Improvements in Dynamo Electric Machines and Electro Motors.
Year: 1889

page_text: Date of Application, 21st May, 1889
Complete Specification Left, 28th Jan., 1890-Accepted, 1st Mar., 1890
PROVISIONAL SPECIFICATION.
Improvements in Dynamo Electric Machines and Electro Motors.
I, THOMAS LEOPOLD WILLSON, Electrician, of No. 163 Joralemon Street in the
City of Brooklyn, in the State of New York, United States of America, do hereby
declare the nature of said invention for "IMPROVEMENTS IN DYNAMO ELECTRIC
MACHINES AND ELECTRO MOTORS" to be as follows:-
This invention introduces to the domain of practical utility a new type of dynamo,
one which heretofore has existed only in theoretical applications, or as laboratory
experiments or philosophical curiosities. This type is distinguished by the employ-
ment of a drum-shaped armature the conductors of which consist of a single layer of
longitudinal bars, with commutating brushes bearing upon these bars at one or both
ends in line with the fields-of-force, to conduct the current to and from each bar
during its passage through the magnetic field. The bars are thus cut out of the
circuit as soon as they pass beyond the field, and remain with open terminals during
their period of inactivity.
My new dynamo, based upon this principle, embodies such mechanical and electrical
improvements that it is rendered efficient, economical of energy, and capable of yielding
a large volume of current under sufficient electro-motive-force to render it suitable
for such purposes as incandescent electric lighting, electro-plating, electric smelting
and electric welding.
The preferred construction of my machine is shown in Figs. 1 to 7 of the
drawings.
Fig. 1 is a side elevation, partly in vertical mid-section. Fig. 2 is an end elevation.
Fig. 3 is a vertical transverse section on the line 3-3 in Fig. 1. Fig. 4 is a
horizontal section on the line 4-4 in Fig. 3. Fig. 5 is a diagram, showing the
armature conductors spread out flat. Fig. 6 is an enlarged fragmentary cross-section
of the armature conductors. Fig. 7 shows one of the coupling yokes.
The machine consists in general of a cylindrical armature A revolving within a
field-magnet F. This field-magnet consists of converging radial pole pieces NS NS
of alternately contrary polarities, all connected together by a cylindrical tube or
neutral portion f. Exciting coils c c are placed over the pole-pieces, and receive a
current from a separate exciting dynamo, or for a self-exciting machine are connected
to the terminal commutator brushes, either in shunt or series, in any usual manner.
The armature A is fixed on the axial shaft C, which turns in bearing frames D D
mounted on a base plate E. The ends of the armature project beyond the field-
magnet, and are rubbed by the commutator brushes B B, there being at each end as
many brushes as the number of field poles N S.
The armature is constructed with a cylindrical core a of soft iron, and with an
exterior layer of longitudinal conducting bars b b surrounding the core and fastened
thereto. The core a should be laminated, prevent Foucault currents. I prefer to
build it up of disks of thin sheet iron, interleaved with tissue paper, vulcanized fibre,
or other insulating material, and keyed on the shaft C. The disks are squeezed
tightly together between a fixed collar d and a movable collar d¹, by screwing up
nuts e e¹ (Fig. 4).
The conducting bars bb, which are transversely tapered, or wedge-shaped, are
placed edgewise against the exterior of the core a, a layer g of insulating material
being first placed around the core, and between the bars are placed thin sheets ii of
insulating material (preferably mica) as shown in Fig. 6. The bars are held tight
against the core by exterior bands hh of fine wire wound around the armature. To
prevent any possible slipping of the core within the bars, I form it with longitudinal
grooves a¹ a¹, into which project certain bars b'b' which are wider than the others,
Fig. 6).

page_text: The soft iron core a forms a means of closing the magnetic circuit between the field
poles N S, the lines of magnetic force. flowing, as indicated (with reference to two of
the poles) by dotted lines in Fig. 3. As the armature revolves within the field
magnet, the bars bb are whirled through a succession of concentrated magnetic fields-
of-force of alternately-reversed polarities, and thereby bave electro-motive force
induced in them during the instant of their passage through these fields, which
may be taken off in the form of electric currents by, applying, commutator. brushes
to the opposite ends of the bars so as to bear upon those bars which are passing
through the respective fields.
The commutator brushes B B bear. upon the projecting, end-portions of the bars bb,
which thus form commutator-segments. The two brushes of each pair are placed at
the opposite ends of the corresponding field pole-piece, and touch the bars for an
angular distance equal to the width of the concentrated field-of-force emanating from
the pole. The pairs of brushes are connected either each to a separate circuit, or all to
one circuit, either in series or derivation.
Fig. 5 shows the circuit arrangement when the brushes are coupled in series. The
current enters at the negative binding-post P, passes from the first brush to the bars
in contact therewith, leftwardly through these, past the N pole of the field-magnet,
out through the brush at the opposite end of these bars, thence through a coupling-
piece or section G, into the next brush in advance, back from left to right through
the bars passing the next S field-pole, out through the brush at the right, and so on
back and forth until finally it passes out by the positive binding-post P¹, its course
being indicated by the tailless arrows. The feathered arrow shows the direction of
movement of the armature-bars.
As each bar enters the magnetic field of force its opposite ends pass into contact
with the respective brushes, so that the electro motive force induced by its movement
through the field of force causes a current to flow through it from one brush to the
other. Upon its passage out of the concentrated field of force; its ends pass out of
contact with the brushes, so that during its movement into the next field of force it
remains open-circuited. When the bar passes into the next field, which is of opposite
polarity, the current generated in it is in the opposite direction.
copper,
All the bars that are in contact with one pair of brushes, being all joined in multiple,
constitute essentially one conductor. Hence the armature resistance is very low, and
the resulting current is of great volume. The commutator brushes must be of corre-
spondingly high conductivity. I therefore make them of a great many leaves of
built
up to form a thick block, and clamped in a holder-frame H, which is
formed with a conducting stud I. All the studs I are fixed in a disk-shaped yoke J,
being insulated therefrom. The two yokes J J are mounted on the frames D D, and
fastened by screws qq, so that by loosening these screws the yokes can be turned slightly
forward or back to alter the "lead" of the brushes. The terminal brush-holder studs I'
have binding-posts P P¹ clamped on them, as shown in Fig. 2. The brushes are
coupled together by the sections G G, shown detached in Fig. 7, but omitted from
Figs. 1 to 4, these sections being clamped on the studs I I.
To secure considerable electro-motive force it is desirable to make the bars b band
the field-magnet as long as possible. To do this it is desirable to subdivide the
elongated pole-pieces into two or more sections, as shown in Figs. 4 and 5.
Figs. 8 and 9 are diagrams, similar to Fig. 5, but showing two different ways of
coupling the commutator brushes. In Fig. 5 they are coupled in series, so that the
total electro-motive force is the product of that generated in one bar 6 in passing
through one field-of-force at a certain speed, multiplied by the number of fields through
which bars are simultaneously passing (or six in the machine shown). In Fig. 8 the
brushes are coupled in multiple, so that the total electro-motive force is equal only to
that generated in one Bar, but the total volume of current is (in a 6-pole machine)
six times that generated in one bar. The coupling-connections are indicated by the
lines for the negative conductors and for the positive conductors.
Fig. 9 shows an 8-pole machine with a multiple-series coupling, the circuit being
divided into as many branches as half the number of fields-of-force, and each branch

page_text: including two bars in series, so that the electro-motive force is twice that developed in
one bar. The terminal connections are made with the brushes at one end of the
machine only, which are connected together in two series by couplings G G and G¹ G¹
as shown in Fig. 10. The brushes at the other end are coupled in pairs as shown
at in Fig. 9. Obviously all the brushes at this end might be connected
together, or all the brushes might be removed and all the bars bb be connected
together at this end, either by soldering them, or by fitting a metal ring against
them.
Figs. 11 and 12 show a modified construction of dynamo. Fig. 11 is half an end
elevation and half a transverse section; and Fig. 12 is a vertical longitudinal mid-
section.
The field-magnet has 12 pole-pieces (instead of six) and the armature is of larger
diameter. Its core a is in the form of a hollow drum, carried on spiders w¹ keyed to
the shaft C. The drum core is preferably made of a cast or wrought iron tube or
barrel to with end flanges, around which is wound varnished iron wire. An insulating
layer is then applied, and the bars b b are laid on, and fastened down tightly by the
exterior bands of wire. The brushes B B are arranged entirely at the right-hand
end, the bars at the left-hand end being all connected together, either by removing
the interposed insulation and soldering them or preferably by fitting a ring a tightly
within them. This machine has the advantage that as many as six different circuits
may be fed from it, or its currents may all be united on, one circuit, according to the
nature of current required for different purposes.
My invention may be variously otherwise modified, both mechanically and in its
electrical proportioning, and I do not limit myself to any of the details which I have
shown. One such modification is illustrated in Figs. 13, 14 and 15.
Fig. 13 is a transverse section, in two planes, cut on the line 13-13 in Fig. 14;
Fig. 14 is a plan, partly in horizontal section; and Fig. 15 is a transverse section on
the line 15-15.
In this machine the field-magnet has only two poles, N and S. The shaft C con-
stitutes the armature core, and the bars b b are laid directly over it, with only an
interposed insulating layer. This construction is suitable for small machines. Owing
to the more extended polar arcs it is necessary to employ two brushes B B at each
end of each field-pole. The holders of both brushes are electrically and mechanically
connected together by a bar t, and the two bars t t are supported by a yoke J.
My new dynamo may be applied as an electro-motor by suitably varying the lead
of the brushes.
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Patent Agent.
COMPLETE SPECIFICATION.
Improvements in Dynamo Electric Machines and Electro Motors.
I, THOMAS LEOPOLD WILLSON, Electrician, of 163 Joralemon Street in the city of
Brooklyn, State of New York, United States of America, 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 introduces to the domain of practical utility a new type of dynamo,
one which has heretofore existed only in theoretical applications, or as laboratory
experiments or philosophical curiosities. This type is distinguished by the employment
of a drum-shaped armature the conductors of which consist of a single layer of longi-
tudinal bars, with commutating brushes bearing upon these bars at one or both ends
in line with the fields-of-force, to conduct the current to and from each bar during its
passage through the magnetic field. The bars are thus cut out of the circuit as soon
as they pass beyond the field, and remain with open terminals during their period of
inactivity.

page_text: My new dynamo, based upon this principle, embodies such mechanical and electrical
improvements that it is rendered efficient, economical of energy, and capable of
yielding a large volume of current under sufficient electromotive force to render it
suitable for such purposes as incandescent electric lighting, electro-plating, electric
smelting and electric welding.
The preferred construction of my machine is shown in Figs. 1 to 7 of the drawings
which accompanied my Provisional Specification, and of which, Fig. 1 is a side
elevation, partly in vertical mid-section. Fig. 2 is an end elevation. Fig. 3 is a
vertical transverse section on the line 3-3 in Fig. 1. Fig. 4 is.a. horizontal section
on the line 4-4 in Fig. 3. Fig. 5 is a diagram, showing the armature conductors
spread out flat. Fig. 6 is an enlarged fragmentary cross-section of the armature
conductors. Fig. 7 shows one of the coupling yokes.
The machine consists in general of a cylindrical armature A revolving within a
field-magnet F. This field-magnet consists of converging radial pole-pieces N S N S
of alternately contrary polarities, all connected together by a cylindrical tube or
neutral portion f. Exciting coils ce are placed over the pole-pieces, and receive a
current from a separate exciting dynamo, or for a self-exciting machine, are con-
nected to the terminal commutator brushes, either in shunt or series, in any usual
manner.
The armature A is fixed on the axial shaft C, which turns in bearing-frames D D
mounted on a base-plate E. The ends of the armature project beyond the field-
magnet, and are rubbed by the commutator brushes B B, there being at each end as
many brushes as the number of field-poles N S.
The armature is constructed with a cylindrical core a of soft iron, and with an
exterior layer of longitudinal conducting bars b b surrounding the core and fastened
thereto. The core a should be laminated, to prevent Foucault currents. 1 prefer to
build it up of disks of thin sheet iron, interleaved with tissue paper, vulcanized fibre,
or other insulating material, and keyed on the shaft C. The disks are squeezed
tightly together between a fixed collar d and a movable collar d', by screwing up
nuts e e¹ (Fig. 4).
The conducting bars 6 b, which are transversely tapered or wedge-shaped, are placed
edgewise against the exterior of the core a, a layer g of insulating material being first
placed around the core, and between the bars are placed thin sheets ii of insulating
material (preferably mica) as shown in Fig. 6. The bars are held tight against the
core by exterior bands h h of fine wire wound around the armature. To prevent any
possible slipping of the core within the bars, I form it with longitudinal grooves a¹ a³,
into which project certain bars b¹ which are wider than the others (Fig. 6).
The soft iron core a forms a means of closing the magnetic circuit between the field
poles N S, the lines of magnetic force flowing as indicated (with reference to two of
the poles) by dotted lines in Fig. 3. As the armature revolves within the field-magnet,
the bars b b are whirled through a succession of concentrated magnetic fields-of-force
of alternately-reversed polarities, and thereby have electromotive force induced in
them during the instant of their passage through these fields, which may be taken off
in the form of electric currents by applying commutator brushes to the opposite ends
of the bars so as to bear upon those bars which are passing through the respective
fields.
The commutator brushes B B bear upon the projecting end portions of the bars b b,
which thus form commutator segments. The two brushes of each pair are placed at
the opposite ends of the corresponding field pole-piece, and touch the bars for an
angular distance equal to the width of the concentrated field-of-force emanating from
the pole. The pairs of brushes are connected either each to a separate circuit, or all
to one circuit, either in series or derivation.
Fig. 5 shows the circuit arrangement when the brushes are coupled in series. The
current enters at the negative binding-post P, passes from the first brush to the bars
in contact therewith, leftwardly through these, past the N pole of the field-magnet,
out through the brush at the opposite end of these bars, thence through a coupling-
piece or section G, into the next brush in advance, back from left to right through the

page_text: bars passing the next S field-pole, out through the brush at the right, and so on back
and forth until finally it passes out by the positive binding-post P¹, its course being
indicated by the tailless arrows. The feathered arrow shows the direction of
movement of the armature bars.
As each bar enters the magnetic field of force its opposite ends pass into contact
with the respective brushes, so that the electromotive force induced by its movement
through the field of force causes a current to flow through it from one brush to the
other. Upon its passage out of the concentrated field of force, its ends pass out of
contact with the brushes, so that during its movement into the next field of force it
remains open-circuited. When the bar passes into the next field, which is of opposite
polarity, the current generated in it is in the opposite direction.
All the bars that are in contact with one pair of brushes, being all joined in multiple,
constitute essentially one conductor. Hence the armature resistance is very low, and
the resulting current is of great volume. The coinmutator brushes must be of corre-
spondingly high conductivity. I therefore make them of a great many leaves of
copper, built up to form a thick block, and clamped in a holder-frame H, which is
formed with a conducting stud I. All the studs I are fixed in a disk-shaped yoke J,
being insulated therefrom. The two yokes J J are mounted on the frames D D, and
fastened by screws 99, so that by loosening these screws the yokes can be turned
slightly forward or back to alter the "lead" of the brushes. The terminal brush-
holder studs I have binding-posts P P clamped on them, as shown in Fig. 2. The
brushes are coupled together by the sections G G, shown detached in Fig. 7, but
omitted from Figs. 1 to 4, these sections being clamped on the studs I I.
To secure considerable electromotive force it is desirable to make the bars bb and
the field-magnet as long as possible. To do this it is desirable to subdivide the elongated
pole-pieces into two or more sections, as shown in Figs. 4 and 5.
Figs. 8 and 9 of the drawings which accompanied my Provisional Specification are
diagrams, similar to Fig. 5, but showing two different ways of coupling the commutator
brushes. In Fig. 5 they are coupled in series, so that the total electromotive force is
the product of that generated in one bar b in passing through one field of force at a
certain speed multiplied by the number of fields through which bars are simultaneously
passing (or six in the machine shown). In Fig. 8 the brushes are coupled in multiple,
so that the total electromotive force is equal only to that generated in one bar, but the
total volume of current is (in a 6-pole machine) six times that generated in one bar.
The coupling-connections are indicated by the lines r r for the negative conductors-
and for the positive conductors.
Fig. 9 of the same drawings shows an 8-pole machine with a multiple-series coupling,
the circuit being divided into as many branches as half the number of fields-of-force,
and each branch including two bars in series, so that the electromotive force is twice
that developed in one bar. The terminal connections are made with the brushes at
one end of the machine only, which are connected together in two series by
couplings G G and G' G¹, as shown in Fig. 10. The brushes at the other end are
coupled in pairs, as shown at 11 in Fig. 9. Obviously all the brushes at this end
might be connected together, or all the brushes might be removed and all the bars b b
be connected together at this end, either by soldering them, or by fitting a metal ring
against them.
Figs. 11 and 12 of the same drawings show a modified construction of dynamo.
Fig. 11 is half an end elevation and half a transverse section; and Fig. 12 is a vertical
longitudinal mid-section.
v
The field-magnet has 12 pole-pieces (instead of six) and the armature is of larger
diameter. Its core a is in the form of a hollow drum, carried on spiders w keyed to
the shaft C. The drum core is preferably made of a cast or wrought iron tube or
barrel with end flanges, around which is wound varnished iron wire. An insulating
layer is then applied, and the bars bb are laid on, and fastened down tightly by the
exterior bands of wire. The brushes B B are arranged entirely at the right-hand end,
the bars at the left hand end being all connected together, either by removing the
interposed insulation and soldering them or preferably by fitting a ring & tightly

page_text: within them. This machine has the advantage that as many as six different circuits
may be fed from it, or its currents may all be united on one circuit, according to the
nature of current required for different purposes.
My invention may be variously otherwise modified, both mechanically and in its
electrical proportioning, and I do not limit myself to any of the details which I have
shown. One such modification is illustrated in Figs. 13, 14 and 15 of the drawings
which accompanied my provisional specification.
Fig. 13 is a transverse section, in two planes, cut on the line 13-13 in Fig. 14;
Fig. 14 is a plan, partly in.horizonaal section; and Fig. 15 is a transverse section on
the line 15-15.
In this machine the field-magnet has only two poles N and S. The shaft C con-
stitutes the armature core, and the bars bb are laid directly over it, with only an
interposed insulating layer. This construction is suitable for small machines. Owing
to the more extended polar arcs it is necessary to employ two brushes B B at each
end of each field-pole. The holders of both brushes are electrically and mechanically
connected together by a bar t, and the two bars t t are supported by a yoke J.
My new dynamo may be applied as an electro-motor by suitably varying the lead
of the brushes.
The armature of iny dynamo is clearly distinguished from those of dynamos
wherein armature-segments insulated from one another are revolved in an annular
space between two contrary magnetic poles, so that they cut the radial lines of force
traversing such space, by reason of the fact that in such dynamos the armature-bars
are connected at their opposite ends to collector rings, by means of which the current
is continually conducted to and from them by means of brushes, so that the bars
are continually in closed circuit, whereas in the case of my armature the bars are
independent of each other and electrically disconnected at one or both ends, so that
the bars are normally open-circuited and are made a part of the circuit only during
the time when they are actually passing beneath the brushes.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The within-described dynamo-armature consisting of an iron core mounted to
.rotate on an axis, with a layer of independent and normally open-circuited conducting
bars insulated from each other, extending longitudinally over the core and fastened
thereto, so as to rotate therewith, substantially in the manner specified.
2. The within-described dynamo-armature consisting of an iron core mounted to
rotate. on an axis, with a single layer of independent and normally open-circuited
segmental conducting bars applied over said core and fastened thereto, extending
longitudinally thereof, insulated therefrom by an interposed insulating-envelope, and
insulated from each other by being alternated with insulating leaves.
3. The within-described dynamo-armature consisting of an iron core formed with
longitudinal grooves, a layer of independent conducting bars insulated from each other
and from the core, and extending longitudinally thereof, and certain bars at intervals
made wider than the others and projecting into said grooves, substantially in the
manner specified.
4. The combination, with a field-magnet formed with converging poles of
alternately-contrary polarities facing a central axis, of an armature consisting of a
cylindrical iron core mounted to rotate on said axis, and a single layer of longitudinal
conducting-bars, insulated from each other, fastened to said core, and extending at
one end (or both) beyond the ends of the poles to form a commutating surface, and
a series of commutator brushes equal in number to the field-poles arranged to bear
on said commutating surface in positions coincident with the respective fields of force,
substantially as specified.
5. The combination of a field-magnet having converging poles of alternately
contrary polarities, an armature consisting of a cylindrical layer of longitudinal
conducting bars mounted to revolve within the field-poles, two series of collecting

page_text: brushes, each equal in number to the field-magnet poles, arranged to bear against said
bars in coincidence with the fields of force, and electrical connections with the
respective brushes, whereby they are all coupled together between the positive and
negative terminals of the machine.
6. The combination with the field-magnet armature, collecting brushes bearing on
the armature bars, and holders for said brushes, of segmental coupling-bars constructed
at their opposite ends for engagement with said holders, to form electrical connections
between the brushes, substantially as specified.
7. The combination with the field-magnet, armature, collecting brushes bearing on
the armature bars, and holders for said brushes, of a yoke or disk carrying said
brushes, and adjustable around a rotative bearing to vary the lead of the brushes.
Dated this 10th day of Jan1800
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Patent Agent.