Improvements in Dynamo-electric Machines.
Year: 1890

page_text: Date of Application, 17th Nov., 1890-Accepted, 3rd Jan., 1891
COMPLETE SPECIFICATION.
Improvements in Dynamo-electric Machines.
I RANKIN KENNEDY Electrician, 10 India Street Kilmarnock N.B. 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 :-
This invention relates to improvements in Dynamo Electric Machines for producing
alternating electric currents whereby the field electro magnets of said machines are
energised by electric currents from a magneto machine without the use of a rectifying
commutator in the exciting circuit.
According to my invention such currents are produced without the use or inter-
vention of any commutators or sliding contacts between the exciter and the field
magnet circuits and also without the uso or intervention of any commutator or sliding
contacts between the generating circuits of the dynamo electric machine and the
external circuits, 1 effect my object by combining a magneto-electric generator with a
dynamo electric generator, the magneto-electric generator has permanent steel field
magnets and its armature is of drum, ring or disc form as used in Gramme, Siemens,
or Schucket dynamos and wound with coils in sections not connected together.
The dynamo electric generator has field magnets of soft iron built up of stampings
these field magnets are wound with exciting coils of wire and there are as many
such exciting coils on the field magnet of the dynamo electric generator as there
are of coil sections on the armature of the magneto electric generator and the
magnet of the dynamo electric generator is mounted on the same shaft as and
revolves together with the armature of the magneto electric generator and each coil
of the dynamo field magnet is connected to a corresponding section of the armature
coils of the magneto electric generator, the magneto electric generator supplies the
exciting currents to the field magnet coils of the dynamo in this way without a
commutator, the terminals of the coils and sections being directly joined together.
This exciting current reverses twice in each revolution on the neutral diameter as
is well known in ring drum and disc armatures, but during each half revolution
these currents are in one direction, hence the excitement of the field magnet poles
on the dynamo is steady and in one direction during each half revolution a reversal
in direction occurring only at two points in the revolution that is on the neutral
diameter of the magneto generator.
The armature of the dynamo electric generator is fixed and is wound with coils in
the usual manner connected together in groups or in series to obtain the desired
pressures and currents and being connected to fixed terminals require no commutator
of any kind.
I therefore effect my object by combining a magneto having a fixed permanent
field magnet and an armature wound in sections with an alternating current dyunmo
electric generator having a fixed armature and a revolving field magnet the sections
of the magneto armature coils being connected to the coils on the dynamo field magnet
for the purpose of exciting said field magnet.
In order to enable others skilled in the art to which my invention relates to under-
stand and put my improvements into practice I have appended hereunto an explanatory
sheet of drawings.
Fig. 1 is an elevation of the polar und of the magneto embracing the armature
of the magneto, and sections shown on the armature, which is shown as a ring
armature.
Fig. 2 is a side elevation showing the combination of the two machines, and
Fig. 3 shows the combination in ond view with the connection between the field
magnet coils and the magneto armature sections, also the polarities of the field poles.

page_text: Fig. is a face and edge view of the iron stampings out of which the neid magnet
is built.
Referring to Fig. 1 S. N. is the permanent field magnet built of steel plates and
securely fixed by binding bolts.
A is the magneto armature wound with coils in twelve sections C. C.
R. K. is the neutral line diameter each coil as it passes this line in its revolution
reverses the direction of its induced current.
Fig. 2.shows the magneto magnet N on one side the magneto armature A and the
yoke piece Y joining the two limbs of the permanent magnet, this yoke piece Y also
forms the bearing of the one end of the shaft.
A is the armature of the dynamo electric generator with coils A' wound on it
as a Gramme ring armature there are twelve coils shown but twenty four may be
wound on this armature in which case alternate coils would have currents in the
same phase generated in them while those between them would have their currents
a quarter of a period different in phase there being twelve poles on the field magnet,
the coils over the poles at any moment would have their currents at a maximum
while those coils between them would be at zero.
The field mugnet coils are connected each to a section of the magneto armature
winding by connecting wires H H, the field magnet is enclosed by the fixed
armature A and is keyed on to the shaft with the magneto armature which is
also keyed on to shaft b, the circular frame D binds the armature of the dynamo A
in place. The stoel field magnets N. S. are of plates laid together to form semi-
circular poles embracing the armature a at one end and being joined magnetically
by an iron yoke of circular shape to fit the circle of the steel plates, these plates
are bound by iron bolts g. 9 and plates hh with wood packing pieces M. M.
Figs. 1 and 2.
Other forms of steel magnets may be used for the field of the magneto the
essential feature being the wide embracing polar surfaces, embracing both halves of
the armature, in the well known mannor common in dynamos with Gramme or
Siemens armatures, for this purpose cast iron or wrot iron pole pieces fitted to steel
magnets may be used.
The arrangement of the parts are shown in elevation in Figure 3, the fixed dynamo
armature A with twelve generating coils A¹ is bound into the frame D. The field
magnet F with twelve radial poles N S moves freely inside; the exciting coils B are
each connected to a section on the magneto armature a by connecting wires H H, to
form the field magnet poles S N S N all round, the reversal of the exciting currents
on the line R. K. produces alternately two S poles and two N poles, one on each side
of this line, but the poles are maintained of the same polarity during their rotation
from R to K and from K to R that is during a half revolution, so that they act
inductively on the fixed coils A¹ and produce alternating currents therein, these coils
are shown connected into two groups having terminals to and V. T. but they can be
connected up in any of the woll known combinations familiar to electricians.
The arrows show the direction of the rotation, of the field magnet and armature.
The field magnet of the dynamo electric generator is built up of thin iron stampings
shown in Figure 4 having radial projections to form the poles of a multipolar
magnet.
"On driving the shaft carrying the field magnet of the dynamo and the armature of
the magneto the currents generated in the sections of the magneto excite the field
coils connected to them, producing poles on the field magnet, these poles induce
currents in the fixed armaturo coils in consequence of their motion past the said coils
in sweeping from one neutral point to the other, these currents are taken directly
from the coils as alternating currents to be used externally in any translating devices.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1st. Exciting the field magnets of an alternating current dynamo electric generator

page_text: by the current from the sections of the winding on the armature of a magneto
electric machine, the said field magnet and armature being fixed on the same shaft
and revolving together, the sections of the armature being connected to the coils
on the field magnet for the purpose of energising the said coils without a com-
mutator or other rectifying apparatus as and for the purpose substantially as herein
set forth and shown in accompanying sheet of drawings.
2nd. The combination of an armature wound in sections revolving in the field
of magnetism produced by permanent magnets, with a multipolar field magnet both
on the same shaft the sections of the armature winding being directly connected
to the coils on the field magnet as and for the purpose herein set forth.
3rd. The combination of a magneto electric generator and a multipolar field magnet
excited by said generator as herein described, with a fixed armature having coils in
which the motion of said multipolar field magnet induces alternating currents as and
for the purpose substantially as herein described.
Dated this 15th day of November 1890.
RANKIN KENNEDY.