Improvements in Multipolar Dynamo Electric Generators and Motors.
Year: 1893

page_text: Date of Application, 22nd July, 1893
Complete Specification Left, 23rd Apr., 1894-Accepted, 25th May, 1894
PROVISIONAL
SPECIFICATION.
Improvements in Multipolar Dynamo Electric Generators and Motors.
We, LAZARUS PYKE and EDWARD STEPHEN HARRIS, both of 34, New
Tothill Street, in the City of Westminster, Electrical Engineers, do hereby
declare the nature of this invention to be as follows:-
This invention relates to multipolar continuous current dynamo electric
generators or motors and has for its object to avoid unequal magnetization of
different parts of the armature and the attendant unequal or counter electric action
due to differences in magnetic power of the several field magnet poles as well as the
unequal air space resistance due to any want of truth in the relative position of the
field poles and armature.
To avoid these sources of inefficiency the field is constructed of a single exciting
coil contained within a deep annular channel formed in a single magnetic mass
which surrounds the exciting coil more or less completely and is provided upon the
opposite walls of and within said channel with two rings or sets of rings of magnetic
material furnished with or forming polar extensions also under the direct influence
of the exciting coil, the said rings which may be built up of iron laminæ fitting in
or on the walls of the channel or one or both of them may form part of the
magnetic mass which as well as the polar extensions may be of cast or wrought
iron or steel.
The two rings of oppositely directed field poles are of different polarity and those
of the one ring are not radially opposite those of the other ring but alternate, those
of the one ring being opposite the spaces between those of the other ring.
The armature revolves in the annular gap between these two sets of polar
extensions so that whilst a like degree of magnetic strength is ensured in each pole
the relative arrangement of the opposite poles is such that whilst the outer surface
of the armature is under the influence of polar extensions of one polarity and the
inner surface to that of polar extensions of the other polarity, the magnetic effect in
any one part will be equal to the magnetic effect in any other part, whether or not the
armature is truly in line or central in the polar gap with equal air spaces between
it and the poles.
The armature may be of the cylindrical ring type and of square, round, or other
convenient sectional form, plain or slotted, two surfaces of its wound conductor
being active and may be attached by one face to a disc or other carrier fixed on a
shaft having its bearing in the centre of the field magnet and provided at its other
ed with a coupling or pulley, the armature carrier bearing the commutator and the
commutator brushes being carried by a bracket fixed upon the outer portion of the
field magnet.
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page_text: Improvements in Multipolar Dynamo Electric Generators and Motors.
We, LAZARUS PYKE and EDWARD STEPHEN HARRIS, both of 34, New
Tothill Street, in the City of Westminster, Electrical Engineers, 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 multipolar continuous current dynamo-electric generators
or motors and has for its object to avoid unequal magnetization of different parts of
the armature and the attendant unequal or counter-electric action due to differences
in magnetic power of the several field magnet poles and to the unequal air space
resistance consequent on any want of truth in the relative position of the field poles
and armature.
In some electric machines either generators or motors designed for working at a
low speed there are more than two field magnet poles; in medium-sized machines
four or six, these machines (termed "multipolar") have their field magnet poles of
alternate N. and S. polarity, arranged either ail acting upon one or other surface of
the armature or if acting on two or more surfaces they are placed so that the field
poles on either side of one portion of the armature are opposite one another and of
like polarity. The disadvantage of this disposition is that unequal magnetization
of different parts of the armature is almost certain to result with attendant unequal
or counter-electric action due to differences in the magnetic power of the several
separate field magnet poles as well as to the unequal air space resistance caused by
want of truth in the relative position of the field poles and armature when first
made up or after wear on the bearings has allowed a deviation from the original
centre of rotation. To abolish these sources of inefficiency, we arrange that the
field consist of a single exciting coil and magnetic mass, suitable projections being
arranged of or upon the polar extremities for the purpose of conveying the
magnetism to the armature thus ensuring a like degree of magnetic strength in each
pole we also cause the field poles to be so arranged in relation to the armature that
one surface of the latter is opposed to the influence of polar extensions of one
polarity and the opposite surface of the same to polar extensions of the one other
polarity, the said polar projections of one polarity occupying positions in relation to
the armature circle midway between those of the opposite polarity. When the
armature is in position between the two sets of field poles as disposed according to
this design the magnetic effect in any one part will be approximately equal to that
in any other irrespective of whether the armature is truly in line and central in the
polar gap with equal air spaces between it and each pole.
The magnetic mass surrounds the exciting coil more or less completely, the
polar extensions being also under the direct influence of the said exciting coil.
The magnetic mass preferably circular contains a deep annular channel in which
is placed the exciting coil, which is of a depth insufficient to fill the said channel,
the remainder of the space being occupied by two rings or sets of rings of magnetic
material furnished with or consisting of polar extensions. The said rings or sets of
rings may fit in or on the walls of the annular channel or one or both of them may
be attached to or form part of the magnetic mass which may be at some other
place divided for the convenient introduction of the current conductor or
magnetising coil.
The field magnet and its polar extensions may be of cast or wrought-iron or of
steel.
The pole rings may be built up of iron laminæ in plate or strip.
The armature revolves in the gap between the two sets of polar extensions and

page_text: embodying the invention, in which the armature is or the SIOLLеd cylindrical ring
type, the pole rings being fitted in and removable from the main field casting. As
before explained, without departing from the essence of this invention the position
of the division or divisions in the magnetic mass might be otherwise arranged.
DESCRIPTION OF DRAWING.
Figure 1 is a central vertical sectional elevation of the machine; Figure 2 is a
half-front elevation, half cross-section on line 1-1 Figure 1; Figure 3 is a plan on
a smaller scale.
For the field magnet we prefer to employ a single exciting coil A contained
within a deep annular channel formed in a single magnetizable mass B B' of cast
or wrought iron or steel, by which the exciting coil A is surrounded on three sides.
Within said channel in front of the coil A we prefer to provide two sets of polar
extensions C C¹ of magnetizable material in the form of laminated plates bolted
together and held in place against the walls B B' of the magnetizable mass, prefer-
ably by brass rings cc', so that said polar extensions are under the direct influence
of the exciting coil A.
The one set of field poles C is of opposite polarity to the other set C¹ and those
of each set are regularly alternated with those of the other set, that is to say they
are centrally opposite the spaces between those of the other set.
The armature D revolves in the annular gap between the two sets of polar
extensions so that whilst the same degree of magnetic strength is ensured in all the
poles, the relative arrangement of the opposite poles is such that whilst the outer
surface of the armature is under the influence of polar extensions of one polarity
and the inner surface under that of polar extensions of opposite polarity, the
magnetic effect in any one part will be equal to the magnetic effect in any other
part, whether or not the armature is truly central in the polar gap with equal air
spaces between it and each series of poles.
The armature core is preferably formed of annular lamine d of sheet iron radially
toothed on their inner and outer edges so as to form gaps d' in which the conductor
coils are wound. These laminæ are bolted together and to the rim of a wheel E
or other carrier of gunmetal fixed on a shaft F, a few only of the ends of the coils
being attached as shown to the corresponding segments 9 of the commutator G with
the usual cross connections.
g
The shaft F has its bearing in the centre of the field magnet B, the end of the
shaft which projects beyond the armature carrier E carrying the commutator G.
Besides this segmental commutator for the commutation of continuous currents, an
additional commutator may be placed upon the shaft, consisting of two insulated
metallic rings connected to the armature winding so that an alternating current may
be collected from them, whilst the brushes H are carried by a crosshead h pivoted
in a bridge piece I attached to arms i fixed upon the outer portion B¹ of the field
magnet. This bridge piece is pivoted at one end to its arm i so as to admit of
being swung aside along with the brushes, as shewn in dotted lines in Figure 3,
when it is desired to remove the armature from the machine. The other end of
shaft F is provided with a coupling or pulley, the field coil A being either in a
shunt, or in series.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. A multipolar continuous current dynamo-electric generator or motor, wherein
the field coil is placed in a deep annular channel in the mass of the field magnet
and wherein the armature revolves in a magnetic field between sets of oppositely-
magnetized poles situated in the same transverse plane and placed those of each set
on alternate radii to those of the other set, substantially as specified.
2. The herein described multipolar continuous current dynamo-electric generator
or motor constructed substantially as specified.
20
L. PYKE,
E. S. HARRIS,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.