Improvement in Electrical Generators.
Year: 1887

page_text: Date of Application, 13th June, 1887
Complete Left, 13th Mar., 1888
Complete Accepted, 13th Apr., 1888
PROVISIONAL SPECIFICATION.
Improvement in Electrical Generators.
I, THOMAS ALVA EDISON of Llewellyn Park, in the County of Essex and State of
New Jersey, in the United States of America, Inventor, do hereby declare the nature
of this invention to be as follows:-
It is a principle made known by scientific investigation, that magnetic materials,
such as nickel and iron, have their capacity for magnetism diminished as they are
raised in temperature, and that there is a critical temperature for each of such metals
at which it is practically diamagnetic. It has also been pointed out by scientific
papers, that a coil of wire wrapped around a bar of iron or nickel which is magnetized
permanently or by a battery, will have a current of electricity developed in it if the
bar is heated and cooled, the current flowing in one direction as the bar is being
raised in temperature and in the opposite direction as the bar is being lowered in
temperature.
The object of this invention is to utilize this principle in the production of a practical
machine for the economical generation of electric currents.
The machine, which is called a :: pyro-magnetic generator," includes as elements
one or more bodies of magnetic material, such as nickel or iron, a source of magnetism
for magnetizing such body or bodies, a source of heat for raising the temperature of
such body or bodies, a conductor of the current located within the influence of the
magnetic field of force of such body or bodies, and, in caso a straight current is desired,
a commutator for collecting the alternating impulses and delivering them as a straight
current to the translating circuit.
The body (one or more) of magnetic material is given a peculiar construction so
that its temperature may be changed with rapidity. It is an interstitial body, so that
heated or cooled currents of air can be passed directly through it, and it is constructed
of thinly disposed magnetic material so as to have the maximum extent of heat
radiating and absorbing surface relative to its mass. This character is given to the
magnetic body by making it of thin sheet metal, arranged to form as compact a body
as possible, but leaving passages through it for air currents or other heating and
cooling media. If nickel is used as the magnetic material, the critical heat being low,

page_text: no protection against oxidation will be required, but with iron the surfaces must be
protected against oxidation by enamelling, or in other ways. The source of magnetism
may be the current from a separate generator of any suitable kind, but when the
current is straightened by a commutator, which is the preferred form, the exciting
current can be taken directly from the machine itself, or both straight and alternating
currents can be taken from the machine and the straight current be used to charge
the field magnet or magnets and for additional work if desired. The source of heat
may be of any convenient form. For a portable or self-contained machine a furnace
is preferred. This furnace is arranged with relation to the magnetized body or bodies
or with reference to a moving director of the heat so that the heat will be alternately
cut off from and turned on to the magnetized body, or, if there are more than one
magnetized body, this will be done progressively, some of the bodies being heated
while others are cooling. A cold air blast may be forced through the magnetized
bodies that are cut off from the heat, and this air may be carried to the furnace to
support combustion and thereby conserve the heat taken from the cooling bodies. The
preferred construction of the machine is to employ a number of interstitial bodies of
magnetic material arranged in a circle and secured at their ends in two annular or
circular pole plates which form the poles of one or more electro-magnets, the interstitial
bodies connecting such pole plates and forming keepers to the magnets. Around these
interstitial bodies is wound the conductor in which the current is generated. The
armature so constructed is mounted upon the top of the furnace or over the exit flue
of the same.
As
A vertical shaft passing centrally through the armature carries a shield or heat
director which revolves below the lower ends of the interstitial bodies covering at one
time one half of them and cutting them off from the heat of the furnace the hot
products of combustion from which pass through the other half of such bodies.
this heat director moves it progressively cuts off the interstitial bodies on one side
from the furnace and opens them to the furnace on the other side. The shaft carrying
the heat director may be hollow, and a passage be formed through the shaft and the
heat director to the interstitial bodies covered by such director, so that a blast of air
can be forced through the shaft and the director into the interstitial bodies that are
cooling, or a hollow shaft may extend from the director to the ash box of the furnace
so that cold air will be drawn through the cooling bodies and be supplied to the
furnace. The moving shaft which carries the heat director also carries a commutator
for straightening the current. This shaft may be revolved through speed reducing
gearing by an electric motor supplied with current from the generator itself. It will
be understood that the cooling bodies induce a current in the wire around them in the
opposite direction to the current induced in the wire around the bodies that are being
heated. Hence to produce a straight current, the circuit connections of the wire.
around a body must be reversed every time the heat director turns the heat on to or
cuts it off from the body. That is what the commutator accomplishes. Proper shields
are provided for protecting the commutator and adjoining parts from the heat of the
furnace.
THOMAS ALVA EDISON.
By Harris & Mills,
23, Southampton Buildings,
Agents.

page_text: I, THOMAS ALVA EDISON of Llewellyn Park, in the County of Essex, and State of
New Jersey, in the United States of America, Inventor do hereby declare the nature
of this invention, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
It is a principle made known by scientific investigation, that magnetic materials,
such as nickel and iron, have their capacity for magnetism diminished as they are
raised in temperature, and that there is a critical temperature for each of such metals
at which it is practically diamagnetic. It has also been pointed out by scientific papers,
that a coil of wire wrapped around a bar of iron or nickel which is magnetized
permanently or by a battery, will have a current of electricity developed in it if the
bar is heated and cooled, the current flowing in one direction as the bar is being raised
in temperature and in the opposite direction as the bar is being lowered in
temperature.
The object of this invention is to utilize this principle in the production of a
practical machine for the economical generation of electric currents.
The machine which is called a "pyro-magnetic generator" includes as clements one
or more bodies of magnetic material, such as nickel or iron, a source of magnetism for
magnetizing such body or bodies, a source of heat for raising the temperature of such
body or bodies, a conductor of the current located within the influence of the magnetic
field of force of such body or bodies, and, in case a straight current is desired, a
commutator for collecting the alternating impulses and delivering them as a straight
current to the translating circuit.
The body (one or more) of magnetic material is given a peculiar construction so
that its temperature may be changed with rapidity. It is an interstitial body, so that
heated or cooled currents of air can be passed directly through it, and it is constructed
of thinly disposed magnetic material so as to have the maximum extent of heat
radiating and absorbing surface relative to its mass. This character is given to the
magnetic body by making it of thin sheet metal, arranged to form as compact a body
as possible, but leaving passages through it for air currents or other heating and
cooling media. If nickel is used as the magnetic material, the critical heat being low,
no protection against oxidation will be required, but with iron the surfaces must be
protected against oxidation by enamelling, or in other ways. The source of magnetism
may be the current from a separate generator of any suitable kind, but when the
current is straightened by a commutator, which is the preferred form, the exciting
current can be taken directly from the machine itself, or both straight and alternating
currents can be taken from the machine and the straight current be used to charge the

page_text: field magnet or magnets and for additional work if desired. The source of heat may
be of any convenient form, for a portable or self contained machine a furnace is
preferred. This furnace is arranged with relation to the magnetized body or bodies or
with reference to a moving director of the heat so that the heat will be alternately cut off
from and turned on to the magnetized body, or if there are more than one magnetized
body, this will be done progressively, some of the bodies being heated while others
are cooling. A cold air blast may be forced through the magnetized bodies that are
cut off from the heat, and this air may be carried to the furnace to support combustion
and thereby conserve the heat taken from the cooling bodies. The preferred
construction of the machine is to employ a number of interstitial bodies of magnetic
material arranged in a circle and secured at their ends in two annular or circular pole
plates which form the poles of one or more electro-magnets, the interstitial bodies
connecting such pole plates and forming keepers to the magnets. Around these inter-
stitial bodies is wound the conductor in which the current is generated. The armature
so constructed is mounted upon the top of the furnace or over the exit flue of the
same.
A vertical shaft passing centrally through the armature carries a shield or heat
director which revolves below the lower ends of the interstitial bodies covering at one
time one half of them and cutting them off from the heat of the furnace the hot
products of combustion from which pass through the other half of such bodies. As
this heat director moves it progressively cuts off the interstitial bodies on one side from
the furnace and opens them to the furnace on the other side. The shaft carrying the
heat director may be hollow, and a passage be formed through the shaft and the heat
director to the interstitial bodies covered by such director, so that a blast of air can
be forced through the shaft and the director into the interstitial bodies that are cooling,
or a hollow shaft may extend from the director to the ash box of the furnace so that
cold air will be drawn through the cooling bodies and he supplied to the furnace. The
moving shaft which carries the heat director also carries a commutator for straightening
the current. This shaft may be revolved through speed reducing gearing by an
electric motor supplied with current from the generator itself. It will be understood
that the cooling bodies induce a current in the wire around them in the opposite
direction to the current induced in the wire around the bodies that are being heated.
Hence to produce a straight current, the circuit connections of the wire around a
body must be reversed every time the heat director turns the heat on to or cuts it
off from the body. That is what the commutator accomplishes. Proper shields are
provided for protecting the commutator and adjoining parts from the heat of the
furnace.
And in order that the said invention may be more clearly understood and readily
carried into effect I will proceed aided by the accompanying drawings more fully to
describe the same.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a vertical section of the machine with the furnace partly broken
away.
T:
1 11
1

page_text: The bodies Bare made of thin sheet metal, protected in the case of iron from oxidation,
and this is disposed so as to be compact and at the same time to present the maximum
heat radiating and absorbing surface relative to the mass. Each body B may be made
up of tubes, which is the construction shown as to seven of such bodies in figure 3,
or each body may be a corrugated sheet rolled into the form of a cylinder which is the
construction shown as to the sight body in figure 3, or each body may be constructed of
plates placed radially within a surrounding tube which is the construction shown in figure 4.
Many other constructions accomplishing the same end may be employed. Between the
pole plates N, S, the interstitial bodies B are wound with bobbins of suitably insulated
wire. 1) is the furnace of any suitable kind. Its top plate a is open in the centre.
Upon this top plate is placed a plate of fire clay having a corresponding open centro
and a rising flange caround its central opening, upon which rests the lower pole
plate S, thus supporting the armature upon the furnace with the lower ends of the
bodies B projecting into the central opening above the furnace. A vertical shaft E
passes centrally through the pole plates N, S. It is supported by a bearing d resting
on the top plate N, while the space around it in the lower plate S is closed by a plate e.
The lower end of the shaft E carries the heat director F. This is made of fire clay in
the shape shown in figures 1 and 2 and is hollow with its upper side open. It covers
and protects from the furnace heat one half of the bodies B. The shaft E may be
hollow and be connected at its upper end with a stationary air pipe through which
cold air will be forced down through the shaft, through the director and up through
the bodies B being cooled, as shown in figure 1, or, as shown in figure 5, the shaft E
may be solid, and a fire clay pipe be carried from the under side of the director F to
the ash box of the furnace in which case the air for supplying the furnace will be
drawn through the bodies B that are being cooled. Upon the top pole plate N are
mounted two annular fire clay shields G, H, the former protecting the shaft and the
commutator and other parts carried by it, from the heat of the furnace, while the
latter protects the magnet windings.
The commutator of the machine (Figure 6) is composed of a disc of insulating
material having two plates g, h, of metal set into its periphery at opposite points. All
the bobbins C are connected together in a ring as shown in figure 6, and between the
bobbins connections are made to springs or brushes i resting on the disc fat different
points on its periphery. The metal plates g, h, are connected by wires with two
insulated rings k, l, upon which rest the springs or brushes m, n, with which the
translation circuit is connected.
It will be seen that the opposite springs i rest on the plates g, h, and deliver current
to the springs m, n, through the rings, k, l. These connections divide the bobbins that
are cooling from those that are being heated and the connections are shifted with the
heat director. The magnets A may be charged from the machine itself or from a
separate source. The shaft E has a wheel o to receive a belt for turning the shaft.
The power for doing this may be an electric motor driven by current from the
machine.
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 pyro-magnetic generator, the inducing body made interstitial and
constructed of thinly disposed magnetic material whereby it is given the maximum
heat radiating and absorbing surface relative to its mass, substantially as hereinbefore
specified..
2. In a pyro-magnetic generator, the combination of a series of stationary
magnetized bodies having conductors within the influence of their fields of force, a
stationary source of heat and a moving heat director, directing the heat to the
magnetized bodies in succession, substantially as set forth.
3. In a pyro-magnetic generator, the moving heat director made hollow and
connected with a cold air channel for forcing or drawing cold air through the
magnetized bodies that are being cooled, substantially as set forth.

page_text: 4. In a pyro-magnetic generator, the combination of the pole plates with magnets,
the interstitial bodies connecting the pole plates, the bobbins wound around such
interstitial bodies, the furnace upon which the parts before enumerated are mounted,
the central shaft, the heat director and the commutator, substantially as herein before
specified.
THOMAS ALVA EDISON.
By Harris & Mills,
23, Southampton Buildings,
Agents.