Improvements in Field-magnets and Supporting Frames for Dynamo- electric Machines.
Year: 1890

page_text: Date of Application, 24th Mar., 1890-ccepted, 26th Apr., 1890
COMPLETE SPECIFICATION.
Improvements in Field-magnets and Supporting Frames for Dynamo-
electric Machines.
FREDERIK VILHELM ANDERSEN, Electrical Engineer of 14 Westdown Road, Catford
in the County of Kent and JOHN OWEN GIRDLESTONE of 16 Davies Street, Berkeley
Square in the County of Middlesex, 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 :-
Our invention has for its object to so construct field-magnets with laminated pole-
pieces that lightness and efficiency is combined with cheapness of production and to
arrange the supports for the bearings of the armature on extensions of certain parts
of the field-magnets in such a manner, that the use of a separate bedplate for the
machine is dispensed with.
Lamination of the field-magnet pole-pieces is requisite in Dynamo-electric machines,
which have Pacinotti, i.e. toothed, armature cores, as otherwise a loss of energy is
caused, when the machine is working, through heating of the said pole-pieces. Since
great advantages, especially in the way of lightness and slow speed can be derived
from the use of the above named armature-cores in the construction of dynamo-
electric machines, it is of importance to so construct the field-magnets, that
a perfect lamination of the pole-pieces is obtained without making the machine
expensive.
Our invention relates preferably to such machines, in which the armature-cores
are built up from sheet iron plates, and according to the same the pole-pieces for the
field-magnets are constructed from parts of the same iron plates from which the
circular discs for the armature-core are made, each armature-disc being stamped or
cut out of the centre of a rectangular-shaped piece of sheet-iron in which four holes
are punched, one near each corner. Two pieces of sheet iron of a suitable shape for
pole-pieces are thus obtained for each armature-disc, and these pieces are built
together to form two pole-pieces by means of four bolts, passing through the above
named holes, and are secured by means of nuts on the said bolts, clamping plates with
corresponding bolt-holes being added at each end of a pole-piece. By thus making
the pole-pieces from the side-cuttings of the plates from which the armature core is
manufactured the usual waste of iron attending the production of the circular
armature discs is avoided.
The two pole-pieces thus constructed are connected to the field-magnet limbs
carrying the exciting coils by means of 4 iron bars of rectangular cross-section and of
such dimensions that they leave a suitable space for winding between the field-magnet
limbs and the horns of the pole-pieces. Two of these connecting bars are of the
same length as the pole-pieces with their clamping plates included, the two others,
generally those at the lower pole-piece, are made to extend beyond the field-magnets
and serve to carry the bearing brackets for the armature spindle. This arrangement
enables us to dispense with the ordinary bed-plate for the machine, whereby a con-
siderable saving is effected both in material and in labour.
In the accompanying sheet of drawings
Fig. 1 is a front elevation and
Fig. 2 a plan of the improved field-magnets and supporting frame constructed
according to our invention.
In Fig. 1 is shown the toothed armature core, A, turned down so as to have the
requisite clearance for revolving inside the pole-pieces.
In Fig. 1and in Fig. 2 B indicates the pole-pieces composed of iron plates, insulated
from each other by means of varnish and paper or in any other suitable manner, C
are the clamping plates made of cast or wrought iron or other suitable material, D are

page_text: the bolt-holes and E the bolts, which by means of the nuts F clamp the pole-pieces
together. The four connecting bars, G are secured to the pole-pieces by means of
the screws H screwing into the clamping plates and to the field-magnet fimbs L by
means of another set of screws M. One of the bearing brackets is indicated at N
and the two lower connecting bars are shown broken off at O, where they in practice
are further extended to carry the bracket for the bearing at the other end of the
machine. The exciting coils of the field-magnets are shown at P.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is :
1. The construction of laminated pole-pieces for field-magnets of dynamo-electric
machines from pieces of sheet iron held together by longitudinal bolts and nuts and
clamping plates, substantially as described and for the purposes set forth.
2. In field-magnets with laminated pole-pieces the arrangement of four iron
bars for connecting the pole-pieces with the field-magnet limbs, substantially as
described.
.
3. The method of completing the frame of a Dynamo-electric machine without the
use of a bed-plate by arranging the bearing-brackets on extensions of two iron bars
which serve for joining one of the pole-pieces to the field-magnet limbs.
4. The construction of field-magnets and supporting frames for Dynamo-electric
machines substantially as described.
Dated this 18th day of March 1890.
F. V. ANDERSEN.
J. O. GIRDLESTONE