Improvement in Dynamo-electric Machines.
Year: 1894

page_text: Date of Application, 20th Feb., 1894-Accepted, 21st Apr., 1394
COMPLETE SPECIFICATION.
Improvement in Dynamo-electric Machines.
1, CHARLES JAMES HALL, Electrical Engineer, of 207 Hyde Park Road,.
Headingley, Leeds, in the County of York, 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 dynamo-machines with revolving field magnets, for:
instance those described in the Patent Specifications No. 16,25 dated 24 September
1891 and No. 11,617 dated 21st June 1892, and more particularly to the means for
keeping the windings of the radially arranged magnets in their place.
My Specification No. 11,617 of 1892 describes non-magnetic caps fitted upon
the polar ends of the U-shaped plates forming the cores of the field magnets.
In order to avoid injurious eddy currents, 1 employ instead of such caps the
device hereafter described and illustrated by the accompanying drawings.
In the drawings;-
Fig. 1 is a side elevation of a pair of field magnets provided with retaining
devices embodying my invention.
Fig. 2 is a plan of the same.
Fig. 3 a longitudinal section between two field magnets.
Fig. 4 shows on a smaller scale an entire ring or system of field magnets con-
structed or mounted according to my invention.
Each magnet core d has near its extremity or pole a pair of grooves extending
the whole width of the core parallel to each other and to the axis of the dynamo,
so as to receive and guide the edges of slides or plates to be inserted between
consecutive poles. Each of the said slides / extends the whole width of the field
magnet, so as to cover the outer face of the exciting coil e, and prevent any motion
in a radial direction in obedience to centrifugal force, and it may be made of one
piece, or (as shown by the drawings) it may be composed of several plates h' of
vulcanized fibre separated from each other by strips h² of brass or other suitable
metal.
To prevent the said slides or plates from shifting in a direction parallel to the axis
of the dynamo, I employ narrow sheets k of metal inserted between the outer faces
of the coils e and the ends of the slides h and connected with the latter by bolts i.
The length of each sheet k measured on the circumference of the magnetic ring
is preferably equal to the distance between two consecutive poles, but commencing
at a point midway between the same, and the width of each sheet k is equal to the
depth of the outer winding or exciting coil e (that is the distance between the inner
and outer circumference of the coil). Each of the said sheets k has on its inner
edge a flap or flange A placed at a right angle to the sheet and radially to the
dynamo axle, as shown in Fig. 1 by dotted lines, the said flap projecting inwardly
between the cheeks or end plates d' of the laminated magnet core d and the
winding e, and being less in length than the narrow side of the magnetic core.
flap prevents the intermediate sheet k and therefore also the slides from shifting
in a direction parallel to the axis of the dynamo.
This
Each of the metal strips & is lined with or rests upon a thin strip of insulating
material.
In Fig. 4 of the drawings;
b indicates one of the two discs or carriers for the field magnets,

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, I declare that what I
cisim is ;-
1. In a dynamo-machine, having a system of electro-maguets arranged radially in
or on a revolving ring, a device for keeping the magnet windings in their places,
which consists of a series of plates (h) held with their edges in parallel grooves
formed in the magnet cores near the poles of the same, and retaining strips or
sheets k facing the magnet windings along the edges of the same, the said strips or
sheets being provided with interual flaps or flanges (k) and connected with the said
plates by bolts, substantially as described.
2. In a dynamo machine having a system of electro-magnets arranged radially on
a revolving ring, the combination of a series of sliding plates held with their edges
in parallel grooves formed in the magnet cores, with means for preventing the
axial shifting of the said plates, substantially as described.
Dated this 17th day of February 1894.
FAIRFAX & WETTER,
433, Strand, London, Agents.