Improvements in Dynamo Electric Machines and Electric Motors.
Year: 1898

page_text: Improvements in Dynamo Electric Machines and Electric Motors.
I, HENRY FRANCIS JOEL, Jun., of 55, Northbrook Road, Ilford, Essex Electrical
Engineer, do hereby declare the nature of this invention to be as follows:-
My improvements in dynamo electric machines and electric motors relate
especially to the construction and arrangement of the polar extensions and polar
faces of the electric magnetic fields, or alternatively of armature cores and polar
faces.
A simple form of my invention is constructed of laminated iron strips or plates.
I take an iron strip of a length of say 3 inches 4" thick and 1" wide and turn up
the ends at right angles, say inch on the back of this plate I place another
iron strip, say 4 inches in length, and also turn up this strip 3" so as to come level
at its ends with the first plate, and I add another plate say 51" long and turn up
its ends 1" and this then becomes level at its ends with the other two plates. I
wind the principal magnetic coil round the central space so as to embrace the
three strips, I then coil two smaller coils round the two first spaces adjoining the'
central coil, these two coils go between the turned up strips and embrace two
strips only, and I wind two other still smaller coils in the spaces left at the ends,
which coils embrace only one strip and I thus graduate the iron and the coils and
extend the polar surfaces at each end into three faces which are all designed to
become equal in magnetic intensity and give off equal lines, and thus give equal
magnetic distribution at the poles. I thus save both iron & wire and produce a
more equal effect. This construction replaces the usual construction of one coil
and an equal core, and also replaces and is better than a coil diminishing at the
ends or a core only diminishing at the ends, and is in fact a combination of the
diminishing coil and core.
By placing a number of these built up electro magnets spaced round a ring I
make a multiple pole machine, the diminishing ends of these electro magnets
being placed end to end with a small coil between them to form a neutral point.
I may replace the built up strip'cores with a solid core tapered off with slots and
the coils wound round same,--or with an iron wire core, or stampings or punched
laminated plates side to side, or a solid core with holes.
In a two pole dynamo electric machine I make slots or grooves across the ends
or faces of the polar extensions parallel with the axis so as to bifurcate those poles
and I wind wire coils of one or more turns in these slots to continue the magnetic
effect of the main magnetic field coils to within the actual magnetic field.
I find that by graduating the main magnetic coil with the smaller coils and
also by graduating the iron in proportion that in addition to the saving of iron
and wire and advantage of more even distribution of magnetism I avoid lead at

page_text: the brushes at varying loads and also sparking at the brushes and effect a saving
of coils of wire or back ampere turns to prevent the action of the demagnetizing
core of the armature usual in ordinary types of dynamos. I thus also reduce the
magnetic leakage to a minimum.
Dated this Twentieth day of June 1898.
Improvements in Dynamo Electric Machines and Electric Motors.
I, HENRY FRANCIS JOEL, Jnr., of 31, Wilson Street, Finsbury Square, London,
E.C., Electrical Engineer (late address, Henry Francis Joel, Junior, 55, North-
brook Road, Ilford, Essex), do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
My improvements in dynamo electric machines and electric motors apply.
especially to the construction and arrangement of the polar extensions and polar
faces of the electric magnetic fields or alternatively of armature cores and polar
faces.
In the drawings Fig. 1 is a side elevation and Fig. 2 a plan of my improved
electric magnet. Figs. 3 and 4 are diagrammatic drawings showing application
to dynamo electric machines and electric motors.
Figs.
and 2 show a simple form of my invention, constructed of laminated
iron strips or plates.
I take an iron strip I, of a length of say 3 inches, " thick, and 1" wide and
turn up the ends at right angles, as shown, say inch, on the back of this plate
I place another strip I say inches in length and also turn up this strip 2", so
as to come level at top ends with the first plate and I add another plate I say 5"
long and turn up its ends 1 inch and this then becomes level at its ends with the
other two plates. I wind the principal magnetic coil C, round the central
space so as to embrace the three strips. I then coil two smaller coils C¹ C¹ round
the first two spaces adjoining the central coil, these two coils go between the turned
up strips and embrace two strips only, and I wind two other still smaller coils C2 C2
in the spaces left at the ends, which coils embrace only one strip, and I thus
graduate the iron and the coils, and extend the polar surfaces N, N, and S, S, at
each end into three faces which are all designed to become equal in magnetic
intensity and give off equal lines and thus give equal magnetic distribution at
the poles. I thus save both iron and wire and produce a more equal effect. This
construction replaces the usual construction of one coil and an equal core, and
also replaces and is better than a coil diminishing at the ends or a core only
diminishing at the ends, and is in fact a combination of the diminishing coil
and core.
By placing a number of these built up electro magnets spaced round a ring,
Fig. 3, to form internal fields with an armature A, outside same, I make a multiple
pole machine with poles N, S, as shown, the diminishing ends of these electro mag-
nets being placed end to end. I may replace the built up strip cores with a solid
core tapered off with slots and the coils wound round same, or with an iron wire
core or stampings or punched laminated plates side to side as shown in Fig. 3, or
a solid core with holes.
In Fig. 4 I show another application with the opposite poles together, having a
small coil M, between them to form a neutral point. In either of these cases, I

page_text: may put the electro magnets outside, with the armature A, inside, and I may
use the same graduation of cores and coils to form a polar armature, in this case,
I should keep the armature fixed and revolve the fields."
I form a two pole dynamo electric machine in a similar manner with slots or
grooves across the ends or faces of the polar extensions parallel with the axis, so
as to bifurcate those poles, and I wind wire coils of one or more turns in the slots
to continue the magnetic effect of the main magnetic field coils to within the
actual magnetic field.
I find that by graduating the main magnetic coil with the smaller coils and
also by graduating the iron in proportion that in addition to the saving of iron
and wire & advantage of more even distribution of magnetism I avoid lead at the
brushes at varying loads & also sparking at the brushes, and effect a saving of
coils of wire or back ampere turns to prevent the action of the demagnetising
core of the armature usual in ordinary types of dynamos, I also thus reduce the
magnetic leakage to a minimum.
Having now particularly described & ascertained the nature of my said inven-
tion, & in what manner the same is to be performed, I declare that what I claim
is:-
(1) In electro magnets for dynamo electric machines and electric motors the
combination of graduated cores with graduated coils of wire to form extended
polar surfaces of equalized magnetic intensity with a saving of both core and
wire coils substantially as shown and described.
Dated this mantinth
1000