IMPROVEMENTS IN DYNAMO-ELECTRIC MACHINES AND ELECTRO-MOTORS
Year: 1884

page_text: I Sir CHARLES TILSTON BRIGHT of 31 Golden Square London W. in the
County of Middlesex, Knight do hereby declare the nature of my Invention
for IMPROVEMENTS IN DYNAMO-ELECTRIC MACHINES AND ELECTRO-MOTORS to be
as follows:-
The object of my invention is to produce a generator or motor more powerful for
the space occupied and less liable to derangement than those which have been
hitherto used. In my invention I make the two poles of the field electro-magnet
or magnets concentric to each other, that is to say that one of the poles is
surrounded by the other, and I employ movable poles or extensions of the poles
in combination with fixed armatures.
The central pole or limb of the field magnet forms the shaft of the machine.
The outer or surrounding part consists of an iron cylinder closed at the end which
is furthest from the actual pole by a comparatively massive termination in which a
chamber is recessed within which a disc or cylinder carried by the shaft or (inner
limb of the electro-magnet) rotates, its circumference being close to the side of the
chamber but not actually in contact with it.
The end of the chamber is bored out to allow the journal of the shaft to pass
through without actually touching.
A coil of insulated wire by which the inner pole is partly polarised is wound
upon a tube fixed to the inside of the cylinder and closely surrounding the shaft
though not touching it.
The outer cylinder is so wound with insulated wire that it is of opposite polarity
to that of the shaft.
At the pole end the shaft is spread out into a segment embracing nearly half a
circle. A circular piece of iron which fits nearly to the pole of the cylinder
without actual contact is mounted on a disc formed of gun metal to which the
fan-like pole of the shaft is also fixed.
A portion of the outer edge of the circular piece of iron is cut out leaving a rim
a little under half a circle, which corresponds to the extended end of the pole of the
shaft; a sufficient distance to separate the polarity of each from the other being
left between their adjacent parts.

page_text: The disc which rotates with the shaft has therefore fixed upon it two iron poles
which occupy the greater part of its edge and which are (for example as to the
North pole) formed by the extension from the shaft, and as to the South by the
movable pole running in close contiguity to the end of the cylinder, of which it
forms an extension.
The outer ends of the poles are shaped to correspond with the coils of the
armature which is fixed to the bed plate of the machine adjacent to the moving
poles of the field magnet.
The movable extensions of the poles above described can be adapted to various
types of armatures; but I prefer to use one of the Pacinotti type, the sides of which
are flattened, and covered by a deep groove in the ends of the moving poles, so that
nearly all of its surface is influenced by them.
The commutator is similar in other respects to that 'described in my patent
N° 2280 of 1883, but it is capable of being moved by means of a worm wheel and
screw through a part of a circle, by which greater accuracy of adjustment may be
effected while the machine is in motion.
In machines of large dimensions the outside cylinder is replaced by a series of
electro magnets terminating at the pole-end in an iron ring or cylinder in close
proximity to which the movable pole piece or extension of the pole revolves.
A fixed central electro-magnet or an annular cluster of electro-magnets may also
be substituted for the movable polarised shaft, a movable pole-piece or extension of
the pole being fixed to the gun metal disc; and it is advantageous in this case to
use a short gun metal or phosphor-bronze shaft.
In machines of small size a steel shaft, and a cylinder of steel either solid or
made up of a number of permanent magnets may be used in place of electro-
magnets.
My invention may be converted into an alternating machine by making the polar
extensions circular and concentric, each pole-piece being divided into as many parts
with spaces between them as there are coils in the fixed armature (which may be
of any type usual with alternating machines) and alternating with each other.
The ordinary system of a moving armature may also be employed in combination
with the arrangement of field magnets herein before described, in which case the
movable extensions of the poles are dispensed with and fixed pole pieces of similar
form to them are substituted.
Also, the movable polar extensions as well as the armature may rotate, but in
opposite directions.
Dated this first day of January 1884

page_text: I, Sir CHARLES TILSTON BRIGHT of 31 Golden Square London W. in the
County of Middlesex, Knight do hereby declare the nature of my invention for
IMPROVEMENTS IN DYNAMO-ELECTRIC MACHINES AND ELECTRO-MOTORS and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The object of my invention is to produce a generator or motor more powerful
for the space occupied and less liable to derangement than those which have been
hitherto used.
In my invention I make the two poles of the field electro-magnet or inagnets
concentric to each other, that is to say that one of the poles is surrounded by the
other, and I employ movable poles or extensions of the poles in combination with
fixed armatures.
The central pole or limb of the field magnet forms the shaft of the machine.
The outer or surrounding part consists of an iron cylinder closed at the end which
is furthest from the actual pole by a comparatively massive termination in which
a chamber is recessed, within which a disc or cylinder carried by the shaft (or
inner limb of the electro magnet) rotates, its circumference being close to the
side of the chamber but not actually in contact with it.
The end of the chamber is bored out to allow the journal of the shaft to pass
through without actually touching.-A coil of insulated wire by which the inner
pole is partly polarised is wound upon a tube fixed to the inside of the cylinder
and closely surrounding the shaft though not touching it.
The outer cylinder is so wound with insulated wire that it is of opposite polarity
to that of the shaft.
At the pole end the shaft is spread out into a segment embracing nearly half a
circle. A circular piece of iron which fits nearly to the pole of the cylinder
without actual contact is mounted on a disc formed of gun metal to which the
fan-like pole of the shaft is also fixed..
A portion of the outer edge of the circular piece of iron is cut out leaving a rim
a little under half a circle, which corresponds to the extended end of the pole of
the shaft; a sufficient distance to separate the polarity of each from the other being
left between their adjacent parts.
The non-magnetic disc which rotates with the shaft has therefore fixed upon it
two iron poles which occupy the greater part of its edge and which are (for
example as to the north pole) formed by the extension from the shaft, and as to
the south by the movable pole running in close contiguity to the end of the cylinder,
of which it forms an extension.
The outer ends of the poles are shaped to correspond with the coils of the
armature which is fixed to the bed plate of the machine adjacent to the moving
poles of the field magnet.
The movable extensions of the poles above described can be adapted to various
types of armatures; but I prefer to use one of the Pacinotti type, the sides of which
are flattened, and covered by a deep groove in the ends of the moving poles, so
that nearly all of its surface is influenced by them.
The commutator is similar in other respects to that described in my patent
No 2280 of 1883 but I make it capable of being shifted by means of a worm-wheel
and screw through a part of a circle by which greater accuracy of adjustment may
be effected while the machine is in motion. The ordinary commutator of a
Gramme" machine may also be used.

page_text: In machines of large dimensions the outside cylinder is replaced by a series of
electro magnets terminating at the pole end in an iron ring or cylinder; in close
proximity to which the movable pole-piece, or extension of the pole, revolves.
A fixed central electro magnet or an annular cluster of electro magnets may also
be substituted for the movable polarised shaft, a movable pole-piece or extension
of the pole being fixed to the gun-metal disc; and it is advantageous in this case to
use a short gun-metal or phosphor-bronze shaft.
In machines of small size a steel shaft, and a cylinder of steel, oither solid or
made up of a number of permanent magnets may be used in place of electro
magnets.
My invention may be converted into an alternating machine by making the
polar extensions circular and concentric, each pole piece being divided into as
many parts with spaces between them as there are coils in the fixed armature
(which may be of any type usual with alternating machines) and alternating with
each other.
No collector or commutator is required with this part of my invention.
The ordinary system of a moving armature may also be employed in combination
with the arrangement of field magnets herein before described, in which case the
movable extensions of the poles are dispensed with and fixed pole-pieces of similar
form to them are substituted.
Also, the movable polar extensions as well as the armature may rotate, but in
opposite directions.
P
The induced pole-pieces of the field-magnets may also be moved in opposite
directions varying the polarity of a fixed armature.
Examples of methods by which I carry out my invention are given in the
appended drawings, in which Fig. 1 shows a section in elevation of one mode of
construction of my machine, in which an iron cylinder, a. a. a. a., fixed to an iron
frame b. b., and surrounded by a coil of insulated wire c c, forms one of the poles of
the field magnet.
Concentric with this is an interior fixed coil d. d. which
polarises the other pole of the field magnet.
This latter pole $ is the end of an iron shaft Se which rotates within coil d. d.,
in close proximity to, but not in contact with it.
A pole-piece N is fixed to the shaft S. e. by a gunmetal or other non-magnetic
attachment f.
The shaft Se is continued through its bearings by a non-magnetic extension g.
h. h show a section of the fixed armature coils attached to a circular bearing.
The dotted spaces represent non-maguetic metal, such as gun-metal or phosphor
bronze.
At Fig. 2 is shown a front view of the movable pole-piece already described in
Fig. 1; the poles being indicated by N and S, and the non-magnetic separating
attachment by f; e corresponds with the same letter in Fig. 1.
Fig. 3 represents a front view of a machine of a larger type, but constructed on
the same principles, in which no coils of wire are moved, but in which the outer
cylinder a. a. a. a. of Fig. 1 is replaced by a series of electro-magnetic coils a. a. etc
terminating in an annular pole-piece . etc e corresponds with the same letter in
Figs. 1 and 2.
Fig. 4 shows a plan of Fig 3 but arranged as an alternating current machine k. k.
etc. being the outer fixed pole-piece.
a. a. etc. correspond with the coils in Fig. 3. The letters N and S respectively
indicate the iron movable induced pole-pieces of the field magnets revolving in
connexion with the opposite field-magnets by which they are polarised;-N being
polarised by its proximity to the annular fixed pole-piece , and S by the coil
surrounding but not actually touching it as at d. in Fig. 1 and the inductive effect
of the mass of metal b, upon e in the same figure.
Fig. 5 shows in plan, and partly in section, a machine constructed on the same
system in which the two sets of movable induced pole-pieces actuated by fixed

page_text: field magnets are arranged to rotate in opposite directions, so as to diminish the
speed of movement requisite for a given electrical development.
In this arrangement two machines such as shown at Figs. 3 and 4 are combined
in one by the three bevelled wheels shown by letters x. y. z. so that the moving
parts p. q. rotate in an opposite direction to each other upon separate bearings
at r, thus by induction continually changing the polarity of the fixed coils m m
(of which only two are shown out of a circular series say of 20 to 50 or more,
fixed on a bearing) opposite which they pass. The movable induced pole-pieces
are shown in this figure by shaded lines.
Linked chain gearing may be employed instead of cogged wheels or any
mechanical equivalent thereof.
a. a and e in Fig. 5 correspond with the same letters in the previous Fig. 4.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is:
The employment for Dynamo-electric and Electromotive machines of concentric
fixed field magnet coils opposite to each other in polarity, combined with movable
induced pole-pieces of iron or other magnetic metal.
Dated this 22nd day of September 1884.
CHARLES T. BRIGHT.
By G. F. Redfern, Agent,
4, South Street, Finsbury, London.