Improvements in Dynamo Electric Machinery.
Year: 1893

page_text: Date of Application, 13th Sept., 1893
Complete Specification Left, 13th June, 1894-Accepted, 21st July, 1894
PROVISIONAL SPECIFICATION.
Improvements in Dynamo Electric Machinery.
We ROOKES EVELYN BELL CROMPTON, of Mansion House Buildings, in the
City of London, and SYDNEY LINTON BRUNTON, of The Arc Works, Chelinsford,
in the County of Essex, Engineers, do hereby declare the nature of this invention
to be as follows:-
Our invention relates to that class of dynamos which are used for generating
alternate currents of electricity hereinafter called alternators, and more particularly
to those alternators having disc armatures without iron cores, such as for example
those of Siemens and Ferranti.
The object of our invention is to enable us to construct a stronger armature and
one in which each separate armature coil can be removed, replaced or tightened up
at pleasure. Armatures of this type are usually constructed of a number of flat
approximately sector shaped coils of insulated wire or ribbon, cach wound on a
non-magnetic centre piece, the whole being arranged round a disc or wheel mounted
on a shaft and so that cach coil is in the plane of the disc. The radial sides of
these coils butt up against one another, so that all the coils together form a
complete and unbroken circle round the disc.
In carrying out our invention we use for the centre pieces of the armature coils
on which the conductor is wound, and hereinafter called coil centres, approximately
sector shaped pieces (of suitable size) of non-magnetic material such as vulcanized
fibre, ebonite or wood, or they may be of some non-magnetic metal such as brass or
bronze, provided they are properly laminated and subdivided to prevent the
generation of Foucault currents which would occur if they were solid as is well
understood. These coil centres if of metal, have one or more holes for a bolt or
bolts, hereinafter referred to, at the end which will be nearest to the centre of the
armature when the armature coil is in position and hereinafter called the inner end
of the armature coil or coil centre as the case may be. If the coil centres are non-
metallic they are provided with a metallic end or socket drilled for the aforesaid
bolt or bolts; in this case the coil centre may simply butt up against the metallic
socket or may be recessed or dovetailed into it in any suitable manner.
On the
coil centre is wound the conductor in which the current is generated, the winding
being in the plane at right angles to the armature shaft when the armature coil is
in position.
The conductor we make of copper strip or ribbon of approximately the same
width as the thickness of the coil centre, and insulated before being wound on by
being covered with continuous insulation of cotton vulcanised fibre, silk or other
suitable material. To provide a good insulation between adjacent armature coils
we fit round each coil a strip of ebonite, fibre or some similar material of the same
width as the copper conductor and of suitable thickness and bent into a Ụ form,
the hollow of the U fitting closely round the inner end of each armature coil.
On the armature shaft is fitted a disc or narrow wheel of iron or other suitable
material hereinafter called simply the disc, and to which all the armature coils are
attached. Each separate armature coil is attached to the disc by means of a pair
of plates of some non-magnetic metal hereinafter called coil clamps. These plates
are, for all the armature coils, arranged radially round the disc near its outer edge
and in pairs facing one another one on each side of the disc, also in such a manner
that about half the length of each pair extends beyond the edge of the disc.
the space thus left between each pair where they extend beyond the disc is placed
he inner end of the corresponding armature coil and a bolt or bolts put through
Into

page_text: both coil clamps and the corresponding holes in the coil centre hereinbefore referred
to, serve to securely attach the armature coil to the coil clamps and so to the disc.
The coil clamps are attached to the disc by bolts. One of these bolts which we
call the cross bolt is placed parallel to the shaft on a radial line passing through
the centre of the shaft and of the armature coil, and by the cross bolts each
armature coil can be drawn radially inwards towards the centre of the armature by
the following means; The cross bolt passes through the coil clamps in holes which
it closely fits, but it passes through the disc in a slot placed radially. The cross
bolt itself has a screw passing through it at right angles to its length and in such a
position that when the armature coil is in place with its coil clamps, cross bolt and
screw, this screw lies in the radial slot in the disc with the head towards the centre
of the disc and the other end butting against the outer end of the slot in the disc.
It follows from this arrangement that if this screw be screwed up the cross bolt,
together with the coil clamps and armature coil are drawn radially inwards towards
the centre of the shaft.
These cross bolts therefore enable us to draw the armature very tightly together
when it is first made or to tighten it up at any time should it become necessary, cr
to slack out and remove any single armature coil for repair or renewal and replace
the same tightly in position. In place of the cross bolts we sometimes use cotters
passing through both coil clamps and armature disc in a direction parallel with the
shaft. We may also use special kind of bolts passing through both coil clamps and
disc having that portion of their length which passes through the disc eccentric to
the rest of their length. In this case these bolts either fit closely the hole in the
disc and work in circumferential slots in the coil clamps or they fit closely the holes
in the coil clamps and work in circumferential slots in the disc so that by turning
the bolts the coil clamps will be drawn radially inwards or outwards. To more
securely fasten the coil clamps we pass other bolts through these and the disc, the
holes in either the coil clamps or disc being slotted so that these bolts will not
interfere with the drawing in of the coil by the cross bolt or other means. Each of
the armature coils is insulated from its coil clamps by plates of ebonite or other
suitable insulation the bolt or bolts passing through the coil clamps and coil centre
may be insulated from the conductors of the armature coil by passing them through
either an insulating collar in the coil centre, or through 2 insulating collars, one in
cach clamp plate, or by insulating the coil centre completely from the winding.
We prefer the second of these methods, and we then use the bolt or bolts as one
terminal of the winding of the coil by connecting one end of the winding to the
metallic inner end of the coil centre. The connecting up of the armature. coils
may be carried out in the usual way, and they may be grouped in any required
manner.
Dated the 9th dow of Candamhau 10019
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Dynamo Electric Machinery.
We ROOKES EVELYN BELL CROMPTON of Mansion House Buildings in the
City of London, and SYDNEY LINTON BRUNTON of The Arc Works Chelmsford
in the County of Essex, Engineers, 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 :-
Our invention relates to that class of dynamo electric machinery used for
generating or utilizing alternate currents of electricity and bereinafter called
alternators, and more particularly to those alternators having disc armatures
without iron cores, such for example as those of Siemens of Ferranti. The
object of our invention is to enable us to construct a stronger armature and

page_text: one in which each separate armature coil can be removed and replaced and
tightened up at pleasure. Armatures of this type are generally constructed
of a number of Hat approximately sector shaped coils of insulated wire or
ribbon each wound on a nou-magnetic centre piece, the whole being arranged
round a disc or hub mounted on a shaft so that each coil is in the plane of the
disc. The radial sides of these coils butt up against one another so that all
the coils together form a complete and unbroken circle round the disc.
Our invention will be best explained by reference to the Figures 1, 2, 3, 4 and 5
herewith.
Fig. 1 is an elevation of a portion of an armature constructed in accordance
with our invention and shewing two of the sector shaped coils and their
attachments.
Fig. 2 shows a portion of one of the sector shaped coils with a different method
of attachment to the hub from that shown in Fig. 1.
Figs. 3 and 4 are transverse sections through an armature coil showing various
methods of attachment.
Fig. 5 is an elevation of the armature coil shewn in Fig. 4.
In carrying out our invention we use for the centre pieces of the armature coils
on which the armature couductor is wound and hereinafter called coil centres and
shewn at A in Figs. 1 to 5 approximately sector shaped pieces (of suitable size) of
non magnetic material such as vulcanized fibre, ebonite or wood, or they may be of
some non-magnetic metal such as brass or bronze provided they are properly
laminated and subdivided to prevent the generation of Foucault currents which
would occur if they were solid as is well understood.
These coil centres if of metal have one or more holes for a bolt or bolts G
hereinafter referred to at the end which will be nearest to the centre of the
armature when the armature coil is in position and hereinafter called the inner end
of the coil or coil centre as the case may be. If the coil centres are non metallic
they are provided with a metallic end or socket B drilled for the aforesaid bolt or
bolts G. In this case the non metallic coil centre may simply butt up against
the metallic socket B or may be recessed or dovetailed into it in any suitable
manner.
On the coil centre is wound the armature conductor C in which the current is
generated, the winding being in a plane at right-angles to that of the armature
shaft when the armature coil is in its proper position. The conductor C we usually
make of copper strip or ribbon of approximately the same width as the thickness
of the coil centre and insulated before being wound on by being covered with a
continuous insulation of cotton, vulcanized fibre, silk or other suitable material. The
number of turns and size of conductor wound on the coil centre A may be varied
to suit varying requirements in the usual manner. To provide a good insulation
between adjacent armature coils we fit round each coil a strip of ebonite, fibre or
some similar insulating material D of the same width as the copper conductor and
of a suitable thickness and bent into a U form, the hollow of the U fitting closely
round the inner end of each armature coil.
On the armature shaft is fitted a hub or narrow wheel of iron or other suitable
material. A portion of this hub is shown at E. To this hub all the armature coils
are attached. Each separate armature coil is attached to the hub by means of a
pair of plates FF of some non-magnetic metal, hereinafter called coil clamps.
These plates are for all the armature coils arranged radially round the hub near
its outer edge and in pairs facing one another one on each side of the hub also in
such a manner that about half the length of each pair extends beyond the edge of
the hub.
Into the space thus left between each pair where they extend beyond the hub is
placed the inner end of the corresponding armature coil, and a bolt or bolts G, put
through the coil clamps F and the corresponding holes in the coil centre B
hereinbefore referred to, serve to securely attach the armature coil to the coil
clamps.

page_text: The coil clamps are attached to the hubs by bolts. One of these bolts H, which
we call the crossbolt, is placed parallel to the armature shaft on a radial line
passing through the centre of the shaft and armature coil to which this bolt belongs.
By this crossbolt the armature coil can be drawn radially inwards towards the
centre of the armature by the following means. The crossbolt passes through the
coil clamps F in holes which it closely fits, but it passes through the hub in a
slot K placed radially. The crossbolt itself has a screw J passing through it at
right angles to its length and in such a position that when the armature coil is in
place together with its coil clamps, crossbolt and screw J this screw lies in the
radial slot K in the hub with its head towards the centre of the hub and the other
end butting against the outer end of the slot K. It follows from this arrangement
that if the screw T be turned in the right direction the crossbolt H together with
the corresponding coil clamps and armature coil are drawn radially inwards towards
the centre of the shaft. Each armature coil is fitted in a similar manner and it
follows therefore that by means of these crossbolts with their screws the whole of
the armature coils may be drawn tightly together towards the centre when the
armature is first built up, also that the coils may any or all of them be tightened
up at any time should it become necessary, also that any coil or coils can be easily
slacked out and removed and a new one put in place and drawn tightly into position
if necessary.
In place of the crossbolts we sometimes use taper cottars passing through slots
in both coil clamps and armature hub in a direction parallel to the shaft and so
arranged that by driving them in, the armature coils are drawn radially inwards
in the same manner as when the crossbolt is used.
We may also use a special kind of bolt passing through both coil clamps and
hub, which we call an eccentric bolt L Figs. 4 and 5, having that portion of its
length which passes through the hub eccentric to the rest of its length so that
turning this bolt draws the coil clamps and armature coil to which it belongs
radially inwards or outwards. The bolt L may be made to fit closely into
cylindrical holes both in the coil clamps and hub E, in which case on turning it
the coil clamps in addition to being drawn radially inwards or outwards will be
rotated through a small arc about the bolt G on either side of the centre line of
the armature coil. Provided the nut on the bolt G is unscrewed at the time the
bolt L is turned this sideways motion of the coil clamps is not detrimental. It
may be avoided however by providing the coil clamps with a slot as shown in Fig. 5,
the bolt L fitting the hole in the hub closely as before, or the bolt L may be made
to fit the holes in the coil clamps closely as before and move in a circumferential
slot in the hub. In either case whether the cross bolt shewn in Figs. 1 and 3 or
the eccentric bolt L shown in Figs. 4 and 5 is used, after the armature coils have
been drawn tightly into place the nuts M on these bolts are securely tightened up
so clamping the coil clamps F to the hub E.
To still more securely attach these coil clamps F to the hub E we pass other
bolts through holes N in the hub between each pair of coil clamps in such a
manner that each bolt tightens up the clamps belonging to two armature coils as
will be readily understood from Fig. 1.
These bolts R instead of being placed between the adjacent coil clamps may be
passed through both hub and coil clamps, but in this case a radial slot must be
provided in the hub or in the coil clamps to allow of the radial movement of the
coil clamps and armature coil.
Each of the armature coils is insulated from its coil clamps by plates O of
ebonite or other suitable insulation. The bolt or bolts G passing through the coil
clamps and coil centre may be, insulated from the conductors of the armature coil
by passing them either through an insulating collar in the socket B or through two.
insulating collars P one in cach coil clamp, or by insulating the coil centre com-
pletely from the winding. We prefer to make use of the second of these methods
and we then use the bolt or bolts G as one terminal of the winding by connecting
one end of the winding to the metallic inner end B of the coil centre. This

page_text: method of construction is shewn in Figs. 1, 3, 4 and 5, the insulating collars in the
coil clamps being shown at P. The connecting up of the armature coils one to
another and the grouping of them either in series, parallel or parallel-series may
be carried out in any suitable manner.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
:-
1. In the armatures of dynamo electric machinery either for generating or as
motors for utilizing alternate currents of electricity and having flat sector shaped
coils arranged round the hub as hereinbefore described, the method of attaching
the said coils to the hub by means of clamp plates and bolts in such a manner that
both coils and clamp plates can be drawn readily inwards towards the centre of
the hub by means of cross bolts eccentric bolts or cottars, substantially or herein-
before described.
2. In dynamo electric machinery either for generating or as motors for utilizing
alternate currents of electricity, of the description indicated, the construction and
arrangement of the adjustable cross bolts and attachments substantially as and for
the purpose set forth with reference to Figs. 1 and 3.
3. In dynamo electric machinery either for generating or as motors for utilizing
alternate currents of electricity of the description indicated, the construction
arrangement and use of eccentric cross bolts and attachments, substantially as and
for the purpose set forth, with reference to Figs. 4 and 5.
4. The general construction and arrangement of parts of armatures of alternate
current dynamo electric machinery (either for generating or as motors for utilizing
alternate currents of electricity) and their attachments so as to facilitate adjust-
ment, replacement, or renewal of individual armature coils, substantially as set
forth.
Dated the 13th dox of June 1894
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicants.