IMPROVE- MENTS IN DYNAMO-ELECTRIC MACHINES
Year: 1882

page_text: LETTERS PATENT to Charles Denton Abel of N° 28 Southampton Buildings
Chancery Lane in the County of Middlesex for an Invention of "IMPROVE-
MENTS IN DYNAMO-ELECTRIC MACHINES" Communicated to him from
abroad by Bruno Abdank-Abakanowicz and Cornelius Roosevelt, both of Paris
in the French Republic
PROVISIONAL SPECIFICATION left by the said Charles Denton Abel at the
Office of the Commissioners of Patents on the 24th November 1882.
"
CHARLES DENTON ABEL of N° 28 Southampton Buildings Chancery Lane in
the County of Middlesex "IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES
[Communicated to him from abroad by Bruno Abdank-Abakanowicz and
Cornelius Roosevelt, both of Paris in the French Republic]
This invention is based on the fact discovered by my said correspondents that
the most economical magnetic field is obtained by interrupting a circular electro-
magnet core at one point for a small distance so that the two poles remain opposite
each other. By this means the effect is rendered much greater than with other
forms of such cores. The best result is however found to be obtained when the
forms of the cores are not exactly circular but with the polar portions formed
straight for some distance. For producing the magnetic field of dynamo electric
machines according to this invention forms of electromagnets are employed such
as are shown at Figs. 1 to 5 of the accompanying drawings. By these forms
electromagnet cores E of considerable length and power can be made to occupy a
comparatively small space. This arrangement also allows the electro-inductors to
be grouped in batteries as indicated at Figa 4 and 5. In some cases the parts C
of the cores can be arranged to carry the shaft of the revolving armatures I as at
Figs 1 to 3. The winding of these cores E E does not present any difficulty, in
particular if the method of winding hereinafter described be employed. In some
cases the inductors are partly wound with ordinary wires and partly by copper
ribbons for partial excitation. In the magnetic field formed by these electromagnet
cores the induced armature I is made to revolve, this being arranged in any known
manner

page_text: For the winding wire is by preference employed metal of a flat section, which
offers great advantages, particularly if means are adopted for preventing the heating
which is produced by the currents formed in the interior of the wire. The wire is
made of laminated copper bands, cut into special forms appropriated to the method
of coiling used. The several coils are insulated from each other by interposed thin
sheets of insulating material. In the space formed by these bands is placed the
soft iron wire of the ring of the "Gramme" machine, such wire being shown by
the sectioning lines indicated at Figs. 6. 7, 8 and 10 of the drawings. Fig. 6
shews such a band shaped for simple continuous helical coiling. Fig. 7 shews a
band shaped for double coiling, in the form of a lemniscatoid. The induced ring or
cylinder wound in this manner can be placed between two contrary poles of the
electro-magnets as shewn at Fig. 8. In this figure is also shewn the arrangement
of the ventilating grooves a a and the slits b b for preventing currents, these being
formed in the width of the bands. These grooves and slits are formed at the
same time that the bands Fig. 7 are shaped.
In order to prevent useless resistances in the induced conductors the width of
the bands are varied according as may be required, as indicated at Fig. 10. In
special cases where the thickness or the form of the bobbins constructed in this
manner has to be changed, a sufficient pressure is employed for producing this result.
The arrangements described may be readily adapted for forming connections and
for constructing collectors. For the latter a special construction is adopted for
preventing sparks. It consists in causing the current passing to the collector to
follow two lines, the resistances of which vary gradually. One of these-resistances
is constant and is placed on a shunt while the other is formed by means of a
microphonic contact of the contact brush.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Denton Abel in the Great Seal Patent Office on the
23rd May 1883.
"
CHARLES DENTON ABEL of N° 28 Southampton Buildings, Chancery Lane in
the county of Middlesex "IMPROVEMENTS IN DYNAMO-ELECTRIC MACHINES
A communication to me from abroad by Bruno Abdank-Abakanowicz and Cornelius
Roosevelt both of Paris in the French Republic.
This invention is based on the fact discovered by my said correspondents that
the most economical magnetic field is obtained by interrupting a circular electro-
magnet core at one point for a small distance so that the two poles remain opposite
each other. By this means the effect is rendered much greater than with other
forms of such cores. The best result is however found to be obtained when the forms
of the cores are not exactly circular but with the polar portions formed straight for
some distance. For producing the magnetic field of dynamo-electric machines
according to this invention, forms of electro-magnets are employed such as are
shewn at figs 1 to 5 of the accompanying drawings. By these forms, electro-
magnet cores E of considerable length and power can be made to occupy a
comparatively small space. This arrangement also allows the electro-inductors to
be grouped in batteries, as indicated at figs 4 and 5. In some cases, the parts C of
the cores can be arranged to carry the shaft of the revolving armatures I, as at
figs. 1 to 3. The winding of these cores E E does not present any difficulty, in
particular if the method of winding hereinafter described be employed. In some
cases, the inductors are partly wound with ordinary wires and partly by copper
ribbons for partial excitation. In the magnetic field formed by these electromagnet
cores, the induced armature I is made to revolve, this being arranged in any known
manner.
For the winding wire, is, by preference, employed metal of a flat section, which
offers great advantages, particularly if means are adopted for preventing the heating
which is produced by the currents formed in the interior of the wire. The wire is
made of laminated copper bands, cut into special forms appropriated to the method
of coiling used. The several coils are insulated from each other by interposed
thin sheets of insulating material. In the space formed by these bands is placed
the soft iron wire of the ring of the "Gramme" machine, such wire being shewn
by the sectioning lines indicated at Figs 6, 7, 8 and 10 of the drawings. Fig 6
shews such a band shaped for simple continuous helical coiling, the band being
folded over at the dotted lines c c. Fig. 7 shews a band shaped for double coiling,
in the form of a lemniscatoid. The induced ring or cylinder wound in this manner
can be placed between two contrary poles of the electro-magnets as shewn at fig 8.
In this figure is also shewn the arrangement of the ventilating grooves a a and the
slits bb for preventing closed currents, these being formed in the width of the
bands. These grooves and slits are formed at the same time as the bands, fig. 7,
are shaped.
In order to prevent useless resistances in the induced conductors, the width of
the bands is varied according as may be required, as indicated at fig. 10. Fig. 9
shews the mode of insulating the separate coils from each other. Sheets of
insulating material pp, such as paper saturated with paraffin, are simply interposed
between the coils c. The insulation can be very thin, as there are no great
differences of potential between the adjacent parts. In special cases, where the
thickness or the form of the bobbins constructed in this manner has to be reduced
or changed, a sufficient pressure is employed for producing this result.

page_text: The arrangements described may be readily adapted for forming connections and
for constructing collectors or commutators. For the latter, a special construction is
adopted for preventing sparking. It consists in causing the current passing to the
collector to follow two lines as shewn at fig. 11.
One of these resistances is constant and is placed on a shunt a while the other is
formed by means of a microphonic contact of the contact brush at b.
Having thus described the nature of this invention, and in what manner the
same is to be performed, as communicated to me by my foreign correspondents, I
claim
First: The construction of electromagnet inductors as herein described and
shewn at figs 1 to 5 of the accompanying drawings
Second: The construction of flat or ribbon like conductors in zig-zag form for
coiling round the core by folding, substantially as herein described with reference
to figs 6 and 7 of the drawings.
Third: The herein described method of coiling with conducting bands of variable
section, for reducing the useless resistances to a minimum.
Fourth: The method of coiling in the form of a lemniscatoid as described with
reference to figs. 7, 8 and 10, whereby the armature or "gramme" ring can be
presented between magnetic fields of opposite sign.
Fifth The method of preventing closed currents and heating in the laminated
conductors by cutting or perforating, as described with reference to fig. 8 of the
drawings.
Sixth In combination with the constructions of laminated conductors referred
to in the preceding claims, the use of thin sheets of insulating material, interposed
between the separate coils as herein described with reference to fig. 9 of the
drawings.
Seventh: The arrangement of the conductors at the commutators herein
described with reference to fig. 11 of the drawings, for preventing sparking.
In Witness whereof, I the said Charles Denton Abel have hereunto set my
hand and seal this twenty second-day of May in the year of our Lord, one
thousand, eight hundred and eighty-three.
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