Year: 1885

page_text: I JOHN CLAYTON MEWBURN, of 169 Fleet Street, in the City of London, Fellow
of the Institute of Patent Agents 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 relates to dynamo-electric machines, and particularly to such
machines when designed for use as motors, to be driven by an electric current for
the electric transmission of power.
Electro-motors as heretofore constructed have been of two classes. The first
class comprises those in which motion is caused by the reaction of a field-of-force
on a system of armature wires carrying a current. Motors with armatures of the
Siemens and Gramme type belong to this class, their armature-coils being filled
with laminated iron. The second class comprises those motors the motion of which
depends mainly or entirely on the mutual attraction of masses of magnetized iron.
The reaction of the field-of-force on moving wire takes place in a subordinate
degree.
My improved motor belongs to the second class as above classified, in that its
action is dependent on the attraction of magnetized masses of iron, and not on the
reaction of moving coils of wire. It differs from such motors as heretofore made,
however, in that there is no reversal of current in the exciting coils, and
consequently no current is consumed in forcing a reversal of polarity to over-
come residual magnetism and effect a repulsion of the mutually-receding masses
of iron.
Figures 1 to 12 of the accompanying drawings show the preferred form of the
improved electro-motor, involving all the features of this invention. Figure 1 is a
side elevation of the machine, Figure 2 is a vertical longitudinal mid-section thereof,
Figure 3 is an elevation of the revolving armature removed, Figure 4 is a transverse
section cut on the line 4... 4 in Figure 2, Figure 5 is an end elevation of Figure 3
showing the arrangement of the armature pole-pieces, Figure 6 is a side and end
view of one of the pole pieces, Figure 7 is an enlarged end elevation of the machine,
showing the commutator, Figure 8 is a vertical longitudinal mid-section of the end-
portion of the machine, Figure 9 is a transverse section of the commutator; and
Figures 10, 11 and 12 are three diagrams showing the circuit connections and the
magnetic changes that take place during the operation of the machine.
The remaining figures illustrate modifications, and will be described hereinafter.

page_text: Referring chiefly to Figures 1, 2 and 3, let A designate the revolving armature,
B the stationary magnet or reactive armature, and C, C the exciting coils.
The armature A is made entirely of soft iron, and consists of a core a and three
pairs of polar-projections, or pole-pieces b, (lettered respectively b¹, bs and b³)
arranged at its opposite ends and at its middle. It also is provided with two soft-
iron discs D, D fixed on the core between the respective pole-pieces. The pole-
pieces bare each two-armed, and are relatively arranged with their diametral axes
successively 60° apart, as shewn in Figure 5, which is an end elevation of the
armature with the discs D omitted. The armature-core has journals d, d formed
at its opposite ends.
The stationary magnet B which takes the place of the usual field magnet is in
the form of a cylindrical tube of soft iron, cut away at its middle and both ends
to form fixed poles or pole-portions c, c, which correspond in position to the
armature-pole-pieces b, b, as shown in Figures 1 and 2, with this difference,
however, that the pole portions c, c are all in line with each other, those of each
of the three pairs occupying the positions shown at c, c in Figure 5.
The coils C, C are stationary, being fixed within the tubular magnet B and
enclosing the core a, and by preference filling the entire space between them,
leaving only a clearance around the core to permit of its free rotation. The coils
are three in number, distinguished as C¹, C₁ and C³, corresponding in position to
the armature pole-pieces b', 63 and 63. The coils C¹ and C³ are arranged at opposite
ends, the intermediate coil C* being divided into two parts or bobbins, arranged on
opposite sides of the pole-pieces 6. The winding of these coils is as shewn in
Figures 10, 11 and 12, being such that if currents were flowing through all three
simultaneously, they would magnetize the armature in such manner as to generate
like poles (as N) in the three pole-pieces b, b, b and the opposite like poles (as S)
in the pole portions c, c, c of the stationary magnet B.
Each coil C acts to magnetize not only the free armature-core within it, but also
the fixed magnet B surrounding it, and both are magnetized with their adjacent
poles at b, c of opposite polarity, so that they mutually attract each other. The
iron discs D are of such diameter that they nearly fill the bore of the tubular
magnet B, leaving clearance to permit of their free rotation with the armnature.
These discs afford a magnetic connection between the armature core and the
magnet B, serving in this respect the same purpose as the back yoke of a common
horse-shoe electro-magnet. At each end of the magnet B is a fixed supporting
frame E, of brass by preference, to which the end pole portions c, c are fastened,
and which forms the bearings for the journals d, d on the armature. One of these
journals d is prolonged and carries the commutator, F, shown best in Figures 8
and 9. This commutator is made up of three interlocking members e, e (lettered
respectively e¹, e¹³ and e³, corresponding with the three coils C¹, C and C³) each
insulated from the journal d and from both the others, and the three formed with
projections f, f which interlock and are presented in triple succession in the same
circumferential plane. The middle member e' has a tubular hub and two opposite
radial arms f, f, the end members e¹ and e³ are each tubular segments, with lateral
aruis f, f as shown in Figure 2. There are thus six projections f, for three to each
half revolution. A wheel or roller g (which is equivalent to a commutator-brush)
rolls against the commutator, touching the projections f, f and it is through this
roller that the current from the line enters the commutator, passing successively
into the members e¹, e² and e³ thereof, and being carried thence to the respective
coils C¹ C and C³. The current is taken off from the commutator members by
rollers h³, h³ and h³, by preference, arranged as shown in Figures 1, 7 and 8, and
mounted on spring-arms by which they are pressed into firm contact with the
commutator.
The machine has now been sufficiently described to enable its operation to be
understood. In Figures 10, 11 and 12 the roller g is shewn in triplicate, and the
three commutator members e¹, and e³ are shown separated. As the commutator
turos, the current is directed into the first coil, C³, during the first sixth of a

page_text: revolution, then into the second coil C during the second sixth, and into the third
coil C³ during the third sixth, the same order being repeated during the remaining
half-revolution.
Figure 10 shows the machine during the first sixth of a revolution, the current
from the line flowing through roller g, commutator-member e¹, and coil C¹, to the
line. The current flows through coil C¹ in such direction, as shown, as to magnetize
the armature A with a north polarity at its pole-piece b¹ and the magnet b with a
north polarity at each of its pole portions of, c¹. The disc D becomes incidentally
of south polarity (8) and the magnet B adjacent to it becomes of north polarity (n).
In effect, the portion of the armature-core enclosed by this coil C¹, and the portion
of the magnet B surrounding it, constitute (through the action of the connecting
disc D) substantially a single horse-shoe magnet, of which the core forms one leg
and the tubular magnet the other leg. The armature A is set with its pole-
pieces b, b in such relation to the commutator, that while the current is flowing
through the coil C¹, the pole piece b¹ is approaching the fixed poles c¹, c¹. The
portions of the armature A and magnet B adjacent to the two remaining coils are
feebly magnetized, by induction from the excited portions, and both exhibit south
polarities at or near the pole-piece 6. As this pole piece is then receding from the
poles c³, c³ their feeble repulsion thus resulting is utilized its effect being to over-
come any back-pull because of residual magnetism that might otherwise exist.
As soon as the pole-piece b¹ reaches alignment with the poles c', c¹ the commutator
diverts the current into the second coil C³, as shown in Figure 11. The two
opposing bobbins of this coil act to form a north pole in the centre of the armature,
in the pole piece b between them, and a south pole in the middle fixed poles o², c³.
By secondary induction both the ends of the armature and magnet become feeble
south poles, as denoted at 8, 8 thus overcoming residual attraction. The pole-
piece b is thus attracted to the polos c², c² until when it is in alignment with them
the commutator diverts the current into the third coil C³, as shown in Figure 12.
The pole-piece 6 then becomes a north pole and the fixed poles c³, become
south poles, thus attracting each other, while feeble like poles 8, 8 are induced in
the remote portions of the armature and magnet, and tend to repel each other.
This continues until the pole-piece 63 is in alignment with the poles c³, c³, when, a
half-revolution having taken place, the current is again directed through the first
coil, and the operation is repeated.
I provide means for readily controlling the machine, shown best in Figures 1, 7,8
and 9. The roller g is borne by a hand-lever G, which is fulcrumed on a boss on
the end frame E, concentric with the armature-bearing. The roller is mounted on
a crank-arm i, which is pivoted on a stud fixed to a lever G, and around the stud
is a spiral-spring j, (Figure 1) which acts to press the roller g into firm contact
with the commutator. When the lever G is in the position shewn in full lines in
Figure 7, the motor will run in one direction (forward) irrespective of the direction
of the current, but if the lever G be thrown over through an arc of 90°, as shown
in dotted lines, the motor will run in the opposite direction (backward). This is
due to the fact that the position of the roller g relatively to the fixed poles c, c is
reversed, so that the several coils are traversed by the current in reverse order,
as may be readily traced by assuming that the rollers g, g in Figures 10, 11 and 12
are at the right or left of the several commutator members, instead of above, as
shown.
On bringing the controlling lever G to an intermediate position, on the axis x, x
in Figure 7, a further change takes place, each of the armature pole-pieces being
attracted toward the fixed poles during only a twelfth instead of a sixth of the
revolution, and on passing the fixed poles it is no longer released by the shunting
of the current to another coil, but continues to be attracted, and consequently
pulled back, for the succeeding twelfth. Thus there is as much pull in one direction
as in the other and the machine quickly comes to a stop, and will afford considerable
resistance to being started. This mid-position of the lever G thus acts as a brake
to stop the motor.

page_text: The lever G is capable of any position intermediate of those shown, and may
As the lever is
thus be used to control to a nicety the working of the motor.
slowly moved from left to right (in Figure 7) the motor gradually runs slower
because of the increase of its self-retardation, until the mid-position is reached,
when the motor stops, and on continuing to move the lever to the right, the motor
will (if not loaded) slowly start backward and increase in speed until the maximum
is reached coincidently with the extreme position of the lever. The lever may even
move beyond the extreme position shown.
I have thus described the three coils as each receiving the current during one-
sixth of the revolution at each impulse. It is obvious, however, that each
armature pole-piece is half the time approaching and half the time receding from
the fixed poles, and therefore it can be made most effective if it is caused to attract
the fixed poles during nearly or quite half the time, or one quarter of the revolution
at each impulse. To admit of this and to provide a means of regulating the
machine according to any special conditions under which it may be placed,
I provide a second roller g¹ for feeding the current from the line to the commutator,
and render it adjustable relatively to the roller g. In Figure 9 the roller g is shown
at the top, and the roller g¹, if placed diametrically opposite (as shown in dotted
lines at g¹), would have no effect; but when this roller is carried forward or back,
one-twelfth of a revolution, to the extreme position shown, it adds a duration of
one-twelfth to the one-sixth duration produced by a single roller, and consequently
causes each coil to receive the current during one-quarter of the revolution. It
follows then that on each alternate twelfth of a revolution the current is traversing
two successive coils simultaneously, the arrangement being such that these two
coils at such time co-operate to drive the armature forward. By setting the roller gl
to positions intermediate of the extremes shown in Figure 9, the action of the
machine may be to a certain extent regulated. To facilitate this regulation, this
roller g¹ is borne by a separate lever G, which is connected to the main lever G
so as to be forced to move with it, by means of a screw H, which is swivelled to
one lever, and engages an oscillating nut k on the other. This screw H can be
turned in either direction, while the machine is running, thus varying the relation
of the rollers g, g' until the best result is attained for the particular speed and the
work being done. The roller g¹ is mounted on the lever G in the same manner as
the roller g on the lever G.
The improved electro-motor has the following advantages:-Its construction is
very simple, particularly in the moving parts. Its armature carries no wire around
with it, thus avoiding much complication of winding and connections, and rendering
"the commutator very simple. The tubular form of the stationary magnet enclosing
the exciting coils secures the maximum inductive effect. The exciting coils are
simple, and are so arranged as to produce a double effect, magnetizing simul-
taneously both the armature and the stationary magnet. There is no back-pull
resulting from wires cutting the field-of-force in the wrong direction, or from
residual magnetism. The commutator is simple, consisting of only three pieces.
The reversing or controlling lever G effects a perfect control of the speed, direction
and effectiveness of the machine, and the regulation by means of the roller g¹
These features
renders the same machine adjustable to different kinds of work.
render it especially advantageous for use on electric locomotives. There are no
dead-points, each armature pole-piece commencing its pull before its predecessor
becomes inert. No electro-motive force is lost by reversing the current in the coils,
in order to generate a repulsive force on the armature poles, such repulsion being
always very feeble as compared with magnetic attraction under like conditions.
It will be observed that by the successive action of the three coils the changes
of polarity in the armature and the stationary magnet occur like waves, traversing
them from one end to the other. Thus there is no violent reversal of polarity
from a concentrated N to a concentrated S pole, such as would occur from a
reversal of current in the exciting coils, and which would entail a waste of electric
energy in overcoming the molecular resistance of the iron.

page_text: I will now proceed to describe some details of construction of the motor, which
are very desirable, especially in large machines doing heavy work, but are not
essential to the operativeness of the machine. The armature A has its core a
constructed of a tube slit longitudinally along one side, and filled with soft iron
wires m, m as shown in Figures 1 and 4. By being thus laminated or subdivided,
Foucault currents around the core are reduced, and its capacity for rapid change
of magnetic polarity is increased. The slit does not extend to the ends of the tube,
and in its ends are tightly driven plugs or shafts n, n the projecting ends of which
are turned down to form the journals d, d. The pole-pieces b, b are laminated,
being made up of several parallel plates of soft iron, as shown, with some insulating
material or non-magnetic metal, as brass, intervening, and with iron caps o, 0
fastened on their opposite ends. Blocks q, q of wood by preference, are applied to
the sides of the pole pieces, to fill them out to the form of a solid disc or cylinder,
in order to prevent beating of the air.
The discs D, D are each made up of laminæ, in the same manner as the pole-
pieces, and they are slotted from their peripheries nearly to the core a at intervals,
as shown in Figure 4, where four slots are shown. These slots act to intercept
Foucault currents.
The tubular magnet B is also slotted to prevent Foucault currents. Figure 1
shows a slot p extending its entire length, in a plane midway between the pole
portions c, c. On the opposite side of the tube there should be another similar
slot, but it need not extend entirely through the length, it being preferable to
interrupt that slot opposite each disc D, leaving the tube separated by two slots
between the discs, and by only one slot (p) at the discs.
It is very desirable that an electro-motor should be housed or cased-in, so that
no dust may gain access to it. The cylindrical shape of my improved motor
renders such casing-in very convenient and sightly. A sheet of brass, or other
suitable material, extending between the end-frames E, E is wrapped around the
tubular magnet B, thus covering the slots therein, and the openings between its
pole portions, and effectually enclosing the working parts. This covering is shown
only in Figures 2 and 4, being lettered I. The only working parts exposed are
the commutator, current rollers, and the controlling and adjusting-levers.
The improved machine, while designed chiefly as an electro-motor, is also
applicable, although less effectively, for use as a dynamo-electric machine. On
power being applied to rotate it, it gives out a current due to the reaction of the
residual magnetism in the tubular magnet and armature.
--
The improved machine is susceptible of considerable modification without
departing from all the essentials of the invention. The constructions shown in
Figures 13 to 27 which I will now describe are instances of such modifications.
Figure 13 is a side elevation of a machine having two coils and four armed
pole-pieces. Figure 14 is a longitudinal mid-section thereof, Figure 15 is a
transverse section cut on line 15 - 15 in Figure 13 and Figure 16 is a diagram.
The two coils C and C are wound like the coils C1 and C³ before described.
There is one disc D. The pole-pieces b¹ b' have each four arms and are set with
the arms of one 45° in advance of the other. The core a is built up of longitudinal
segments as shewn in Figure 15. The tubular magnet B has four pole-portions oc
at each end and is slotted through at p and has partial slots p₁ p₁ extending from
opposite ends. The commutator F is a two-part commutator and the current
enters it through a roller g carried by the lever G.
Figure 17 is a plan of a modified machine embodying some of the features of
the invention. Figure 18 is an end elevation thereof. Figure 19 is a diagram
shewing the winding and connections to render the machine efficient as a dynamo-
electric generator.
The coils C C, armature A and disc D are substantially as
in the construction last described except that the pole-pieces b are two-armed.
The magnet B consists of two round bars J J united to each other at their middles
by a yoke K which has a central opening in which the disc D rotates. Pole-
pieces c c are fixed on the opposite ends of the bars, and on the bars are wound-

page_text: coils L L. The current through these coils converts the bars J J into veritable
field-magnets. They are wound preferably as shewn in Figure 19, so that all four
pole-pieces c c are of like polarity. Running as a motor, the current passes from
the line through the commutator to coil C, thence successively through coils L' L'
on one side, and thence through coils L1 and L2 on the other side, and thence to
line. The pole-piece 6 of N polarity is attracted toward the S poles c c until
alignment is reached when the commutator shunts the current to coil (without
changing its relation to the four coils L) whereupon the pole-piece b¹ becomes of
N polarity and is attracted to the fixed S poles. Used as a dynamo, the alternate
recession of the pole-pieces b b while they are N poles, from the S poles c c induces
currents alternately in the coils CC, which currents, being both of the same
name, are merely sent to the line by the commutator without transposition.
Figure 20 is a longitudinal mid-section of a machine with six poles. For the
sake of clearness the two coils C C are omitted. Figure 21 is a transverse section
on the line 21 21, and Figure 22 is a transverse section on the line 22 - 22.
The pole-pieces 6 b of the armature are six-armed as shown in Figure 22. The
stationary magnet B is made of six bars arranged equidistantly around the outside
of the coils. At the middle (in place of a revolving disc D) is a stationary frame D¹
of soft iron, having a central hole through which the armature core turns freely.
The commutator F is in two parts with twelve alternations of current from one
coil to the other during each revolution.
Figure 23 is a side elevation partly in section, of a machine with two distinct
magnets B B with their pole portions c c turned toward each other and arranged
in alternation with a single pole-piece b on the armature A, arranged at the middle
of the core. Iron discs D¹ D¹ are placed at opposite ends to magnetically connect
the magnets B B with the core a. The coils C C are excited alternately and are
wound oppositely, so that the pole-piece b has always the same polarity (as S)
while the poles cc of the magnet B enclosing the particular coil which is excited
have the opposite polarity (as N). Figure 24 is a transverse section on the
line 2424 in Figure 23.
Figure 25 is a vertical section and Figure 26 is a plan of a small single-acting
motor, suitable for very light work at high speeds. There is only one coil C.
During the time that the pole-piece b is approaching the poles cc the current is
flowing through the coil, but while the pole-piece is receding, the current is
interrupted or short circuited. A fly wheel W will be desirable because the motive
force is intermittent.
Figure 27 is a longitudinal mid-section (corresponding to Figure 14) showing a
modification wherein the coils C C revolve with the armature. The coils are
wound directly on the armature, and the ends of the insulated wires are carried
through or along the core a and are connected with the commutator F. The
current enters the commutator at g passes through one coil or the other and
emerges at h.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed as communicated to
me what I claim is
1. A dynamo-electric machine or electro-motor wherein the armature consists
of a core having polar projections with a stationary coil enclosing the said core
and stationary poles to receive the magnetic reaction of the said polar projections
as the armature revolves, substantially as set forth.
2. A dynamo-electric machine or electro-motor consisting of an armature having
polar projections in combination with stationary poles to receive the magnetic
reaction of the said polar projections as the armature revolves, an exciting coil
enclosing the said core, and a commutator adapted to shunt the said coil into
circuit while the said polar projections are approaching the said stationary poles,
and to cut it out of circuit while they are receding therefrom, substantially as set
forth.

page_text: 3. A dynamo-electric machine or electro motor consisting of the combination of
an exciting coil, a revolving armature consisting of a core in the axis of the said
coil and polar projections on the said core, and a stationary magnet arranged
outside of the said coil and within the inductive influence thereof, and having pole-
portions corresponding to the said polar projections and arranged to receive the
magnetic reaction thereof, whereby the same coil excites both the armature and
the stationary magnet, substantially as set forth.
4. The combination of a revolving armature, two or more exciting coils
surrounding the core of the said armature, stationary poles arranged to receive
the magnetic reaction of the polar projections on the said armature, and a com-
mutator adapted to cause an alternate (or,-in the case of more than two coils,―
a successive) excitation of said coils, substantially as set forth.
5. The combination of a revolving armature, two or more exciting coils
surrounding the core thereof, stationary poles arranged to receive the magnetic
reaction of the polar projections of the said armature, and a commutator adapted
to direct the current into the said coils alternately or successively, whereby each
coil receives its current always in the same direction relatively to the external
line instead of reversing the current through the coils, substantially as set forth.
6. The combination of revolving armature having polar projections, a stationary
magnet having corresponding pole-portions, one or more exciting coils arranged
around the core of the said armature and within the said magnet so as to excite
them both, and a magnetic inductive connection (such as the disc D or its
equivalent) between the said armature and magnet, substantially as set forth.
7. In an electro-motor, the combination of a revolving armature having polar
projections, stationary poles receiving the reaction of the said projections, exciting
coils enclosing the core of the said armature, and the commutator F with the roller
or conductor g through which the current enters the said commutator, and a
controlling lever G carrying the conductor g and adapted to move the same to
different positions around the commutator, and thereby to stop, start or reverse the
motor, substantially as set forth.
8. In an electro motor or dynamo-electric machine the stationary magnet B
made in the form of a tube enclosing the exciting coil or coils and magnetized
thereby, substantially as set forth.
9. The tubular magnet B cut away at its ends to form pole portions c c and
divided longitudinally to suppress Foucault currents, as described.
10. The combination with the cylindrical electro-motor with circular end-
frames E E, of the non-magnetic tubular casing I, whereby the magnetic parts are
enclosed and protected from dust, as described.
11. The combination of revolving armature A, stationary magnet B, and two or
more coils C, C, with a commutator F having as many members as there are coils,
and adapted to direct the current into the said coils successively, with roller or
conductor g by which the current enters the commutator, and another roller or
conductor g' angularly adjustable relatively to the roller g whereby the duration
of the current through each coil may be prolonged, and the current may be
admitted to each coil for a longer or shorter interval before being cut off from the
preceding coil, substantially as set forth.