Improvements in Construction of Low Tension Dynamo Electric Machinery.
Year: 1896

page_text: Improvements in Construction of Low Tension Dynamo Electric
Machinery.
I, FRANCIS EDWARD ELMORE, of Pontefract Road, Hunslet, Leeds, in the
County of York, Electrometallurgist, do hereby declare the nature of this invention
to be as follows:-
This invention has for its object a new or improved construction of dynamo
electric machine of the type known as the "Unipolar" or "Faraday" disc
machine for generating a large volume of current at a low pressure.
Heretofore such machines have generally consisted of a shaft or disc rapidly
rotating in a powerful magnetic field, the current being collected at the two ends
in case of a shaft or at the periphery and axis in the case of a disc.
Various materials have been suggested for the collectors in such machines, but
these have generally consisted of metallic brushes of much the same character as
those commonly used in connection with ordinary continuous current dynamos.
At the very high speed at which Unipolar machines have to run, the wear of the
brushes and of the surface upon which they hear is very considerable, and the loss
of power in friction, by reason of the large area of contact which is necessary, has
been a great drawback to the use of such machines.
According to the present invention, both the wearing of the contact surfaces and
the loss of power by friction are greatly reduced.
In carrying my invention into practice I proceed as follows:-
When the machine is of the disc type it may be supported by a ball bearing at
its shaft which constitutes the one collector and a ring of balls or rollers
embracing its periphery is made to serve as the other collector.
When the machine is of the shaft character, I turn on its periphery in the
position which the brushes would naturally occupy collars or paths, and I-
surround the armature at that place with a ring so that the armature is supported
by balls running against the collar and in the ring these constituting collectors
as well as bearings.
When balls are applied in this manner to operate as bearings and collectors with
very little friction, a number of such collectors can he applied to one armature
without involving great expenditure of power. I take advantage of this to
increase the pressure of the current produced by a machine of this kind, by fixing
on the armature a number of concentric sleeves insulated from one another, and
applying a ball collector to each. By connecting these collectors in series, a
current of high pressure as well as of large volume can be obtained. As a con-
venient and comparatively inexpensive mode of forming and fixing the sleeves, I
deposit copper electrolytically upon insulating films such as paraffined paper
coated with plumbago or other conducting material, these films serving to insulate
each sleeve from the next.
Although I have described balls as a means of conveying the current to and

page_text: from the rotating parts of the machines, it is to be understood that for these may
be substituted cylindrical or barrel shaped rollers.
Dated this 2nd day of Santamhan 180
COMPLETE SPECIFICATION. og
Improvements in Construction of Low Tension Dynamo Electric
Machinery.
I, FRANCIS EDWARD ELMORE, of Pontefract Road, Hunslet, Leeds, in the
County of York, Electrometallurgist, 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 for its object a new or improved construction of dynamo
electric machine of the type known as the "Unipolar" or "Faraday" disc
machine for generating a large volume of current at a low pressure.
Heretofore such machines have generally consisted of a shaft or disc rapidly.
rotating in a powerful magnetic field, the current being collected at the two ends
in case of a shaft or at the periphery and axis in the case of a disc.
Various materials have been suggested for the collectors in such machines, but
these have generally consisted of metallic brushes of much the same character as
those commonly used in connection with ordinary continuous current dynamos.
At the very high speed at which Unipolar machines have to run, the wear of the
brushes and of the surface upon which they bear is very considerable, and the loss
of power in friction, by reason of the large area of contact which is necessary, has
been a great drawback to the use of such machines.
According to the present invention, both the wearing of the contact surfaces and
the loss of power by friction are greatly reduced.
In carrying my invention into practice I proceed as follows:-
When the machine is of the disc type it may be supported by a ball bearing at
its shaft which constitutes the one collector and a ring of balls or rollers
embracing its periphery is made to serve as the other collector.
When the machine is of the shaft character, I turn on its periphery in the
position which the brushes would naturally occupy collars or paths, and I
surround the armature at that place with a ring so that the armature is supported
by balls running against the collar, and in the ring these constituting collectors
as well as bearings.
When balls are applied in this manner to operate as bearings and collectors
with very little friction, a number of such collectors can be applied to one armature
without involving great expenditure of power. I take advantage of this: to
increase the pressure of the current produced by a machine of this kind, by fixing
on the armature a number of concentric sleeves insulated from one another, and
applying a ball collector to each. By connecting these collectors in series, a
current of high pressure as well as of large volume can be obtained... As.a.con-
venient and comparatively inexpensive mode of forming and fixing the sleeves; I
deposit copper electrolytically upon insulating films such as paraffined paper
coated with plumbago or other conducting material, these films serving to insulate
each sleeve from the next.
Although I have described balls as a means of conveying the current to and from
the rotating parts of the machines, it is to be understood that for these may be
substituted cylindrical or barrel shaped rollers.

page_text: Figure 1 of the accompanying drawings is a longitudinal section partly in
elevation and Figure 2 is a transverse section of a shaft machine according to my
invention. Figure 3 shews a machine having two sleeves and two sets of
collectors. Figures 4 and 5 shew how rollers may be substituted for balls in the
ecllector.
As shewn in Figures 1 and 2 the shaft A passes through the two side limbs BB
and the middle limb C of an electromagnet having the exciting coil D. On the
shaft are two collars, E which may be in one piece with the shaft, and F which
may be fixed on by screwing or otherwise cach collar being situated between a pair
of conducting pieces G, H, the lower ends of which dip into mercury in cups KL
which form the terminals of the machine. In the collars E, F, and the
pieces G, H, are turned races for balls which constitute the conductors connecting
the collars with the conducting pieces. To prevent the conducting pieces from
rotating with the shaft, each has a projecting arm P held stationary by a spring Q.
As shewn in Figure 3 there are two metal sleeves M N on the shaft separated
from it and from each other by insulating layers. Each of these sleeves has a pair
of collars and conducting pieces with balls as above described.
As shewn in Figures 4 and 5 rollers R pivotted in rings S revolve in contact with
the collar E and the conducting pieces G H. These rollers instead of balls con-
stitute the conducting connections between the shaft collars and the conducting
pieces G H.
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:-
In a unipolar electric machine the use of anti-friction balls or rollers instead of
rubbers as conducting connections.
Dated this 21st day of June 1897.
ABEL
& IMRAY,
Agents for the Applicant.