IMPROVEMENTS IN ELECTRIC GENERATORS
Year: 1881

page_text: LETTERS PATENT to Sydney Pitt, of Sutton, in the County of Surrey, for an
Invention of "IMPROVEMENTS IN ELECTRIC GENERATORS." A communication
from abroad by Simeon J. M. Bear, of Mitchell, in the County of Mitchell and
State of Iowa, United States of America.
PROVISIONAL SPECIFICATION left by the said Sydney Pitt at the Office of
the Commissioners of Patents on the 26th July 1881.
SYDNEY PITT, of Sutton, in the County of Surrey. " IMPROVEMENTS IN
ELECTRIC GENERATORS." [A communication from abroad by Simeon J. M. Bear,
of Mitchell, in the County of Mitchell and State of Iowa, United States of
America.]
This Invention relates to machinery or apparatus which is employed for the
conversion of mechanical into electrical energy, which are known as magneto-électric
or dynamo-electric generators.
In the construction of electric generators of this class it has hitherto been a
desideratum to arrange the poles of the moving armature in such a manner that
they approach as closely as possible to the poles of the field magnets in passing by,
without actually coming in contact with them. Nevertheless, it has in all cases
been found necessary to provide considerable space between the stationary and
moving poles of the system, in order to guard against any possibility of their
being accidentally brought in contact when the machine is in rapid revolution.
The object of this Invention is to enable a machine of this character to be con-
structed, in which the poles of the armature and the field magnets may be brought
into the closest proximity, or even into absolute contact with each other, without
lessening the efficiency of the machine, but on the contrary, with the effect of
materially augmenting it.
The general principle of the Invention consists in so constructing, combining,
and organizing the armatures and field magnets with reference to each other that
the armatures or moving parts of the machine shall roll upon or revolve in contact
with the surface of the field magnets or fixed portions of the machine, or vice versa.
En
.
77

page_text: The form of apparatus which it is preferred to make use of in carrying out the
Invention consists in general of two or more electro-magnets or permanent and
electro-magnets mounted upon parallel axes in such a manner that the poles or
polar extensions of each shall rotate in either close proximity or preferably in
actual contact with each other. In this construction a double leverage is made use
of, but by a simple change in the mechanical construction a single leverage may be
applied. This latter method consists in pivotting a cylindrical armature upon an
axis which is mounted near the periphery of a drive-wheel, having its axis of
rotation parallel with that of the armature. The rotation of the drive-wheel causes
the pivot upon which the armature is hung to describe a circle at every revolution
of the drive-wheel. An epicycloidal motion is thus produced by the combination
of the revolution of the arinature itself about the pivot of the drive wheel, and the
revolution of the armature about its own axis. The axis of the drive-wheel is
coincident with the centre of the magnetic field within which the armature
travels.
The form and construction of the field magnets and armatures and their relations
to each other are susceptible of various modifications. In the accompanying
Drawings several methods of applying the Invention are shown in connection with
various forms of armatures and field magnets which it may be found desirable
to use.
In the Drawings, Figures 1 and 2 represent respectively side and end elevations
of one form of construction, in which A, B, and C are three straight electro-
magnets having their respective soft iron cores parallel to each other.
These are
wound in the usual manner with an insulated conducting wire, so as to produce
opposite magnetic polarity at the respective ends of each magnet. The cores of
these electro-magnets are provided with polar extensions a, a. The spaces between
the polar extensions are preferably filled with some non-magnetic material b, b.
The method of applying the motive power to the machine may be by means of
a belt from a steam engine, or other suitable source of power, to the pulley c,
while the friction of the surfaces, together with the mutual magnetic attraction
exerted by the poles of the field magnets and armature upon each other, may be.
relied upon to cause the field magnets A and C to revolve at the required rate of
speed.
A modification of this construction is shown in Figure 3, in which D represents
an armature constructed in the form of the well known Gramme's ring. The two
field magnets E and F are constructed upon the principle of the well known
Siemens' armature. The field magnets E, F, may be permanent magnets having
the spaces e, f, filled with non-magnetic material.
In Figure 7 is shown a method of combining one armature with one fiel
maguet. In this Figure the armature H consists of several electro-magnets h, h,
wound in the usual manner and united in a ring. The field magnet I may be
made up of permanent magnets i, i, or of electro-magnets similarly constructed.
In the plan shown in Figure 8, a small Siemens' armature K is substituted for
the field magnet I, shown in Figure 7. It is evident that the number of these
field magnets may be increased, so as to extend completely around the armature H
if desired.
An important modification consists in the application of a single leverage. In
Figure 4 is shown one convenient method of applying such a leverage. L represents
the field magnet, which consists in this instance of a permanent magnet, the poles
of which are cut away on the inside in the form of arcs of a circle, the space
between the poles being bridged across by means of non-magnetic material in such
a manner as to complete that circle, as shown at 1, 1; R represents a driving-wheel,
near the edge of which are placed pivots n, o, parallel with its axis. Upon the
pivots n, o, are mounted two revolving arinatures N, O, which are caused to rotate
upon the interior surface of the magnetic field formed within the magnet L by the
motion of the drive-wheel R. The revolution of the armatures N, O, upon their
own axes may be secured by any suitable mechanical means, or by merely allowing

page_text: them to come in contact with the interior of the metallic circle. It will be obvious
that the number of such armatures which may be used is limited only by the
dimensions or capacity of the wheel R.
In Figures 5 and 6 the armatures P, Q, are mounted upon one and the same
axis 2, which is carried near the periphery of the drive-wheel R. The magnetic
field is produced in this instance by a series of magnets S, T.
A. modification of the arrangement shown in Figures 1 and 2 consists in con-
structing all of the coils or helices stationary, also the cores of the magnets A and C.
The moveable parts will then consist of the core of the armature B and all of the
polar extensions or discs.
Another modification is shown in Figure 12, wherein the cores of the field
magnets A and C of Figure 1 are replaced by the two opposite poles of an electro-
magnet, upon which stationary helices A' and C are placed. The discs a2 and c
are placed upon the extremities of the poles and constructed to revolve in
magnetic contact with the armature D¹, which preferably is in the form of a.
Gramme ring. The electro-magnet may be constructed with yielding joints
at as and c
Figures 9 and 10 represent a method of applying the form of armature shown
in Figure 1 to a field magnet constructed on the plan of a double horse-shoe
magnet.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Sydney Pitt in the Great Seal Patent Office on the 26th January
1882.
SYDNEY PITT, of Sutton, in the County of Surrey. "IMPROVEMENTS IN
ELECTRIC GENERATORS." A communication from abroad by Simeon J. M. Bear,
of Mitchell, in the County of Mitchell and State of Iowa, United States of
America..
This Invention relates to machinery or apparatus which is employed for the
conversion of mechanical into electrical energy, which are known as magneto-
electric or dynamo-electric generators, the former term being applied more especially
to that class of apparatus in which a permanent magnet or magnets are employed
to produce the magnetic field in which the inducing armature revolves, while the
latter term is more properly confined to machines in which the magnetic field
is maintained by the inductive action of an electric current upon a mass of soft
iron.
In the construction of electric generators of this class it has hitherto been a
desideratum to arrange the poles of the moving armature in such a manner that
they approach as closely as possible to the poles of the field magnets in passing by,
without actually coming in contact with them, it being well known that the closer
the approximation of the poles the more powerful the magnetic induction between
them, and the greater the efficiency of the apparatus. Nevertheless it has in all
cases been found necessary to provide considerable space between the stationary
and moving poles of the system in order to guard against any possibility of their
being accidentally brought in contact when the machine is in rapid revolution, a
result which may occur either in consequence of the expansion of the metallic
parts when heated by the action of the current by the wearing of the bearings in
which the armature shaft revolves, or by the springing of the parts under the
influence of the powerful magnetic attraction developed between them. In either
case such contact not only arrests the action of the generator, but is liable to result
in great damage to the apparatus.
The object of this Invention is to enable a machine of this character to be con-
structed, in which the poles of the armature and the field magnets may be brought
into the closet proximity, or even into absolute contact with each other, without
lessening the efficiency of the machine, but, on the contrary, with the effect of
materially augmenting it.
The general principle of the Invention consists in so constructing, combining,
and organizing the armatures and field magnets with reference to each other that
the armatures or moving parts of the machine shall roll upon or revolve in contact
with the surface of the field magnets or fixed portions of the machine, or vice versa,
in contradistinction to the usual arrangement, in which the armatures revolve in
front of the field magnets. The Invention is capable of many different modifica-
tions, all of which however involve the essential principle of construction herein-
before referred to. Some of the most efficient of these will be hereinafter described.
The form of apparatus which it is preferred to make use of in carrying out the
Invention consists in general of two or more electro-magnets or permanent and
electro-magnets, mounted upon parallel axes in such a manner that the poles or
polar extensions of each shall rotate in either close proximity, or, preferably, in
actual contact with each other. In this construction a double leverage is made use
of, but by a simple change in the mechanical construction a single leverage may be
applied. This latter method consists in pivotting a cylindrical armature upon an
axis which is mounted near the periphery of a drive wheel having its axis of
rotation parallel with that of the armature. The rotation of the drive-wheel causes

page_text: the pivot upon which the armature is hung to describe a circle at every revolution
of the drive-wheel. An epicycloidal motion is thus produced by the combination
of the revolution of the arinature itself about the pivot of the drive-wheel and the
revolution of the armature about its own axis. The axis of the drive-wheel is
coincident with the centre of the magnetic field within which the armature
travels.
The form and construction of the field magnets and armatures, and their relations
to each other, are susceptible of various modifications. In the accompanying
Drawings several methods of applying the Invention are shown in connection with
various forms of armatures and field magnets which it may be found desirable to
use.
In the Drawings, Figure 1 is an elevation, showing the working parts of a
dynamo-electric generator embodying the improvements, and Figure 2 is an end
view of the same; Figures 3, 4, 5, 6, 7, 8, 9 10, and 12 represent various modifi-
cations of the apparatus; and Figure 11 is a detached view of a portion of the
mechanism shown in Figure 4.
Figures 1 and 2 represent respectively side and end elevations of one form of
construction, in which A, B, and C are three straight electro-magnets having their
respective soft iron cores parallel to each other. These are wound in the usual
manner with an insulated conducting wire, so as to produce opposite magnetic
polarity at the respective ends of each magnet. The cores of these electro-magnets
are provided with polar extensions a, a. A continuous coil or helix of wire may
be used for each core, but it is preferred to leave the central portion of the core
uncovered, as represented in Figure 1, since the magnetization of the core due to a
current traversing that portion of the helix would be comparatively small; while the
resistance of the conductor would be increased in consequence of its greater length.
Any desirable number of polar extensions a may be used; five are represented for
convenience in the Drawings. The spaces between the polar extensions are
preferably filled with some non-magnetic material b, b, so as to complete a solid
disc or wheel at each end of each of the magnets. The three magnets A, B, C, are
assumed to be mounted in a suitable frame, and supported thereby in such a
manner as to allow the revolution of each magnet about an axis concentric with its
core, with the solid polar discs or wheels at their extremities either in actual
contact or in close proximity to each other. Considering the central core B with
its coils as an armature, and the exterior magnets A and C as field magnets, the
like poles of the two latter should lie in the same direction, and be presented to
the armature. The angular positions of the polar extensions a, a, with reference to
each other are shown in Figure 2. It will be understood from this Figure that
whenever an extension upon the armature B is receding from a corresponding
extension upon one of the field magnets A or C, that another extension of the
armature is approaching a corresponding extension upon the opposite field magnet,
and vice versa. In this manner an equalization of the generating power at all
times is secured, and a consequent uniformity in the production of the electric
current.
•
The method of applying the motive power to the machine may be by means of a
belt from a steam engine or other suitable source of power to the pulley c, while
the friction of the surfaces, together with the mutual magnetic attraction exerted
by the poles of the field magnets and armature upon each other may be relied upon
to cause the field magnets A and C to revolve at the required rate of speed. If
preferred, each magnet may be provided with a pulley, and the motive power
applied through any well known mechanical device or devices. By employing
toothed wheels in the form of spur-gearing, the relative positions of the polar
extensions upon the different magnets may be maintained with absolute correctness.
If the extensions at one end of each of the cores are parallel with the corresponding
extensions at the opposite end of the same core, the opposite poles of the field
magnets will simultaneously come in contact with those of the armatures, thus
securing a temporary magnetic circuit or ring, and a consequent increase in the

page_text: magnetism developed therein by the current.
As the armature B is driven in one
direction, the field-magnets A and C revolve at an equal rate of speed in the
opposite direction, bringing the cores of the armature B in contact with the cores
of A and C alternately through the polar extensions a, a. Suitable commutators
of well known construction may be applied for producing a continuous current in
one direction. It is not necessary to the operation of the machine that the poles
should be in actual contact, but the distance between the armature and field
magnets may be varied, as found desirable for specific purposes, although the
currents produced are far more powerful when the parts are in actual contact.
A modification of this construction is shown in Figure 3, in which D represents
an armature constructed in the form of the well known Grainme's ring. The two
field magnets E and F are constructed upon the principle of the well known
Siemens armature. The field magnets E, F, may be permanent magnets, having
the spaces e, f, ordinarily occupied by wire filled with non-magnetic material, or
they may be electro-magnets, in which case the spaces are to be wound full of
insulated wire in the usual way. The armature and magnets of this system are so
constructed as to revolve in a manner similar to the first described form. As the
pole & comes in contact with the armature D, the non-magnetic portion of the field.
magnet F is in contact with the opposite side of the armature, and vice versa.
this manner a constant generating force is produced, as in the organization first
described.
In
The method of applying the motive power to this system is similar to that
described in connection with Figures 1 and 2. It is not necessary that the number
of magnetic bodies employed be limited to the three which I have shown; the
number may be varied as desired.
In Figure 7 is shown a method of combining one armature with one field magnet.
In this Figure the armature H consists of several electro-magnets h, h, wound in
the usual manner, and united in a ring in accordance with a well known form of
construction. The field-magnet I may be made up of permanent magnets i, i, or of
electro-magnets similarly constructed. The number and distance apart of poles at
the periphery of each of the rings is the same. The two rings are caused to
revolve in actual contact with each other, the direction of revolution of course
being opposite, as indicated by the arrows. Thus it will be seen that the
respective poles are brought into contact and separated from each other in succession
as they revolve. In the plan shown in Figure 8, a small Siemens' armature K is
substituted for the field magnet I, shown in Figure 7. This is constructed of such
dimensions that it will describe one-half of a complete revolution about its own
axis, between the passage of each consecutive pole of the armature H, so that its
opposite poles come in contact with the alternate poles of the armature H. It is
evident that the number of these field magnets may be increased so as to extend
completely around the armature H if desired.
In each of the organizations hereinbefore described, the armatures and field
magnets are mounted upon axes turning in stationary bearings, the relative
positions of which remain unchanged, and a double leverage is used in each case for
applying the motive power. An important modification of this arrangement
consists in the application of a single leverage. In Figure 4 is shown one con-
venient method of applying such a leverage. L represents the field magnet which
consists in this instance of a permanent magnet, the poles of which are cut away on
the inside in the form of arcs of a circle, the space between the poles being bridged
across by means of non-magnetic material in such a manner as to complete that
circle, as shown at l, L. R represents a driving wheel, near the edge of which are
placed pivots n, o, parallel with its axis. Upon the pivots n, o, are mounted two
revolving armatures N, O, which are caused to rotate upon the interior surface of
the magnetic field formed within the magnet L by the motion of the drive-wheel R.
The revolution of the armatures N, O, upon their own axes may be secured by any
suitable mechanical means, or by merely allowing them to come in contact with the
interior of the metallic circle. It is not necessary that there should be two

page_text: armatures N, O, as a single armature may be desirable in certain cases, and the.
particular form and construction of armature used may be varied in any desirable
manner. Figure 11 shows a method of mounting the armature N or Ŏ upon the
wheel R. It will be obvious that the number of such armatures which may be
used is limited only by the dimensions or capacity of the wheel R. It is preferred
as a rule to construct this form of generator with two or more revolving
armatures N and O, in order to secure a more uniform current by having the effect
of each separation counteracted by that of a corresponding approach of the poles.
The manner in which this is effected is shown in Figure +, where as the armature N
leaves the pole L', the armature L" approaches the same. Any well known system
of commutators may be applied to any of the forms of the Invention herein shown
in order to produce à continuous current.
Figures 5 and 6 illustrate a method of applying armatures similar to that
described in connection with Figures 1 and 2 to the single leverage system of
generators. The armatures P, Q, are mounted upon one and the same axis p which
is carried near the periphery of the drive-wheel R. The magnetic field is produced
in this instance by a series of magnets S, T, the poles of which converge towards
a common centre, the spaces between them being filled with non-magnetic material,
as herein before explained, in order to complete a cylinder, against the interior of
which the armatures revolve as the axis p is rotated by the motion of the drive-
wheel R. The polar projections R, as in the organization shown in Figure 1,
parallel with each other upon each of the armatures P and Q, but the extensions
of the armature P are in such a position with reference to the extensions of the
armature that as two of the former are receding from the poles of a field
magnet S two corresponding extensions of the latter are approaching a corre-
sponding field magnet T. In this manner a practically continuous current will
be secured. A completion of the magnetic circuit referred to in connection with
Figure 1 is obtained in a manner similar to that shown and described in connection
with the said Figure by causing the two poles of an armature to be brought
simultaneously into contact with the two poles of a field magnet.
A modification of the arrangement shown in Figures 1 and 2 consists in con-
structing all of the coils or helices stationary, also the cores of the magnets A
and C. The movable parts will then consist of the core of the armature B and
all of the polar extensions or discs. The polar extensions of the magnets A and C
revolve upon and in magnetic contact with their respective cores. The operation
of the machine so constructed will be the same as that described in connection
with Figure 1, with the exception that the helices and the cores of A and C will
not be revolved, and less power will therefore be required to operate the machine.
If desired the core of the armature B may also be stationary, and the discs revolve
at each end, though for convenience in applying the motive power the former
arrangeinent is preferred.
Another modification is shewn in Figure 12, wherein the cores of the field
magnets A and C of Figure 1 are replaced by the two opposite poles of an electro-
magnet, upon which stationary helices A¹ and C' are placed. The discs a² and c²
are placed upon the extremities of the poles and constructed to revolve in magnetic
contact with the armature D₁, which preferably is in the form of a Gramme ring.
The electro-magnet may be constructed with yielding joints at a³ and c³ to allow
of any displacement at the poles due to the expansion of the armature and polar
discs when heated by use. Any other suitable form of armature may replace the
Gramme ring represented. The polar extensions or discs in either of these cases
may be constructed with a continuous periphery of magnetic material, or with the
intervening spaces filled with non-magnetic material, according to the form of
armature used in any given case. They should in all cases have a good magnetic
contact with their respective cores or poles.
Figures 9 and 10 represent respectively side and end elevations of a method of
applying the form of armature shown in Figure 1 to a field magnet constructed on
the plan of a double horse-shoe magnet. U and V represent two electro-magnets

page_text: which are constructed with their like poles presented to and in contact with each
other. The poles are cut away at the point where they meet to form a circular
magnetic field, within which an armature B' is revolved. This armature is
preferably constructed with stationary helices b' and 2, through the centre of each
of which extends a soft iron core p¹ capable of being rotated within the stationary
helices. At either end of the core is attached a short crank of magnetic material,
upon the outer end of which a polar disc n² is pivotted. The length of the crank
required will depend upon the size of the polar discs. These are preferably con-
structed with a diameter about three fourths the diameter of the open magnetic
field. The polar disc should be pivotted upon the crank at such a distance from
the core as to bring their peripheries into contact with the surfaces of the field
magnets. The movement of each disc will in this instance be similar to that
described in reference to Figure 5, that is, epicycloidal. The motive power may
be applied to the core at a point på between the two helices. The magnets U and
V may be constructed with continuous poles, as shown in the Drawing, and with
lateral openings on each side of the space in which the armature revolves to allow
the air to circulate and provide against over heating. One advantage resulting
from combining the armature with this form of field magnet is the short circuiting
of the magnetic ring by the simultaneous contact of the polar discs with the opposite
poles and u² or v¹ and v². This modification in the form of the armature also
has especial advantages in that it allows the disc to be revolved and the changes
in magnetism to be secured without requiring any motion of the helices. It is
obvious that this form of armature may be adapted to various other forms of field
magnets; for example, in Figure 5 a large magnetising helix may be employed,
filling nearly the entire space between the poles of the field magnet, and the polar
disc or extensions may be revolved against the surfaces of the. field magnets
without necessitating the expenditure of power in revolving the helices themselves.
It may be found desirable in some instances to attach counter weights to balanco
the weight of the polar disc.
In all the modifications which have been herein before described, the field magnets
may be either electro-magnets or permanent magnets, whose magnetism may be
increased by winding them with coils and conducting through these coils the
current induced by said permanent magnet. It will be readily seen also that it is
not absolutely necessary in any case that the magnet poles or polar extensions
should come into actual contact with each other, though it is preferred that
construction for reasons herein before set forth. In order to secure concurrent
movement of the armatures where the field magnets as well as the armature
revolve any well known mechanical means may be adopted. I do not propose to
limit myself to the precise mode of construction or to the particular mechanical
combinations shown in the accompanying Drawings, for the Invention may be
readily adapted to a variety of the well known forms of armatures and field
magnets. The advantages of the system of construction will be readily seen to
consist in the close proximity into which the poles of the field magnets and
armatures are temporarily brought, and in the distance to which they are afterwards
separated, and in the mechanical organization which enables the poles to be brought
into actual contact with each other without abrasion or friction. Another advantage
consists in the economical consumption of motive power which may be secured by
this method of application. This is the necessary result of the epicycloidal
movement of the generating armature within a circular magnetic field, thus
interposing a compound leverage between the power and the resistance due to the
magnetic attraction which it is required to overcome. A third important result
due to the bringing the poles into actual contact is the completion of the magnetic
ring or circuit, as shown in connection with Figure 1, whereby increased magnetic
capacity is secured, which is accompanied with a corresponding increase of
generating force and of dynamic electricity produced thereby.
I claim as the Invention,―
First. The improved method of converting mechanical into electrical energy,

page_text: herein before set forth, which consists in causing the poles of the armature of the
generator to roll upon or revolve in contact with the poles of the field magnet in
contradistinction to rotating in proximity thereto.
•
Second. The combination, substantially as hereinbefore set forth, of one or more
field magnets, an armature, and mechanism for placing the armature temporarily in
contact with the poles of the field magnet.
Third: The combination, substantially as herein before set forth, of a constantly
polarized field-magnet, an armature surrounded by a magnetizing helix, and
mechanism substantially such as described, whereby the field-inagnet and armature
are caused to roll one upon the other.
Fourth. The combination, substantially as hereinbefore set forth, of a core
surrounded by a magnetizing helix and a series of radial polar extensions at each
end thereof, the ends of which form arcs of a circle concentric with the axis of the
core.
Fifth. The combination, substantially as herein before set forth, of a field magnet
and an armature, each consisting of a core surrounded by a magnetizing helix, and
a series of radial polar extensions at each end thereof, the ends of which form arcs
of circles concentric with the axes of their respective cores.
•
Sixth. The combination, substantially as herein before set forth, of an armature
and two or more field magnets, said armature and magnets each consisting of a
core surrounded by a magnetizing helix, and a series of polar extensions at each
end thereof, the ends of which form arcs of circles concentric with the axes of
their respective cores.
Seventh. The combination, substantially as hereinbefore set forth, of an
armature, a field magnet, and mechanism for simultaneously bringing into
contact and simultaneously separating the opposite poles of the armature and the
field magnet.
Eighth. The combination, substantially as herein before set forth, of a stationary
magnetizing helix, a core rotating concentrically therein, crank-arms on said core,
and polar extensions of said core revolving on said crank-armus eccentrically with
reference to said core.
Ninth. The combination, substantially as herein before set forth, of a core
surrounded by a stationary magnetizing helix, and a polar extension at each end
thereof revolving concentrically with the core.
Tenth. The combination, substantially as hereinbefore set forth, of two stationary
helices, each surrounding a core, said cores being in magnetic contact with each
other, and a revolving polar extension at the end of each core.
Eleventh. The combination, substantially as hereinbefore set forth, of two
stationary helices, each provided with a core, the said cores being in magnetic
contact with each other, a revolving polar extension at the end of each core, and
an armature for placing said polar extensions simultaneously in temporary
magnetic contact with each other.
In witness whereof, I, the said Sydney Pitt, have hereunto set my hand and
seal, this Twenty eighth day of December, in the year of our Lord One
thousand eight hundred and eighty one.
SYDNEY PITT. (L.S.)