Year: 1887

page_text: Date of Application, 3rd Feb., 1887
Complete Left, 22nd Oct., 1887
Complete Accepted, 22nd Nov., 1887
I, CHARLES DENTON ABEL of No. 28 Southampton Buildings, Chancery Lane, in
the County of Middlesex, Consulting Engineer and Patent Agent do hereby declare
the nature of this invention to be as follows:-
In Dynamo electric continuous current machines constructed with the Paccinotti
ring, the poles of the exciting electro-magnets are situated opposite the outer surfaces
of the ring. With this arrangement the said poles have in addition to those surfaces
that face the ring and that are consequently operative, other surfaces of comparatively
large extent that do not face the ring and that are consequently inoperative, and this
is more particularly the case when the axes of the exciting inagnets depart materially
from the radial position.
If on the other hand in order to utilize the whole of the polar surfaces by placing
them so as to face the ring, long connecting pieces are required between the parts of
the magnet that are directed away from the ring, more particularly when these are
arranged in more or less radial positions.
In the first named case a large portion of the magnetic force produced passes from
the inoperative surfaces of one magnet to corresponding surfaces of the next magnet
forming magnetic lines of force that are not passed through by the revolving coils of
the armature.
This defect was not improved by so forming the poles as to extend round to the
inner surface of the ring; on the contrary the quantity of lines of magnetic force
that are not given off without being operative are only increased by this arrangement.
In the second above mentioned case the long connecting pieces operate very
detrimentally by weakening the magnetism produced.
It has been endeavoured to increase the power of the external poles by the use of
separate electro-magnets having their poles so arranged as to face the inner surface

page_text: of the ring, but such magnets have only an insignificant action as compared with the
external magnets on account of their small size.
The present invention consists in employing for such continuous current ring
machines exciting electro-magnets that are only situated within the ring armature,
which is for this purpose made of a large size, so that the outwardly directed polar
fields face the inner surface of the ring, the limbs of these electro-magnets being
made as massive as possible, either with or without extension of the polar fields.
With this arrangment either a single pair or several pairs of electromagnet limbs may
be used, such limbs being either in line with each other when only one pair is employed
or arranged in a cross or star shape when two or more pairs are used.
The peculiar features and advantages of dynamo electric machines thus constructed
are, firstly, that nearly all the magnetic lines of force emanating from the poles of the
electro-magnets are traversed by the revolving ring armature, and are therefore
utilised secondly, that the parts of the electro-magnets that are directed away from
the ring towards the centre thereof only require a very short magnetic connecting
piece, so that the detrimental magnetic resistance due to the connecting pieces is in
this case reduced to a minimum; thirdly, that as all magnetic lines of force are, so
to speak, intercepted by the ring and utilised, the improved construction will only
have a small amount of so called free magnetism, operating outwardly and at a distance,
which magnetism has a very detrimental and dangerous effect both on the measuring
instruments employed in electrical installations, and on the proper working of ships
compasses, when such machines are used on board vessels.
Dated this 3rd day of February 1887.

page_text: I, CHARLES DENTON ABEL of No. 28 Southampton Buildings, Chancery Lane in
the County of Middlesex, Consulting Engineer and Patent Agent 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:-
In dynamo-electric continuous current machines constructed with the Paccinotti
ring, the poles of the exciting electro magnets are situated opposite the outer surfaces
of the ring. With this arrangement the said poles have, in addition to those surfaces
that face the ring and that are consequently operative, other surfaces of comparatively
large extent that do not face the ring and that are consequently inoperative, and that
is more particularly the case when the axes of the exciting magnets depart materially
from the radial position.
If on the other hand, in order to utilize the whole of the polar surfaces, they are
placed so as to face the ring, long connecting pieces are required between the parts
of the magnet that are directed away from the ring, more particularly when these
are arranged in more or less radial positions.
In the first named case a large portion of the magnetic force produced passes
from the inoperative surfaces of one magnet to corresponding surfaces of the next
magnet forming magnetic lines of force that are not cut by the revolving coils of the
armature.
This defect was not improved by so forming the poles as to extend round to the
inner surface of the ring on the contrary, the quantity of lines of magnetic force
that are given off without being operative are only increased by this arrangement.
In the second above mentioned case the long connecting pieces operate very
detrimentally by weakening the magnetism produced.
Endeavours have been made to increase the power of the external poles by the use
of separate electro magnets having their poles so arranged as to face the inner surface
of the ring, but such magnets have only an insignificant action as compared with the
external magnets on account of their sinall size.
The present invention consists in employing for such continuous current ring
machines exciting electro magnets that are situated entirely within the ring armature,
which is for this purpose made of a large size, so that the outwardly directed polar
fields face the inner surface of the ring, the limbs of these electro magnets being
made as massive as possible, either with or without extension of the polar fields.
With this arrangement, either a single pair or several pairs of electro magnet limbs
may be used, such limbs being either in line with each other when only one pair is
employed, or arranged in a cross or star shape when two or more pairs are used.
The peculiar features and advantages of dynamo electric machines thus constructed
are, firstly, that nearly all the magnetic lines of force emanating from the poles of the
electro magnets are cut by the revolving ring armature, and are therefore utilised ;
secondly, that the parts of the electro magnets that are directed away from the ring

page_text: towards the centre thereof only require a very short magnetic connecting piece, so
that the detrimental magnetic resistance, due to the connecting pieces, is in this case
reduced to a minimum, thirdly, that as all magnetic lines of force are, so to speak,
intercepted by the ring and utilised, the improved construction will only have a small
amount of so-called free magnetisin, operating outwardly and at a distance, which
magnetism has a very detrimental and dangerous effect both in the measuring
instruments employed in electrical installations, and on the proper working of
ships compasses, when such machines are used on board vessels.
Figs. 1 and 2 of the accompanying drawing shew respectively a cross section and
longitudinal section of a dynamo electric machine constructed according to the above
described invention. A A A A are four radially arranged electro magnets, whose
inner poles are attached to the common central connecting piece B while the outer
poles are presented to the inner surface of the Paccinotti ring C. Fig. 3 shews an
arrangement in which a single pair of electro magnets is used.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim is :-
In continuous current dynamo electric machines with Paccinotti ring, the use of
exciting electro magnets situated entirely within the ring, so that the exciting poles
thereof are only presented to the inner surface of the ring substantially as herein
described.
Dated this 22nd day of October 1887
ABEL & IMRAY,
Agents for the Applicant.