Improvements in Dynamo-electric Machines.
Year: 1896

page_text: Date of Application, 13th May, 1896
Complete Specification Left 15th Mar 1897 Accented 1st May 1807
Improvements in Dynamo-electric Machines.
I, HAYDN THIES HARRISON, of Albany Buildings, 47' Victoria Street,
Westminster, in the County of London, Consulting Electrical Engineer, do hereby
declare the nature of this invention to be as follows:-
This invention has reference to alternating current generators of the kind
constructed with a magnetic divider of iron having polar projections arranged in
proximity to an annular magnetic pole without polar teeth or projections the
arrangement being such as to divide the magnetic flux induced between the annular
pole and polar projections by the field magnet winding, into tafts which are caused
to rotate relatively to the armature coils which are without magnetic cores, so that
the total magnetic flux is kept constant and the efficiency of the machine is
prevented from being reduced by hysteresis in the iron and by the generation of
Foucault currents in the several parts of the magnetic circuit.
Now my invention has reference to an improved construction of such a generator
whereby Í attain the further advantages of simplicity of construction; increased
mechanical strength without increased weight of the machine per unit of electrical
output, and, as compared with some inductor machines as heretofore constructed, a
very low armature self-induction.
In one construction of my machine both the armature coils and the field magnet
are stationary except that part of the latter which is required to constantly shift
the lines of magnetic force from one position to another in a circular direction.
The field magnet exciting coil is wound on a bobbin having a cylindrical hole
through its centre, and the field magnet, which may be of wrought iron or mild
steel, is made in two parts one of which consists of a stationary annular plate
arranged at one side of the exciting coil and provided with an annular rim or
projection that surrounds and is concentric with the said coil and forms an annular
magnetic pole, and the other part of which consists of a rotary cylindrical core
that is fixed on the driving shaft, extends centrally through the field magnet coil
and the stationary annular plate, and carries at the opposite end of the said core a
plate having radially projecting magnetic poles arranged to rotate within the
annular magnetic pole. On the inner side of the fixed annular rim or projection
and concentrically therewith, is fixed a laminated iron ring consisting preferably of
a number of annular plates of sheet iron. Against the plain inner periphery of
this ring, but insulated therefrom, are fixed the armature coils which are of a
shallow flattened form with non-magnetic cores, and curved to fit the inner
periphery of the laminated iron ring which is without polar projections. The said
armature coils may conveniently be fixed in place by inserting their inner curved
ends into slots forined in a ring of insulating material fixed within the annular rim
between the stationary annular plate and the laminated iron ring, and the outer
ends of which are clamped against the inner periphery of the said annular rim by
curved strips of insulating material secured in place by suitable fastening devices
such as screws. The rotary magnetic poles, similar in appearance to a star, project
out radially sufficiently far to come into close proximity to the armature coils and
laminated iron ring. There are twice as many armature coils as there are polar
projections, the arrangement being such that when a polar projection coincides with

page_text: and is opposite to the core of one armature coil there is another armature coil
between it and the coil which is opposite to and coincides with the next polar
projection.
The action of the machine is as follows:-When an electric current is caused to
pass through the field magnet exciting coil, lines of magnetic force are set up
which pass from the polar projections of the rotary star shaped plate into the
laminated iron ring which concentrically surrounds them, the lines of force passing
through the armature coils and returning to the rotating part through the stationary
annular rim and the side plate carrying this rim. When the star shaped plate is
rotated, the tufts of lines of force proceeding from its polar projections travel
round with it and in doing so alternately increase and decrease the number of lines
of force passing through each armature coil, thus inducing an alternating potential
difference within them, the total number of lines of force passing from the polar
projections to the stationary annular pole remaining constant.
Dated this 12th day of May 1896.
Improvements in Dynamo-electric Machines.
I, HAYDN THIES HARRISON, of Albany Buildings, 47 Victoria Street,
Westminster, in the County of London, Consulting Electrical 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 :-
This invention has reference to alternating current generators of the kind
constructed with a magnetic divider of iron having polar projections arranged in
proximity to an annular magnetic pole without polar teeth or projections, the
arrangement being such as to divide the magnetic flux, induced between the
annular pole and polar projections by the field magnet winding, into tufts which are
caused to rotate relatively to the armature coils, which are without magnetic cores,
so that the total magnetic flux is kept constant, and the efficiency of the machine
is prevented from being reduced by hysteresis in the iron and by the generation of
Foucault currents in the several parts of the magnetic circuit. Now my invention
has reference to an improved construction of such a generator whereby I attain
the further advantages of simplicity of construction, increased mechanical strength
without increased weight of the machine per unit of electrical output, and, as
compared with this class of machines as heretofore constructed, a very low
armature self-induction.
In the accompanying drawings,
Fig. 1 is a side elevation, Fig. 2 an end elevation, Fig. 3 a plan and Fig. 4
a vertical longitudinal section, showing a dynamo electric machine constructed
according to this invention.
Fig. 5 is an end elevation of the magnetic divider alone and Fig. 6 is a section
thereof on the line of Fig. 5.
Fig. 7 is a part end elevation and Fig. 8 a part cross section, showing details of
the armature connections, drawn to a larger scale than the other figures.
In this construction of my machine both the armature coils, and the field magnet
are stationary except that part of the latter which is required to constantly shift
the lines of magnetic force from one position to another in a circular direction.

page_text: A is the field magnet exciting coil wound on a bobbin A having a cylindrical
hole through its centre. The field magnet, which may be of wrought iron or
mild steel, is made in two parts one of which consists of a stationary annular
plate B arranged at one side of and carrying upon a tubular boss B the exciting
coil A and provided with an annular rim or projection B' that surrounds and is
concentric with the said coil and forms an annular magnetic pole. The other
part of the magnet, constituting the magnetic divider, consists of a rotary
cylindrical core B2 that is fixed on the driving shaft C, extends centrally through
the field magnet coil A and the stationary annular plate B, and carries at the
opposite end of the said core radially projecting magnetic poles B arranged to
rotate within the annular magnetic pole B'. The rotary magnetic divider con-
sequently revolves between two fixed and co-axial annular magnetic poles, viz. the
outer annular pole formed by the rim B' and the inner annular polo formed at
the central portion of the plate B through which the core B' extends. The said
divider or rotary part of the field magnet thus serves to complete the magnetic
circuit of the fixed part of the electro-magnet, the magnetic flux between the
two parts being kept constant. On the inner side of the fixed annular rim or
projection B and concentrically therewith, is fixed by a ring D a laminated iron
ring B consisting preferably of a number of annular plates of sheet iron. Against
the plain inner periphery of this ring B but insulated therefrom, are fixed the
armature coils E which are of a shallow flattened form with non-magnetic cores
and curved to fit the inner periphery of the laminated iron ring B which is
without polar projections. The said armature cuils E may conveniently be fixed
in place by inserting their inner curved ends into slots F formed in a ring F of
insulating material, for example wood, fixed within the annular rim B' between the
stationary annular plate B and the laminated iron ring B' the outer ends of the
said coils being clamped against the inner periphery of a ring G of insulating
material by curved strips H of insulating material that are arranged in a circle and
are secured in place by suitable fastening devices such as screws H' and nuts H³.
The ring G and strips H also serve to carry the screws I and connections J for
joining up the armature coils. The whole of these armature connections are
covered by an annular plate K fixed to the ring G. The rotary magnetic poles B,
similar in appearance to a star, project out radially sufficiently far to come into
close proximity to the armature coils E and laminated iron ring B. There are
twice as many armature coils as there are polar projections, the arrangement being
such that when a polar projection coincides with and is opposite to the core of one
armature coil there is another armature coil between it and the coil which is
opposite to and coincides with the next polar projection.
The action of the machine is as follows:-When an electric current is caused to
pass through the field magnet exciting coil A lines of magnetic force are set up
which pass from the polar projections B of the rotary star shaped portion of the
divider into the laminated iron ring B which concentrically surrounds them, the
lines of force passing through the armature coils E and returning to the rotating
part through the stationary annular rim B' and the side plate B carrying this rim.
When the star shaped part with core is rotated, the tufts of lines of force
proceeding from its polar projections travel round with it and in doing so
alternately incrense and decrease the number of lines of force passing through each
armature coil thus inducing an alternating potential difference within the coils, the
total number of lines of force passing from the polar projections to the stationary
annular pole remaining constant.
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 I am aware
of Mr. Mordey's Patent No. 8262 of 1887 and I do not seek to claim anything
described or claimed in the specification thereof but what I do claim is :-
1. A dynamo electric machine of the hereinabove described construction and
arrangement according to which the polar projections arranged to rotate within

page_text: and concentrically to the stationary annular magnetic pole without polar pro-
jections are carried by one end of a rotary cylindrical magnetic core that is
concentric with the said annular magnetic pole and near its other end is located
within so as to be surrounded by the stationary part of the field magnet carrying
the field magnet exciting coil, substantially as described.
2. My improved dynamo-electric machine constructed arranged and operating as
hereinbefore described with reference to and shown in the drawings annexed.
Dated this 15th day of March 1897.
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.