Improvements in Dynamo Electric Generators and Motors.
Year: 1896

page_text: Date of Application, 3rd Oct., 1896
Complete Specification Left, 30th June, 1897-Accepted, 28th Aug., 1897
UNAL SPEC
TON.
Improvements in Dynamo Electric Generators and Motors.
I, SIDNEY GEORGE BROWN, of 1 St. John's Road, Chelmsford, in the County of
Essex, Electrical Engineer, do hereby declare tho nature of this invention to be as
follows:-
This invention relates to dynamo-electric generators and motors and has for its
object to provide a new armature winding which will ensure a sparkless break at
the commutator under conditions that allow of a backward lead of the brushes with
all the attendant advantages of such backward lead. The said invention is
applicable to drum armatures aud to Gramme ring armatures.
According to my invention, instead of winding the several sections or coils
symmetrically throughout as has heretofore been the practice, I wind a portion of
each section in a plane which is at an angle to that of the main part of the
section so that such portion in the case of a generator may cut the lines of
induction proceeding from the forward pols and thereby induce a back E.M.F.
in the section sufficient to stop and then reverse tho current in the whole
section while the said section is short circuited by the brush. The displacement
of such portion of the section is in a forward or a backward direction relatively
to the main part of the section according as the machine is a generator or a motor.
In some instances the direction of displacement and the direction of winding of
the displaced portion relatively to the main part of the section are reversed.
With an armature wound as above indicated the commutator brushes can be
given a backward lead in the case of a generator or a forward lead in the case of a
motor whereby the demagnetising action of the arinature current upon the field
is reduced or is even replaced by an action that tends to augment the magnetism
of the field.
If it is desired to provide a reversible armature, that is to say, one that can
be run in either direction, I wind a portion of each section in a plane in advance
of and at an angle to the main part of the section and another portion in a
plane behind the main part of the section and at an anglo thereto. Such forward
and backward displaced portions of the section are preferably symmetrical with
regard to the main part of the section. In order that the effect produced by one
of the displaced portions of the section may not be counteracted or neutralized
by the effect of the other displaced portion I provide notches in the field magnets
of such dimensions and in such positions that when one of the displaced portions
of each section is operating to reverse the current in said section, the other
displaced portion is passing under a notch in the field magnet and consequently
through a weakened part of the field whereby its neutralizing effect is cancelled
or largely minimised.

page_text: Improvements in Dynamo Electric Generators and Motors.
I, SIDNEY GEORGE BROWN, of 1 St. John's Road, Chelmsford, in the County of
Essex, 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 :-
This invention relates to a new drum armature winding for dymano electric
generators and motors, the said winding being such that the brushes can be set
with a backward lead and still have a sparkless break, thus obtaining all the
advantages of a backward lead.
According to my invention, instead of winding the several sections or coils of
the armature as heretofore, I wind a portion of each section forward or backward of
what may be termed the main part of the section according as tho machine is a
generator or a motor. The forward or backward turns or conductors as the case.
may be of each section serve to cut the lines of force proceeding from the forward
or backward pole and thereby induce a back E.M.F. in the section sufficient to
reverse the current in the whole section while the said section is short circuited by
the brush.
With an armature wound as above indicated the commutator brushes can be
given a backward lead in the case of a generator or a forward lead in the case of a
motor, the demagnetizing action of the armature current upon the field being
thereby minimised or even replaced by an action that tends to increase the strength
of the field.
If it is desired to construct an armature to run in either direction and at the
same time have the brushes set with a considerable backward or forward lead I
wind a portion of each section with a forward displacement and another portion
with a backward displacement with reference to the main part of the section. Such
forward and backward portions of the section are proferably symmetrical with
regard to the main part of the section, and in order that the effect produced by
one of them may not be counteracted or neutralized by the other, suitable notches
are provided in the field magnets so that when one of the said portions is operating
to reverse the current in the section, the other portion is passing under a notch in
he field magnet and consequently through a weakened part of the field whereby its
neutralizing effect is cancelled or largely minimized.
Referring to the accompanying drawings which illustrate my invention:
Figure 1 is a diagrammatic end view of an armature and shows two sections of a
winding, each consisting of two turns, in the position for being commutated.
Figure 2 is a perspective view of one of the said sections.
Figure 3 is a development of the armature winding to illustrate the complete
scheme of winding.
Figure 4 illustrates a modification wherein notches are provided in the faces of
the poles for a purpose hereinafter described.
Figure 5 is a diagrammatic end view of an armature constructed to revolve in
either direction, two sections of winding being shown.
Figure 6 is a perspective view of a modified method of winding for accomplishing
the purpose of my invention, and
Figure 7 illustrates a suitable combination of end connectors for the several
sections.
Referring to Figure 1 the armature is furnished with 12 commutator bars (of
which 1. 2. 7. 8. are numbered) and is wound with twelve sections, only two of
which are shown. The winding starting from the bar 1 takes the course A B C D,

page_text: the appearance of the section being indicated in Figure 2. The drawing shows
only two'turns to each section of the winding consisting of four conductors A, B, C, D,
but of course it will be understood that any number of turns may be used and the
proportion of the forward turns or conductors to the whole number of turns or
conductors of the section may have any suitable value. The commutator may be
constructed with any desired number of bars, the armature having a corresponding
number of soctions laid on it. The winding of the section connecting the
bars 7 and 8 is also shown in Figure 1 and takes the path 7 A, D, C, D, 8. The
whole scheme of winding is fully indicated in the developed plan Figure 3 from
which it is obvious that the scheme can be extended to multipolar machines the
parts marked N S representing two poles only, and the winding being continued
on either side of the figure.
It will be seen that while the conductors A B D and A, B, D, of the sections are
out of or nearly out of the field of the trailing pole tips and in a position to be
commutated, the forward conductors C C, which are in series with them are cutting.
lines of force proceeding from the forward pole tips and are therefore in a position for
effecting the commutation of the sections. By my improved method of winding,
that is to say, by winding a portion of each section forward in the case of a
generator or backward in the case of a motor and by properly proportioning such
forward or backward portions it is possible to run with what is known as a back-
ward lead to the brushes. As a consequence of such backward lead the current
which flows in the conductors situated between the pole tips can be made to
augment the magnetism passing through the armature and the use of compound
winding of the field is thereby obviated. My improved method of winding also
allows of the use of toothed, slotted or tunnelled armatures and short air spaces
so that a great saving in the weight of the field magnots and exciting coils is
effected.
In Figure 4 I have shown a modification wherein suitable notches are cut in the
pole faces to enable the distortion of the field caused by the armature current to
increase the lines of force round the forward conductors, represented in this case
by C and C,, in proportion to the requirements needed for commutating the current
in the sections as the load increases. By this construction the shifting of the
brushes is avoided.
When the armaturo is required to run in either direction I wind each section with
both forward and backward conductors as indicated in Figure 5 which shows two
sections so wound each having three complete turns. C, C₁ are the forward
conductors, E, E, are the backward conductors.
In the above description I have assumed that the forward or backward.
conductors make complete turns. It is not however necessary that this should be
so as will be seen from Figure 6 which illustrates a section consisting of one turn
only but still carrying out the principle of my invention. In this method of
winding, the conductor m extends only partially along the armature and then
merges into a circular conductor n which again merges into the conductor o
that extends to the end of the armature, the winding then descending across
the end and returning by the conductor p to the front end where it joins the
next bar. The conductors m and p in this winding constitute what I call
the main part of the section and correspond with the conductors A B D in the
previously described winding. The conductor o in this modification corresponds
to the forward turn C in the previously described winding. The relative lengths
of the conductors m and o are proportioned to suit the requirements. The
part n of the winding is let into an annular recess formed in the armature. If
desired the conductors may be laid in two separate armatures and coupled electrically
in the manner indicated."
The conductors A B C D above described may be connected to form one
section by end connectors of the kind shown in Figure 7 in which a, b, is a
connector of ordinary form, and c, d, e a connector of special form, the parts c, d,
of said connector being united by a U-shaped piece e which bridges over the part a

page_text: of the connector a, b. The part e may be soldered or otherwise suitably fastened
to the two separato parts c, d, or the whole connector c, d, e may be stamped or
formed out of one piece of metal suitably bent to the desired shape.
The angular displacement of the forward or backward portions of the sections
may be decided by the particular requirements of the machine but preferably it
should be kept somewhat within the angle subtended by the polar horns.
It will be seen that my invention has particular reference to the shape given to
the individual sections of the winding of the armature the individual sections of
the winding being split into two or more parts which are placed forward or back-
ward of the main portion of the section (or what may be considered as the main
part of the section) for the purpose of reducing armature interference and for
purposes of commutation as above described, and I do not wish to limit myself to
the particular shapes illustrated and particularly described as many other shapes
some of them somewhat complicated could be evolved for particular purposes which
would carry out the spirit of my invention.
It will be further observed that the series of sections constructed according to
my invention if properly spaced can be wrapped round the armature not only once
but twice or three times before being finally closed on themselves thus forming
what is called duplex and triplex winding.
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 I do
not claim chord windings as applied to smooth drum armatures which I know to
be old, but what I claim is
1. The herein described drum armature winding consisting of sections each
containing one turn, or two or more turns, and having a portion of its circuit
wound forward or backward of the main part of the section, substantially as, and
for the purposes, specified.
2. A modification of the said winding wherein a portion of the circuit is
wound forward of the main part of the section and another portion is wound
backward of the main part of the section substantially as, and for the purpose,
specified.
3: The combination of such a winding with a slotted, toothed or tunnelled
armature, substantially as described.
4. The combination with such an armature winding of notches in the pole
faces, substantially as, and for the purposes specified.
5. The modified form of winding substantially as described with reference to
Figure 4.
6. The end connectors substantially as described with reference to Figure 7 for
connecting the conductors A B C D in series with each other.
7. A dynamo-electric generator or motor furnished with an armature constructed
substantially as described with reference to one or other of the forms illustrated in
the accompanying drawings, for the purposes spécified.
Dated this 17th day of June 1897.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.