Improvements in Alternate Current Dynamos and Synchronizing Motors.
Year: 1893

page_text: Date of Application, 28th July, 1893
Complete Specification Left, 28th Apr., 1894-Accepted. 9th June, 1894
TRUVIDIONAL SPECIFICATION.
Improvements in Alternate Current Dynamos and Synchronizing
Motors.
We, HENRY WILLOCK RAVENSHAW, and LLEWELYN BIRCHALL ATKINSON,
both of Woodfield Works, Woodfield Road, Harrow Road, in the County of
Middlesex, Electricians, do hereby declare the nature of this invention to be as
follows:-
This invention relates to alternators of the class illustrated in Letters Patent
No. 6883, 25th April 1889 granted to Llewelyn Birchall Atkinson in which the
armature coils are threaded by magnetic induction of varying strength but uniform
direction and consists in modifications of the arrangement of the armature coils
and magnetic inductors or poles.
It is known that if a number of coils are attached and stationary round the
periphery of a circular laminated core with their magnetic axes in a radial direction,
and a suitable number of magnetic poles are caused to rotate round the core,
currents of alternating E.M.F. will be set up in the armature coils, by the variation
of the magnetic induction in them.
In our improved arrangement adapted for large alternators, and particularly
where direct driven by an engine, the armature core may consist of an iron cylinder
having a thick flange at each end projecting outwards, one or both or these flanges
being built up of laminated iron plates arranged in a plane at right angles to the
axis of the core. In the channel between the flanges is wound a magnetizing coil
so that the two flanges are of opposite polarity. On the periphery of the laminated
flange or flanges are fixed a number of flat armature coils of insulated wire or tape
with their magnetic axes in a radial direction, the other flange being left bare.
The revolving part consists of a shaft supported in suitable bearings. The shaft
carries a wheel or wheels from the face of which a number of iron or steel arms
project, forming magnetic poles, herein called polar arms, in such a way that the
magnetic circuit is completed in a number of places between them, and the
peripheries of the two flanges. The width of each polar arm is rather less than
the total width of each armature coil, the number of coils being a multiple of
the number of poles.
In the case where the polar arms cover the periphery of the bare flange, which
need not be laminated, they are so constructed that they form a nearly complete
circle, the clearance between the flange and the arms being only sufficient to allow
the latter to revolve.
At the laminated flange the distance of the arms from the core is sufficient to
clear the armature coils. The complete core carrying the armature and magnetizing
coils is so supported from the bedplate or foundations that it can be revolved round
its axis for the purpose of examination; it however being fixed when the dynamo
is at work.
Although for the purposes mentioned we prefer the arrangement of one magnetizing
coil one laminated armature and face and polar wheel on one side only, the poles
being external to the armature, we may arrange to use two magnetizing coils, and
two polar wheels, or to place the polar wheel on the internal periphery of the
laminated armature.
In connection with our invention we provide suitable means for fixing and readily
detaching individual coils, and for the removal of the centre magnetizing coil.

page_text: The machine may be separately excited or may be excited by a modification of
the method described by Patent No. 6883, 25th April, A.D. 1889.
Dated this 28th day of July 1893.
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicants.
Improvements in Alternate Current Dynamos and Synchronizing
Motors.
We, HENRY WILLOCK RAVENSHAW, and LLEWELYN BIRCHALL ATKINSON,
both of Woodfield Works, Woodfield Road, Harrow Road, in the County of
Middlesex, Electricians, do hereby declare the nature of this invention and the
manner in which the same is to be performed to be particularly described and
ascertained in and by the following statement :-
This invention refers to alternators of the class described in Letters Patent
granted to Llewellyn B. Atkinson under No. 6883 and dated the 25th April 1889,
in which the armature coils are threaded by magnetic induction of varying strength
but uniform direction, and consists in modifications of the arrangement of the
armature coils and magnetic inductors or poles and in the method of mounting and
the construction of the cores carrying the magnetizing and armature coils.
It is known that if a number of coils are attached and stationary round the
periphery of a circular laminated core, with their magnetic axes in a radial direc-
tion, and a suitable number of magnetic poles are caused to rotate about the core
carrying the primary magnetising coils, currents of alternating E.M.F. will be set
up in the armature coils, by reason of the variation of the magnetic induction in
them.
And in order that our invention may be the better understood we now proceed
to describe the same in reference to the drawings hereto annexed and to the letters
and figures marked thereon.
Figure is a sectional elevation of our improved dynamo or motor, with a single
set of armature coils.
Figure 2 is a front elevation of the same.
Figure 3 is a sectional elevation of our improved dynamo or motor, with a double
set of armature coils.
A is the central core, consisting of an iron cylinder with a central orifice B,
which is convenient for leading through the terminal wires from the magnetizing
coil C, which latter is wound upon the central body of the said core.
The core is mounted as a fixture at one end upon a circular step D in the frame
of the machine. From the circular shape of the core and step, the core, when
disengaged, may be revolved, but in the arrangement as shown it is held stationary
by the bolt E, the armature flanges F. F being arranged so as to be turned, when
disengaged from the bolts and lugs G. G. on the frame, so that any armature coil
may be brought to the top for examination or removal.
In the machine as shown in Figs. 1 and 2, with a single series of armature coils,
the inner end of the core is brought up into a flange H, forming one pole of the
primary magnetic field, the other pole being in this case the armature-carrying
ring or flange F, which is laminated and capable of rotation round the central core
for examination, when disengaged from the lugs and bolts G G.
In the arrangement shown in Figure 3, with duplicate armature coils, both flange
poles of opposite polarity, on either side of the central magnetizing coil C, are
represented by the annular flanges FF carrying duplicate sets of armature coils
and each are of laminated iron.

page_text: The flat armature coils K of insulated wire or tape are arranged horizontally
on the periphery of the flanges FF with their magnetic axes in a radial.
direction.
The pole flange H, which has no armature coils, (in Figure 1) is left bare, and
is brought as close as possible to the revolving polar arms Ĺ without actual
contact.
The revolving part of the mechanism, in each arrangement shown, consists of a
shaft M supported in suitable bearings, and carrying a disc wheel or wheels N,.
from the face of which a number of iron or steel arms L project, forming inductive
poles or polar arms, completing the magnetic circuit about the primary magnetising
coil C. The polar arms L are attached to the revolving disc N by bolts, to admit
of easy detachinent, and they are confined against the action of centrifugal force, at.
their ends farthest from the disc, by a ring Q.
The width of each polar arm L where it traverses the armature coils, is rather
less than the width of each armature coil K, and the polar arms have a space
between them greater than the width of each armature coil, the number of armature
coils being any multiple of the number of the polar arms L. Where the polar-
arms traverse the periphery of the bare flange H, which need not be laminated,
they are preferably so constructed that they form a nearly complete circle.
The polar arms, the magnetising coil, and armature coils, may be all readily
fixed and detached for examination at any time or for renewal.
The machine may be separately excited, or may be excited by a similar method
to that described in the Letters Patent No. 6883 of 1889 before referred to.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1st. In an alternate current dynamo or motor, a hollow cylindrical core; over
hanging from bed plate; and capable of rotation in bearing-step, when unbolted, for
examination of parts, substantially as described.
2nd. In an alternate current dynamo or motor, the combination of a central
overhanging core supporting the magnetising coil, with annular laminated supple-
mentary cores, capable of rotation about former, when unbolted, and carrying the
armature coils, substantially as described.
3rd. In an alternate current dynamo or motor, the combination with a revolving
disc, of polar arms, bolted thereto and easily detachable therefrom, and of a ring
flange confining ends of polar arms, farthest from the disc, against centrifugal
force, substantially as described.
4th. The construction and arrangement of parts, constituting an alternate.
current dynamo or motor, substantially as described and illustrated herewith.
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicants..