Improvements in Armatures for Dynamo-electric Machines and Electric Motors.
Year: 1890

page_text: Date of Application, 16th Apr., 1890
Complete Specification Left, 15th Jan., 1891-Accepted, 28th Feb., 1891
PROVISIONAL SPECIFICATION.
Improvements in Armatures for Dynamo-electric Machines and
Electric Motors.
1, ROOKES EVELYN BELL CROMPTON, of Arc Works, Chelmsford, in the
County of Essex, and of Mansion House Buildings, Queen Victoria Street, in the
City of London, Engineer, (partly communicated to me from abroad by Waldemar.
Fritsche, of 4 Kupfergraben, Berlin, in the German Empire, Engineer, and is
partly the result of invention and discovery made by myself,) do hereby declare the
nature of this invention to be as follows:-
The improvements consist in the construction of armatures for dynamo electric
machines and electric motors, and are more particularly applicable to that form of
machine in which the armature is of disc or wheel form. In dynamo machines as
ordinarily constructed it is very usual to build up the armature winding on a
separate framework. In some cases this framework forms part of the magnetic
circuit and is called the armature core. In other cases the framework may be of non-
magnetisable material, and then merely performs the duty of acting as a hub or
centre for the mechanical support of the armature winding. In the construction of
my new form of dynamo electric machine, which I hereafter call a wheel armature
dynamo, I so arrange the separate bars or staves which constitute the winding that
they themselves form the armature core or framework.
My improved wheel armature may be described as consisting of a central
hub made of any material magnetisable or non-magnetisable providing that it
possesses sufficient strength and rigidity for the purpose. This hub or centre is in
two parts, one of which forms its body and the other part is a separate flange or
ring which holds the staves or spokes I hereafter describe firmly in their correct
position.
The armature winding consists of a number of soft iron strips or staves of spoke-
like form. These spokes are held on their inner ends by the above described hubs,
and are provided that their outer ends with abutting segments so that when
arranged in correct order and position they form a complete wheel with hub, spokes
and periphery of great mechanical strength to resist centrifugal and tangential
forces. These staves can be connected electrically so as to form the required
electrical armature circuits at points inside and outside the ring of field magnets by
curved segments which I hereafter call connectors. The soft iron spokes which I
hereafter call staves are made so that every alternate one is of greater length than
the others. These longer staves are connected to properly formed segments which
in some cases may form the commutator of the dynamo machine, although in other
cases I find it convenient to connect separate commutator segments to other portions
of the staves.
I form my staves with notches or projections or a combination of notches and
projections cut on one or both edges of them in such a manner, as to make con-
venient means of attaching the above mentioned connectors to them at these notches
or projections. The connectors are attached to the notches on the staves so as to
form two concentric rings of connections; the inner ring connecting the inner ends
of the staves, the outer ends connecting the outer ends of the staves. In order to
better secure the inner ends of the staves in the hub or centre, they may be formed
with pairs of notches cut on their edges or the ends may be cut in the shape of a
dovetail. The arrangement of the electrical connections of the staves by means of
the connectors to form the complete armature winding, may be the same as that
described in the Specification of Letters Patent granted to Waldemar Fritsche;
dated the 27th of September 1887 No. 13,080. It will be seen that my invention

page_text: enables me to construct a wheel armature of which the winding consists of iron
staves arranged as spokes in one single plane of rotation, the staves being connected
together by means of connectors arranged in two concentric circles which may be
placed either on one or on both sides of these radial staves. The radial staves
moreover being of soft iron can fulfil the threefold duty of 1st. Acting as the
mechanical framework of the armature. 2nd. When placed in the proper working
position in a suitable magnetic field they form part of the magnetic circuit and so
act as a corc. 3rd. They are arranged so as to obtain the maximum of induction
when passing thro the magnetic field.
A further improvement is that I can attach my sections which form the commu-
tator to the radial staves at any convenient point between the periphery and
central hub.
In order to connect the outer ends of the staves so as to resist tangential and
centrifugal forces in the best possible manner, I provide them with suitably formed
segments which abut against one another separated by insulating material and are
confined in their places by a band preferably made of steel pianoforte wire which
can be wound into a deep groove turned in the external periphery of the circle
made up of these segments. These segments may be of metal and insulated from
one another by insulating material, as is well understood by those accustomed to
make the commutators of dynamo machines, or in some cases I may find it convenient
to make the segments altogether of insulating material.
In order to reduce the electrical resistance of the armature staves and at the
same time to increase the mass of iron interposed by the armature between the
poles of the field magnets I sometimes form them in such a manner that although
the area of cross section throughout their length remains constant or approximately
constant, the breadths and thickness required to make up this cross section are varied,
so that when the armature is viewed from the side these staves appear of wedge
like or sector form so that the air space between them is of equal width at the
centre and at the circumference. As the thickness is increased at the periphery
the width of the staves at this point is proportionately decreased, and similarly at
the end nearer the hub the width is increased. For the purpose of increasing the
electrical conductivity of the staves 1 deposit copper on them by any convenient
electrolytic process either throughout their whole length or throughout that portion
of their length which lies between the connectors. The electro deposited copper
may be of any desired thickness. In some cases I remove the copper from the
narrow edges in order to allow the pole pieces to be approached as nearly as possible
to the iron armature.
Dated the 10th 1
SA1 1000
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicant.
.
COMPLETE SPECIFICATION.
Improvements in Armatures for Dynamo-electric Machines and
Electric Motors.
I, ROOKES EVELYN BELL CROMPTON, of Arc Works, Chelmsford, in the
County of Essex, and of Mansion House Buildings, Queen Victoria Street, in the
City of London, Engineer, (partly communicated to me from abroad by Waldemar
Fritsche, of 4 Kupfergraben, Berlin, in the German Empire, Engineer, and is partly
the result of invention and discovery made by myself) 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 :-
The improvements consist in the construction of armatures for dynamo electric
machines and electric motors, and are more particularly applicable to that form of
machine in which the armature, is of disc or wheel form. In dynamo machines as
ordinarily constructed it is very usual to build up the armature winding on a

page_text: separate framework. In some cases this framework forms part of the magnetic
circuit and is called the armature core. In other cases the framework may be of
non-magnetisable material, and then merely performs the duty of acting as a hub
or centre for the mechanical support of the armature winding. In the construction
of my new form of dynamo electric machine, which I hereafter call a wheel armature
dynamo, I so arrange the separate bars or staves which constitute the winding that
they themselves form the armature core or framework.
My improved wheel armature may be described as consisting of a central hub n
(Figures 1 and 2) made of any material magnetisable or non-magnetisable provided
that it possesses sufficient strength and rigidity for the purpose. This hub or centre
is in two parts, one of which n forms its body and the other part n' is a separate
flange or ring which holds the staves or spokes s¹, s², I hereafter describe, firmly in
their correct position.
The armature winding consists of a number of soft iron strips or staves s¹, s² of
spoke like form. These spokes are held on their inner ends by the above described
hubs n, n¹ and each alternate spoke s is longer than the next spoke s² and is
provided at its outer ends with abutting segments c so that when arranged in
correct order and position the staves s¹ form a complete wheel, with hub, spokes
and periphery of great mechanical strength to resist centrifugal and tangential
forces.
These staves s¹, can be connected electrically so as to form the required
electrical armature circuits at points inside and outside the ring of field magnets N S
(Figure 1) by curved segments which I hereafter call connectors. The soft iron
spokes s', s which I hereafter call staves are made in two lengths, there being an
equal number of each kind arranged alternately. The longer staves s' are connected
to the properly formed segments c which in some cases may form the commutator of
the dynamo machine, (as in Figures 1, 2, and 4) although in other cases I find it
convenient to form the staves s¹, s² of equal length and to connect separate
commutator segments to other portions of each alternate stave (Figures 9, 10
and 11).
In Figures 9 and 11 are shown the collectors or segments c arranged vertically
at the side of the staves s whilst Figure 10 shows the same arranged horizontally.
I form my staves s¹² with notches or projections or a combination of notches and
projections situated on one or both edges of them in such a manner, as to make
convenient means of attaching the above mentioned connectors to them at these
notches or projections. Figures 1, 4 and 5 show notches e¹, e², e³, e, cut in the
staves s', s² in which to place the connectors v so as to form two concentric rings of
connections; the inner ring kl k² connecting the inner ends of the staves, the outer
ring K', K² connecting the outer ends of the staves. Figure 6 shows projections d²,
d, d³, d, on the staves s¹, s in place of the grooves or notches e¹, e², e³, e₁.
In order to better secure the inner ends of the staves 1, 2 in the hub or
centre n, n¹ they may be formed with notches t1, t2, cut on their edges.
These notches may be either on one edge only (Figures 6, 8 and 9) or they may
be cut in both edges (Figures 1 and 10). Or the lower ends of the staves may be
cut in the shape of a dovetail (Figure 7). The arrangement of the electrical
connections of the staves by means of the connectors to form the complete
armature winding, may be the same as that described in the Specification of Letters
Patent granted to Waldemar Fritsche dated the 27th of September 1887
No. 13080. It will be seen that my invention enables me to construct a wheel
armature of which the winding consists of soft iron staves arranged as spokes in one
single plane of rotation, the staves being connected together by means of connectors
arranged in two concentric circles which may be placed either on one or on both sides
of these radial staves. By this invention I obtain-three distinct advantages. 1st. The
staves act as the mechanical framework of the armature. 2nd. When placed
in the proper working position in a suitable magnetic field, they form part of the
magnetic circuit and so act as a core. 3rd. They are arranged so as to obtain the
maximum of induction when passing through the magnetic field.

page_text: A further improvement is that I can attach my sections which form the
commutator to the radial staves at any convenient point between the periphery and
the central hub.
In order to connect the outer ends of the staves so as to resist tangential and
centrifugal forces in the best possible manner, I provide a band preferably made of
steel pianoforte wire which can be wound into a deep groove w turned in the
external periphery of the circle made up of these segments c, when these are placed at
the outer ends of the staves (Figures 1, 2, 4 and 12), or in cases where the
segments c are placed at the side or sides of the staves (Figures 9, 10, and 11) 1
provide additional suitably formed segments which abut against one another.
separated by insulating material in which to cut the groove for the band w..
These segments may be of metal and insulated from one another by suitable
material, as is well understood by those accustomed to make the commutators of
dynamo machines; or in some cases I may find it convenient to make the segments
altogether of insulating material.
In order to reduce the electrical resistance of the armature staves and at the
same time to increase the mass of iron interposed by the armature between the
poles of the field magnets, I sometimes form them in such a manner that although
the area of cross section throughout their length remains constant or approximately
constant, the breadth and thickness required to make up this cross section are
varied, so that when the armature is viewed from the side or from the front these
staves appear of wedge-like or sector form, so that the air space between them
equal width at the centre and at the circumference (Figures 11 and 12). As the
thickness is increased at the periphery the width of the staves at this point is
proportionately decreased, and similarly at the end nearer the hub the width is
increased.
of
For the purpose of increasing the electrical conductivity of the staves I may
deposit copper on them by any convenient electrolytic process, either throughout
their whole length or throughout that portion of their. length which lies between
the connectors. The electro deposited copper may be of any desired thickness.
In some cases I remove the copper from the narrow edges in order to allow the
pole pieces to be approached as nearly as possible to the iron armature.
It may finally be remarked that the entire construction above described, may
also be adapted to armatures of a cylindrical shape.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, 1 declare that what I
claim is
1. A wheel armature composed of any number of parts of iron staves placed by
the side of each other in one plane substantially as described only one stave of each
pair having at one end or its side a collector segment which construction subject to
a connection of the staves as described forms at the same time the core the collector
the support and the winding of the armature.
2. The manufacture and use of armatures for dynamo electric machines and
electric motors arranged and operating substantially as set forth.
Dated the 14th day of January 1891.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicant.