Improvements in Dynamo-electric Machines.
Year: 1889

page_text: Date of Application, 26th Nov., 1889
Complete Specification Left, 30th July, 1890-Accepted, 18th Oct., 1890
PROVISIONAL SPECIFICATION.
Improvements in Dynamo-electric Machines.
I, JOHN HOPKINSON F.R.S. of 4 Westminster Chambers in the City of Westminster
do hereby declare the nature of this invention to be as follows:—
It is usual to construct the cores of the armatures of dynamo machines of plates of
iron insulated from each other. These plates are in the form of rings and when of
large size are expensive. I attain the same effect as is obtained by entire rings both
magnetically and mechanically by employing segments of rings arranged in layers
the joints between the segments breaking joint between successive layers. The
friction between the plates is sufficient to keep them in place just as well as if they
were entire rings. The advantage of this construction is of course great in ring
armatures of multiple pole dynamos. Such ring armatures may be wound either on
a generalization of the methods of Gramme or Von Alteneck. In either case I may
use copper bars between the core and the poles and connect the said bars by strips
of copper. When a high tension is required I wind the conductor on the following
principle for example, suppose there be twelve poles I wind a number of sections
on the armature then advance one sixth part of the circumference and wind a like
number then advance another sixth part and wind on and so on until the whole is
wound. If there be twelve commutator bars these should be connected in groups of
six arranged equidistance round the commutator. When the Von Alteneck winding
is used the winding may proceed in a zig zag direction round the armature. These
improvements are applicable to dynamo machines whether used as generators or as
motors and are in part applicable to alternate current machines as well as continuous
current machines.
Dotad this 27th day of November 1880
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, Agents.
COMPLETE SPECIFICATION.
Improvements in Dynamo-electric Machines.
I, JOHN HOPKINSON F.R.S. of 5 Victoria Street in the City of Westminster 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:-
-
It has hitherto been usual to construct the cores of the armature of dynamo
machines of plates of iron insulated from each other. These plates are in the form
of entire rings and when of large size are expensive. I attain the same effect as is
attained by entire rings both magnetically and mechanically by employing segments
of rings arranged in layers the joints between the segments of successive layers
breaking joint. The friction between the plates is sufficient to keep them in place
just as well as if they were entire rings. The advantage of this construction is of
course in ring armatures of multiple pole dynamos. Such ring armatures may be
wound either on
generalisation of the methods of Gramme or Von Alteneck. In
either case I may use copper bars between the core and the poles and connect the
said bars by strips of copper. When a high tension current is required I wind the
conductor on the following principle suppose for example there be twelve poles I wind
a number of sections on the armature then advance one sixth part of the circum-
ference and wind a like number then advance another sixth part and wind a further
like number and so on until the whole is wound. When the Von Alteneck winding
is used the winding may proceed in a zig-zag direction round the armature. These

page_text: mprovements are applicable to dynamo machines whether used as generators or as
motors and are in part applicable to alternate current machines as well as to continuous
current machines.
The whole of these improvements relate to multiple pole machines in which the
active parts of the conductor are placed upon the cylindrical parts of the armature.
In Figure 1 is shewn in side elevation the mode of constructing the core of the
armature, A A are comparatively thick plates for compressing the thin soft iron
plates B B together. The said thin soft iron plates have more or less insulation
between them. They are in segments for greater economy and are of the general
form shewn in Figure 2 in which the dotted lines shew two annular series of plates
out of the plane of the section. Each ring of segments of plates breaks joint with
the plates on either side of it. Both magnetically and mechanically the ring of
layers of plates thus formed is as good as if the several plates were entire rings.
The mode of arranging the convolutions is peculiar. Suppose for example, the
Gramme form be adopted. The successive convolutions may be connected each to
its neighbour throughout, such an arrangement is not new and is not here claimed.
But the connections may be made as follows: Suppose there be 2m magnets and
mnp convolutions there being np convolutions to each magnet destined to be
divided into n groups of 1 each wind p convolutions successively and connect the
pth convolution to the (2 np + 1)th wind p convolutions, connect to the (4 np + 1) th
and so on to the {(2 m-2) np + pth convolution there are now connected 2 mp
convolutions. Next connect the {(2m-2) np + pth convolution to the (p + 1) th
and so continue. Or I may combine the Gramme mode of connecting with the Von
Alteneck thus:- -Wind a given number of convolutions p on the Gramme system
connect the last to the (np + 1) but connect it on the same side in a manner
analogous to the Von Alteneck, connect p convolutions on the Gramine plan,
connect the last to the (2 np + 1) on the method of Von Alteneck and so on.
The following are modes of winding analogous to the winding of Von Alteneck the
first is for tension and the second for quantity.
Let there be 2m magnets and let there be 2 mp 2 bars or active sections of
conductor it being assumed in this case that p is an odd number, let the bars be
numbered successively around the armature, connect as follows taking for example
the negative sign above
and so on until the connection comes round to No. 1 bar again. The brackets at the
left hand of the columns indicate connections made at the commutator side of the
armature those on the right connections at the other side. The left hand brackets
also indicate connections made to the commutator bars. It will be seen that the
connections are made zig-zag fashion around the armature. There are 2 m brushes
on the commutator the first third-(2 m-1)th brushes tonch sections very near to
each other in potential and also in connection; the second fourth-(2 m)th touch
sections also near to each other both in connection and potential but most remote
in potential from the first third-(2 m - 1) th. For example as this is the most difficult
arrangement to understand let there be six magnets and let there be 28 bars or
active sections of conductor that is to say in the preceding general formula let m = = 3
and p
= 5 and therefore 2 mp-2=28. Figure 3 shews in elevation the connections
at the commutator end of the armature, Figure 4 at the opposite end following the
directions of the formula with the figure the mode of connection and the way in

page_text: which it is expressed by the formula is apparent to the eye.
connections be mastered the other modifications are easy.
For quantity the bars may be connected as follows:-
If this system of
and so on until section 1 is reentered again. In this case also there are 2 m brushes
but the first, third, fifth ete brushes touch bars near to each other in potential but
distant in connection. When arranged for tension the potential will be m times as
great as when arranged for quantity if the number of bars be the same.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1. In continuous current or alternate current dynamo electric machines a ring
armature constructed with plates in segments.
2. In continuous current dynamo electric machines the connections of the
successive convolutions of the armature substantially as herein described.
Dated this 30th day of July 1890.
J. HOPKINSON.