IMPROVEMENTS IN DYNAMO OR MAGNETO- ELECTRIC MACHINES
Year: 1881

page_text: LETTERS PATENT to Peter Jensen, of 33, Chancery Lane, in the County of
Middlesex, for an Invention of "IMPROVEMENTS IN DYNAMO OR MAGNETO-
ELECTRIC MACHINES." A communication from abroad by Thomas Alva
Edison, of Menlo Park, in the State of New Jersey, United States of
.America..
PROVISIONAL SPECIFICATION left by the said Peter Jensen at the Office
of the Commissioners of Patents on the 10th September, 1881.
PETER JENSEN, of 33, Chancery Lane, in the County of Middlesex. "IMPROVE-
MENTS IN DYNAMO OR MAGNETO ELECTRIC MACHINES." A communication from
abroad by Thomas Alva Edison, of Menlo Park in the State of New Jersey,
United States of America.
The object of one part of this Invention is to produce such improvements upon
the dynamo or magneto electric machines, wherein are employed inductive barз
running lengthwise of the armature and connected at their ends by discs, as shown
in British Letters Patent No. 1240 of March 21, 1881, that a better connection
between the ends of the bars and the dises will be formed so as to prevent heating
at those points; the connections between the discs and the commutator bars will
have a larger conducting area, and be more rigid than in the construction shown in
said Patent, in order to prevent the heating of such connections, and also to prevent
their breakage by vibration; the contacts of bars and rods with discs will be
reduced in resistance and prevented from oxidizing: the copper discs for connecting
the ends of the bars will be located outside of the field of force or nearly so, and
will not be heated by the circulation of currents induced in them when the
circuit is open at the commutator by movement in the magnetic field: means will
be provided for preventing efectrical creeping between the edges of the copper
dise and finally the copper inductive bars will be so insulated that the insulation
cannot be pierced by the electricity and at the same time the heat will be
conducted off and not allowed to accumulate in the bars.
In this dynamo or magneto electric machine, the copper bars are connected at
their ends to ears or lugs on copper discs insulated from each other, which ears are

page_text: arranged in a spiral line, extending twice or nearly so around the circumference of
the cylinder formed by the discs at each end of the armature.
Heretofore these ears have been made of the same size as the unenlarged ends
of the copper bars and they have been separated the width of a bar, every alternate
bar passing between two ears of the first line to an ear of the second line.
By the present Invention, these ears are widened so as to close up the spaces
between them, and the copper bars are provided with T shaped ends which are
secured to said ears. The alternate bars are curved outwardly so as to pass over
the first line of ears and inwardly again to make connection with cars of the second
line. This construction provides a larger contact between the bars and discs.
To lessen the resistance of this contact and prevent oxidation, the surfaces are
plated with gold or silver. or amalgamated with mercury, or the surfaces may be
first plated with silver and then amalgamated.
In addition, to give strength and a larger conducting area washers are used
which are placed on the outside of the ears and are secured by the same bolts that
pass through the ears and the ends of the bars.
For commutator connections, the tongues extending from the open centres of
discs to the commutator bars. shown in said Patent are dispensed with, and
instead thereof exterior rods, which have the same or nearly the same conducting
area as the inductive bars, are employed.
These rods have T shaped ends and are secured to, alternate ears of the discs by
the same bolts that secured the inductive bars thereto. This gives one commutator
connection for each disc, of great strength and low resistance. The rods that are
secured to ears of the inner line are curved outwardly to avoid, ears of the second
line.
The surface contacts of these rods and The ears are also plated with gold or
silver, or amalgamated, or plated with silver and then amalgamated.
To secure the benefits of locating the copper dises outside of the field of force
or nearly so, thimbles are placed upon the bolts which secure the discs to the
armature core, which thimbles are situated between the core and discs and separate
the discs a certain distance from the core.
Since the polar extensions of the exciting magnet or magnets terminate at the
ends of the armature core, the copper dises will be wholly outside of such polar
extensions and consequently outside of the magnetic field, or nearly so.
An air space is also formed between each end of the armature core and the discs
by this construction through which-space-air-circulates-and-serves-to-conduet-off-
heat generated in the parts.
To prevent, electrical creeping between the edges of the copper discs, such discs
are bevelled on both sides at their edges and the paper sheets which are used to
insulate the copper discs from each other are extended a short distance beyond the
edges of the discs and are pressed down into the angular spaces formed by the
bevelled edges.
For insulating the copper inductive bars they are wrapped with parchment
paper. The parchment paper it is found is not only a good insulator, but is also a
good conductor of heat, on account of its compactness, and is tough and durable,
and otherwise well adapted for the purpose.
Ordinary paper or other fibrous material may be made a good conductor of heat
by filling the air spaces therein by any suitable substance, such as japan varnish
or linseed oil, and such prepared paper or fibrous material is considered the
equivalent of the parchment paper.
It is preferred to use in connection with the wrapping of parchment paper, a
layer of mica, which is wrapped from the parchment paper, being held by the
same and prevented from breaking into pieces and falling from place. The bars
may also be japanned, or covered with rubber which is afterwards vulcanized.
The object of another part of this Invention is to produce means for cooling the
armature of a dynamo or magneto electric machine.
In carrying out this part of the Invention the spaces between the polar extensions

page_text: of the exciting magnet or magnets at the sides of the armature are closed by
means of.brass plates or other non-magnetic metal or material.
At the non-commutator end of the machine, the shaft is surrounded by an air-
chamber, which is a drum having an open side secured to the ends of the polar
extensions and covering the end of the armature so as to enclose the space between
the inductive portion of such armature and the polar extensions.
To this air chamber is connected by a pipe the case of an air blower, which
blower is preferably driven by the armature shaft by means of a belt and pulleys,
or the blower may be driven by power from the same sourco applied in a different
manner, or by power from another source.
During the operation of the machine, the blower is driven and air is forced from
end to end of the armature through the space between the same and the polar
extensions of the exciting magnet or magnets. By connecting, the edges of the
polar extensions the space around the armature is closed except at the ends,
causing the currents of air to traverse the whole length of the armature.
Instead of having the air chamber at the end of the armature, the polar
entensions of the field magnets may be divided at the centre and the space covered
by exterior plates. A number of pipes (say three) will lead from the blower to
this space, and the air will be forced in both directions from the centre towards the
ends of the armature.
This latter construction has the advantage that there is but one half the
resistance to the passage of the air that there is with the first construction, and
consequently with same power, four times the amount of air can be forced over the
armature.
In addition the air will not be heated to such an extent and both ends of the
armature will have the same temperature.
To allow the currents of air supplied in either way before described to circulate
freely around the inductive portion of the armature and between such inductive
portion and the core, the following construction has been devised.
The copper inductive bars which are arranged parallel upon the armature core
are spaced a certain distance apart and are raised off of the core and separated by
small blocks, or by projections either on the core or bars...
The bars are held in this position by their end connections and by being bound
at a number of points by wire drawn tightly around the armature.
In this manner air spaces are formed entirely around the inductive bars, through
which the currents of air from the blower pass.
Air passages are also made longitudinally through the core of the armature, and
radial passages extend from the longitudinal passages to the exterior of the core
at various points. A portion of the air from the blower is forced through these
passages and assists to cool the armature.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Peter Jensen in the Great Seal Patent Office on the 10th March
1882.
PETER JENSEN, of 33, Chancery Lane, in the County of Middlesex. IMPROVE
MENTS IN DYNAMO OR MAGNETO ELECTRIC MACHINES." A communication from
abroad by Thomas Alva Edison, of Menlo Park in the State of New Jersey,
United States of America.
The object of one part of this Invention is to produce such improvements upon
the dynamo or magneto electric machines, wherein are employed inductive bars
running lengthwise of the armature and connected at their ends by disks, as shown
in British Letters l'atent No. 1240 of March 21, 1881, that a better connection
between the ends of the bars and the disks will be formed so as to prevent heating
at those points; the connections between the disks and the commutator bars will
have a larger conducting area, and be more rigid than in the construction shown in
said Patent in order to prevent the heating of such connections and also to
prevent their breakage by vibration; the contacts of bars and rods with disks will
be reduced in resistance and prevented from oxidizing, the copper disks for con-
necting the ends of the bars will be located outside of the field of force or nearly
so, and will not be heated by the circulation of currents. induced in them when
the circuit is open at the commutator by movement in the magnetic field,; means
will be provided for preventing electrical creeping between the edges of the copper
disks and finally the copper inductive bars will be so insulated that the
insulation cannot be pierced by the electricity and at the same time the heat will
be conducted off and not allowed to accumulate in the bars.
In this dynamo or magneto electric machine, the copper bars are connected at
their ends to ears or hugs on copper disks insulated from each other, which
ears are arranged in a spiral line, extending twice or nearly so around the
circumference of the cylinder formed by the disks at each end of the
armature.
Heretofore these ears have been made of the same size as the unenlarged ends
of the copper bars and they have been separated the width of a 'bar, every
alternate bar passing between two ears of the first line to an ear of the second
line.
By-the-present-Tnvention these ears are widened so as to close up the space
between them and the copper bars are provided with T shaped ends which are
secured to said ears. The alternate bars are curved outwardly so as to pass
over the first line of ears and inwardly again to make connection with ears of
the second line. This construction provides a larger contact between the bars and
disks.
•
To lessen the resistance of this contact and prevent oxidation, the surfaces are
plated with gold or silver, or amalgamated with mercury, or the surfaces may be
first plated with silver and then -amalgamated.
In addition, to give strength and a larger conducting area washers are used
which are placed on the outside of the ears and are secured by the same bolts that
pass through the ears and the ends of the bars.
For commutator connections, the tongues extending from the open centres of
disks to the commutator bars shown in said Patent are dispensed with and instead
thereof exterior rods which have the same or nearly the same conducting area as
the inductive bars are employed.
Those rods have T shaped ends and are secured to alternate ears of the disks
by the same bolts that secure the inductive bars thereto. This gives one

page_text: The rods
mutator connection for each disk, of great strength and low resistance:
that are secured to cars of the inner line are curved outwardly to avoid ears of the
second line.
The surface contacts of these rods and the ears are also plated with gold or
silver, or amalgamated, or plated with silver and then amalgamated.
To secure the benefits of locating the copper disks outside of the field of force or
nearly so, thimbles are placed upon the bolts which secure the disks to the armature
core, which thimbles are situated between the core and disks and separate the
disks a certain distance from the core.
Since the polar extensions of the exciting magnet or magnets terminate at the
ends of the armature core, the copper disks will be wholly outside of such polar
extensions and consequently outside of the magnetic field, or nearly so.
An air space is also formed between each end of the armature corc and the disks
by this construction, through which space air circulates and serves to conduct off
heat generated in the parts.
To prevent electrical creeping between the edges of the copper disks, such disks
are bevelled on both sides at their edges and the paper sheets which are used to
insulate the copper disks from each other are extended a short distance beyond the
edges of the disks and are pressed down into the angular spaces formed by the
bevelled edges.
For insulating the copper inductive bars they are wrapped with parchment
paper. The parchment paper it is found is not only a good insulator, but is also a
good conductor of heat on account of its compactness and is tough and durable and
otherwise well adapted for the purpose.
Ordinary paper or other fibrous material may be made a good conductor of heat
by filling the air spaces therein by any suitable substance, such as japan varnish
or linseed oil and such prepared paper or fibrous material is considered the
equivalent of the parchment paper.
It is preferred to use in connection with the wrapping of parchment paper a
layer of mica which is wrapped with the parchment paper being held by the
same and prevented from breaking into pieces and falling from place. The
bars may also be japanned or covered with rubber which is afterward
vulcanized.
This part of the Invention is illustrated in Figures 1 and 2 of the Drawings.
Figure 1 is a perspective view from the commutator end of this machine, showing
a few of the parts separated for clear illustration.
Figure 2 is a side elevation of some of the parts at the commutator end of the
armature.
With reference to these Figures A is the core of the armature-B. B are the
copper inductive bars extending longitudinally along the core A and connected at
their ends to copper disks C. insulated from each other. The bars B extend
straight to the ears a. of the disks, while the alternate bars B' are curved over the
.first line of ears to ears b. of the second line. D is the commutator and E
represents the rods extending from alternate ears to the bars of the commutator.
The contacts of B and B and of E with the ears of disks C are plated or
amalgamated or both as before described. The thimbles e on bolts separate the
disks C from the ends of the core A for the purpose before set forth. The copper
disks C.have double bevelled edges c.formingangular spaces intowhich the projecting
edges of paper sheets are pressed to prevent electrical creeping between the
edges of disks.
F is the insulating wrapping of parchment paper and .G the
mica.
:
The object of another part of this Invention is to produce means for cooling the
armature of a dynamo or magneto electric machine.
In carrying out this part of the Invention the spaces between the polar
extensions of the exciting magnet or magnets at the sides of the armature are
closed by means of brass plates or other non magnetic metal or material.
At the non commutator end of the machine the shaft is surrounded by an air

page_text: To
chamber, which is a drum having a open side secured to the ends of the polar
extensions and covering the end of the armature so as to enclose the spaco
between the inductive portion of such armature and the polar extension.
this air chamber is connected by a pipe the case of an air blower, which blower is
driven preferably by the armature shaft by means of a belt and pulleys, or the
blower may be driven by power from the same source applied in a different
manner or by power from another source.
and the
During the operation of the machine the blower is driven and air is forced from
end to end of the armature through the space between the same
polar extensions of the exciting magnet or magnets.
By connecting the edges of
the polar extensions the space around the armature is closed except at the ends,
causing the currents of air to traverse the whole length of the armature.
Instead of having the air chamber at the end of the armature, the polar
extensions of the field magnets may be divided at the center and the space covered
by exterior plates. A number of pipes (say three) will lead from the blower to
this space and the air will be forced in both directions from the centre towards
the ends of the armature.
This latter construction has the advantage that there is. but one half the
resistance to the passage of the air that there is with the first construction and
consequently with same power four times the amount of air can be forced over the
armature.
In addition the air will not be heated to such an extent and both ends of the
armature will have the same temperature.
To allow the currents of air, supplied in either way before described to circulate
freely around the inductive portion of the armature and between such inductive
portion and the core, the following construction has been devised.
The copper inductive bars which are arranged parallel upon the armature core
are spaced a certain distance apart and are raised off of the core and separated by
small blocks or by projections either on the core or bars.
The bars are held in this position by their end connections and by being bound
at a number of points by wire drawn tightly around the armature. In this
manner air spaces are formed entirely around the inductive bars through which the
currents of air from the blower pass.
Air passages are also made longitudinally through the core of the armature and
radial passages extend from the longitudinal passages to the exterior of the core at
various points. A portion of the air from the blower is forced through these
passages and assists to cool the armature.
This part of the Invention is illustrated in Figures 3 and 4 of the Drawing.
Figure 3-is-a-perspective-view-of-the-principal-parts-of-a-dynamo-or-magneto-
electric machine embodying this Invention.
Figure 4 a cross section showing spacing of the copper inductive bars.
With reference to these Figures A. B. are the polar extensions of the exciting
magnet or magnets, and C is one of the plates for closing the spaces between the
side edges of such polar extensions.
D is the armature shaft, E is the air chamber or drum enclosing the non
commutator end of armature; F is the air blower driven by belt a. and pulleys b. c.
from armature shaft D. and having its case connected by piped with air-chamber E.
G represents the wrapped copper inductive bars supported off of the armature
core by blocks or projections e and is the wire wrapping for holding bars in
place.
What is claimed is:
First. In a dynamo or magneto electric machine the inductive bars broadened at
their ends for connection with the disks, substantially as set forth.
Second. In a dynamo or magneto electric machine the combination of the disks
having a double spiral line of projecting ears, with the inductive bars connected
with such ears, the alternate bars being curved outwardly to avoid the first line of
ears, substantially as set forth.

page_text: Third. In a dynamo or magneto electric machine, the combination of the
inductive bars and cross connecting disks having their contacts plated or
amalgamated, substantially as and for the purposes set forth.
Fourth. In a dynamo or magneto electric machine having cross connecting
disks, the outside rods connecting the disks with the commutator substantially as
set forth.
Fifth. In a dynamo or magneto electric machine the combination of the
inductive bars and the disks having projecting ears with the outside rods extending
from alternate ears to the commutator bars substantially as set forth.
Sixth. In a dynamo or magneto electric machine the cross connecting disks,
located outside the magnetic field substantially as set forth.
Seventh. In a dynamo or magneto electric machine the combination with the
armature core of the cross connecting disks separated from the ends of such core.
leaving air spaces and removing disks from magnetic field, substantially as set
forth.
Eighth. In a dynamo or magneto electric machine the cross connecting disks
having bevelled edges, in combination with intermediate insulation, substantially
as set forth.
Ninth. In a dynamo or magneto electric machine, the copper inducting bars
wrapped with parchment paper or its equivalent, substantially as set forth.
Tenth. In a dynamo or magneto electric machine, the copper inductive bars
having an insulation of mica held by an exterior wrapping, substantially as
set forth.
Eleventh. In a dynamo or magneto electric machine, the copper inductive bars
having an insulation of mica and parchment paper or its equivalent substantially
as set forth.
Twelfth. In a dynamo or magneto electric machine an air blower situated
outside of the machine and forcing air through the space around the armature
substantially as set forth.
Thirteenth. In a dynamo or magneto electric machine the air blower driven by
the armature shaft and forcing currents of air through the space between the
armature and the polar extensions of the exciting magnet or magnets substantially
as set forth.
Fourteenth. In a dynamo or magneto electric machine the polar extensions of
the exciting magnet or magnets connected at their side edges so as to form a
chamber surrounding the armature and open only at the ends of such armature in
combination with a blower forcing air through said chamber, substantially as
set forth.
Fifteenth. In a dynamo or magneto electric machine the inductive bars supported
off of the armature core and separated from each other leaving spaces entirely
around said bars, substantially as set forth.
Sixteenth. In a dynamo or magneto electric machine the combination of the
inductive bars supported off of the armatüre and separated from each other with a
blower for forcing air into the space between the armature and the polar extensions
of the exciting magnet or magnets substantially as set forth.
In witness whereof I the said Peter Jensen have hereunto set my hand and
seal this Eighth day of March in the year of our Lord One thousand eight
P. JENSEN. (L.S)