Improvements in Dynamo-electric machines and mectro-motors.
Year: 1886

page_text: Date of Application, 15th Nov., 1886.
Complete Left, 15th Aug., 1887.
Complete Accepted, 16th Sept., 1887.
Improvements in Dynamo-electric machines and mectro-motors.
I CHARLES LEVER of Bowdon in the County of Chester, Electrical Engineer do
hereby declare the nature of this invention to be as follows:-
My invention relates to improvements in dynamo-electric or electro-dynamic
machines which have armatures of the Paccinotti or polar type although it is also
applicable to other forms of machines having for their armatures a series of rings.
According to this invention I increase the surface of the iron of the armaturo
which revolves close to the poles of the field magnets so that the lines of force
passing through the armature will be increased. In machines of the Paccinotti type
where the armatures have teeth and where cast iron pole pieces are used I turn a
series of grooves (preferably equidistant from each other) after the pole pieces have
been bored out in the usual manner. These grooves are preferably of similar depth
and width with the corners at right angles. Instead of the teeth of the armature
being all alike I make some of the teeth project further than the others according to
the position and size of the grooves in the pole pieces. For example if there be six
equidistant grooves in the pole pieces and the armature be built up of sixty plates I
make the teeth of every alternato five plates project farther out than the remainder so
as to revolve inside the grooves of the pole pieces. These projecting teeth should in all
cases revolve freely inside said grooves, and in order to provide ventilation holes may
be drilled from the outside of the pole pieces into the grooves.
The armature may be wound either drum fashion or ring fashion and it will readily
be seen that when so wound it will not all be even and of one diameter but the teeth
which revolve in the grooves will project above the wire and the remaining teeth of
the armature. By this means an increased surface of the iron of the armature will
be brought in close proximity to the pole pieces.
When a polar armature is employed the projecting polar extensions revolve in the
grooves of the pole pieces in a similar manner to the projecting teeth of the Paccinotti
type of armature as also may a series of ring armatures when suitably mounted on
the spindle of the machine.

page_text: Instead of turning the grooves in the pole pieces they may be cast in same or the
pole pieces may be cast with slits in them and the projecting teeth or polar extensions
may revolve between these slits or ribs which must be finished up after casting. The
grooves may also be of a corrugated form with the armature teeth or polar extensions
to correspond, but I prefer to make the grooves or slits as described.
When, however, these slits or ribs are used I prefer to build up the field magnets of
a series of heavy wrought iron bars with bent ribs like the field magnets of a Siemens
machine and planed at the sides but having a much greater distance between cach rib.
The wrought iron bars are bolted to suitable iron yokes or cheeks having feet attached
thereto so that the machine may be firmly bolted to its hed. The iron bars may either
be wound separately or in the usual manner.
Of
If therefore thore be fourteen such bars mounted equidistantly seven on each side
of the yokes or cheeks and wound in the usual way to give consequent N and S poles
the six projecting teeth of the built up armature already described would revolve in
the slits or between the ribs of the field magnets and in close proximity thereto.
course it is not necessary to have either the projections of the armature-be it of the
Paccinotti or polar type-or the grooves or slits of the field magnet poles equidistant
but I prefer them to be so on account of simplicity of construction.
Dated this 12th day of November 1886

page_text: COMPLETE SPECIFICATION.
Improvements in Dynamo-electric Machines and Electro-motors.
I, CHARLES LEVER of Bowdon in the County of Chester 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 relates to improvements in dynamo electric or electro-dynamic
machines which have armatures of the Paccinotti or polar type, although it is also
applicable to other forms of machines having for their armatures a series of rings.
According to this invention I increase the surface of the iron of the arinature
which revolves close to the poles of the field magnets so that the lines of force passing
through the armature will be increased. In machines of the Paccinotti type where
the armatures have teeth and where cast iron pole pieces are used I turn a series of
grooves (preferably equidistant from each other) after the polo piecos have been bored
out in the usual manner.
Figure 1 of the accompanying drawings is an end view, figure 2 a vertical longi-
tudinal section and Figuro 3 another such section of a modified form of the armature
and pole pieces of a Paccinotti machine. A is the armature and B B the pole pieces,
with grooves. These grooves are preferably of similar depth and width, with the
corners at right angles. Instead of the teeth of the armature being all alike I mako
as shown in figure 1 some of the teeth project further than the others according to
the position and size of the grooves in the pole pieces. For example if there be six
cquidistant grooves in the pole pieces and the armature be built up of sixty plates I
make the teeth of every alternate five plates project farther out than the remainder so
as to revolve inside the grooves of the pole pieces. The figures in the drawing show
three grooves which I find to be sufficient for most purposes. These projecting teeth
should in all cases revolve freely inside said grooves, and in order to provide
ventilation holes may be drilled from the outside of the pole pieces into the grooves as
shown in figures 2 and 5. Figure 3 shows pole pieces without ventilating holes.
The arinature may be wound either drum fashion, or ring fashion as shown in
figure 1 and it will readily be seen that when so wound it will not all be even and of
one diameter but the teeth which revolve in the grooves will project above the wire
and the remaining shorter teeth of the armature. By this means an increased surface
of the iron of the armature A will be brought in close proximity to the pole pieces B.
When a polar armature is employed as shewn perspectively at figure 4 the pro-
jecting polar extensions C revolve in the grooves of the pole pieces in a similar
manner to the projecting teeth of the Paccinotti type of armature.
Instead of turning the grooves in the pole pieces they may be cast in same or the
polo pieces may be cast with slits in them as shown in the longitudinal sectional view
figure 5 and the projecting teeth or polar extensions may revolve between these slits
or ribs which must be finished up after casting. The grooves may also be of a

page_text: corrugated form such as shown in the longitudinal sectional view figure 6 with the
armature teeth or polar extensions to correspond, but I prefer to make the grooves or
slits as described as being easier to make and affording larger armature surface.
When however these slits or ribs are used I prefer as shown in the end view
figure 7 and figure 8 in longitudinal section to build up the field inagnets B of a
series of heavy wrought iron bars B with bent ribs or curved parts like the field
magnets of a Siemens machine and planed at the sides but having a much greater
distance between each two ribs as shown in figure 8. The wrought iron bars are
bolted to suitable iron yokes or cheeks D having feet attached thereto so that the
machine may be firmly bolted to its bed. The iron bars may either be wound
separately or in the usual manner.
If therefore there be fourteen such bars mounted equidistantly seven on each side
of the yokes or cheeks and wound in the usual way to give consequent N and S poles
the six projecting teeth of the built up armature already described would revolve in
the slits or between the ribs of the field magnets and in close proximity thereto.
Figure 8 shows field magnets consisting of 4 bars B on each side of the armature and
three spaces in which the long teeth of the armature revolve.
It will be noticed that the armature laminations or plates having long teeth are not
as in previous figures of an equal number with the plates having shorter teeth, but
the former are in this case fewer in number than the latter.
Of course it is not necessary to have either the projections of the armature-be it
of the Paccinotti or polar type-or the grooves or slits of the field magnet poles
equidistant but I prefer them to be so on account of simplicity of construction.
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:-
First. In dynamo-electric or electro-dynamic machines the application of pole
pieces having annular grooves or corrugations in their inner surfaces in combination
with armatures formed or coiled correspondingly to rotate in the said pole pieces
substantially as set forth.
Second. In a dynamo-electric or electro-dynamic machine an armature formed with
teeth or projections of different lengths in the radial direction, in combination with
pole pieces having grooves of correspondingly different depths wherein the said teeth
revolve substantially as, and for the purpose, set forth.
Third. The construction of armatures and pole pieces described with reference to
the drawings.
Do thin 15th 11007