IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES
Year: 1884

page_text: I, SYDNEY PITT of Sutton in the County of Surrey, Gentleman do hereby declare
the nature of my invention for "IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES,"
a communication to me from abroad by Charles de Nottbeck of St Petersburgh
in the Empire of Russia to be as follows:-
The collectors at present employed in continuous current dynamo electric
machines have the serious defect of heating rapidly and of producing irregularities
which affect the continuity and the regularity of the light, besides their construction
is costly and it is difficult and expensive to repair them otherwise than in special
workshops.
My invention is intended to remedy this. The annexed drawings will be
sufficient to explain the proposed modifications.
Figure 1 is a partial front view of the disc of the collector seen from the
exterior on the side opposite to the armature.
Figure 2 is a lateral partial elevation of this disc.
Figure 3 is a vertical section of one of the plates full size.
My collector is composed of a disc A of hard wood or other strong non-conducting
material of a diameter about double the ordinary collector, it is mounted and driven
in the same way. This disc is divided vertically into two parts separated the one
from the other by a space about five or six millimetres; this space may remain
empty but it is preferable to fill it with insulating material-for example, hard
wood varnished.
On the periphery of this divided dise there aro arranged 74 plates B, such as are
usually attached to the collector of a dynamo suitable to supply sixty lamps of
sixteen candle power; it is to such a machine that the drawings apply. These
plates are arranged 37 upon each portion of the disc, and they are arranged so as
to alternate, the plate on one part faces the interval between the plates on the
other part so that the brushes which rub against the periphery of the disc never
cease to be in metallic contact and so all disconnection is avoided.
The increase in the size of the disc has also the advantage of increasing
considerably the speed of rotation of the plates which allows the pressure of the

page_text: brushes which are arranged tangentially to be diminished. Finally, the strong
current of air occasioned by this rapid rotation maintains the brushes and the
plates, as well as the armature of the machine in a comparatively cool state. To
increase this effect I make the ends of the plates to project as is seen at C in
Figure 3. These projections (which serve also to connect the plates to the wires D
which lead the current to them) cause a circulation of the air which has a great
effect in keeping down the temperature.
The arin of the lever, which presents the brush to the collector, is prolonged and
jointed to allow the position of the brush upon the periphery of the disc to be
regulated at will.
The conducting wires are soldered or attached in any other suitable manner
underneath the projection C of each plate B. To reach the exterior surface of the
disc these wires pass through holes pierced horizontally through the entire thickness
of the disc, whilst the wires intended for the plates on the portion of the disc
which faces the armature of the machine pass directly to the projection of these
plates as is seen in Figure 2.
:
It should be observed that the plates are retained upon the periphery of the disc
by a simple screw as is seen in Figure 3 and taper pieces of wood are filled in
between them rendering the whole arrangement solid on the periphery of the disc.
In machines originally constructed with this collector I prefer to give to the
collector the same diameter as the armature, so that the collector and the armature
together form one cylindrical body, the wires passing in a straight line avoiding
angles. This simplifies also the construction and facilitates the working of the
dynamo.
In large dynamos it is convenient to space the two parts of the disc vertically
with an interval of two or three centimetres and to arrange in this space ventilating
blades suitably arranged to cause a strong current of air from the centre to the
periphery; the air being led in through holes formed in the body of the disc near
the axis. Thus coolness of the parts is ensured.
In these machines it is convenient to put two brushes in place of one on cach
side of the dynamo and also to support each plate by means of a screw countersunk
into the metal and attaching it to the periphery.
These arrangements have for their effect to prevent risk of heating and sparks
which renders the construction, the repair and the working of these machines more
economical and safo.
Dated 10L
1007

page_text: I SYDNEY PITT of Sutton in the County of Surrey Gentleman do hereby declare
the nature of my invention for "IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES"
a communication to me from abroad by Charles de Nottbeck of St Petersburg in
the Empire of Russia and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement:-
The collectors at present employed in continuous current dynamo electric
machines have a serious defect; of heating rapidly and producing irregularities
which affect the continuity and the regularity of the light; besides their
construction is costly and it is difficult and expensive to repair them otherwise
than in special workshops.
My invention is intended to remedy this. The annexed drawings will be sufficient
to explain the proposed modifications.
Figure 1 is a partial front view of the disc of the collector seen from the
exterior on the side opposite the armature.
Figure 2 is a lateral partial elevation of this disc.
Figure 3 is a vertical section of one of the plates full size.
My collector is composed of a disc A. of hard wood or other strong non conducting
material of a diameter about double the ordinary collector, it is mounted and
driven in the same way. This disc is divided vertically into two parts separated
the one from the other by a space about five or six millimetres; this space may
remain empty but it is preferable to fill it with insulating material-for example
hard wood varnished.
On the periphery of this divided disc there are arranged 74 plates B such as are
usually attached to the collector of a dynamo suitable to supply sixty lamps of
sixteen candle power; it is to such a machine that the drawings apply. These
plates are arranged 37 upon each portion of the disc and they are arranged so as
to alternate; the plate on one part faces the interval between the plate on the other
part so that the brushes which rub against the periphery of the disc never cease to
be in metallic contact and so all disconnection is avoided. The increase in the size
of the disc has also the advantage of increasing considerably the speed of rotation
of the plates which allows the pressure of the brushes which are arranged tangentially
to be diminished. Finally the strong current of air occasioned by this rapid
rotation maintains the brushes and the plates as well as the armature of the machine
in a comparatively cool state. To increase this effect I make the ends of the plates
to project as is seen at C in Figure 3. These projections (which serve also to
connect the plates to the wires D which lead the current to them) cause a circulation
of the air which has a great effect in keeping down the temperature.
The arm of the lever which presents the brush to the collector is prolonged and
jointed to allow the position of the brush upon the periphery of the disc to be
regulated at will.
The conducting wires are soldered or attached in any other suitable manner
underneath the projection C of each plate B. To reach the exterior surface of the:
dise these wires pass through holes pierced horizontally through the entire thickness

page_text: of the disc, whilst the wires intended for the plates on the portion of the disc which
faces the armature of the machine pass directly to the projection of these plates
as is seen in Figure 2.
It should be observed that the plates are retained upon the periphery of the disc
by an inwardly extending projection a³, and a simple screw as is seen in Figure 3
at a and taper pieces of wood a are filled in between them rendering the whole
arrangement solid on the periphery of the disc. The wing as which extends
inward furnishes the means by which the plate is fastened to the wood or other
body and by which the wires connecting with the armature are fastened, preferably
by solder although any other method of fastening may be employed.
The plates of each series are arranged upon the circumference of the body A in
a manner to provide comparatively wide spaces between them. These spaces are
filled or packed with cross pieces of wood or other insulating material a, which
are fastened to the wood or other insulating body A by screws or by glue or in any
other desirable way, and the two series of plates are separated from each other by
the curved strips a7 of wood or other material, also held to the body of the roll by
glueing or in any other desirable way.
I nin enabled to use this cheap and effective insulation because the spaces between
the plates (owing to the enlargement of the diameter of the collector as well as to
the fact that a less number of plates on each side is used) are wide enough to enable
it to be successfully employed.
The wires which connect with the outer series of collector plates pass through
holes a formed in the wood or other body A. The brushes are arranged to be
brought into simultaneous contact with a plate of each series.
It will be observed that by making the collector for a given sized dynamo of
larger diameter than that now used for each machine, that in addition to the
advantages which arise from the cheaper construction and improved action of the
machine, the collector as well as the armature is kept cool by the rapid circulation
of air about them, created by the revolution of the collector itself. In other words
the collector acts as a sort of centrifugal blower, and the side projections of the
collector plates to a certain extent act as wings or fans in producing this blowing
action or rapid circulation.
Figure 4 is an end elevation partly in section and Figure 5 is a transverse section
of an arrangement in which the forms of the parts are somewhat modified.
The collector body is shown as made in two sections A A' one of which the
section A is a frustrum of a cone which fits into the section A¹ and the two parts
aro fastened together by the metal ring plate d². The section A¹ has an undercut
circumferential recess d³ which receives the fastening arms of the collector plates
which are half dove-tail as shown and the plates are locked to the body by
wedges d' of wood which also act as insulators. The wires are fastened to tho
plates by clamping screws instead of by solder.
It will be seen that the armature is thus as in the previous case connected in a
straight line with the corresponding collector plates and that by this arrangement
change in the direction of the electric current is avoided thus doing away with the
counter currents which are ordinarily produced in the part of the connecting wires
which are still under the influence of the magnetic field.
It will also be seen that by using a large collector with plates isolated by
non conducting material the shaft and its bearings cannot be heated by any
conduction of heat from the collector.
In large dynamos it is convenient to space the two parts of the disc vertically
with an interval of two or three centimetres and to arrange in this space ventilating
blades suitably arranged to cause a strong current of air from the centre to the
periphery; the air being led in through holes formed in the body of the disc nearer
the axis. Thus coolness of the parts is insured.
•
In Figure 6 I have represented this modified form of collector by which a rapid
eirculation of air is obtained. The two series of collector plates are therein shown
as separated by a recess c across which are arranged radial plates c' and small

page_text: holes c provide passages from the sides of the body A to said recesses. Upon the
rapid revolution of the collector the wings act as a fan blower expelling the air
from the circumference of the roll and causing the air to be drawn in through the
side holes thereby providing for a very thorough ventilation about the collector its
shaft and bearings and the armature.
In machines originally constructed with my collector I prefer to give to the
collector the same diameter as the armature so that the collector and the armature
together form one cylindrical body the wires passing in a straight line avoiding
angles. This simplifies also the construction and facilitates the working of the
dynamo.
In these machines it is convenient to put two brushes in place of one on each
side of the dynamo and also to support each plate by means of a screw counter-
sunk into the metal and attaching it to the periphery.
These arrangements have for their effect to prevent risk of heating and sparks
which renders the construction the repair and the working of these machines more
economical and safe.
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
1. In a dynamo electric machine a collector consisting of a body or ring of wood
or other non conducting material and the collector plates B arranged alternately in
parallel rows or series thereon all substantially as and for the purposes described.
2. In a dynamo electric machine the construction of the body or ring of wood or
other non conducting material the collector plates B arranged in relation to each
other substantially as described and with spaces between them receiving wood,
india rubber or other non-conducting or insulating material all substantially as and
for the purposes specified.
3. In a dynamo electric machino the combination of the body or ring of wood
or other non conducting material the collector plates B having the extensions a³ by
which they are fastened in place all substantially as and for the purposes described.
4. In a dynamo electric machine the combination of a body or ring of wood or
other non conducting material the plates B their extensions a³ and the projections C
to which the wires are soldered or otherwise connected all substantially as and for
the purposes described.
5. In a dynamo electric machine the combination of the body or ring of wood or
other non conducting material the collector plates B secured to the circumference
thereof and isolated in relation to each other as specified and the straight wire
connections coupling the said plates with the armature all substantially as
specified.
6. In a dynamo electric machine the collector with wings or plates creating a
rapid circulation of air in the immediate vicinity of the collector plates and armature
substantially as and for the purposes described.
7. In a dynamo electric machine the combination of the collector having the
collector plates B arranged in two series as and for the purposes described and the
brushes adapted to have a simultaneous contact with a plate of each series all
substantially as and for the purposes set forth.
CARPMAEL & Co.,
Agents for the Applicant.