Year: 1886

page_text: I, SILVANUS PHILLIPS THOMPSON of 20 Arundel Gardens Notting Hill in the
County of Middlesex, Doctor of Science and Professor of Experimental Physics 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:
One
My Improvements relate to the construction of simple dynamo-electric machines
and particularly to that kind of machine in which there is a single magnetic
circuit, the field magnet being formed preferably in one piece without joint as set
forth in the Specification of Letters Patent No 5122 of 1882 granted to me.
of the advantages of the field magnet being thus constructed as a simple magnetic
circuit is, as stated in my said Specification, that the same castings which serve as
cheeks or cores for the Electro magnets can serve also as the bed plate for the
machine. The improved machine constructed according to my present Invention
may be regarded as a modification of the said type of machine, the chief improve-
ment being in the construction of the armature as hereinafter set forth. By my
present improvements I obtain the advantages set forth in my said former Speci-
fication, but I also obtain other advantages, the object of my present improvements
being the obtaining of a more efficient machine, having greater electrical output in
proportion to its size and cost, less liable to wasteful heating in the Electro
magnets or in the polar surfaces thereof and having in general better magnetic
and Electric conductivity.
As in the machine shewn in Figure 10 of the Drawings accompanying my said
former Specification I prefer to employ a single core to receive the field magnet
coil and I make the said core shorter and thicker in proportion than in the older
form of machine. I also prefer, for convenience of winding, to make it straight
rather than arched. The core which receives the coil may be made in one with
the pole pieces by casting or otherwise or it may be of wrought iron, the pole
pieces being cast upon it or screwed or rivetted to it. The field magnet itself
serves as a framework for the machine and its pole pieces or either of them may
constitute the bed plate of the machine, the magnets themselves being of great
solidity and mechanical strength and presenting the advantage of a magnetic
structure without joints. As in my aforesaid former Machine, so in this improved
Machine, the field magnets may be wound and excited in any of the ways known
017

page_text: in the construction of dynamo machines, the coils being joined either in series
with or as a shunt to the external circuit or they may be separately excited
or they may be excited in any combination of these ways according to the
circumstances in which the machine is to be used.
Figure 1 and Figure 2 illustrate the two ways of forming the field magnets of
my improved machine, the magnets themselves M M being as aforesaid of great
solidity, having great mechanical strength and possessing the advantage of a
magnetic structure without joint. The coils are shewn in position at C C.
The armature is constructed upon spiders of suitable material such as a non-
magnetic metal, keyed or otherwise suitably fixed upon the driving shaft; the said
spiders being formed with shoulders to receive and support a thin supporting
cylinder or mantle, preferably made of thin sheet iron, well insulated from the
spiders, but the cylinder or mantle may be of some strong insulating material, such
as hard vulcanised fibre or dermatine. There may be one or more such cylinders
or mantles, each being borne at its ends upon the shoulders of a spiders. The
said cylinders or mantles support and keep in place a number of thin iron washers
which are either plain or toothed externally.
The process of construction of the armature frame and core consists in fixing one
spider on the shaft by its key or other convenient and suitable mechanical means,
then placing upon it one of the aforesaid cylinders or mantles, then outside this
the washers to a suitable number, preferably insulated from one another by sheets
of varnished or paraffined paper, or asbestos, or other non-conducting material,
then the next spider is fixed in position on the shaft thereby securing the cylinder
and washers in their proper places and so on until the requisite number has been
provided Instead of washers of thin iron, iron wire preferably varnished or
oxidised on its surface may be wound upon the cylinder, as in the armature known
as Gramme's to serve as a magnetic core Outside the core whether constructed of
washers or of wire a layer of varnished paper or other insulating material is placed
The end washers may for greater strength be made thicker and be secured to the
spiders by screws.
The core and frame so constructed secures great strength requisite magnetic
properties proper insulation and simplicity of construction. The armature coils are
then wound over the core which may if so desired be effected in any of the
ordinary or known manners either ring fashion or drum fashion but I prefer the
ring method of winding When armatures of low resistance are required (such as
for electro plating) I prefer to make the coils of thin copper tape two three four or
more pieces of which are laid upon one another to form a single laminated con-
ductor which after securing the usual insulation, is wound over the core This is
more flexible than solid copper conductors.
In some cases I lace bind or weave together the portions of the wires or tapes
which lie on the external periphery of the armature by means of a peripheral
lacing of thongs laces strips or straps of leather, catgut or dermatine or other
similar or suitable material such as thin metal wires covered with suitable flexible
insulation the said thongs or straps passing over one conductor and under the next
one and so on after the manner of wickerwork thereby holding the wires or tapes
firmly in place and preventing flying. Where only one external layer of con-
ductors is used this layer may be woven as aforesaid before the ends of the
conducting tapes or wires are drawn through the interior of the ring Or if more
layers than one are wound upon the core frame the outer layer only of conductors
may be thus woven or laced.
Figures 3. 4. 5 and 6 illustrate a method of carrying out my improved con-
struction of armatures 88 being the spiders A A the supporting mantles or
cylinders W W the iron washers B B the outer layer of insulating material
DD the conductors In Figures 3 and 4 these are shewn as of ordinary insulated
wire In Figures 5 and 6 they are shewn as constructed of copper tape T T―The
method of securing the outer conductors by lacing or weaving with thongs laces
strips or straps L L is shewn at Figure 6.

page_text: Having now described and particularly ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is
First. The improved dynamo electric machine as hereinbefore described and
illustrated in the accompanying drawings.
Second. The improved construction of armature frame and core for dynamo
electric machines consisting of washers supported on an insulating or insulated
cylinder or mantle or cylinders or mantles held upon spiders substantially as
hereinbefore described.
Third. The method of securing the external conductors of an armature for
dynamo electric machines by weaving or lacing the said conductors with insulated
or insulating thongs laces strips or straps as hereinbefore described.
Dated this 11th day of June 1886.
J. HENRY JOHNSON,
Agent.
J. HENRY JOHNSON,
Agent.