Improvements in Dynamo Electric Machines.
Year: 1892

page_text: Date of Application, 7th Apr., 1892
Complete Specification Left, 7th Jan., 1893-Accepted, 18th Feb., 1893
PROVISIONAL SPECIFICATION
Improvements in Dynamo Electric Machines.
I, JOHN AUGUSTINE KINGDON of 29 Marlborough Hill, St. John's Wood, in
the County of London, Electrical Engineer, do hereby declare the nature of this
invention to be as follows:-
My invention has for its object improvements in dynamo electric machines for
generating alternating currents of electricity and consists in improvements partly in
field magnets and partly in armatures.
According to my invention I employ for the field magnets a very efficient type
of electromagnet suggested by Holmes in 1868, and consisting of a single exciting
coil of conducting wire surrounding an iron core from the two ends of which spring
a number of polar projections
In his electromagnetic machine described in Patent No. 2060, of 1868 Holmes
employs two of these electromagnets having four systems of poles which act
inductively on the two sides of a ring of armature bobbins. Holmes mounts his
magnets on the shaft, so that the order of the magnetic poles of the exciting coils is
say north, south, north, south, and so that systems of unlike poles say south and
north are near each other in the centre of the machine.
The result is that nearly all the lines of magnetic force, instead of passing from
the inner system of poles on one side of the armatures through the iron cores of
alternate helices to the inner system of poles on the other side of the armatures
pass along the shaft or leak across the air space between the two central systems of
poles and so produce no useful effect in one half of the armature coils.
According to my present invention I may employ two of the Holmes type of
magnets fixed on a shaft so that the two central systems of poles have a like,
instead of an unlike polarity, and extend radially alternately on either side of the
armature. The order of the poles of the exciting coils is say north, south, south,
north or, south, north, north, south. The two outside systems of poles, which are
of the opposite polarity to that of the central systems spring out radially and may
then turn at right angles towards each other and the armature. Or they may be
suitably curved round the exciting coils. The outside and inside poles approach
the armature alternately on both sides of it. Outside poles, according to my
invention are faced by inside poles on the other side of the armature and vice versa,
whereas in Holmes machine outside poles faced outside poles and inside poles
faced inside poles.
In the space between the two sets of poles, so as to be acted upon by them
1 place my armature which may be of any known type suitable, or may be of my
improved construction.
My improved armature has it core constructed of lengths of thin soft, iron tape,
varnished or separated by paper, and coiled round a hub or other convenient
support, which may be afterwards removed. Holes may pass radially through the
laminated ring of iron thus formed through which pass bolts for securing the core
to any convenient castings or supports outside or inside. I prefer to insulate the
bolts and I may employ tubes screwed at either end instead of solid bolts so as to
allow circulation of air through the armature.
On the faces of the core I may place thin flat coils of insulated copper wire or
tape suitably secured and corresponding in number and shape to the magnet poles.
The coils on one face may be connected as convenient so as to form one generating
system and may be used quite independently of the coils on the other face which
may be connected in a similar manner to form a second generating system. I thus

page_text: obtain certain of the advantages of having two alternating current dynamos always
running in absolute synchronism without the expense of building two separate
machines and coupling their shafts together.
By fixing the bobbins on one side of the armature in advance of those on the
other side of the armature I obtain currents differing in phase as desired.
I may
also connect the two systems on the two sides of the armature to form one
dynamo.
The armature cores may be smooth or may have slots cut radially on their
faces to allow the coils of wire to be inserted. The iron cores may be omitted
altogether. The poles of the fields may be grooved to prevent Foucault currents
or laminated poles may be used. The fields and poles may be constructed in any
suitable manner of wrought or cast iron or of a number of wrought iron bars
suitably shaped and secured to a central hub or core. Or the bars may be wrought
iron cast into a central hub of cast iron. Pole pieces of suitable shape may be
fixed to or cast on these bars. The fields and armature may be divided in any
convenient manner so as to allow the machine to be easily taken apart for
inspection, cleaning or repairs.
The armature coils may be secured by bolts or screws to the core or its supports
or to insulators fixed thereon. Plates or lugs may be brazed or fastened to the
copper of the coils, and secured by screws or otherwise to the frame in any con-
Mica or ebonite or other insulator may be placed between the
core and the coils. The centres of the coils may be filled up with wood, slate or
other material.
venient manner.
The armature may be rotated and the fields fixed, or both may rotate. Rubbing
contacts are provided to supply exciting current from any convenient source to the
rotating field coils.
The field magnet cores may have air passages formed in them to allow air to
pass through past the exciting coils or the armature coils or through the hollow
bolts of the armature, to keep the machine cool.
Instead of fixing my armature coils on the faces of the core I may wind them
through holes or slots cut radially in the core into or very near the faces. Or
I may build up my armature of a number of coils wound on cores composed of a
number of thin soft iron plates of the shape of the letter I and bolted together and
to the supports. The armature then presents an almost unbroken surface of iron to
the field poles, which may be placed very close to it.
The number of coils may be equal to half the number of magnet poles. Or
I may use Holmes arrangements of field magnets omitting the two central sets of
useless poles, & making the number of armature coils equal to the number of poles.
Another modification of my improved dynamo consists of field magnets mounted
on a shaft and having two sets of poles with their faces in planes at right angles to
the shaft and rotating between two armatures.
The magnets may be constructed of an inner iron cylinder fixed on the shaft and
coaxial with it and having poles projecting parallel to the axis towards the two
armatures and then bent so as to project radially outwards. An iron web
may be cast midway between the poles, and on either side of this exciting coils
may be wound or the web may be omitted and one exciting coil only used.
Outside the exciting coils may be fixed by bolts to the web or otherwise a second
iron cylinder divided as convenient with poles projecting axially and radially
inwards.
Instead of a complete cylinder iron bars having their ends bent inwards may be
bolted outside the exciting coils. Non magnetic bolts or fastenings may be used.
The outside poles are equal in number to and intermediate in position between the
inside poles.
The armatures may be fixed one at each end of the field magnets and may have
cores wound with iron tape & with coils fixed on the face near the fields.
The armatures may be securely fastened together by rods or bars outside the
fields, so as to take the magnetic pull.

page_text: The armatures may be cophasal and connected as one machine or used as two
independent machines or they may have different phases.
Dated this 7th day of April 1892.
J. A. KINGDON.
COMPLETE SPECIFICATION.
Improvements in Dynamo Electric Machines.
I, JOHN AUGUSTINE KINGDON, of 29 Marlborough Hill, St. John's Wood, in
the County of London, Electrical Engineer, 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 for its object improvements in dynamo electric machines for
generating alternating currents of electricity and consists in improvements partly in
field magnets and partly in armatures.
According to my invention I employ for the field magnets a very efficient type of
electromagnet suggested by Holmes in 1868, Patent No. 2060 of that year and
consisting of a single exciting coil of conducting wire surrounding an iron core from
the two ends of which spring a number of polar projections.
In his electromagnetic machine described in Patent Specification No. 2060 of 1868
Holmes employs two of these electromagnets having four systems of poles which act
inductively on the two sides of a ring of armature bobbins. Holmes mounts his
magnets on the shafts so that the order of the magnetic poles of the exciting coils
is north, south, north, south, with unlike poles at the extremities of the systems and
inside poles face inside poles and outside poles face outside poles.
In Figure 1 is illustrated a cross section of Holmes arrangement where C, C,
are the exciting coils, N, S, the poles produced by C and N, S₂, the poles produced
by C,, A, A, are armature coils or helices acted upon by the systems of poles N., S,
which are shown in section springing from the centre of the magnets. It is obvious
that to produce any effect the polarity of N2, must be unlike that of S.
The result is that nearly all the lines of magnetic force instead of passing through
from the inner system of poles N2, N2, on one side of the armature coils A through
the iron cores of alternate coils to the inner system of poles S, S, on the other side
of the armature coils A, pass along the shaft in the direction of the arrows without
producing any useful effect in the armature coils A, A.
According to my present invention I may employ two magnets of the Holmes
type fixed on a shaft so that the poles of the inner systems are faced by poles of the
outside systems on the opposite side of the armature and the order of the poles pro-
duced by the exciting coils are north, south, south, north or south, north, north,
south. The two outside poles are of the same sign instead of opposite signs as in
Holmes machine, and there is a consequent pole in the centre of the systems so that
the two inner systems of poles have the same polarity.
In Figures 2 and 3 which are an end view and a cross section of my improved
form of field magnets like letters refer to the same parts.
A and Fare two cast steel or iron bosses bored out to fit the shaft K on which
they are keyed. Any convenient number of arins D spring radially from the outer
ends of the bosses and curve round towards each other forming the poles N, N, N. N,
and N₁, N1, N1, N₁. B and E are a second pair of bosses keyed on the shaft in
between A and D, and having a similar number of straight arms or poles S, S, S, S,
and S,, S₁, S₁, S₁. The bosses are keyed on the shaft K in such a manner that the
poles N, N, N, N, springing from the outside boss A are faced by the poles S₁, S₁,
S, S₁, springing from the inside boss E, and the poles N₁, N1, N1, N1, springing
from the outside boss F are faced by the poles S, S, S, S, springing from the inside
boss B.
C and C₁, are the two coils of conducting wire. The inner ends of C and C₁, are

page_text: connected together and their outer ends are connected respectively to the two
contact rings Q and R carried on the shaft K.
Brushes are fixed as convenient making rubbing contact with Q and R and
convey current from an exciting dynamo through the coils C and C₁. This current
magnetises the bosses and poles so that the poles S, S, S, S, and S₁, S₁, S₁, S₁,
springing from the centre between the coils are of one sign and the poles N, N,
N, N, and N₁, N₁, N₁, N₁, springing from outside the bosses and curving round
towards the armature coils are of the opposite sign.
The shaft K with the magnets coils and contact rings is supported in suitable
bearings so as to rotate.
The armature I may be of any known suitable form fixed to the bed of the
dynamo or may be of my improved construction.
My improved armature has its core constructed of lengths of soft iron tape wound
into a coil I in Figure 4. Holes may pass radially through the laminated ring
thus formed through which pass bolts K securing the core to any convenient
castings or supports.
I prefer to insulate the bolts and I may employ tubes screwed at either end and
fitted with nuts so as to allow circulation of air through the armature_core.
On the faces of the armature core bolt or otherwise secure coils L of insulated
copper strip or wire and corresponding in number and shape to the magnet poles.
The coils on one face may be connected as convenient so as to form one generating
system, and may be quite independent of the coils on the other face which may be
connected in a similar manner to form a second generating system, or all the coils
may be connected as one system.
Having now particularly described and ascertained the nature of my said inven-
declare that what I
tion and in what manner the same is to be performed,
claim is :-
1. Constructing the rotating fields of a dynamo of four systems of magnet poles,
two systems having curved arms or polar extensions and the other two systems
having straight or approximately straight arms or polar extensions.
2. In a dynamo having rotating fields as hereinbefore described keying or fixing
the magnets on the shaft so that straight arms and curved arms on one side of
the armature are faced by curved arms and straight arms respectively on the other
side of the armature.
3. A dynamo having four systems of poles and two exciting coils so connected
that the central systems of magnet poles have polarity of one sign and the outside
systems of magnet poles have the opposite polarity.
4. The combination in a dynamo of a fixed armature with rotating fields excited
by two magnetising coils connected so as to produce consequent poles in the centre
of the exciting coils.
5. My improved dynamo electric machine substantially as herein before described
and illustrated in Figures 23 and 4 of the accompanying drawings.
Dated this 7th day of January 1893.
J. A. KINGDON.