Improvements in Dynamo Electric Machines
Year: 1896

page_text: A Communication from abroad by AKTIEBOLAGET DE LAVALS ÅNGTURBIN, of Jerla
Stockholm.
I, WILLIAM LLOYD WISE, of 46 Lincoln's Inn Fields, in the County of London,
Consulting Engineer and Chartered Patent Agent, do hereby declare the nature of
this invention to be as follows:-
two
This invention has for its object improvements in alternating-current generators
of the kind in which the stationary part of the magnetic field consists of an iron
casing provided with inwardly projecting pole pieces surrounded by induction
coils. The improvement consists in an arrangement by means of which the
uaguetic spreading is reduced to a minimum, and induction action upon the
magnetizing coils is obviated, although such coils are placed in the immediate
proximity of the armature coils in which electric currents are induced. In au
arrangement for this purpose according to this invention
every
adjacent pole pieces of the casing are surrounded by a common exciting
coil in such a way that one such pair of pole pieces receives north
magnetism, the following pair south magnetism and so on, when a continuous
current is passing through the said coils. A rotating iron core is placed centrally
in the casing and is provided with projections, preferably equal in number to half
that of the pole pieces in the casing. The said projections are made so broad
(preferably double the width of the stationary pole pieces) that no magnetic
variations will arise within the exciting coil of two adjacent pole pieces having
the same polarity during the rotation of the core. On the contrary the magnetism
within the armature coils belonging to these two pole pieces will be submitted to
rapid variations. While the magnetism in the stationary pole pieces in a machine
according to this invention varies between nearly o and a maximum, the magnetism
is reversed in the rotating core. In the outer casing the magnetism is partly
constant and partly varying; in those parte, which are situated between a north
pole and a south pole, the magnetism is constant.
Doted this 20th day of November 1896
Improvements in Dynamo Electric Machines.
A Communication from abroad by AKTIEBOLAGET DE LAVALS ÅNGTURBIN, of Jerla
Stockholm.
I, WILLIAM LLOYD WISE, of 40 Lincoln's Inn Fields, in the County of London,
Consulting Engineer and Chartered Patent Agent, do hereby declare the nature

page_text: 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 has for its object improvements in alternating-current generators
of the kind in which the stationary part of the magnetic field consists of an iron
casing provided with inwardly projecting pole pieces surrounded by induction
coils. The improvement consists in an arrangement by means of which the
magnetic spreading is reduced to a minimum, and induction action upon the
magnetizing coils is obviated, although such coils are placed in the immediate
proximity of the armature coila in which electric currents are induced.
The accompanying drawing shows in front elevation a dynamo electric
machine embodying the present improvement, part of the coils on one of the polo
pieces being removed.
A indicates the iron casing which may be formed as usual of layers of sheet
iron, or partly of such layers and partly of solid iron. nn and s s ure the inwardly
projecting pole pieces carried by the casing, and I are the induction or armature
coils surrounding these pole pieces. B is a rotating iron core placed centrally
within the casing A and formed of layers of sheet iron. This core has no coils but
is provided with projections b, preferably equal in number to half that of the
pole pieces in the casing A.
According to this invention every two adjacent pole pieces nn, ss, in the
casing A are surronded by a common exciting coil M in such a way, that que such
pair of pole pieces receives north magnetism, the following pair south magnetism
and so on, when a continuous current is passing through the coils M. The pro-
joctions of the iron core B are made so broad (preferably double the width of the
stationary pole pieces n n, s s) that no magnotio variations will arise within the
exciting coil of two adjacent pole pieces having the same polarity during
the rotation of the core B. On the contrary the magnetism within the induction or
armature coils I belonging to each pair of poles is submitted to rapid variations.
While the magnetism in the stationary pole pieces in the machine described
varies between nearly zero and a maximum, the magnetism is reversed in the
rotating core. In the outer casing the magnetism is partly constant and partly
varying; in those parts which are situated between a north pole and a south pole,
the magnetism is constant. These parts may therefore be formed of solid iron.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what I
lain is:-
1. In an alternating current generator comprising a casing provided with
inwardly projecting pole pieces each surrounded by an induction coil, surrounding
every two adjacent pole pieces with exciting coils adapted to magnetise such pairs
of pole pieces alternately north and south substantially as and for the purpose set
forth.
2. In an alternating current generator the combination with a casing providing
with inwardly projecting pole pieces each surrounded by an induction coil, of
exciting coils surrounding every two of said polo picces and adapted to magnetise
such pairs of pole pieces alternately north and south, and a rotating iron core placed
centrally within the casing and provided with projections equal in number to half
that of the pole pieces, substantially as and for the purpose set forth.
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.