical machines, the
combination with a strip or strips (of which the core of the armature ring is
formed) of "gap" pieces which form the cheeks for the winding of the coils the
said "gap" pieces being constructed or formed so that when put in place they are
not electrically or magnetically continuous from side to side of the armature
whether the spaces between the parts be filled with insulating material or be left
free or partly free as air channels and whether the gap pieces be used alone or with
filling pieces as illustrated in Fig. 7 or be formed with turned back parts or filling
pieces upon themselves.
4th Securing the laps or convolutions of ribbon or strip iron armature coils by
means of an annular disc or discs corrugated or not and with tongue pieces on the
outer or inner or both outer and inner edges turned down over the said laps or
convolutions as shewn in Sheet 1 and whether used or not with ear pieces K. K, to
form cheek pieces for the coils as shewn on Sheet 2.
Dated this 10th day of Droomsbar 198