Improvements in Alternate Current Dynamo Electric Machines.
Year: 1889

page_text: Date of Application, 5th Jan, 1889
Complete Specification Left. 5th June, 1889-Accepted, 6th July, 1889
PROVISIONAL SPECIFICATION.
Improvements in Alternate Current Dynamo Electric Machines.
We JOHN DIXON GIBBS Esquire and EMILE FESQUET Engineer both of 18 War-
wick Street Regent Street in the County of Middlesex do hereby declare the nature
of this Invention to be as follows:-
The object of this Invention is to provide an alternate current dynamo, electric,
machine which is economical in first cost and simple in: construction and which has
very high efficiency.
Generally we believe that the most convenient arrangement of our Invention, will be
one in which the armature is stationary and in the form of an annulus within which,
the electro or field magnet rotates and we will describe the. Invention as so arranged
from which its general application, for example where the armature revolves and the
electro or field magnet is stationary, will also be understood.
The electro or field magnet consists of a coil wound on a mass of soft iron carried
by a spindle which is rotated and provided with means (such as brushes bearing upon
collars on the spindle) for conducting the current to the coil. At each. end of this,
core is formed or fixed a flange or collar having pole pieces which extend over the
coil parallel with the spindle to or nearly to the full width of the coil the pole pieces of
the flange or collar at one end of the coil being situated between the pole pieces of
the flange or collar at the other end of the coil with a clearance between them the
poles of opposite denominations thus alternating with each other around the coil. The
spaces between the pole pieces may be filled in with a non-magnetic or insulating
material to constitute a continuous outside surface. The armature is preferably built
up of thin sheets or plates of iron insulated from each other and with inward pro-
jections (corresponding in number to the pole pieces of the field magnet) on which are
wound the coils for the induced current or currents which coils are connected, up in
any desired manner according to the resulting induced current, or currents required
to be produced. The plates can be connected together and to a suitable frame by
insulated bolts.
COMPLETE SPECIFICATION.
Improvements in Alternate Current Dynamo Electric Machines.
We, JOHN DIXON GIBBS Esquire and EMILE FESQUET Engineer both of 18 Warwick
Street Regent Street in the County of Middlesex 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 :-
The object of this Invention is to provide an alternate current dynamo electric
machine which is economical in first cost and simple in construction and which has
a very high efficiency.
Generally we believe that the most convenient arrangement of our Invention will be
one in which the armature is stationary and in the form of an annulus within which
the electro or field magnet rotates and we will describe the Invention as so arranged
from which its general application for example where the, armature revolves and the
electro or field magnet is stationary, will also be understood.
According to this Invention there are provided an electro magnet or field magnte
with a single exciting coil wound on a central cylindrical mass of soft iron (or there

page_text: may be two central coils connected in series so as to form practically one single coil)
and projecting and alternating polar pieces arranged as hereinafter explained.
Figure 1 of the accompanying drawings is an end elevation partly in section and
Figure 2 is a vertical section of a dynamo in which the field magnet made according
to our Invention revolves inside the armature. Figures 3 and 4 illustrate the pro-
jecting polar pieces of the electro magnet.
The electro magnet or field magnet consists in this arrangement of a single exciting
bobbin a wound on a central cylindrical mass of soft iron b mounted on a spindle b².
At one end of this iron core is fixed in magnetic connection with it a flange S which
carries cast with it, projecting polar pieces S S (shewn separately in Figure 4) parallel
to the spindle and of a length equal or about equal to the width of the armature and
of an outside diameter slightly less than the inside diameter of the armature, so
as to give the necessary clearance and yet bring the magnetizing influence of the
central hobbin as near as practicable to the bobbins of the arinature. At the other end
of the iron core b is fixed in the same way a similar flange N. with projecting polar
pieces this being placed on the spindle so that its polar pieces lie parallel to and at an
equal distance between the poles or polar pieces projecting from the other flange on
the opposite side as shewn clearly in Figure 1
The flanges with their polar pieces, are made of soft cast iron or preferably of cast
Bessemer steel.
When an exciting current is sent through the central bobbin a a magnetic pole
say N. will be created at all the polar pieces connected by their flange to one end
of the iron. core and an S pole at all the polar pieces connected by their flange to
the other end of the iron core, so that each successive projecting pole or polar piece
will have a polarity different from the next N. S. N. S. and so on.
The armature is preferably built up of thin sheets g of charcoal iron stamped to
shape with short projections g³ inwards of a number equal to the number of projecting
poles or polar pieces of the electro magnet or field magnet, these iron sheets g being
magnetically insulated from one another by a layer of non-magnetic material such for
instance as tissue paper or other material. These plates in appropriate number are
put together and bolted on to suitable cast iron frames e the bolts f being sufficiently
insulated, and on the projections g² inside are wound the coils for the induced current,
which coils are connected together in the usual way, according to the voltage required
in the external circuit.
The plates for the armature can be stamped whole or they can be made up in
several segments care being taken to place the plates so that those of one layer over-
lap the joints of the plates of the adjacent layer or layers that is they "break bond"
as shown Figure 8.
For a large size machine the plates of the armature are preferably made up of a
number of independent segments having each two short inward projections (g).
These plates (see Figures 9 and 10) are put together and bolted by the bolts c to the
flanges & which flanges are preferably of gun metal and fit tightly between the cast
iron frames e of the machine and are held firmly by the screws f³ screwing into
bosses on the flanges d.
By this construction it is very easy to get at the coils of the armature when neces-
sary as by unscrewing the screws 12 any segment with its two coils can be removed
and a spare one be put on in its place.
Figure 5 is an end elevation. Figure 6 a section on the line C. D Figure 5, and
Figure 7 is a section on the line E F Figure 5 of a modification in the way of con-
structing the improved field magnet according to this Invention.
In this case the iron core is made of two pieces and in the centre between them is
a flange S with projecting poles or polar pieces of a double T shape. On the ends of
the core are mounted (one at each end) flanges with projecting polar pieces N. N. N.
the polar pieces S. S. and N. N. alternate with each other after the manner of those
shewn in Figures 1 and 2. On the core are mounted two exciting coils m connected
in such a way as to create a consequent or similar pole in the centre of the core, so
that when an exciting current is sent through the coils m a magnetic pole say S will

page_text: be created at all the projecting polar pieces in magnetic connection with the centre of
the core and an N pole at all the polar pieces connected with the ends of the iron
core, so that each successive projecting pole or polar piece will have a polarity
different from the next N. $. N. S. and so on. In place of the soft iron core being in
two pieces it may be in one piece and the part S may be slipped on over it instead of
over the spindle or shaft.
Having now particularly described and ascertained the nature of our said Inven-
tion and in what manner the same is to be performed we declare that what we
claim is
1. In or for an alternating current dynamo machine, an electro magnet or field
magnet composed of a central soft iron core with a single exciting coil wound round it
and with projecting polar pieces of alternate polarities arranged as described with
reference to Figures 1. 2. 3. and 4 of the accompanying drawings.
2. In or for an alternating current dynamo machine an electro magnet or field
magnet composed of a central soft iron core with exciting coils wound round it and
with projecting poles or polar pieces of alternate polarities arranged as described with
reference to Figures 5. 6 and 7 of the accompanying drawings.
3. The general arrangement and combination of parts constituting an alternating
current dynamo machine whether arranged as in Figures 1 to 4 or modified as
explained with reference to Figures 5 to 10.
Tinted thin 5th day of T1000