IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES to be as follows:-
Year: 1884

page_text: TRUVIDIONAL
DIECIFICATION.
We, JOHN HOPKINSON F.R.S of Westminster Chambers in the City of
Westminster and WILLIAM MATHER of Manchester in the County of Lancaster
do hereby declare the nature of said Invention for "IMPROVEMENTS IN DYNAMO
ELECTRIC MACHINES to be as follows:-
"
The Invention relates to increasing the output from and the security of dynamo
machines also to increasing the facility with which they may be applied to diverse
purposes.
The Invention is more particularly applicable to the type of machine known as
the Siemens Alteneck and modifications thereof but is in part capable of being used
with other dynamo machines. In order to remove the heat generated in the
armature wires we make use of a fan which may be fixed to the driving pulley or
to the shaft of the machine. We also provide fixed covers for the armature and in
some cases an extension of a portion of the fan to surround a portion of the
armature so that the fan may either drive or draw a current of air over the surface
of the armature. These covers also serve as a mechanical protection against injury.
We may cut a groove in the pole pieces of the magnets to receive the extension or
flange of the fan. In some cases more particularly in machines of the Siemens-
Alteneck type or modification thereof we provide air channels along the shaft of
the armature and draw air through these for the purpose of removing heat from the
interior of the armature and so keeping the shaft and bearings cool, in such cases it
is well to use a duplex fan having channels for producing the current of air around
and other channels for producing the current within the armature. The collecting
brushes instead of being formed in wide bundles of wire as in the Edison machines
have each bundle divided into fascicles each of which may be removed separately
being held by a separate screw without stopping the machine In order to put a
greater quantity of copper into a given space we wind the armature with a number
of strands of naked wire and insulate the whole group of wires when the armature
is wound by a covering of fabric surrounding the whole. In this construction it is
preferable to use square wire or wire of rectangular section. In constructing an
armature with copper bars we modify the construction used by Edison by forming
a palm on the ends of the bars and making the end plates of smaller diameter
baving a longer extension than in the Edison plates with a shoulder on either side,

page_text: we also provide a tooth on some of the copper bars to engage into recesses in the
rim plates of the armature. To reduce sparking on the commutator we connect the
successive sections of the conductor of the armature to the commutator plates by a
ribbon or wire of metal of less section than the conductor itself. For machines of
low electro-motive force we modify the method of winding and connecting the
armature and commutator usual in the machines of Gramme and Siemens thus-
suppose there to be m n sections in the armature and bars in the commutator, call
the bars (1) (2) (3) and so on to (mn) the sections of the armature are successively
connected to plates (1) and (m + 1), (m + 1) and (2m + 1) and so on till {(n - 1)
m + 1} and (1) again (2) and (m + 2) and so on so that instead of having m n
sections connected seriatim as in the usual method we have m so connected and n
parallel. The brushes on either side must never touch less than n plates at once.
It is often desirable to use the powerful shunt machines used for incandescent
lighting for the production of a single arc light this we accomplish by adding a
resistance to the resistance of the armature when the arc is to be used.
resistance is introduced so that the whole current generated passes through it before
the magnet circuit is derived.
This
J. HENRY JOHNSON,
47, Lincoln's Inn Fields, London, W.C.,
Agent for the said John Hopkinson, F.R.S.,
and William Mather.

page_text: 25
We JOHN HOPKINSON F.R.S of Westminster Chambers, in the City of
Westminster and WILLIAM MATHER of Manchester in the County of Lancaster
do hereby declare the nature of said invention for IMPROVEMENTS IN DYNAMO
ELECTRIC MACHINES" and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
This Invention has for its object to increase the output from and the security of
dynamo machines and also to increase the facility with which the said machines
may be applied to divers purposes.
The Invention is more particularly applicable to the type of machine known as
Siemens Alteneck and modifications thereof but is in part capable of being used
with other dynamo machines. According to the said Invention in order to remove
the heat generated in the armature wires we make use of a fan or fans which may
be fixed to the driving pulley or to the shaft of the machine. In combination with
the said fan or fans we may also provide fixed covers for the armature, and an
extension of a portion of the fan or fans to surround a portion of the armature, so
that the fan or fans may either drive or draw a current of air over the surface
of the armature in addition to drawing or driving air through the armature
The said covers also serve as a mechanical protection against injury to the parts
which they cover.
We may cut a groove in the pole pieces of the magnets to receive the extension
or flange of the fan. We may provide air channels along the shaft of the armature
and draw or drive air through these channels for the purpose of removing heat
from the interior of the armature and so keep the shaft and bearings cool, in such
cases it is well to use a duplex fan having channels for producing the current of
air around, and other channels for producing the current within the armature.
In order to put a greater quantity of copper into a given space, we wind the
armature with a number of strands of naked wire, and insulate the whole group of
wires when the armature is wound by a covering of fabric surrounding the whole.
In this construction it is preferable to use square wire or wire of rectangular
section This construction is specially suited to the Siemens armature as it enables
the group of wires to be more easily bent than a single bar or ribbon of copper and
also to be spread out flat and conveniently distributed where the wires pass across
at the ends of the armature.
To reduce sparking on the commutator we connect the successive sections of the
conductor of the armature to the commutator plates by a ribbon or wire of metal
of less section or of greater specific resistance than the conductor itself.
Suppose for example that the machine has forty sections in the commutator and
as many in the armature, and that the resistance of each section is 0.001 obm if
the juncture of the successive sections of the armature are connected by thick short
conductors to the commutator plates as is usual the effective resistance of the
armature will be 0.01. Now when a joint between commutator plates passes
under a brush the corresponding section of the armature is short circuited for a
short time and its resistance being low a great current will pass and sparking
result if the brushes deviate a little from the neutral point. This evil we remedy
or mitigate by making the connection of sensible resistance (in the case cited
0.001 Ohm would be good) thus the resistance of the armature will be increased
to 0.012 but the resistance of each section when short circuited by the brush will
be 0.003 and the current when the section is short circuited will be reduced

page_text: greatly. Since the whole current only passes through these resistances in this case
for one twentieth of the whole time the section may be small without risk of
undue heating For Machines of low electro motive force we modify the method
of winding and connecting the armature and commutator usual in the Machines of
Gramme and Siemens thus suppose there to be m x n sections in the armature and
as many bars or plates in the commutator call the bars (1) (2) (3) and so on
to (mxn) the sections of the armature are succesively connected to plates (1)
and (m1), (m + 1) and (2m + 1) and so on till (n - 1) x m + 1 and (1,)
again, (2) and (m + 2) and 80 on so that instead of having m x n Sections
connected seriatim as in the usual method we have n so connected, and m parallel.
The brushes on either side must never touch less than m plates at once. The
diagram No 1 illustrates the application of this method by a case wherein m = 2
and n = 4. The short straight lines illustrate the bars or plates of the commutator,
the two circles the armature ring, and the coils represent the wires connected up to
the commutator bars or plates in the manner hereinbefore described. The diagram
N° 2 shews the method applied to an Edison machine wound with four layers of
wire. In this case m = 4 and n = 16. This diagram may be regarded as a
Section through the wires on the armature the numerals indicating the bars or
plates of the commutator.
Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed we declare that what
we claim is
First. The use in combination with the armature of a Dynamo Electric Machine
of a fan or fans for cooling the said armature as hereinbefore described.
Second. The method hereinbefore described of winding the armature of a
Siemens Dynamo Electric Machine with parallel wires insulated in groups at the
time of winding the armature as and for the purpose hereinbefore described.
Third. The use of connections of sensible resistance between the sections of the
armature and of the commutator of a Dynamo Electric Machine substantially as
and for the purpose hereinbefore described.
Fourth. The system of winding the armature and connecting the windings with
the commutator sections of Dynamo Electric Machines for low potential as
herein before described and illustrated.
.י.ו.ב
BALL 1
1.
1004