IMPROVEMENTS IN ELECTRO-DYNAMIC MACHINES
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Herbert John Allison at the Office of
the Commissioners of Patents on the 31st July 1883 communicated to him
from abroad by Robert N. King, of Dayton, Ohio, United States of America,
HERBERT JOHN ALLISON, of the firm of Allison Brothers, Patent Agents,
Southampton Buildings, London, "IMPROVEMENTS IN ELECTRO-DYNAMIC
MACHINES" a communication to me from abroad by Robert N. King, of Dayton,
Ohio, United States of America,
This invention relates to an improvement in Electro-Dynamic Machines, the
object of which is first, to provide an armaturo the core of which is formed of a
series of parallel iron wire rings each of which is wound in U shaped strips and
suspended upon tie-rods, and at intervals apart from each other, which tie-rods are
secured to disks or hubs, which are rigidly secured upon a revolving shaft, and
being further provided with a dia-magnetic coro, which is preferably made of a
series of wooden disks lying within the core rings, and secured to the shaft between
the hubs to which the tic-rods are attached.
Another feature of my invention consists in ventilating the iron core rings
which are overlapped by a series of longitudinal transverse wire coils, wound over
the core rings and dia-magnetic core of the armature, the ends of which transverso
coils aro enclosed by perforated metallic disks, or drums, leaving a space between
the disks and the transverse coils for circulation of air currents, which air space
has connection with the interior surfaces of the core coils from which it escapes
radially out through the spaces between these core coils, thereby effecting a
thorough ventilation of the armature coils, which prevents the heating of the same
in operation.
Another part of this invention relates to the mode of constructing the
commutator, which is mounted upon the armature shaft.
It consists in providing a series of commutators arranged parallel with each
other upon the shaft, each of which is formed of two semi-circular rings, which are
gained or notched each side of their opposide ends, which gains or notches are filled
with a transverse metallic bridge or plate, the ends of which are arcs of a circle,
and form a portion of the commutator surfaces..
Each of these commutators is connected to an individual armature coil, one pole
being connected to one section of the commutator ring, and the opposite pole to

page_text: the opposite section of said commutator, there being as many commutators as there
are coils wound upon the armature, and these commutators are arranged in
alternating series. In connection with these commutators are arranged a duplex
series of brushes.
The object of this part of the invention is to shunt the current of each coil
through the transverse circuit radially through the shaft, a short period of time
before the coil arrives at each of the reversing points, and continuing it in shunt
circuit for a short period after the reversal, so as to lessen the resistance due to the
reversals of the coils.
Another feature of invention consists in a serial circuit connection of the
commutator and series of brushes operating thereon so that the current to line
from each of the coils passes through the series of brushes and coils, except during
the operation of the reversal of a coil, the currents are shunted through the
transverse metallic bridge, instead of passing through the coil at reversal, the object
being to maintain a continuous closed circuit at all times, for all of the coils of the
armature by employing a shunt circuit for each of the coils, at, and during the
periods of reversal, or while it is developing the minimum amount of current.
The series of wooden disks are pierced with axial holes, and rigidly secured to
the armature and commutator shaft. Supporting disks are rigidly secured upon
this shaft, and to the core sections or wooden disks just mentioned. These disks
are provided with a series of ears, which are pierced with holes for securing a
circular series of tie-rods. In order to more substantially connect the armaturo
and its coils. to the shaft, I provide metallic plates which are secured to the disks.
They are connected to the core by screw bolts. An inwardly projecting hub or
sleeve forms suitable means for securing the disks and coro upon the shaft.
In order to produce an effective core with the least amount of metal, I form the
core of a series of wire rings; each of which is formed of an endless coil of fine wire,
wound in spool form, and supported in U shaped bracket loops which aro preferably
made of metal, and pierced with holes, through which holes the tie-rods are passed,
so as to string several coils upon the tie-rods. Those tie-rods are preferably made
of dia-magnetic material, but the rings should be insulated thereon if made of
metal. Between each of these wire coils is a space, which is formed by means of
rubber or other suitable washers for separating the coils. Between the inner
periphery of these series of coils and the wooden core, I provide a series of air spaces
radially under the loops and which are formed by grooving out the cores. Any
number of these air spaces may be employed, and they may be formed to occupy a
larger segmental circumference of the coil.
Connecting with each one of these air spaces I provide air conduits which are
pierced through the supporting disks, and connect with the spaces between the
end of the coils and other disks. The transverso longitudinal coils are wound
around out-side of the core coils. Between each of the coils are spaces through
which air passes to enter the conduits. Metallic disks enclose the outer ends of
the armature and air spaces between them, and the transverse longitudinal coils.
An orifice is pierced in last named disk which is larger than the armature and
commutator shaft, which passes through it, so as to allow the air to enter freely
around the shaft and be forced by the revolution of the armature through the
spaces and conduits into the spaces under the core coils, from which it is forced
radially outwardly through the spaces between the core coils.
The rapid
revolution of the armature causes the air to be forced rapidly after the manner of
a compression blower, around through the end coils and out through the air spaces
above described, keeping the entire coils cool, and carrying off heat which would
otherwise be accumulated by the revolution of the armature between the field
magnets. The commutator is constructed as follows:-A series of segmental rings
are cast with notches or gains. Two of these sections form the principal portion of
a single commutator. A metallic disk is pierced with a hole. It is larger in
diameter than the shaft which passes loosely through it. Segmental tenons are
made at their ends to form segments to fit and lie between the sections of the

page_text: commutator rings, and occupying considerable space each side of the inner ends of
said section. In practice these sections and segments are insulated from each other,
and the spaces between the segment branches, sectional rings, and the space
between the rings and the shaft which passes through it, are filled with insulating
material, so as to prevent a current passing from the commutator to the shaft.
Tie bolts are employed for connecting the series of commutators together, and
also form metallic connection of each section with its individual armature coil.
Metallic cars are placed between the bolts and the faces of the rings, so that
when the wire is connected to one of these bolts, metallic connection with the ring
is secured through these cars. There is a pair of bolts for each commutator section.
Thus, bolts pass through all of the sections. But there being ears only at one end,
the bolts will connect currents only to the sections which abut these ears.
Bolts pass through three of the series of commutators having one set of cars, and
connecting with that next in series. Likewise other bolts pass through only two
of the series, and again other bolts pass through only one.
A duplex series of brushes are employed, each of which is in contact with a
single section of the commutator. One brush is placed opposite the other, so as to
bear upon the opposite section of the same commutator, so that as the sections aro
in contact with the latter brush, the opposite segment will be in contact with the
first brush, which will form a shunt circuit connection radially through the bridge,
so that the coil connected with this commutator will be short circuited by means
of terminal ends which are connected with one sot of sections, being also in circuit
with the segment, by reason of the brushes being in contact with the notched
segment of the ring, at the same time it is in contact with the segment of the
branch circuit.
These several brushes are connected in series, a wire connecting the first brush
which is, say, of negative polarity, with the positive brush of the next in series, and
the second brush is in like manner connected with the third brush of the opposite
polarity, and so on, there being as many commutators and brushes as there aro
coils wound upon the armature, which may bo varied in number at pleasure.
This serial mode of connection forms a continuous circuit through the brushes
from the commutator to line by wires, and this mode of constructing the
commutator coils of the core in continuous closed circuit, but shunts cach coil
through a transverse branch and continuing it until after the period of reversal
without cutting it out of circuit, thereby avoiding a great amount of resistance,
usually obtained in the reversal of the armature coils. .