Improvements in Engines or Prime Motors.
Year: 1887

page_text: Date of Application, 13th June, 1887
Complete Left, 13th Mar., 1888
Complete Accepted, 11th May, 1888
PROVISIONAL SPECIFICATION.
Improvements in Engines or Prime Motors.
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:-
My invention relates to engines or prime motors, and is based upon the principle
that the capacity of nickel or iron for magnetism diminishes as its temperature is
raised, and that for each of such metals there is a critical heat at which it is practically
non-magnetic. Advantage is taken of this fact to construct an apparatus in which
motion is produced by the combined action of heat and magnetism, and to this
machine I have applied the term " pyro-magnetic engine." The heat is utilized to
destroy the magnetic balance of nickel or iron parts moving in the field of one or
more magnets, or to successively make magnetic parts diamagnetic as they reach
centres of attraction.
I am aware that it has been suggested that this principle might be utilized to
produce motion, but no practical means capable of developing a useful amount of
power has been proposed for that purpose so far as I know.
In carrying out my invention I employ an interstitial armature constructed of thin
sheet nickel or iron, so that it will be capable of rapid changes in temperature, it
having the maximum heat radiating and absorbing surface relative to its mass. This
armature is one having interstices extending through it, and it may be made up of
or provided with nickel or iron tubes extending longitudinally of the armature, the
armature being mounted on a vertical shaft so that the tubes will act as flues, or a
corrugated sheet could be rolled up to form an equivalent construction, or sheets
could be placed radially in an enclosing casing, or the interstitial armature could be
made in many other ways that would suggest themselves to skilled persons. Beneath
the interstitial armature may be located a suitable furnace with flues for the exit of
the products of combustion extending to and covering at their ends opposite portions
of the armature. The ends of the armature tubes or channels will move in close
relation with the open ends of the furnace exit flues, so that the products of combustion
will be directed into the armature channels as they successively come over the flues.

page_text: The intermediate armature channels are protected from the furnace, and since the
power of the machine depends largely upon the rapidity with which the armature
sections can be heated and cooled, these intermediate channels or tubes may be
covered by a stationary box connected by a flue with the furnace, beneath its grate, so
that the fresh air for supporting combustion will be drawn or forced down through
the armature channels that are being cooled.
To increase the power of the machine or change the position of the points of
attraction, a fixed coil of wire for magnetizing or polarizing the armature may be
wound in recesses formed in the pole pieces of the field magnet.
The field magnet may be a permanent magnet, but for large machines I prefer to
employ an electro-magnet, which may be charged by a battery or by a small dynamo
run by the machine, and which can be turned by hand for starting the machine, unless
indeed the residual magnetism is sufficient for that purpose.
Dated this 5th day of December 1887.
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 :-
My invention relates to engines or prime motors, and is based upon the principle
that the capacity of nickel or iron for magnetism diminishes as its temperature is
raised, and that for each of such metals there is a critical heat at which it is practically
non-magnetic. Advantage is taken of this fact to construct an apparatus in which
motion is produced by the combined action of heat and magnetism, and to this
machine I have applied the term "pyro-magnetic engine." The heat is utilized to
destroy the magnetic balance of nickel or iron parts moving in the field of one or
more magnets, or to successively make magnetic parts diamagnetic as they reach.
centres of attraction.
I am aware that it has been suggested that this principle might be utilized to
produce motion, but no practical means capable of developing a useful amount of power
has been proposed for that purpose so far as I know.
In carrying out my invention, employ an interstitial armature, constructed of.
thin sheet nickel or iron, so that it will be capable of rapid changes in temperature,
it having the maximum heat radiating and absorbing surface relative to its mass.
This armature is one having interstices extending through it, and it may be made
up of or provided with nickel or iron tubes extending longitudinally of the armature,
the armature being mounted on a vertical shaft so that the tubes will act as flues, or
a corrugated sheet could be rolled up to form an equivalent construction, or sheets
could be placed radially in an enclosing casing, or the interstitial armature could be.
made in many other ways that would suggest themselves to skilled persons. Beneath
the interstitial armature may be located a suitable furnace with flues for the exit of
the products of combustion extending to and covering at their ends opposite portions
of the armature. The ends of the armature tubes or channels will move in close
relation with the open ends of the furnace exit flues, so that the products of
combustion will be directed into the armature channels as they successively come
over the flues. The intermediate armature channels are protected from the furnace,
and since the power of the machine depends largely upon the rapidity with which the
armature sections can be heated and cooled, these intermediate channels or tubes
may be covered by a stationary box connected by a flue with the furnace, beneath its
grate, so that the fresh air for supporting combustion will be drawn or forced down
through the armature channels that are being cooled.
To increase the power of the machine or change the position of the points of
attraction, a fixed coil of wire for magnetizing or polarizing the armature may be
wound in recesses formed in the pole pieces of the field magnet.
The field magnet may be a permanent magnet, but for large machines I prefer to

page_text: employ an electro-magnet, which may be charged by a battery or by a small dynamo
run by the machine, and which can be turned by hand for starting the machine, unless
indeed the residual magnetism is sufficient for that purpose.
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.
Figure 1 is a vertical section of the machine the armature being in elevation.
Figure 2, a section at right angles to Figure 1, the field magnet and armature being
in elevation.
Figure 3, a top view of the machine with the flues removed.
Figure 4, a top view of a modified form of the armature; and
Figure 5, a view showing the armature magnetizing coils.
A is a cylindrical armature, mounted upon a shaft a and composed of thin tubes
of nickel or iron; or thin sheets of the material wound into a cylinder or disposed
in other ways to form an interstitial body having a great heat radiating and
absorbing surface relative to its mass, such armature being suitably held to the shaft.
If the armature is made of sheet iron it may be nickel plated or thinly covered with
enamel or otherwise protected to prevent oxidation. This armature is mounted
between the poles N, S, of a magnet, which may be a permanent magnet, but is
preferably an electro-magnet. The parts are suitably supported so that the armature
has a vertical position, the armature channels or tubes extending longitudinally
thereof. Beneath the armature is a furnace B having two exit flues b, c, extending.
upwardly and covering the open lower ends of a number of the armature tubes on
opposite sides of the armature. The open upper ends of these furnace exit flues fit
as closely as possible against the ends of the armature tubes while permitting the
armature to turn. Between the flues b, c, the lower end of the armature is prefer-.
ably covered with a cold air box d which is stationary and is connected by the shaft a,
with the furnace beneath the grate bars, such shaft being made hollow and provided
with proper openings for that purpose as shown. A pipe e connected with the
upper end of the shaft a supplies fresh air from a blower or by the natural draught
of the furnace. Above the armature are flues f, g, forming continuations of the
furnace exit flues b, c, through the armature tubes. The tubes between the flues f, g
at the upper end of the armature may be left uncovered.
A fixed coil of wire is located in recesses in the pole pieces N, S. The coil C
may be connected in series with the coils of the field magnet. Its function is to
magnetize or polarize the armature; its tendency is to produce poles in the armature
at right angles to the poles of the field magnet and to cause a repulsion as well as an
attraction between the field magnet and the armature, or at least to reduce the
retarding attraction between each pole of the field magnet and that portion of the
armature which is moving away from it.
The cold air box d is arranged to cover a central section of the tubes, and the
flues b, c, cover the spaces left uncovered by that box; the tubes will be heated on
the diametrically opposite sides of the armature that come opposite the centres of
the poles, N. S. These heated portions of the armature being diamagnetic or less
magnetic than the remaining portion of the armature, it will be seen that the
armature will occupy an unbalanced position in the field and consequently it will
be turned in the field by the attraction of the magnetic poles N, S, for the poles
formed at the opposite sides of the armature by the coil C. The unbalanced position
of the armature is maintained by the fact that the heat is always applied to those
portions of the armature at opposite points in the magnetic field. Hence the rotation
of the armature will be continuous, its rapidity of movement being.largely dependent
upon the rapidity with which the armature tubes can be heated and cooled.
The wire winding of the field magnet as well as the wire of the coil C will be
covered by an insulation capable of withstanding heat. I preferably use a very few

page_text: turns of large size copper wire both in the field winding and in the fixed coil, and
energize the same by a current of a sufficiently large quantity to give the desired
magnetizing effects. With the large wire insulating washers of some infusible
material, such as porcelain, may be used to separate the wires.
A small dynamo may be employed to supply the current for energizing the field
and fixed coil. This dynamo if employed will be operated by the engine through a
speed increasing gearing, and it may have a hand crank for giving the field magnet
energy in starting the engine.
A machine driven by the engine will be connected with the armature by speed
increasing gearing, unless the machine is one having a low rate of speed.
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. A prime motor having a revolving interstitial armature constructed of thinly
disposed magnetic material and having a great heat radiating and absorbing surface
relative to its mass, in combination with a magnetic field in which the armature
revolves and a furnace or other source of heat producing an unbalanced magnetic
condition of the armature, substantially as hereinbefore specified.
2. In a prime motor operating as described by the combined effects of heat
and magnetism, the coil for polarizing the armature, substantially as hereinbefore
specified.