Apparatus for Adjusting Commutators of Dynamo Electric Machines and Motors to Varying Speed.
Year: 1892

page_text: Date of Application, 25th Jan., 1892
Complete Specification Left, 25'h Oct., 1892-Accepted, 10th Dec., 1892
PROVISIONAL SPECIFICATION.
Apparatus for Adjusting Commutators of Dynamo Electric Machines
and Motors to Varying Speed.
We, WILLIAM WHITE, of 58 Bread Street, in the City of London, Electrical
Engineer, JAMES RADCLIFFE, of East Retford in the County of Nottingham,
Telegraph Engineer, and FREDERICK WILLIAM COOкE, also of East Retford in
the County of Nottingham, Electrical Engineer, do hereby declare the nature of
this invention to be as follows:-
When a dynamo-electric machine is driven or an electric motor worked at
varying speed, it is pecessary to vary the relative positions of the commutator and
its brushes. This is usually effected by shifting the brushes while the commutator
remains fixed on the armature shaft. According to the present invention, the
brushes are arranged to be stationary while the commutator is turned more or less
round upon the armature shaft to suit variation of speed. For this purpose, within
the driving pulley of the machine two weights are fitted to slide radially outwards
in opposition to springs these taking the place of the balls of a centrifugal governor,
sliding farther out the greater the speed with which the pulley rotates.
Each of these weights bears against one end of a lever mounted on the pulley and
suitably guided, the other end of which lever is engaged in a cam groove formed
in the face of a disc attached to the commutator.
The ends of the levers are moved more or less towards the centre of the disc,
according as the governor weights are moved more or less outwards by the
centrifugal force due to the speed of the pulley, and these lever ends acting on the
curved edges of the cam grooves shift the disc and commutator more or less back-
wards relatively to the armature coils.
This has the same effect as if the brushes themselves were shifted more or less
forwards relatively to the commutator, the lead of the brushes being thus increased
as the speed of the machine increases.
As the commutator has thus to be turned more or less round relatively to the
armature, its segments are necessarily connected to the coils of the armature by
flexible or sliding connections.
It is preferred to employ flexible connections consisting of insulated wire cords
which pass along the interior of the tubular armature shaft, spread outwards
from its open end and are attached to the cam grooved disc which drives the
commutator.
The ends of the levers, which are moved by the centrifugal action of the weights,
instead of being engaged in cam grooves of a disc attached to the commutator, may
be jointed to radial links pivotted on the face of this disc at such points that as the
ends of the levers move outwards or inwards these links are partly turned on their
pivots and move the disc forwards or backwards as the case may be.
Dated this 25th day of January 1892.
ABEL & IMRAY,
Agents for the Applicants.

page_text: COMPLETE SPECIFICATION.
Apparatus for Adjusting Commutators of Dynamo Electric Machines:
and Motors to Varying Speed.
We, WILLIAM WHITE of 58 Bread Street, in the City of London, Electrical
Engineer, JAMES RADCLIFFE, of East Retford in the County of Nottingham,
Telegraph Engineer, and FREDERICK WILLIAM COOKE, also of East Retford in
the County of Nottingham, 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 :—
When a dynamo-electric machine or motor moves at varying speed, it is necessary
to vary the relative positions of the commutator and its brushes. This is usually
effected by shifting the brushes while the commutator remains fixed on the armature
shaft.
According to the present invention, the brushes are arranged to be stationary
while the commutator is automatically turned more or less round upon the armature
shaft to suit variation of speed. For this purpose, within the driving pulley or on a
disc or the like fixed on the armature shaft of the machine two weights are fitted to
slide radially outwards in opposition to springs these taking the place of the balls
of a centrifugal governor, sliding farther out the greater the speed with which the
pulley rotates.
Each of these weights bears against one end of a lever mounted on the pulley or
part carrying the weights and suitably guided, the other end of which lever is
engaged in a cam groove formed in the face of a disc attached to the commutator.
The ends of the levers are moved more or less towards the centre of the disc,
according as the governor weights are moved more or less outwards by the
centrifugal force due to the speed of the pulley, and these lever ends acting on the
curved edges of the cam grooves shift the disc and commutator more or less back-
wards relatively to the armature coils and brushes.
This has the same effect as if the brushes themselves were shifted more or less
forwards relatively to the commutator, the lead of the brushes being thus increased
as the speed of the machine increases.
As the commutator has thus to be turned more or less round relatively to the
armature, its segments are necessarily connected to the coils of the armature by
flexible or sliding connections.
It is preferred to employ flexible connections consisting of insulated wire cords
which pass along the interior of the tubular armature shaft, spread outwards
from its open end and are attached to the cam grooved disc which drives the
commutator.
The ends of the levers, which are moved by the centrifugal action of the weights,
instead of being engaged in cam grooves of a disc attached to the commutator, may
be jointed to radial links pivotted on the face of this disc at such points that as the
ends of the levers move outwards or inwards these links are partly turned on their
pivots and move the disc forwards or backwards as the case may be.
Fig. 1 of the accompanying drawings is a section shewing adjusting apparatus
according to our invention.
Fig. 2 is an elevation of the commutator disc.
A is the shaft of the dynamo machine or electric motor, B a pulley or disc fixed
on A, and having two levers C C pivotted upon it, the one end of each lever being
connected to a weight D, and the other end travelling in a cam groove E sunk in
the face of a disc F which is attached to the commutator G.
The weights D D are fitted to slide on rods H and are pressed towards the shaft
by springs.
According as the speed of revolution is greater or less, so the weights D take a
position more or less distant from the axis, and the opposite ends of the levers C

page_text: are moved more or less towards the axis along the cam grooves E, thereby turning
the commutator more or less round relatively to stationary brushes.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is:
Apparatus for automatically turning the commutator of a dynamo electric
machine or motor more or less round relatively to stationary brushes, substantially
as herein described.
ABEL & IMRAY,
Agents for the Applicants.