Improvements in Dynamo Electric Generators.
Year: 1889

page_text: COMPLETE SPECIFICATION.
Improvements in Dynamo Electric Generators.
I GUSTAV PFANNKUCHE of Cleveland in the County of Cuyahoga, and State of
Ohio, United States of America, 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 :-
.. My invention has reference to that class of electric generators known under the
generic name of Dynamo Electric Generators; and it more particularly relates to that
specific form of dynamo machines known as alternating current generators, although
it is applied with advantage to dynamo machines, the current from which in the
external circuit is what is known in the art as "a straight current"; and the particular
object of my invention is to produce a dynamo electric generator in which the
generating armature embodies in its construction neither iron nor any other magnetic
metal, either for the purpose of straightening the mechanical structure of the machine,
or for the purpose of intensifying the influence of the field magnets; at the same time
the unavoidable metallic parts for supporting the armature are so located that they are
beyond or outside of the effective portion of the magnetic field, so that the latter acts
upon the armature coils alone thus avoiding any inducing effect on any other part of
the armature except the armature coils.
In addition thereto and as part of my invention, the armature is constructed to be
stationary, while the field magnets rotate, and this arrangement enables me to reduce
the weight, and the mechanical rigidity and strength of the armature, since the same
is subjected to but little mechanical strain.
I am aware that prior to my invention, dynamos have been constructed wheroin
the armatures were devoid of iron cores and structural supports, as for instance in
the Brush Machine described in U.S. patent No. 302319, and in the Siemens
alternating current generators; the Arago disk generator is also a specimen of this
type. In all these generators, however, the armature was the rotating member, while
the field magnets were stationary.
I am also aware that alternating current dynamos of the Gordon- or Gramme type
have been constructed, wherein the armature is stationary and the field rotates ; but
in these, heavy masses of iron constitute the cores of the armatures and the rigid and
violent molecular, changes taking place in the cores, generate a great amount of heat,
whereby the efficiency of such dynamos is lowered to such an extent as to make them
practically useless for the requirements of the modern state of the art. When
in machines of this character the armatures are rotated and the field magnets
made stationary, the former must be made of unreasonable weight and size of
a given output, and the liability of destruction by heat is increased to a dangerous
extent.
All this is avoided by my invention, and in addition thereto, I reduce the Foucault
currents, which are a deplorable source of waste, to a minimum. The rotation of the
field magnets can be effected without trouble and danger for the reason that the
magnets are invariably made, and must in the nature of things, be made very
strong and heavy, and they will, therefore, resist the action of centrifugal force,
which when the armature revolves, might be, and often is destructive, and the
absence of these forces in the stationary armature permits the same to built
extremely light and thin without metallic hubs, spiders or spokes, or any other
metallic supports projecting within the effective magnetic field of the rotating
magnets. The possibility of keeping the armature very thin is one of the main
objects of my invention since by this construction, it is very easy to bring a very
powerful magnetic field to bear on the stationary induced coils.
Owing to the absence of any metal exposed to the effective field excepting the

page_text: armature coils the field can be made exceedingly dense or concentrated where it inter-
sects the effective portion of the armature coils and thus produce a
high electromotive
force with short lengths of conductors, and low resistance of the same; and in the
absence of heating and wasteful induction, high electrical and commercial efficiency,
as well as the safety of the machine, is insured.
All this will more fully appear from the following detailed description with reference
to the accompanying drawing, which form a part hereof, and in which I have illustrated
one form of machine constructed in accordance with
my invention.
Fig. 1, is a perspective view of my improved dynamo.
Fig. La represents a longitudinal vertical section of my improved dynamo, with
some of the field magnets on one side and the driving pulley, omitted.
Fig. 2, is an end elevation of the armature, with some of the field cores shown in
section and with relation thereto.
Fig. 3. is a front view of the armature frame with a segment a x indicated by dotted
lines in figure 2, cut away..
Fig. 4 is an end elevation of one of the armature coils, mounted on its segmental
support.
Fig. 5 is a section on the line y-y of figure 4.
Fig. 6 is a perspective view of the armature, with one of the segmental armature
sections about to be inserted and another section removed.
Fig. 7 is a sectional view on line x-x of fig. 5, and
Figs. 8 and 9 are diagrams illustrating the inductive relations of armatures and field
magnets.
Like letters of reference indicate like parts all throughout the drawings.
The base 1, of the machine is a hollow casting of suitable shape, the upper plate of
which is in the nature of a skeleton frame, from the two ends of which rise the
standards 2, 2, on which bearings for a shaft 3 are formed. This shaft 3 extends at
each end beyond the bearings and the driving pulley of the machine is secured to one
of these extensions, and the collector rings or sleeves are mounted upon the other
extension, as will hereinafter more fully appear. A suitable distance from the
middle of the shaft, and on each side thereof, is keyed an iron disk composed of
a central hub 4, and a heavy rim 5, connected to the hub by radial spokes 6. It
is not essential that the hub and spokes be made of iron, so long as the rim 5,
is made of that material or of any other magnetic material; but by preference,
and chiefly for the sake of cheapness, the whole disk is cast of one piece of
iron, but since the essential part of said disk is the rim of the same, which con-
sidered by itself, is an annulus, and which carries the field magnets proper, as
will presently appear, said rim will hereinafter be referred to as the annular yoke
of one set of the field inagnets.
The field cores 7 are segmental in cross section, as shown and screwed by bolts 8, 9,
to the inner face of the annular yoke, properly spaced.
In the drawing twelve magnet cores are shown on each yoke, but any other number
may be used. The segmental cores are secured to the yoke in radial positions, and
they are each supplied with a thin sleeve 10, and with flanges 11, both of insulating
material, and the energizing coils are wound upon said sleeve between the flanges in
the usual well known manner.
The free pole faces of the magnet cores project a short distance beyond the frames,
and the two sets of field magnets are so mounted upon the shaft 3, that a small space
is left between the opposing faces of the magnet cores, and, as will hereinafter more
fully appear this space is occupied by the effective portions of the armature coils.
The field magnet coils are connected on each side either in series or in parallel arc,
and the coils of one set are connected with the coils of the other set, either in series or
in parallel arc; this connection being made within the shaft, which for this purpose is
made hollow, or the wire connecting one set of magnet coils with the other magnet
coils extended between the two hubs 4, 4, suitably secured to the outer face of shaft 3.
One terminal of the field magnet coils extends through the hollow shaft and where
it projects from the same, it is bent upon itself and is secured to one of the collector

page_text: sleeves 12; and the other terminal similarly extending through the hollow shaft, is
secured to the other collector disk 12¹. Brushes 13, 131, constituting the terminals
of the exciter, bear upon the collector sleeves 12, 121.
It will now be understood that if the exciter furnishes current, the same will pass
to and through the field magnet coils, in series of in parallel, or in any other way,
according to the connections of the field magnet coils, and will energize the magnet
cores according to the direction of the winding.
This winding may be so that the successive pole faces of each set are alternately of
south and north polarity: while the pole faces of the opposing sets have a north and
south polarity, so that there will be as many distinct magnetic fields as there are
opposing sets of pole faces.
Another mode of winding would be such as will produce like polarity in all the
pole faces of one set of magnets, and the opposite polarity in the pole faces of the
other set of magnets, in which case the shaft or supporting frame would form
the medium for completing the magnetic current.
If now, the shaft 3, is rotated by power applied to the driving pulley, the two sets
of field magnets participate in that rotation, and a conductor extending radially
within the space between the opposing pole faces, will have currents of alternating
direction generated within itself, as is well understood by those skilled in the art, and
such radial generating conductor or conductors are provided in dynamo machines by
what is technically known as the armature of the machine.
In accordance with my invention the armature is stationary and is constructed as
follows:
There is an annular skeleton frame 14, which will hereinafter be referred to as the
armature frame, and which is made of German silver, or other nonmagnetic metal, of
high electrical resistance. This frame is made in sections and by preference, in two
sections, which may be bolted together and taken apart with ease. Each half of the
armature frame is composed of two semicircular angular flanges 15, 15, the plane
faces of which are parallel to each other, and held a suitable distance apart by bridge
pieces 16, 16, which may either be cast in one piece with the flanges or may be
seperately screwed on to the curved faces of the same, and they are of such width and
so spaced as to leave a number of equal, segmental slots between the two flanges of
the armature frame, and the arrangement is such as to provide as many free slots as
there are armature coils to be used in the machine for these slots are intended to
receive the armature coils, as will presently appear. Each half of the armature frame
has formed upon it at the lower end thereof an expanded foot 17 terminating below in
a straight flange 18 and the diameter faces of each half of the frame are also provided
with flanges 19, 19 by which the two halves are bolted together by bolts and nuts, as
shown at 20.
On the base of the machine there is provided a central bridge 21 in which a wide
slot 22 extending all the way across the machine under the middle of the shaft 3 and
at right angles thereto is formed and on each side of the slot and bridge piece is
recessed and planed off smoothly, and into these recesses fit the plane flanges of the
feet 17, of the armature frame, so that each half of the latter can be moved to and
from the middle of the machine. When the armature coils have been mounted in the
frame as will hereinafter more fully appear, each half of the frame is inserted with its
flanged feet in the recesses formed on the bridge piece and they are then moved
toward each other until the flanges 19, 19 formed on their diameter faces meet, when
the bolts 20 are inserted and the two halves of the armature frame secured together.
The frame as a whole is then secured to the base by bolts 23 passing into holes in the
Hanges of the feet registering with similar holes in the bridge piece.
The armature coils 24, 24 &c. are wound as segmental flat discs upon segmental
cores 25 of insulating material, such as vulcanized fibre asbestos board or wood, but I
preferably use segmental cores composed of porcelain, china, glass or other silicious or
equivalent material, and to each flat side of the upper wider portion of the coil is
applied an insulating plate 26 of segmental shape extending on each side beyond the
coil, and to each such insulated plate is applied a segmental flange plate 27 of

page_text: German silver or other non magnetic material of high electrical resistance. Screw
bolts 28, 28 etc. passing through the metal and insulating plates secure these
mountings to the outer part of the armature coil so that the latter is securely clamped
in its mountings. The curved flanges 27' of the metal plates 27 project on each side
laterally; these flanges 27¹ have holes formed in them and screw bolts 29 are used for
securing these flanges to the curved faces of the angular flanges 15, 15 of the
armature frame after the coil has been inserted in the slots provided in said frame
hereinbefore referred to.
The lower narrower portion of each coil has applied to each side a semicircular or
similarly shaped plate 30 of German silver or other non magnetic metal, and screw
bolts passing through these plates secure the same together and to the armature coil.
Between the upper and lower mountings of each armature coil are inserted segmental
pieces 32, 32 of insulating material which may be made of the same material the
cores 25 are made of, one radial edge of which bears upon the outer edge of the coi!
while the other edge of the insulating piece is either grooved or tongued so that there
will be a groove on one of these pieces and a tongue on the next adjoining one.
The projecting ends of the insulating plates 26 and of the segmental flange
plates 27 are cut off parallel to each other so that the distance between these two
ends is equal or nearly so to the distance between the edges of one bridge piece 16
and the edge of the next succeeding bridge piece 16.
If now an armature coil thus mounted is slipped into one of the slots in the
armature frame between two bridge pieces 16, 16, and secured in place by the
bolts 29, as above described, the next succeeding armature coil with its mountings
when inserted in the next slot in the armature frame, will engage with the tongue
formed on the edge of one of its segmental insulating plates 32, a groove formed in
the radial edge of the adjacent insulating plate 32 of the coil already in position and
when these armature coils are inserted in all the slots provided for them in the
armature frame, they will be all interlocked and when in position between the
opposing pole faces of the field magnets they will present on each side an annular
recess within which the pole faces can be brought very close up to the faces of the
coils without touching the same.
The free ends of the armature coils are secured to the binding posts 33 mounted
upon but insulated from the curved flanges of the segmental plates 27 and these coils
may be connected up in series or in quantity or in any other desired way by
conductors extending between the binding posts of the successive armature coils and
the currents generated in the armature coils are carried from the machine to the
external current in a manner well understood by those skilled in the art.
From the foregoing description it will be seen that the armaturo when built up
and in position for operation, consists essentially of a skeleton frame of non magnetic
material concentric to but outside of the effective inducing influence of the magnetic
field of force, the induced coils extend with their active generating portions radially
through the space between the opposing pole faces of the two sets of field magnets
and the wider inactive portions of these coils are arranged concentric with but
outside of the effective inducing influence of the magnets, similar in this respect to
the body of the armature frame. The narrower and inner portions of the coils, are
also arranged concentric to the annular space occupied by the magnetic fields, but
being arranged upon a smaller circle they are not subjected to the action of the
effective part of the magnetic field.
The annular space between the opposing pole faces of the field magnets can be
made as narrow as desired, and this space being completely occupied by the active
generating portions of the armature coils, and by the insulating spacing blocks or
plates 32, the magnetic lines of force will be substantially straight lines extending
between the opposing pole faces. Consequently the magnetic fields will be of uniform
density throughout and will act almost exclusively upon the radial portions of the
induced coils no substantial part of the magneto-electric induction will therefore be
consumed in un-productive work and the maximum useful effect will be obtained.
In a dynamo machine constructed in accordance with my invention, each armature

page_text: coil may be used as an independent enity and without connection with or dependant
upon the other coils; each may be removed and inserted without effecting the
functions of the others since, if so desired each coil may furnish currents to an
independent external circuit. All that is necessary for this purpose is, to open
the connections between the adjacent coils and to connect the binding posts of each
coil with a separate external circuit.
These binding posts being readily accessible, even when the machine is running,
the desired changes can be made without stopping the machine.
For inspection or repair the whole armature can be removed with ease, and
without entting of wires by simply withdrawing the bolts 20, 20 and 23, 23 and
"sliding each half of the armature frame outwardly the connections between the
adjacent binding posts of the coils next to the diameter faces of the two halves
having been first removed.
.
In the drawing I have shown twice the number of pole pieces in each set of
'field magnets; that there are armature coils, each coil extending over two successive
pole faces, when this construction is employed, the successive pole faces having
alternately south and north polarity. But I am not limited to this construction,
since I may use as many armature coils as there are pole faces in each set of
field magnets, in which case, however one radial branch only of each coil will at
any time he in inductive relation to the field magnets. When this construction is
'employed' the windings of the field magnets will be such as to produce the same
polarity in all pole faces of one set, and the opposite polarity in all pole faces of the
other set, while the shaft or the supporting frame would be the medium for completing
the magnetic circuit.
The two arrangements are diagrametrically illustrated in figures 8 and 9.
In figure 8 one set of pole faces, represented by shaded squares, is marked
successively NS, NS, &c. and the armature coils 24 are each shown as a single solid
linė and as bridging the space between two successive pole faces, and with each radial
branch 24¹ over one of these pole faces. This represents the arrangement shown in
detail in the other figures of the drawing which is used by preference.
The external circuit is indicated by dotted lines, showing also a converter the
primary coil of which is fed by the alternating current from the dynamo, while the
stationary coil of the converter is connected with a working circuit.
In figure 9 there are shown in one set of field magnets as many pole faces of
the same polarity as there are armature coils 24, the coils however in this instance
have only one of their radial branches 24' at the same time in inductive relation to
the field magnets for the latter are now spaced so far apart that a single coil cannot
bridge the space between two of them. The external circuit is here shown in the
same manner as in figure 8.
1. Some features of construction herein shown and described may be employed with
advantage in ordinary dynamos wherein the armature rotates between stationary field
magnets and hence I would have it understood that with reference to such features of
improvement as are applicable to both stationary and rotary armatures. I claim them
in 'either....
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
1. In a dynamo electric generator the combination of rotating field magnets and
a stationary armature made of non magnetic material substantially as set forth.
2. In a dynamo electric generator, consisting essentially of rotating field magnets
and a stationary armature, the generating portions of which are exposed to the
inductive action of the magnets, and the inactive and structural portions of which
are beyond in inductive sphere of the same substantially as described.
3. In a dynamo electric generator consisting essentially of annular series of rotating
field magnets, and an annular series of stationary armature coils, arranged with their

page_text: active portions within the field or fields of force and with their inactive portions outside
of said field or fields substantially as described.
4. In a dynamo electric generator the combination of annular series of rotating
field magnets, with an annular series of stationary armature coils mounted upon a non
magnetic support and wound upon insulating cores, said coils being arranged with
their active portions within the field or fields of force and with their inactive portions
outside of said field or fields substantially as set forth.
5. In a dynamo electric generator the combination of two annular series of rotating
field magnets forming an annular magnetic field of force or an annular series of
magnetic fields of force between the opposed pole faces of the magnets, with an
annular series of stationary segmental armature coils, wound upon non magnetic cores
and occupying with their radial branches the magnetic field while their inactive
portions are outside of said field substantially as described.
6. In a dynamo electric generator, the combination of two annular series of rotating
field magnets forming an annular magnetic field of force or an annular series of
magnetic fields of force between the opposed pole faces of the magnets with a stationary
annular armature support of non-magnetic metal, composed of detachable segments
and located in the plane of the magnetic field but beyond the inductive influence of
the same substantially as set forth.
7. In a dynamo electric generator the combination of two annular series of rotating
field magnets forming an annular magnetic field of force, or an annular series of
magnetic fields of force between the opposed faces of the magnets with a stationary
annular armature support of non magnetic metal composed of detachable segments
and located in the plane of the magnetic field but beyond the inductive influence of
the same and a series of segmental armature coils removably mounted in the annular
support with their radial periphal portions beyond the inductive sphere of the
magnets substantially as described.
8. In a dynamo electric machine the combination of a series of rotating field
magnets with a series of stationary armature coils mounted on a nonmagnetic support,
the conductor of the armature coils being disposed in a plane parallel to the plane of
rotation of the field magnets substantially as described.
9. In a dynamo electric machine, the combination of a series of rotating field
magnets with a series of stationary armature coils mounted on a non magnetic support,
the conductor of the armature coils being disposed in a plane parallel to the plane of
rotation of the field magnets, and the outer portion of the coils being faced with
insulating material substantially as set forth.
10. In a dynamo electric machine the combination of a series of rotating field
magnets with a series of stationary armature coils mounted on a support located outside
of the field of force substantially as set forth.
11. In a dynamo electric machine the combination of a series of rotating field
magnets with a series of stationary armature coils mounted on a non-magnetic support
located outside of the field of force substantially as set forth.
12. In a dynamo electric machine the combination of a series of rotating field
magnets with a stationary supporting frame encircling the field of force and armature
coils removable secured thereto substantially as set forth.
13. In a dynamo electric machine the combination with a series of rotating field
magnets of a series of stationary armature coils mounted on a non magnetic support,
the inner ends of said coils arranged to encircle, but out of contact with the shaft of
the field magnets substantially as set forth.
14. In a dynamo, electric machine an armature consisting in the combination with
a supporting frame of a series of radially detachable coils secured at their outer ends
to said frame substantially as set forth.
15. In a dynamo electric machine an armature comprising a supporting frame and
a series of armature coils connected together by interlocking plates, and secured at
their outer ends to said supporting frame substantially as set forth.
16. In a dynamo electric machine an armature comprising a supporting frame, a

page_text: series of armature coils provided with tongue and grooved plates for connecting
together the adjacent coils said coils being secured at their outer ends to the supporting
frame substantially as set forth.
17. In a dynamo electric machine the combination with a support, of a series of
radially disposed armature coils connected with said supports said armature coils
mounted on interlocking supports substantially as set forth.
18. In a dynamo electric machine an armature composed of a series of armature
coils each having a plate of insulating material secured to its side which plates are
furnished with interlocking tongues and grooves substantially as set forth.
19. In a dynamo electric machine the combination of rotating field magnets with a
stationary annular armature support of non magnetic metal surrounding the field of
force and provided with equally spaced slots and armature coils removable seated in
said slots and extending into the field of force substantially as described.
20. In a dynamo electric generator the combination of rotating field magnets with
a stationary annular armature support of non magnetic metal surrounding the field of
force and provided with equally spaced slots, armature coils clamped at their inactive
ends between non-magnetic plates seated in said slots and interlocking spacing plates
of insulating material between the coils substantially as set forth.
21. In a dynamo electric generator the combination of a field magnet carried by a
rotating shaft with an annular armature support of non magnetic metal concentric to
but not in contact with the shaft and composed of two semi-circular sections detach-
ably secured together upon the line of a diameter whereby the armature may be
removed from the machine without disturbing the shaft substantially as set forth.
22. In a dynamo electric generator the combination of field magnets carried by a
rotating shaft and a series of armature coils mounted on the two semi circular
detachable sections, of an annular support of non magnetic material, each semi-
circular section being movable upon guides at right angles to said shaft substantially
as described.
23. In a dynamo electric machine a stationary armature composed of a series of
segmental coils removable seated in an annular skeleton support of non magnetic metal
composed of flanged plates parallel to each other with bridge pieces extending between
them whereby the support is divided into a number of equally spaced seats for the
coils substantially as described.
24. In a dynamo electric machine the combination of parallel annular series of
rotating field magnets, with an armature composed of a series of segmental coils
removably seated in a stationary annular skeleton support of non-magnetic metal in
the plane of, but beyond the inductive influence of the magnetic field of force said
support consisting of flanged plates arranged parallel to each other with bridge pieces
extending between them whereby the support is divided into a number of equally
spaced seats for the coils substantially as set forth.
25. In a dynamo electric machine an armature provided with coils wound upon
cores composed of silicious or other equivalent material substantially as set forth.
26. In a dynamo electric machine an armature provided with coils wound upon
cores of insulating material said coils being provided with interlocking plates
composed of silicious or equivalent material substantially as set forth.
Dated the
day
bo 1000
HERBERT & Co.,
18, Buckingham Street, Strand, London, W.C., Agents to Applicant.