An Improved Ventilating Armature for Dynamo Electric Machines.
Year: 1885

page_text: An Improved Ventilating Armature for Dynamo Electric
Machines.
I ALBERT LEWIS DAVIS of 134 York Road Lambeth in the County of Surrey
Student in Electricity do hereby declare the nature of my invention for
AN IMPROVED VENTILATING ARMATURE FOR DYNAMO ELECTRIC MACHINES to be
as follows:-
An armature of the ordinary H Iron shape but instead of being either of solid
iron or consisting of T shaped pieces joined at the axis of the armature as is
generally done I form my armature of discs of sheet iron of suitable thickness
punched out in shape of the end section of the aforesaid H iron armature with
holes through each disc near the perphery of such disc through which pass two or
more longitudinal bars or rods of metal.
These bars or rods are covered with a tube or layer of ebonite or of other non
conducting substance so as to effectually insulate them from the sheet iron discs,
which discs are separated and kept at equal distances apart by alternate washers
of iron and insulating material threaded on the longitudinal bars aforesaid.
These bars are secured at each end to a plate or hub of gun or other non
magnetisable metal by means of suitable nuts and screws so as to ensure the
rigidity of the whole structure.
To these plates or hubs are again secured the journals or spindle on which the
armature revolves.
After sufficient of the H shaped discs with the requisite number of washers have
been threaded on the bars according to the length of armature required, the
remaining space between these discs and the gun metal, or other plate, or hub is
filled up with pieces of sheet iron of the same thickness as the former discs and of
the size and shape of the projecting pole pieces of the armature; being segments of
a circle of about of a diameter in height. The centre or connecting part of the
former discs being cut away to allow of the wire being wound evenly between the
ends of the armature instead of overlapping them as is the case with the usual
form of armature..
These pieces or segments are also kept at equal distances apart by means of
suitable washers threaded on the aforesaid longitudinal bars and are kept parallel

page_text: by means of a piece of sheet iron bent twice at right angles the ends being
parallel to each other as are the upper parts of the letter U these parallel ends
also lying parallel to the connecting bars.
In the space thus formed by the H shaped discs and the U shaped sheets of iron
is wound the wire as before mentioned which wire is prevented from being cut or
damaged by the edges of the segments of discs by lying evenly between the legs
of the said U shaped piece of sheet iron.
The whole of the discs and segments of discs have imparted to them either in
the process of punching fixing or otherwise, a belical twist similar to the pitch of
a screw propellor and as the whole of discs are separated from each other both in
the centre and at their extreme ends, must, while revolving produce and ensure
the circulation of a current of air through the centre of the coil and throughout
the armature generally.

page_text: An Improved Ventilating Armature for Dynamo Electric
Machines.
ALBERT LEWIS DAVIS 134 York Road Lambeth in the County of Surrey
Student in Electricity 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 :-
An armature of the ordinary H Iron shape but instead of being either of solid
iron or consisting of T shaped pieces joined at the axis of the armature as is
generally done, I form my armature of discs of Sheet Iron of suitable thickness
punched out in the shape of the end section of the aforesaid H Iron armature with
holes through each disc near the periphery of such discs through which pass two or
more longitudinal bars or rods of metal. These bars or rods are covered with a
tube or layer of ebonite or other non-conducting substance so as to effectually
insulate them from the sheet iron discs which discs are separated and kept at
equal distances apart by alternate washers of Iron and insulating material threaded
on the longitudinal bars aforesaid. These bars are secured at each end to a plate
or hub of gun or other non-magnetisable metal by means of suitable nuts and
screws so as to insure rigidity of the whole structure.
To these plates or hubs are again attached the journal or spindle on which the
armature revolves.
After sufficient of the H shaped discs with the requisite number of washers have
been threaded on the bars according to the length of armature required the
remaining space between these discs and the gun metal or other plate or hub is
filled up with pieces of sheet iron of the same thickness as the former discs and of
the size and shape of the projecting polo pieces of the armature being segments of
a circle of about one third of a diameter in height. The centre or connecting part
of the former discs being cut away to allow of the wire being wound evenly
between the ends of the armature instead of overlapping them as is the case with
the usual form of armature. These pieces or segments are also kept at equal
distances apart by means of suitable washers threaded on the aforesaid longitudinal
bars and are kept parallel by means of a piece of sheet iron bent twice at right
angles the ends being parallel to each other as are the upper parts of the
letter U. These parallel ends also lying parallel to the connecting bars. In the
space thus formed by the H shaped discs and U shaped sheets of iron is. wound
the wire as before mentioned which wire is prevented from being cut or damaged
by the edges of the segments of discs by lying evenly between the legs of the
said U shaped piece of sheet iron.
I wish it also to be understood that if the square rods are used the U shaped
pieces may be dispensed with.
The whole of the discs and segments of discs have during the process of either
punching or fixing or otherwise imported to them a helical twist similar to the
pitch of a screw propeller and as the whole of the discs are separated from each
other both in the centre and at their extreme ends and while revolving produces
and ensures the circulation of a current of air through the centre of the coil and
throughout the armature generally.

page_text: In order that my said Invention may be most fully understood and readily
carried into effect I will proceed to describe the drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1. A represents end view of disc of soft sheet iron d. d. being square
holes therein C. is the intervening washer also of soft iron B is top view of A
shewing the twist for assistance in ventilation.
Figure 2 shews a portion of armature built up the discs A Fig. 1 shewn at
fff Fig. 2 being threaded upon two square bolts g. g. and the whole being
compressed by the nuts thereon.
bis the armature end of gun metal or other non-magnetic material carrying the
armaturo spindle.
ae. e. are the intervening washers before mentioned.
Figure 3 shews a segment of the disc A. Fig. 1 which is used as shewn at c. c. c
fig. 2 for the purpose of allowing a wire space.
Figure 4 shews the whole armature fitted up wound with commutator &c.
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. In the armature of a "Dynamo Electric Machine building up the major part
of the armature of H shaped pieces of soft sheet iron carried on suitable connecting
bolts the said H shaped pieces being formed so as to produce two multiple
threaded helices pitched right and left or to one hand only.
2. Constructing the armature of a dynamo Electric machine without a central
shaft.
3. Constructing the armature of a dynamo electric machine of H shaped pieces
.as defined in the first claim and completing the armature by means of segmental
pieces continuing the helices..
4. In the armature of a Dynamo Electric Machine which is built up principally
of H shaped pieces holding the same together by means of bolts (preferably of
a square section) passing through the centre of the segmental parts of the said
H shaped pieces as well as through the segmental pieces.
5. The combination of the before mentioned parts forming an armature of a
Dynamo Electric Machine substantially as described and shewn in Fig. 4.
of November 1985