Improvements in Electric Motors.
Year: 1894

page_text: Date of Aplication, 24th Feb., 1894-Accepted, 14th Apr., 1894
Improvements in Electric Motors.
A communication by THE RIES ELECTRIC SPECIALTY COMPANY, of South
Broadway, Baltimore, in the County of Baltimore and State of Maryland,
United States of America.
I, WILLIAM PHILLIPS THOMPSON F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool and 6, Bank Street,
Manchester, both in the County of Lancaster and 323 High Holborn in the
County of Middlesex, Civil Engineer, 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 :-
This invention has reference to Improvements in Electric Motors, designed
primarily to be operated by single phase alternating currents such as are
derived from ordinary lighting circuits, but which motors are also capable of
being operated by two- and multi-phase alternating currents, as well as by
continuous or straight current:
As a single phase alternating current motor, this machine is distinguished from
those heretofore known in that it is self starting under any load, and will run with
any speed with great power and efficiency, without heating. The speed can be
regulated at will and the motor can be reversed almost instantaneously, whereby it
is particularly adapted for the propulsion of vehicles.
Another important feature of the motor, arising from the peculiar and novel
principle of its construction, is that it can be efficiently operated on alternating
current circuits of comparatively high frequency thus permitting great economy
in the use of the current and in the weight of iron and copper in a motor of a
given output.
In alternating current motors heretofore constructed, the most serious difficulty
experienced was that by reason of the great counter-electro-motive force generated
in the coils of the motor, the amount of current which could be passed through the
motor was very small in comparison with the size of the motor, so that these motors
had to be made much larger than straight current motors of the same power. This
difficulty was so great that it became impracticable to build and run alternating
current motors of sufficient power to work heavy machinery and especially for
electric locomotion.
Self starting, non-synchronous, single-phase alternating current motors could not
heretofore be made, with the exception of motors of exceedingly small powers
operating with low efficiency; but as soon as these types of motors were attempted
upon a larger scale, the excessive self induction of the same would invariably prevent
the passage of sufficient current. Other difficulties present itself in the operation
of such motors, due to the imperfect magnetic circuit and great leakage of the
magnetic lines of force, and these difficulties increase with the frequency of
alternations of the current and with the size of the motor.
With this invention these imperfections are very greatly reduced, if not entirely
abolished, and more especially, is the self induction of the motor, reduced to
a minimum, whereby a large amount of current is allowed to pass through the
motor, and the efficiency of translation of the current into motive power largely
increased, so that the size of the motor, for any given power, need not be larger,
and in many cases may be smaller than that of a continuous current motor having
the same power.
These results are accomplished by the employment of two or more sets of

page_text: subdivided field and armature magnets arranged to form substantially closed
magnetic circuits of exceedingly short length; by so arranging the field and
armature magnets that they have the relation of a divided or two-part transformer
or transformers, in the preferred type of. which, however, the windings of the two
parts are connected in serics,, the moving portions of these divided magnets being
rotated under the action of two or more progressively shifting fields, in such manner
as to simultaneously exert the rotating effort at different circumferential points; by
so winding and locating the subdivided magnets that their energizing coils are in
such inductive relation to each other as to neutralize or counteract the self-
induction of the coils, thereby allowing a practically unrestricted flow of current
and permitting the generation of an exceedingly intense magnetic field, by
distributing the magnet windings over a large number of independent laminated
cores of comparatively small cross section instead of winding them upon a few
massive cores of large cross-section; and lastly by practically eliminating the
losses due to hysteresis and eddy currents in the iron by maintaining the iron of the
field and armature magnets, or a portion thereof, in a continuous state of stress or
magnetic neutrality and thereby transferring the energy that would thus be wasted
into useful work in the coils of the motor. These are the principal features of the
improved motor and it is found in practice that the fundamental idea of the invention
may be embodied in a variety of ways.
In one type of the motor is employed both attraction and repulsion of the field
magnets upon the armature magnets; in another type the attractive force only is
employed to produce rotation. In one form of the motor each field magnet system,
or in some cases the armature magnet system may be subdivided into a large
number of sections or poles, thereby producing a slow-speed motor, developing a
high torque, such as is required for railway and power work; while in another
form of the motor, the field or the armature system is subdivided into a lesser
number of sections, thus obtaining high speed with correspondingly diminished
torque, as is suitable-for example-for operating small ventilating fans. In some
cases, especially in larger motors running under variable loads, where self
regulation is desirable, both the fixed and the rotating elements are provided
with suitable windings which are usually connected in series with each other; in
other cases, either the fixed or the movable element of the motor is alone provided
with a winding. In the first case the motor after self-starting, will run up
to synchronism with the generator, at which point it will tend to remain, and in
the latter case the motor will run at any desired speed, either below or above
synchronism.
From all this it will be seen that motors constructed in accordance with the
invention may be of many different types and therefore it is to be understood
that the invention is not limited to the specific forms and construction herein
shown and described.
All this will more fully appear from the following detail description with
reference to the accompanying drawing in which :-
Figure 1, represents an end view of one form of the motor with the pulley for
transmitting motion removed.
Figure 2, is a vertical axial section of this motor ;
Figure 3, represents a central transverse section of the same;
Figure 4, a perspective view of a portion of one armature core and head, with
the commutator brush mounted on the latter;
Figure 5, perspective views of details of one shaft bearing and lubricator.
Figure 6 is a perspective view of one field magnet;
Figure 7, is an end view of the commutator;
Figures 8 and 9, are diagrams showing two forms of winding and connection
of the field magnets and
Figure 10, is a longitudinal section of the commutator and its support.
Figure 11, is a diagram illustrating the field magnet connection and commutator
of another type of motor embodying the invention, and

page_text: Figures 12 and 13, represent perspective views of different forms of field
magnets and armature cores or armature magnets.
Like numerals of reference indicate like parts all throughout the drawing.
'The invention will be first described with reference to the structures illustrated
in Figures 1 to 10, inclusive.
The armature of the motor is composed of a series of laminated iron cores 1, the
lamine of which are magnetically separated, either by special insulations, such as
sheets of paper or by the natural or artificial oxides covering the surfaces of the
laminæ. These laminæ extend across the motor in a direction parallel with the
motor shaft and are made quite thin and of the softest sheet iron, and by preference,
of iron that is free of carbon, although it is found that sheet steel will in many
cases answer the purpose quite as well. The shape of an element of these cores is
shown in Fig. 2, where it is represented as a plate which in the main is a rectangle,
with a rectangular recess 2, cut in the middle of one side, and a dove-tail notch 3,
at each end. A number of such blanks are assembled in the manner shown in
Fig. 4, to form a prismatic body, and they are bound together by a thin tape,
which in the drawing has been omitted for the sake of clearness of illustration.
These individual armature core sections 1, are mounted between two heads 4, 5,
each formed with a wedge-shaped circumferential flange 6, which matches the
dove-tail notches 3, and with a hub 7, through which the armature shaft 8, passes.
The head 4, is keyed to the shaft, while the hub of the head 5, passes loosely upon
the shaft, which is screw-threaded at that point, as shown, and a nut 9, clamps this
head and the core sections together. The thickness of the core sections is such
that when a certain number of them are radially mounted between the heads, their
inner edges 10, are in contact, as shown in Figures 2 and 3, while their outer
edges 11, 11, are widely separated.
The recesses 2, of the laminæ, form in the aggregate a circumferential channel
in the assembled core sections, and in this channel is wound a single coil 12, so that
the armature becomes a bar electro-magnet, composed of individual prismatic
groups 1, of laminæ, each group in magnetic contact with the adjacent groups
along the two inner edges only, while the lamina of each group are magnetically
separated. The assembled edges. 11, 11, of the lamina constitute at the outer side
of each end of each core section a polar projection 13, and since all core sections
are energized by the same coil 12, the polar projections at the same end of the
armature will be north or south-magnetic at the same time; these polar
projections will henceforth be called the "armature poles."
In the drawings are shown ten armature core sections, but any other number
may be used as will appear further on.
In accordance with the invention this type of motor has three times as many
field magnets as there are armature core sections; in the instance here shown there
are consequently, thirty field magnets 14, formed and mounted as shown in Figs. 2
and 6. It will be seen that each field magnet core is shaped exactly like the
armature core sections, built up of lamina formed with central rectangular
recesses 2', and dove-tail notches 31. Each of these field magnets has a separate
winding 15, and all these field magnets likewise extend across the motor in a
direction parallel with that of the motor shaft and are mounted between
beads 16, 17; these heads are made of non-magnetic material and are formed with
annular wedge-shaped flanges 18, which engage the dove-tail notches 3 of the
field magnets, and the heads are held together and clamp the field magnets between
them, by means of binding rods 19, 19, 19, passing through ears 20, 20, 20, on the
heads. The heads are also shown as formed with feet 21, 21, to support the
machine, but this feature is only an incident, and is omitted or changed as circum-
stances may require. Owing to the central position of the recess 2', each field.
magnet has two polar projections 22, 22, corresponding to the like polar
projections 13, of the armature core sections, and the dimensions of the parts are ·
such that the armuture pole faces are exceedingly near the field pole-faces, only;
sufficient clearance. being left to insure-freedom of motion of the armature:

page_text: Owing to this close proximity of the armature and field pole faces as well as
their respective length, and owing to the fact that each armature core and each
field core is a straight and comparatively short magnetic prism, the resistance to
the passage of the lines of force or the reluctance for each field .core when the
armature and field poles are similarly energized, is increased to a maximum, and
when dissimilarly energized is reduced to a minimum; indeed for all practical
purposes it may be said that the magnetic circuit, although in two parts, is
normally complete or closed so that there is no, or practically. no, leakage of
magnetic lines of force and thus both the opposing and attracting forces are used
to their fullest extent.
The field magnets are mounted radially, like the armature core sections, with
this difference, that while in the latter the polar extensions are turned outwardly,
these are turned inwardly in the case of the field magnets, and in the type of motor
now under consideration, they are so crowded together that the side edges of the
adjacent pole extensions are either actually in contact, as shown, or are very close
together. The proportionate thickness of the field core and armature core sections
is such that each pole extensions of the latter faces one and one-half polo extensions
of the former as shown in Figure 3.
Owing to the great number of field magnets, and notwithstanding the radial.
position of the same, the sides of any two consecutive field magnets and the coils
of the same are very nearly parallel to each other and are so close together that,
when any two magnets or sets of magnets are simultaneously energized by the
field current, each will act inductively upon the other. This is an important
feature of the invention as will appear further on.
To the face of the head 16, is screwed a circular hood 23, and to the face of the
head 17, is secured a similar but deeper hood 24, and either secured to or in one
piece with these hoods are the cups 25, 26, respectively, in which the shaft
bearings 27, 28, are nounted, as shown. One of these bearings 27, together with
its appurtenances is shown in perspective in Figure 5; it is a cylindrical sleeve
with a flange 29, at one end, and formed with two diametrically opposite, wide
slots 30. This bearing 27, is fixed in any suitable manner in the cup 25, so that
its axis is in alignment with the axis of the hubs of the two heads 5, 6. The
bearing 28, is represented upon a somewhat enlarged scale; in section, in Fig. 10;
it serves at the same time as a means for holding the commutator 31.
These parts
are constructed as follows:
The bearing 28, is a cylinder, formed with a flange 29', which in this case is
intermediate between the two ends, and at one end the cylinder is screw-threaded
for the reception of a nut 32. This cylinder is bored out, with a wide bore 33,
and a reduced bore 34, as shown, and the armature shaft 8, is stepped at one end
so as to fit the stepped bores of the bearing 28, and is thereby prevented from
shifting laterally toward the right.
Between the flange 29', and the nut 32, the commutator 31, is mounted upon the
cylinder 28. This commutator may be constructed in any suitable manner, but is
shown in the drawing as composed of a series of metal bars 35, each formed with
two dove-tail incisions on the underside, as shown, and these metal bars are
assembled and clamped between two insulating heads 36, 36, each formed with a
circumferential wedge-shaped flange 37. The commutator bars 35, are separated
by thin sheets of mica or other suitable insulating material, as usual. The bearing
cylinder 28, has also two diametrically opposite wide slots 30' similar to the
slots 30, in the bearing cylinder 27. The cylinder 28, is journalled in the end
walls of the cup 26, as shown, and a rod 37, projecting from the cylinder
and provided with a handle 38, permits this cylinder, and with it the commutator,
to; be turned in either direction to a limited extent. The rod 37, may engage a
rack fixed to the face of the hood 24, or may be held in any adjusted position,
by any other well known means. Ordinarily, it will be sufficient to make the
rod 37, elastic and so mount it on the cylinder 28, as to bear with considerable
friction against the face of the hood 24; for this reason no special means for
"

page_text: helding the commutator in its adjusted positions are illustrated. In the cups 25, 26,
the lubricating oil for the armature shaft is poured, and is kept at a level below
the bearings 27, 28; in these cups is placed a suitable looped wick 39, which
loosely embraces the bearings, with its two ends reaching into the slots 30, 30',
where they are held and are gently pressed against the armature shaft, by an
elastic wire clip 40. The loop of the wick dips into the lubricator oil and the
latter rises in the wick by capillary action. To the head 5, is secured, but
insulated therefrom, an elastic brush holder 41, in which the brush 42, is so
mounted, that it bears upon the face of the commutator with moderate pressure.
There are as many commutator bars as there are field magnets, consequently in the
instance here shown there are thirty commutator bars, and they form three groups;
the bars belonging to one group are marked 35*, those belonging to the next
group 35, and those belonging to the third group are marked 35. The commutator
bars belonging to the same group are all connected by wires 43, or in any
other suitable manner. From each group of these commutator bars extend a
wire 44, 44, 44%, respectively, for connection with the field maguet coils, and
from the brush holder 41, extends a wire 45, for connection with one terminal of
the armature coil, the other end of which is connected by a wire 46, to a collector
disk 47, mounted upon but insulated from the face of head 4, as shown in Figure 2.
Upon this collector disk 47, bears a spring brush 48, which is secured to an
insulated binding post 49, mounted upon the hood 23; upon this hood is also
another insulated binding post 50, to which the wires coming from the field
magnets are connected, as will appear further on, and from the binding posts 49, 50,
the leading conductors 51, 52, extend.
The diagram, Figure 8, illustrates one mode of connecting the field coils, and at :
the same time the whole internal circuit of the motor.
The thirty field magnets are formed into three groups, corresponding to the three:
groups of commutator bars, and the magnet cores and coils are marked according
to the groups to which they belong with the reference numerals 14ª, 14, 14%,
nd 15, 15, 15%, respectively. The coils 15, are all connected in series, by the
wires 53, the coils 15b, are connected in series by the wires 53b, and the coils 15,
are connected in series by the wires 53°. The series of field coils 15" has one end
connected to a commutator bar 35ª, by means of the wire 44; the series of field
coils 15 has one end connected with a commutator bar 35, by means of the
wire 44, and the series of field coils 15, has one end connected to a commutator
bar 35, by means of the wire 44°. The other ends of these three series of coils
are formed by the wires 54", 54, 54, which are united upon one conductor 55,
which in turn is connected to the binding post 50.
The commutator brush 42, is of a width equal to the width of one commutator
bar plus the thickness of two insulating partitions between these bars; the result
of, this construction is that, as the brush rotates, it will bear, during by far the
greater portion of the time, upon two commutator bars, only during exceedingly
short intervals upon a single bar, and never upon three bars. The intervals during
which the brush bears upon a single commutator .bar only, are so very short that
they may be disregarded, and for all practical effects the construction may be said
to be such that the brush always bridges two commutator bars.
The circuit through the motor can now be readily traced, by reference to
Figures 2 and 8.
The currents entering by leading conductor 51, and binding post 49, proceeded
by spring 48, collector disk 47, and wire 46, to and through the armature coil 12;
leaving this coil by conductor 45, Figure 2, they proceed by brush holder 41, and
brush 42, to the commutator 31. Since the brush bears upon two adjacent com-
mutator bars, the current divides at the commutator and passes in two parallel
branches through two of the three series groups of field magnet coils, leaving the
same by two of the three wires 54", 54, 54, and by conductor 55, binding post 50,
out by leading conductor 52.
:
Since the operation of the motor is the same, whether the current flows..in. one

page_text: direction or the other, the alternations of current may be disregarded in contem-
plating, at this stage, the polarities developed and their reactions; it is, therefore,
admissible to consider the current as a straight or continuous current. Under this
assumption it will be seen that the armature poles at one end will all be north-
magnetic, and those at the other end south-magnetic, while the corresponding poles
of the two series of field magnet cores through the coils of which current is flowing
at a given moment, will likewise be north-and-south, magnetic, respectively.
From the construction of the machine it follows that there are always, or practi-
eally always, pairs of field magnets directly energized by the current through their
coils, separated by single field magnets which are not directly energized by the
current.
Supposing now, that the current be turned on when the armature and field poles
are in the relation shown in Figure 3, and that the commutator at that moment be
.so adjusted that the brush is in contact with two bars of the series 3, and 35.
In that case the field magnets 14" and 14b, will receive current, while the
magnets 14, will be apparently idle. The resultant magnetic meridian (or polar
line) of any of the pairs of field magnets 14", 14, pass through the contacting
edges of the same, while the polar lines of the armature sections bisect the width
of these sections.
At the phase of operation here considered, each armature pole covers a field
pole 14 entirely and in addition thereto one half of a field pole 14%, so that the
pelar lines of the energized pairs of field magnets and of the corresponding sections
of the armature do not coincide, but are separated by a small are (an arc of three
degrees) from each other. The consequence of this is that the armature sections
are repelled by the field magnets 14", 14, and attracted by field magnets 14°, and
the armature rotates in the direction of the arrow indicated, until the poles of the
armature fully cover the poles 14 of the field magnet. At the same time that the
armature poles are repelled by the electrically energized field poles 14", 14b, they
are also attracted by the intermediate field poles 14. These latter are acted upon
by magnetic induction both by the adjacent field poles 14", 14, as also by the
nearest armature poles, receiving from both polarity which is opposite to the
polarities of the adjacent field poles and the armature poles ;, thus it will be seen
that the latter will be attracted by the field magnets 14° so as to produce motion in
the same direction in which they are repelled by the field magnets 14ª, 14b.
The armature is thus acted upon by all field magnets at the same time, so that
there are in reality no idle field magnets. At the moment when the armature poles
fully cover the poles 14 of the field magnet, the armature brush leaves the com-
mutator bar 35, still remaining on bar 35, and passes on to the bar 35º, whereby
current is now admitted to the coils of field magnets 14" and 14" and the poles of
the field magnets are shifted accordingly. Field magnets 14" and 14%, now act
upon the armature by repulsion, while field magnets 14ª, now act by attraction.
When the brush passes on to the next commutator bar, the field magnets 14 and 14ª
act by repulsion and field magnets 14 act by attraction, and so forth.
It will be seen at once that the direction of rotation of the armature depends
upon the position of the commutator bars with reference to the field magnets. If,
when the machine is in the condition shown in Figure 3, the commutator were so
.shifted that current is first admitted to the coils of field magnets 14" and 14°, the
armature would rotate in the opposite direction; so that by a very small shift of
the commutator the motor can be reversed. It will also be clear, without further
explanation, that at intermediate positions of the commutator the motor will run
with reduced speed, but with greater power.
There is one critical position of the commutator with reference to the field
magnets and the armature sections, when the motor cannot start. This position is
that which, sends current to such pairs of field magnets with the resultant polar
lines of which the polar lines of the armature sections coincide, when the armature
is at rest; it is then only necessary to shift the commutator to the right or to the
_left, no matter how little, in order to start the motor in one or the other direction.

page_text: This is a peculiarity of the motor which permits the stopping and reversing of the
same without breaking the circuit, for when, while the motor is running, may be
at its highest speed, the commutator is turned to the critical position, the armature
rapidly slows down and comes to rest; and if the commutator is turned beyond
the critical position, the armature will at once turn in the opposite direction::
It requires no further explanation to see that alternating currents will act upon
this motor precisely the same as straight currents, since the armature coil is in.
series with the field magnet coils, so that the relations of the polarities remain
unchanged. In fact this motor, while well adapted to be worked with straight.
currents, is particularly and especially useful with alternating currents owing to
the novel and peculiar reaction between the armature and field magnet system:
which its construction provides and which we have found by actual test are of such
a. nature that it heats only very moderately even after long continued use under
heavy loads.
A very important feature of the invention is the small angle at which the
adjacent field magnets, and consequently field magnet coils are inclined toward
each other. This is owing to the fact that there are a comparatively great number
of field magnets of rather small cross-section, crowded together as closely as
practicable so that the adjacent sides of the field coils are very nearly parallel..
It is within the invention to make these coils perfectly parallel, in which case, of
course, the magnet cores instead of being rectangular in cross section, will be
segmental. By reference to Fig. 8, it will be seen that the currents passing
through the coils of the field magnets are in opposite directions in the adjacent.
sides of any two adjacent magnets, and we have found that from this results a
partial or complete neutralization of self induction of each magnet coil. The-
practical result of this is that the counter electro-motive forces which otherwise-
would be generated in these coils when.alternating currents are passed through the
same, are very greatly reduced, so that a far greater amount of current can now
be passed through these coils. This neutralization of self induction, therefore, is
due to the close inductive proximity of the adjacent magnet coils, to the parallelism,.
or nearly parallelism of these coils, and to the fact that the currents pass through
the adjacent sides of the adjacent magnets in opposite directions: The counter-
electro-motive forces, will therefore, be reduced so much more as these conditions.
are more closely fulfilled.
It will further be seen that since the armature, during a great portion of its.
rotation, is acted upon by repulsion from the field magnets, both the field and the
armature magnets are, when in repelling relation, partly neutralized by each other,.
that is to say, they present poles of the same name to each other and are at these
times approaching the condition of magnetic neutrality, as if they were of non-
magnetic material, and therefore very little counter-electro-motive force is generated
in their coils, which consequently will permit an unimpeded flow of effective current
through the same.
It has been found by practical experience that an alternating current motor
built in this manner will permit the passing of a much greater amount of current
than has heretofore been possible, and as a result of this a motor of a given size-
constructed in accordance with the invention develops' much greater power than
otherwise alternating motors of the same size.
As a result of this construction, as well as the fact that the magnetism between
the opposing field and armature poles is under a continual state of opposing or
neutral stress, the frequency of the alternating current can be very much increased
and may be almost disregarded.
}
Another mode of connecting the field coils is indicated in Figure 9. The coils
of magnets 14° are connected in one closed circuit by the wires 53, and the coils.
of magnets 14 and 14° are similarly connected in independent closed circuits, by
the wires 53 and 53, respectively. At diametrically opposite sides these three
closed circuits are tapped by the wires 44*, 44°, 44° and 54*, 54, 54°, respectively,

page_text: the former leading to the groups of commutator bars 35", 35, and 35°, respectively.
while the latter are joined upon the conductor 55, which connects with the binding
post 50.
With this construction each group of field magnet coils is split into two parallel
series, whereby the internal resistance of the motor is considerably reduced, and it
will be evident to those skilled in the art, that the division of the field coils into
multiple series may be carried still further.
It will be evident to those skilled in the art that it is not absolutely necessary
that the armature cores be provided with a winding, or that a single winding
common to all the armature core sections, be used; for it is quite practicable, and
for certain purposes, even desirable, that the armature cores are left bare without
winding, in which case the motor will work purely by magnetic attraction, and it is
equally practicable to provide each armature core section with a separate coil, in
which case these coils may be connected either in series or in multiple arc, but
preferably in series with the field coils.
It has been found by actual work that when the armature cores in the arrange-
ment and with the connection of magnets shown in Figure 8, are provided with a
coil or coils, the armature, when started will run up to synchronism with the
generator, with a slight tendency to maintain synchronism, while when there are no
coils on the armature, there is no tendency towards synchronism, and the motor
works equally well with any speed.
In Figure 11, is illustrated another mode of connecting the field coils and
consequently another mode of carrying current to and from the same.
In this case the conductor 55; which leads to the binding post 50, is directly
connected to a single circular distributing wire 53, from which multiple arc branches
pass to all the magnet coils, as shown; the other ends of these coils being connected
by wires 44, each to one commutator bar. There are in this case two or more
commutator brushes 41, as will presently be seen. If only two commutator brushes
are used, as shown in solid lines, they are disposed for contact at diametrically
opposite sides of the commutator. These brushes are connected by a conductor 41',
from which the wire 45, leads either to one terminal of the armature coil or coils,
if such are used, as in the constructions heretofore described, or directly to the
collector disk 47, when no armature coils are used. In the drawing the brushes 41,
are shown of such width that they extend over three commutator bars and over the
insulations separating the terminal bars from those beyond them. With this
construction, it is evident that most of the time there will be current through two
sets of four field magnets, and only during exceedingly short moments through two
sets of three field magnet coils. Now it is within the invention to give to these
brushes any desired width; thus each brush may be expanded so as to cover one-
half the number of commutator bars minus one, or each brush may be made so
narrow as to cover only one bar.
.
In the drawing is shown in dotted. lines an additional set of brushes 41", each
spanning only two commutator bars, and these brushes may be used either alone or
together with the brushes 41, and any additional number of pairs of commutator
brushes may be used.
It will be seen that in this manner one is enabled to adapt the motor either for
low speed and great power or for high speed and small power by simply changing
either the width or the number of pairs of commutator brushes, or both.
In Figures 12 and 13, are illustrated modified forms of field and armature cores,
in which the magnetic resistance is reduced to a minimum, and which provides a
double magnetic circuit.
:
In Figure 12, the cores are E-shaped with a coil on the middle bar of the E of
each field magnet, while the armature core is represented bare, that is to say;
without a coil, although, as has heretofore been explained it may also have a coil
upon its middle bar. In this case at any given moment one pole of the magnet is
at the middle bar while the other is found in the two end-bars, so that there is a

page_text: double magnetic circuit, and each branch, being very short, has an exceedingly
low reluctance. The middle bar is of such length that a large proportion of the
coils are in inductive parallelism.
In Figure 13, the cores are also E-shaped, but in this case the middle bar as well
as the end bars are dovetails; whereby the reluctance is still further reduced. In
this construction there are two coils 15, 151, on the main stem of the E, one
in each space between the middle and end-bars. These two coils must be wound'in
opposite directions in order to produce the same polarities as are produced in the
construction shown in Figure 12, as will be readily understood by those skilled in
the art.
The field and armature sections may be assembled either in the manner shown in
Figure 2, or in any other convenient manner.
From what has been said it will be apparent that numerous other modifications
may be made without departing from the fundamental ideas upon which the
invention is based, and it is therefore not confined to the identical forms of motors
hereinbefore described.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, as communicated to me by
my foreign correspondents, I declare that what I claim is :-
1. An alternating current motor, having two or more sets of laminated circularly
arranged field magnets, and a laminated armature concentrically arranged with
respect thereto, the laminations of the said field magnets and armature extending
across the motor in a direction substantially parallel with the armature shaft,
substantially as described.
2. An alternating current motor composed of two or more sets of sectional,
laminated and circularly arranged field magnets, a concentric, sectional, laminated
armature and a commutator for shifting the polar lines of the field by sections in
regular succession, substantially as described.
3. An alternating current motor having two or more interlaced sets of circularly
arranged field magnets, with the energizing coils of each set in such relation to the
coils of the adjacent set or sets as to reduce the counter electro-motive, force of
self-induction of the current flowing in the same, by the inductive action of
the current flowing through the coils of the adjacent set or sets, substantially as
described.
4. An alternating current motor having a number of sub-divided circularly
arranged field magnets whose energizing coils are in inductive proximity to each
other, and circuit connections for passing the energizing current or currents
simultaneously through the coils of adjacent magnets or subdivisions thereof in
such a direction that the current in one coil tends to oppose or neutralize the self
induction of the current in the adjacent coil, substantially as described.
5. An alternating current motor, having a number of interlaced sets of circularly
arranged field magnets, with the adjacent sides of the coils of adjacent sets substan-
tially parallel and in inductive proximity, and circuit connections for passing the
energizing currents simultaneously through the adjacent sides of two or more sets
of the field magnet coils in opposite directions whereby the flow of. alternating
energizing currents to the field magnets is increased, substantially as described.
6. An electric motor having two or more sets of field bar electro-magnets
circularly arranged with their polar ends facing inwardly and their line of direction
or length extending parallel with the motor shaft, and an armature composed of
circularly arranged bar-sections whose poles are in close proximity to the poles of
the field bars and whose line of direction or length is likewise parallel with the
armature shaft. whereby the magnetic lines of force of each magnet traverse
the armature bars through a magnetic circuit of low reluctance and in a direction
at right angles to the direction of rotation of the armature, substantially as
described.
7. An electric motor composed of a number of interlaced groups of parallel bar
R

page_text: field electric magnets circularly arranged, with their polar ends facing the
armature and their line of direction extending parallel with the motor shaft, a
similar group of armature sections likewise extending parallel with the motor shaft,
and a commutator for passing current through two or more adjacent groups of field
magnet coils in progressive succession, substantially as described.
"
8. An electric motor composed of three interlaced groups of parallel field bar-
electro magnets, circularly arranged and in inductive proximity to each other, an
armature having a circular series of as many parallel sections as there are field
magnets in each group, and a commutator and brush for passing current through
two adjacent groups of field magnet coils in progressive succession, in such a manner
that the groups of field magnets act upon the armature by attraction and one group
by repulsion, substantially as described.
9. An electric motor composed of three interlaced groups of field electro-magnets,
circularly arranged, each group connected in one series or in a number of parallel
series, an armature having as many core sections as there are field magnets in each
group and a magnetizing coil or coils for the armature, in series with the field coils,
and a commutator for passing current through two adjacent groups of field coils in
progressive succession, substantially as described.
10. An electric motor having a field composed of three interlaced groups of
parallel laminated bar electro-magnets, circularly arranged, with their like poles at
their like ends and each group connected in one series or in a number of parallel
series, an armature having as many parallel core sections as there are field magnets
in each group, a magnetizing coil or coils for the armature in series with the field
coils, and a commutator for passing current through two adjacent groups of field
coils in progressive succession, substantially as described.
11. An electric motor composed of three interlaced groups of parallel bar-electro-
magnets normally having their like poles at their like ends, and in inductive
proximity to each other, and constituting the fields of force of the motor, each
group connected in one series or in a number of parallel series; in combination
with an armature formed of as many laminated parallel bar sections as there are
field magnets in each group, a magnetizing coil or coils for the armature in series
with the field coils, and a commutator for passing current through two adjacent
groups of field coils in progressive succession, substantially as described.
12. An alternating current motor having two or more sets of sectional field bar-
electro-magnets, circularly arranged, whose poles, when directly energized, are of
like denomination at each end and of opposite denomination in the middle, and an
armature composed of circularly arranged bar sections in close proximity to
the poles of the field bars, whereby the magnetic lines of force of each magnet
form two short parallel circuits of normally low reluctance, substantially as
described.
13. In an electric motor, the combination of a field magnet system composed of
two or more sets of circularly arranged bar magnets, each provided with a separate
winding, an armature mounted in operative relation with the said field magnet
system and composed of a number of circularly arranged bar magnets having a
single winding common to all, and circuit connections for including the field and
armature windings in the supply circuit, substantially as described.
14. In an electric motor, the combination of a field magnet system composed
of two or more sets of circularly arranged bar magnets, the magnets of each set
being provided with a separate winding having one end of each winding connected
to separate branches of a suitable commutator, an armature likewise composed
of a number of circularly arranged bar magnets having a single winding common
to all the said magnets, and circuit connections for including the armature winding
in series with the several sets of field windings in regular succession, substantially
as described.
15. In an alternating current motor, the combination of a field magnet system
composed of two or more sets of circularly arranged laminated bar electro-magnets,
a commutator having as many sets of sections as there are sets of field magnets,

page_text: connections between the coils of each field magnet and the corresponding section
of the commutator, an armature composed of a single group of circularly arranged
laminated bar electro-magnets having a common energizing coil one end of which is
permanently in connection with one terminal of the supply circuit, and a brush or
brushes connected to the other end of the said energizing coil designed and adapted
to successively connect the coil or coils of each set of fiell magnets in series with.
the armature coil, substantially as described.
16. An electric motor having a fixed and movable electro-magnetic system,.
arranged one inside the other and means, substantially such as described, consisting
of properly arranged fixed and movable energizing coils and circuit connections.
therefor, whereby the inner magnetic system is magnetized as a whole at all times
and the outer one magnetized in sets or divisions, the poles of which, when thus
magnetized being always of like sign with those of the inner system, substantially
as described.
17. An electric motor having a number of sets of individually wound field
magnets, an armature wound with a single concentric coil generating poles of
opposite polarity on opposite ends, a commutator for progressively shifting the
field current from one set of field magnets to another as the armature revolves, and.
circuit connections between the armature coil and the field coils whereby the
armature poles are repelled from the field poles that are energized and attracted
toward those that are idle, substantially as described.
18. An alternating current motor having a number of sets of individually wound
laminated field magnets, a suitable commutator or revolving switch for rendering
each set of field magnets alternately active and passive, an armature having as
many alternating electro-magnetic poles as there are poles in each set of field
magnets, and circuit connections for maintaining the armature poles always of the
same sign as the poles of the directly energized set or sets of field magnets,.
whereby motion is imparted to the armature by the combined endeavour of the
active field magnets to repel the armature poles of like sign, the effort of the
armature poles to attract themselves to the poles of the passive set of field magnets,.
and the exertion of the armature to place itself in such a position with relation to
the field magnets as to enable it to create a counter electro-motive force or self
induction in its own coil, substantially as described.
19. An alternating current motor having two interposed sets of field magnets
designed and adapted to be made active and passive in succession, an armature
constructed to co-operate with said field magnets and arranged to rotate by virtue
of repelling itself from the active and attracting itself to the passive set of
magnets, and a suitable switching device for shifting the energizing current
alternately from one set of field magnets to the other in more or less rapid
succession, substantially as described.
20. In an electric motor, the combination of a single group or set of interior
magnets and a series of groups or sets of exterior magnets arranged concentrically
and circumferentially around a common axis about which one is adapted to revolve,.
with a commutator or rotating switch having its sections electrically connected
with corresponding magnets of the exterior series, and circuit connections so.
arranged that the individual magnets of each group or set of the exterior magnets
co-operate in succession with the single group or set of interior magnets during
each revolution, substantially as described.
21. In an electric motor, the combination of a single group of radial interior-
magnets provided with an energizing coil common to all the magnets of the group,
a series of groups of radial exterior magnets arranged concentrically about the
group of interior magnets, the individual magnets of the exterior groups being
provided with separate windings, a commutator and circuit connections for con-
necting the individual magnets of one of the exterior groups with corresponding
magnets of the other exterior groups so as to form as many sets as there are
magnets in each group, and one or more brushes for shifting the operating or-
energizing current through the several sets of exterior magnets in progressive.

page_text: Huccession during each revolution, whereby the machine is continuously and
éffectively acted upon by one or nore magnets in each group at different
circumferential points, substantially as described.
;
22. An alternating current motor having its field and armature cores composed
wholly of iron stampings extending across the motor in a direction substantially
parallel with the armature shaft, the said stampings having projecting ears or
recesses by which they are held in proper alignment and clamped in position,
substantially as described.
23. An alternating current motor having its field and armature coils wound upon
cores built up of iron stampings arranged with their laminæ extending: across the
motor in a direction substantially parallel with the motor shaft, the said field
and armature cores being clamped in position and forming with each other
substantially closed magnetic circuits of low magnetic resistance and short length,
substantially as described.
'
24. In an electric motor, a field magnet and armature system composed of
similar U-shaped iron stampings, assembled in groups with their lamina at right
angles to the direction of rotation of the armature and in such a manner that the
free poles of the field and of the armature magnets face each other and 'form
practically closed magnetic circuit, substantially as described.
25. In an electric motor the combination of a series of iron magnet cores built
up of U-shaped stampings or laminæ having projecting ears or recesses at opposite
ends, with two or more end places or rings having annular grooves or flanges
adapted to engage with the ears or recesses of the stampings, and means for
adjustably clamping the stampings between the said end plates or disks, whereby
the stampings are held between them in circular alignment, substantially as
described.
26. In an electric motor, the combination of iron magnet cores having projecting
ears or recesses at opposite ends, with a frame work consisting of nou-magnetic
end plates or rings having annular grooves or flanges adapted to engage with
the ears or recesses of the cores and to hold the same in circular alignment,
substantially as described.
Dated this 23rd day of February 1894.