IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES
Year: 1884

page_text: I, JOHN HAYTON GREENHILL of (now) King Street Belfast in the County
of Antrim, Electrical and Mechanical Engineer, do hereby declare the nature
of my invention for IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES to be as
follows:-
In a modification of armatures known as the "Burgin" type, I make the rings
of thin sheet iron, hexagonal in shape, but instead of coiling one length of wire on
each of the spaces between the projecting corners of the ring, I wind two lengths
and bring the ends out to the commutator plates, by this menus getting a sufficient
number of commutator plates with half the number of iron rings, but of more than
double width, thus getting a higher efficiency.

page_text: Improvements in Dynamo Electric Machines.
I JOHN HAYTON GREENHILL of New King Street Belfast in the County of
Antrim, Electrical and Mechanical Engineer do hereby, declare the nature of my
invention for IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
I employ a polygonal ring armature, built. of thin sheets of iron which when
placed side by side form a wide ring. To prevent Focault currents in the same,
insulate each or some of the sheets of iron from the neighbouring ones, and there
may be also air spaces at intervals for ventillation. Instead of coiling ono length
of copper wire or tapo, in which the electrical currents are generated; on each space
between the projecting corners of the iron rings as formerly adopted in what is
known as the "Bürgin" armature, I occupy the space with two coils and bring the
ends out to the commutator plates. I thus obtain double the number of sections
in the commutator for a given number of iron rings, and each coil only embraces
half the length of the arc of a circle compared to what would be occupied if one
coil filled the space between the corners. One or more wide rings with the several
coils of copper wire may be mounted on brass or other non-magnetic spokes or
centres, and carried by the rotating shaft, but in order to facilitate the coiling of
the copper wire on the iron rings which form the core, especially in armatures
of small diameter, the various iron sheets which form the ring are mounted on
"sleeves" into which the brass or other supporting spokes or centros are inserted
after the copper wire has been coiled. These "sleeves" prevent the abrasion of
the insulation of the wire while the spokes are being inserted, and also support the
iron core during the coiling of the copper wire.
In order to more fully indicate the mode of construction, I herewith annex
drawings of the armature.
Figs. I. IA and II. shew various forms of a single iron sheet or ring of hexa-
gonal, square, or polygonal shape. When a number of these of any particular
construction are placed side by side they form the iron core.
Figs. III, and IIIA represent portions of a ring of modified shape.
Fig. IV. is a perspective view of a ring composed of a number of thin sheets, as
indicated by Fig. I mounted on the "sleeves" (S) and showing air spaces.
Fig. V. is an end view of Fig. IV. with one coil of wire wrapped upon it. The
"sleeves are also indicated by the letters S. S. S. S. S. S.
"
Fig. VI. is an end view of a completed ring with all tho coils wrapped upon it,
and the brass centre inserted.
Fig. VII, shews a complete armature composed of two rings, with commutator
and shaft. The end of coil A is joined to the beginning of coil B with a connection
to a section of the commutator. Likewise the end of coil B is joined to the
beginning of coil A 1. and with a connection to the next section of the commutator.

page_text: The end of A 1. to the beginning of B1. The end of B1. to the beginning of C,
and so on for each coil and each section of the commutator.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed, I declare that what
I claim is
1. The construction of armatures composed of Iron cores having two coils of
wire in each space as shewn, and built on "sleeves" for the purpose indicated.
Dated this 6th day of August 1885.