Improvements in Dynamo Electric Machines.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improvements in Dynamo Electric Machines.
1, WILLIAM MORRIS MORDEY, of Victoria Works, Lambeth, in the County of
Surrey, Electrician, 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 :-
My invention has reference to dynamo electric machines of the type in which
an armature having an annular series of coils is arranged between two series of
magnetic poles or polar extensions, as for example in a dynamo electric machine
of the kind described in the Specification of Letters Patent granted to me under
date 8th June 1887 No. 8262.
My present improvements hereinafter described relate to details of construction
of such machines and more particularly to the mode of supporting and arranging
the armature coils, and to means for placing the rotating field magnet winding
in connection with a source of electric energy, as I will now proceed to describe
by the aid of the accompanying drawings in which,
Fig. 1 is an end elevation of an alternate current dynamo electric machine, or
alternator such as above referred to constructed according to my present invention,
certain supporting parts being omitted for the sake of clearness.
Fig. 2 is a longitudinal elevation, partly in section.
Figs. 3 and 4 shew in detail, the construction of an armature coil and my
mode of supporting it; Fig. 3 being a longitudinal section, and Fig. 4 a full
side view.
Figs. 5 and 6 are diagrammatic views showing modified arrangements of the
armature coils.
Referring to Figs. 1 to 4 inclusive, 1 is an armature supporting frame or ring. It
is preferably made of some metal or alloy, for example gun metal, that is non-mag-
netic and of high specific electrical resistance. To give it rigidity in both directions
it is made of the section shown in Fig. 3 wherein it is shown as a rim with an inner
flange or web 1 to which the armature coils 2, 2, are secured as hereinafter
described. Each of these coils 2 is held between two plates 3, 33 by bolts 4, 4, in
the following manner. Each plate is formed with three holes for the three
bolts 4, 4, 4, the front plate having also 2 additional holes 5, 5 lined with
insulating bushes, through which the ends of the conductor constituting the coil 2
are brought.
In high tension armatures the plates 3, 3 are covered or protected on their
inner surfaces, and also to a certain extent on their outer surfaces, with an insu-
lating substance. For this purpose I prefer to partly or wholly embed these plates
in layers 6 of material suitable for insulating, which is put on in a plastic state,
and afterwards vulcanized, as for example ebonite. This secures good insulation
and prevents surface leakage. Each of the bolts 4 (one of which is fully shown
in Fig. 3), is provided with a collar or shoulder 7. To secure the coil between
the plates 3, 3, the bolts 4 are first passed through their respective holes in the
plates, and the nuts 4 then screwed up tight, thereby firmly holding the coil in
place between the plates. Each coil so held is then ready to be mounted on the
ring 1.
To enable this to be done, the flange 1 is provided with radially slotted
holes 8, through which are passed the short ends of the bolts 4 that project beyond
the plate 3º. A nut 4 is then screwed on to the end of each of the said bolts,
thus firmly holding the plates and coil against the turned face of the flange 1.
The complete armature is made up by mounting on the ring 1 in the manner
described the proper number of armature coils. In order that the coil- may be readily

page_text: put exactly in their proper radial positions, and also to enable any coil to be easily
and quickly taken out or put in place laterally, and especially for the purpose of
rendering it easy to so mount the coils that they may mutually support one another
and so form a strong structure and prevent looseness or vibration, the following
arrangement is adopted. The outer periphery of the plate 3* of each coil is formed
with two recessed projections 9. The ring I has a number of radial holes drilled
and tapped to correspond in position with the middle of each of the coils. For each
coil a screw 10, or there may be more than one for each coil, is screwed into the
ring this screw being so arranged that its head enters within the recess between
the projections 9. When placing a coil 2 in position, it is first put as far out
radially as it will go, the nuts 4 being at this time loose on the bolts 4.
screw 10 is then turned until the coil is forced ralially inwards to its proper
position. The nuts 4 are then tightened up, finally securing the coil in place.
Each armature coil 2 is formed of copper ribbon wound with the requisite number
of turns, a ribbon of suitable insulating material being wound between the turns.
The space within each coil is sometimes left blank, and sometimes filled with a
corp 2 of a non-metallic substance such as slate, porcelain, marble or glass.
The
The armature supporting ring 1 is divided at its vertical diameter into two equal
portions which are bolted together at the points of junction 1". In the particular
armature shown in Figs. 1 and 2, there are eighteen armature coils, equally spaced
around the ring, these coils being shewn in front view in Fig. 1 except those
thereof which are hidden by the field magnet.
parts
The several coils are shewn
electrically connected in series by the connecting conductors 11 11 and the ends
of the whole series are brought out to the terminals 12 12ª (Fig. 1) which are
carried on an insulating base 13.
As machines constructed according to this invention are intended principally for
high tension working, and as it is not usually convenient to measure the full E. M. F.,
two special volt meter terminals 14 14° are connected to the ends of one of the
coils, the E.M.F. of which can be readily taken by an ordinary low pressure volt-
meter, and the full E. M.F. of the armature thus ascertained indirectly.
may, however, as well understood, connect the armature coils in any other
convenient manner; thus two portions may be connected parallel or separate
external circuits may be supplied from separate portions of the armature winding.
The complete armature ring 1 is firmly bolted to the bed plate 15, and is or may
be supported laterally by wing stays or brackets springing from the bearing
pedestals at 16, 16 and bolted to the ring 1 at the points 17, 17, or at other suitable
points. These wing stays are not shewn in the drawings.
The field magnet, which is the rotating part of the machine, is carried by the
driving shaft 18 which runs in bearings 19 19. These bearings, which for
magnetic reasons are preferably carried by non-magnetic seats or blocks 20, 20',
are supported on the pedestals 15 15 which rise from the bed plate 15. In Fig. 1
the pedestal 15" and bearing carried thereby are omitted for the sake of clearness.
The field magnet is constructed substantially in the manner described in my
said former Specification and usually consists of three principal parts, ris. a central
portion or core 21, and two end or polar portions. The core is provided with
Hanges 22 between which is usually wound the magnetizing winding 23. It is
not necessary that this winding 23 should rotate, and it may be supported in a
fixed position. For structural reasons, however I prefer to rotate the winding 23,
and therefore attach it to the core 21. The end or polar portions of the magnet
are of the well known peculiar construction, each being a circular dished casting
from the central solid portion 24 of which spring a number of ralial curved
projections 25, of like polarity, forming polar extensions, the projections at one
end of the core being of opposite polarity to that of the projections at the other
end of the core as in my former construction of machine. These two series of
polar extensions are curvel towards and face each other, there being left between
them a
narrow gap in which the armature coils are fixed. In the machine
illustrated there are nine polar extensions 25 on each side of the armature.
The

page_text: number of such polar extensions and of armature coils, will however vary according
to the size and speed of the machine, and the required periodicity of the current.
26 are webs forming part of the corresponding polar casting and arranged to
partly close the spaces between the polar extensions and thus serve to prevent
excessive air disturbance; 26 are air holes to allow of sufficient passage of air
for ventilating and cooling purposes; and 27 are nuts screwed on the driving shaft
for securely holding the three main portions of the field magnet together all as in
my former machine. The driving shaft is provided near each end with a shoulder
or collar that takes into the corresponding bearing 19, or 19. The bearing
blocks 20, 20 are made capable of end adjustment to enable the proper relative
position of magnet and armature to be ensured.
When the magnetizing winding 23 rotates with the magnet, it is necessary to
provide means for connecting the said winding with the source of excitation, which
may be a separate direct current machine, or a portion, or the whole of the
armature coils. In the latter case a commutator is used to redress or commute
the alternate currents, in a manner well understood. The arrangement for passing the
exciting current to the field winding 23 according to this invention, comprises a pair
of metallic rings 28 and 29 carried by the ariving shaft but insulated from this
shaft and from one another. The ends of the winding 23 are connected by the
wires 30 and 31 to the rings 28 and 29 respectively. On the bearing block 20 are
supported two insulated studs 32, 32 each having at one end a terminal 30* for
the reception of one of the wires conveying the exciting current. To the other
ends of these studs are attached flexible metallic contact strips or bands 33 33*
which pass over the rings 28 and 29 respectively, and are kept in good contact with
these rings by weights 34 34. Sometimes I attach wearing blocks of carbon or
anti-friction metal to the flexible strips 33, 33ª to prevent these strips rubbing
directly on the rings. By these means I secure a simple and excellent rubbing
contact for the passage of the exciting current.
I may however use only one of these rings to which one end of the winding is
attached, the other end of the winding being connected with the iron of the machine
which is thus used as one terminal of the said winding.
The armature coils of dynamo electric machines of the kind herein before
referred to can be so arranged as to adapt such machines to give two or more
periodic electro-motive forces and currents differing from one another in phase.
Thus to produce two E.M.F.'s or currents differing by 90° or a quarter period, that
is to say, so that one current attains a maximum at the time the other reaches :
minimum, I displace one half or other suitable proportion of the armature coils in
either direction to an amount equal to one half the angular width of a single coil.
and fix these coils to the supporting ring 1 in this position. Again to produce
three E.M.F.'s or currents differing from one another in phase by any required
angle or proportion of a complete period I may divide the armature coils into three
equal or unequal portions. For example if three periodic currents are required
differing by one-third of a period or 120°, I displace two portions of the armature
coils, relatively to a third portion, the one portion being moved forward and another
portion backward by an amount equal to one third of the angular width of a single
coil. To enable this displacement of coils to be carried out I usually remove one
coil. In the case of the two phase arrangement this leaves two vacant spaces 35 in
the armature, as shown in the diagrammatic view Fig. 5 each space being equal in
width to half a coil. In the three-phase arrangement, three spaces are left between
the sets of coils each space being equal in width to a third of a coil if the currents
are to differ by one third of a period, or 120°. These vacant spaces may be filled
up by distance pieces of suitable material, for example slate or porcelain, or by
small coils that can be used for any subsidiary purpose. Another way in which I
carry out this object is by using two or more annular series of armature coils placed
in parallel planes, the coils in one series being set the requisite distance in advance
of the coils in the other series to give the required difference of phase. Fig. 6
shews such an arrangement for producing two periodic E.M.F.'s or
currents

page_text: differing from each other by 90° or a quarter period. For this purpose each of the
coils in the one series 2 is displaced relatively to those in the other series 2* through
an angular space equal to one half of the angular width of a coil.
When such multiple phase machines are used as generators, the currents produced
may be conveyed away by means of separate pairs of wires for each portion of
the armature as indicated in full lines in Fig. 5. or three wires may be used for two
phase currents as indicated in dotted lines in the said figure, one wire being
common to two circuits, and so on. Thus for two windings I
may use three
mains instead of four, and for three windings may use four mains instead
of six.
It will be understood that machines constructed as described whether single or
multiple phase are suitable for use as generators or motors.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In a dynamo electric machine of the type referred to, a detachable armature
coil removable laterally, and held at its outer end between plates by bolts that
project laterally from one side of the coil and are adapted to be secured to the
armature supporting frame, substantially as herein described.
2. In a dynamo electric machine of the type referred to, an armature comprising
a supporting frame with inwardly projecting flange and a series of detachable coils
removable laterally, each of which is held between plates by horizontal bolts
having extensions adapted to be secured to said frame, the outer of the said plates
being formed with holes for the passage of the ends of the coil, substantially as
herein described.
3. In an armature comprising a supporting frame with inwardly projecting flange
and an annular series of coils, connecting each coil to the supporting frame so that
it is detachable in a lateral direction from and is adjustable in a radial direction on
the said frame substantially as herein described.
4. In a dynamo electric machine of the type referred to, the combination of a
rotary field magnet having two series of magnetic poles, a non-magnetic supporting
frame having an inwardly projecting flange formed with series of radial slots, and
an annular series of armature coils each held at its outer end between two plates by
bolts secured to the said flange so as to be adjustable radially in the said slots,
substantially as herein described.
5. In a dynamo electric machine of the type referred to, the combination with a
stationary armature and a rotary field magnet having its magnetising field winding
arranged to rotate therewith, of an insulated metallic ring connected with one end
of the field winding, and arranged to rotate with the field magnet, a flexible metallic
trip extending over the said ring and pressed in contact therewith by
gravity, and terminals in connection with the ends of the field winding, one of the
said terminals being in connection with the flexible contact strip, substantially as
herein described for the purpose specified.
6. In a dynamo electric machine of the type referred to, the combination with a
stationary armature and a rotary field magnet having its magnetising field winding
arranged to rotate therewith, of two insulated metallic rings connected with the
respective ends of the winding and arranged to rotate with the magnet, and two
flexible metallic contact strips arranged to pass one over each of the discs,
each of these strips being fixed at one tal to an insulated stud and carrying at its
other end a weight, substantially as herein described for the purpose specified.
7. In a dynamo electric machine of the type referred to, an armature comprising
two or more series or groups of coils, the coils in one, or in each of said series or
groups being displaced in a circular direction relatively to those in the other group
or groups, substantially as herein described for the purpose specified.
8. In a dynamo electric machine of the type referred to, an armature comprising
an amular series of coils divided into two or more groups, the coils in each of the

page_text: groups being displaced in a circular direction relatively to the coils in the other
group or groups, substantially as herein described for the purpose specified.
9. A multiple-phase dynamo electric mnachine comprising a rotary field magnet
baving two series of magnetic poles, and a stationary armature comprising
coils carried by a non-magnetic support and arranged in two or more groups
located between the two series of magnetic poles, the coils in each of said groups
being displaced in a circular direction relatively to the coils in the other group or
groups, substantially as herein described for the purpose specified.
10. The improved dynamo electric machine hereinabove described and shown in
the drawings annexed."
D
L
1001
W. M. MORDEY.
W. Lloyd Wise,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.