IMPROVEMENTS IN DYNAMO- ELECTRIC MACHINES
Year: 1883

page_text: LETTERS PATENT to Alexander Melville Clark of the firm of A. M and
W Clark of 53 Chancery Lane in the County of Middlesex Fellow of the
Institute of Patent Agents for an Invention of IMPROVEMENTS IN DYNAMO-
ELECTRIC MACHINES communicated to him from abroad by La Société Solignac
et Cie of Paris France
1
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 21st April 1883.
ALEXANDER MELVILLE CLARK of the firm of A. M and W. Clark of 53 Chancery
Lane in the County of Middlesex Fellow of the Institute of Patent Agents
"IMROVEMENTS IN DYNAMO-ELECTRIC MACHINES" [communicated to him from abroad
by La Société Solignac et Cie, of Paris France]
This Invention relates to a continuous current machine in which the induction
of the wire is utilized as in the Gramme machine and the induction by the iron as
in the Siemens machine baving an armature core of section, It is very difficult
in electrical machines to superpose the actions on the wire and on the iron and the
weaker induction is therefore sacrificed. In the Gramme machine there is both,
the induction of the wire which tends to determine two consequent magnetic
points on the diameter A B Figure 1 and the induction by the iron which is
polarised on the diameter C D passing through the poles E F of the field. From
these two effects which partially neutralize each other there result two consequent
poles situate on a diameter between the diameters A, B, C D. These two poles
determine the points of taking off the current and they oscillate between A and D,
and C and B according to the conditions of working of the machine. These
magnetic points remain fixed in space whilst it is the iron ring which moves, hence.
the changes of polarity in this ring are less powerful than in an open core.
On the other hand in the Siemens core of section the currents are produced
only by the change of polarity of the iron, and not by direct inductive action on
the wire, for in considering the action of a Siemens bobbin with enlarged pole
pieces for the field magnets, as in Figure 2, it will be seen that the wire shown in
section at a is traversed by a current in a certain direction, for example from the
driving pulley to the collector, and the wire shown in section at 6 is traversed by
a current in the same direction, they cannot therefore be joined for tension, and it
is just this grouping which a bobbin coiled in the ordinary manner upon the
.1

page_text: core A B would produce. These effects might be attenuated by making the pole
pieces of the bobbin and field equal, but in either case a collector analogous to
those of Paccinotti, Gramme, Siemens' (drum), Maxim, Edison, &c, would be
unsuitable for a machine of this kind, and as the bar collector is one of the most
suitable owing to its progressive commutation, it has been sought to produce a
machine combining at once the advantages of those having an open core, and those
having an annular core and in which such a collector can be employed.
These considerations have resulted in the system of bi-polar drum machine of
which several examples are represented in the drawing. AB Figure 3 are 'two
circular bobbins separated at C and D and which together form a ring open at
C and D; they are provided with cheeks at each of these points, and the whole
turns between two pole pieces E F. If the wire be wound as in the Gramme
machine in a continuous ring upon the cores. A and B, the effects both of the
Gramme ring and of the Siemens drum of section are produced.
Referring to Figure 4, suppose the bobbin A to be moving from 1 to 2, a current
will be produced by reason of the change of polarity of the iron core, and this
current will be in the same direction as that produced in the wire by direct
induction, a current will be also produced in bobbin B in consequence of the
change of polarity, and in consequence of the passage of the wire in front of the
pole F, these two currents produced in bobbin B are again superposed, and at C
and D we have the points at which the current is taken off, as in the Gramme
machine. The iron core while passing the centre of the cheeks E and F does not
sensibly change its magnetism and will not therefore affect the ring which thus
acts as a closed ring especially as the polarity of the iron core is situated as in the
Gramme ring on a diameter passing through the poles of the field; in this position
the place of the brushes thus remains as in the case of 1 to 2 between these two
latter points.
It will thus be seen that in this machine the place of the brushes is substantially
the same as for a closed ring, and a bar collector can be easily adapted thereto.
Figure 6 shows the best arrangement of the armature coils. A B are two
circular bobbins covered with wire upon one. fourth only of the total circumference
and at the central portion.
The machine is also provided with a bar collector.
This arrangement is intended only as an example the proportions of the various
parts being capable of variation such as the cheeks of the armature or of the field
magnets the width of the collector bars and their reciprocal importance &c.
The wire may also be wound upon the exterior of a core upon this system so as
to form a drum like that of Siemens, but having two poles situated on the
armature at the extremity of a same diameter. The distance between the
cheeks CD Figure 3 may be as little as is deemed necessary and they may even
be united if desired so as to have but a single pole. The machine may be used as
an alternating machine by collecting the current by means of simple rubbers
The right is reserved of grouping upon a single shaft a series of bobbins revolving
within field magnets excited by an independent service of electricity.
Figure 7 shows a collector in which the bars have the sectional form of the teeth
of a gear wheel. In this arrangement the brushes would be replaced by two
pinions A A in gear with the collector B and each tooth C being separated from:
the adjoining ones by suitable insulating material D would communicate with a
section of the ring.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Great Seal Patent Office on
the 20th October 1883.
ALEXANDER MELVILLE CLARK of the firm of A. M. and W. Clark of 53 Chancery
Lane in the County of Middlesex, Fellow of the Institute of Patent Agents
"IMPROVEMENTS IN DYNAMO-ELECTRIC MACHINES" A communication to me from
abroad by La Société Solignac et C of Paris, France.
This Invention relates to a continuous current machine in which the induction
of the wire is utilized as in the Gramme machine and the induction by the iron
core as in the Siemens machine having an armature core of H section. It is
very difficult in electrical machines to superpose the inductive actions on the wire
and on the iron core and the weaker induction is therefore sacrificed. In the
Gramme machine there is both the induction of the wire which tends to determine
two consequent magnetic points on the diameter A B, Figure 1 (see drawing) and
the induction. by the iron core which is polarized on the diameter C D passing
through the poles E F of the fields. From these two effects which partly neutralize
each other there result two consequent poles situate on a diameter between the
diameters A-B, C-D These two poles determine the points of taking off the
current and they oscillate between A D and CB according to the conditions of
working of the machine. These magnetic points remain fixed in space whilst it is.
the iron ring which moves, hence the changes of polarity in this ring are less
powerful than in an open core.
On the other hand in the Siemens core of Hsection the currents are produced
only by the change of polarity of the iron and not by direct inductive action on
the wire for in considering the action of a Siemens bobbin with enlarged pole pieces
for the field magnets as in Figure 2 it will be seen that the wire shown in section
at a is traversed by a current in a certain direction for example from the driving
pulley to the collector and the wire shown in section at 6 is traversed by a current
in the same direction; they cannot therefore be joined for tension which is just
the grouping which a bobbin coiled in the ordinary manner upon the core A B
would have. These effects might be attenuated by making the pole pieces of this.
bobbin and field equal but in either case a collector analogous to those of Paccinotté,
Gramme, Siemens' (drum) Maxim, Edison & would be unsuitable for a machine of
this kind and as the bar collector is one of the most suitable owing to its progressive
commutation, it has been sought to produce a machine combining at once the
advantages of those having an open core, and those having an annular core and in
which such a Collector can be employed.
These considerations have resulted in the system of bi-polar machine of this
Invention of which several examples are represented in the drawing. A B Figure 3
are two circular bobbins separated at C and D and which together form a ring
open at C and D; they are provided with cheeks at each of these points, and the
whole turns between two pole pieces E F.
If the wire be wound as in the Gramme machine in a continuous ring upon the
cores A and B, the effects both of the Gramme ring and of the Siemens drum of
section are produced.
Referring to Figure 4, suppose the bobbin A to be moving from 1 to 2, a current
will be produced by reason of the change of polarity of the iron core, and this
current will be in the same direction as that produced in the wire by direct
nduction, a current will also be produced in bobbin B in consequence of the
:

page_text: change of polarity, and in consequence of the passage of the wire in front of the
pole F, these two currents produced in bobbin B being also superposed and at C
and D we have the points at which the current is taken off, as in the Gramme
machine. The iron core while passing the centre of the pole pieces E and F does
not sensibly change its magnetism and will not therefore affect the ring which
thus acts as a closed ring especially as the polarity of the iron core is situated as
in the Gramme ring on a diameter passing through the poles of the field magnets;
in this position the place of the brushes thus remains as in the case of 1 to 2 between
these two latter points. It will thus be seen that in this machine the place of the
brushes is substantially the same as for a closed ring, and a bar collector can be
easily adapted thereto.
Figure 5 shows the best arrangement of the armature coils. A B are two circular
bobbins covered with wire upon one fourth only of the total circumference and at
the central portion. The machine is also provided with a bar collector. This
arrangement is intended only as an example; the proportions of the various parts
being capable of variation, such as the cheeks of the armature or of the field
magnets the width of the Collector bars and their reciprocal importance &°.
The wire may also be wound upon the exterior of a core upon this system so as
to form a drun like that of Siemens, but having two poles situated on the armature
at the extremity of a same diameter. The distance between the cheeks C D
Figure 3 may be as little as is deemed necessary and they may even be united if
desired so as to have but a single pole. The machine may be used as an alternating
machine by collecting the current by means of simple rubbers.
The right is reserved of grouping upon a single shaft a series of bobbins revolving
within field magnets excited by an independent source of electricity.
Figure 6 shows a Collector in which the bars have the sectional form of the
teeth of a gear wheel. In this arrangement the brushes would be replaced by two
pinions A. A in gear with the Collector B and each tooth C being separated from
the adjoining ones by suitable insulating material D would communicate with a
section of the ring.
Having described the nature of the said Invention and the manner of performing
the same I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is
A dynamo electric machine having a cylindrical armature constructed substantially
as herein described and shown in the drawings, with single or double enlargements
of the core at diametrically opposite points, as and for the purpose specified the
currents produced being either alternating or rectified by the means described.
In witness whereof I the said Alexander Melville Clark have hereunto set
my hand and seal this twentieth day of October A.D. 1883.
AM CLARK (L.S.)