Year: 1886

page_text: GUY CAREY FRICKER, of No. 9 Montserrat Road, Putney in the county of Surrey,
Electrical Engineer 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:—
These Improvements relate to the construction of, and particularly to the method
of winding ring armatures of the Gramme or Paccinotti types. Each conducting
coil is formed of two parts, the one part being channel shaped to embrace the inner
annulus and side faces of the ring, and the other part. consisting merely of a rod
or bar passing longitudinally across the outer circumference of the ring.
This latter portion makes electrical connection between the opposite ends of
contiguous channel pieces.
A continuous "Gramme" circuit is thus formed around the ring.
A certain number of the outside rods are of sufficient length to make connection
to the commutator.
The commutator preferably constitutes a distinct portion of the apparatus ;
the elongated portion of the top bars might, however, be made to serve as a
commutator.
The main object in thus forming the coils is to admit of a firm mechanical con-
struction in this part of the apparatus, and especially to effect an improvement in
those machines wherein the inner part of the coils consists merely of straight bars
in the form of a commutator, and in which the outer portion is channel shaped.
It is evident in such armatures that there is difficulty in making connection
between the two portions of the coils on account of the smallness of the radius at
which such joints are effected, and for this reason the number of coils which can
be placed side by side around the ring is limited.
By reversing the relative positions of the two portions of the coil the joint is
made at a point where the radius is at, or near its maximum.
One method of carrying out this invention is shewn in Figs. 1, 2 and 3.
Here the driving centre is composite, the hub and driving arms A being cast in
one piece, and the cylindrical shell B in three parts as shewn in Figs. 1 and 2.
The joints are made to butt at the ends as shewn at C. C. C. in Fig. 2. but are
recessed in the centre part to allow for the insertion of the driving arins which
project through flush with the surface of the shell at this part, as shewn at D in
Fig. 1.
In building up the armature, the channel shaped copper pieces are first arranged
in position and insulated from each other and from the metal centre with sheets of
mica, asbestos or other suitable material.
A sheet of insulating material is then wrapped around them and the shell is
fitted over into its place and secured by the screws E, E, Fig. 1.

page_text: The whole thing is then put between centres and soft iron wire, preferably of
rectangular cross section, is wound in between the sides of the copper channel
pieces from which it is insulated with stout sheets of suitable material.
The iron wire is insulated by paint or varnish during process of winding and is
built up until flush with, or nearly flush with the tops of the channel pieces.
In Figs. 1 and 3 the iron wire is shewn flush with the tops of the channel
pieces.
The circuit is completed with straight bars of copper as shewn at F. in Figs. 1
and 3.
6
It must be understood that the drawings are not intended to represent the top
bars as joining the opposite ends of each channel piece, but as joining the ends of
contiguous channel pieces in order to form the ordinary "Gramme" circuit around
the armature.
The number of bars projecting to form connection to the commutator may be
varied to suit the circumstances of the case. In Fig. 3 G. represents a bar of the
commutator connected to the elongated portion of one of the top bara.
A preferable way of making the driving centre is shewn in Figs. 4, 5 and 6.
Here the shell is cast solid with the driving arms, which latter project beyond
the cylindrical shell at each end and are fitted into radial grooves cut in suitable
collars shewn at H. H. in Fig. 4 and in Fig. 6.
These collars inay both slide freely on their keys and be held up by lock nuts at
each end, or, as I prefer, one of them may be shrunk on the shaft, or stopped by
a shoulder as shewn at I. in Fig. 4 and the other one nutted up as shewn at J. J.
in Fig. 4.
The driving arms extend right down to the spindle as shown in Fig. 5 and thus
serve to centre the armature.
When this plan is adopted, the inner portions of the coils are arranged in
position before the insertion of the spindle, and the iron wire may be wound on
the shell before these are so placed.
In this arrangement I do not limit myself to the use of iron wire in the
construction of the core, but I also use thin iron washers sometimes in place of
the wire.
The external portions of the coils are formed of straight bars as before.
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:
1. The method of winding substantially as herein described in reference to, and
illustrated in, Figs. 1, 3 and 4 of the accompanying drawings, wherein each coil is
composed of two parts, the internal portion consisting of a channel shaped piece
embracing the ring from the inside, and the external portion consisting of a rod or
bar connecting contiguous channel pieces across the top part of the ring so as to
form the ordinary "Gramme" circuit.
2. The method of constructing and holding in position the driving centre sub-
stantially as herein described in reference to, and illustrated in, Figs. 4, 5 and 6
of the accompanying drawings, wherein the cylindrical shell is cast in one piece
with the driving arms, which latter project beyond the shell at each end and are
sunk in grooves prepared for their reception in the faces of suitable collars made
fast to the shaft.