Improvements in Dynamo-electric Machines for Electro Plating and like Work.
Year: 1889

page_text: Date of Application, 7th Oct., 1889
Complete Specification Left, 7th July, 1890-Accepted, 30th Aug., 1890
PROVISIONAL SPECIFICATION.
Improvements in Dynamo-electric Machines for Electro Plating and
like Work.
I, WILLIAM BROOKS SAYERS Electrical Engineer, 24 Glycena Road Lavender Hill,
London S.W. do hereby declare the nature of this invention to be as follows:-
The object of this invention is to facilitate the manufacture of dynamo electric
machines for electro plating and at the same time to produce a more economical
machine and one which shall offer the electro plater increased facilities in the
execution of his work. There are practical difficulties met with in constructing
dynamo machines with either ring or drum armatures capable of delivering a good
output for the size and cost of the machine at the low pressure or voltage required in
electro plating work. This results from the fact that after the coils on the armature
and the sections of the commutator have been reduced to the smallest practicable
number the E M F is generally much too high for the work when the machine is run
at a fair speed. Also electro platers require a higher E M F at the commencement of
any piece of work than during the greater part of the operation.
My invention consists in forming one or more slots or divisions across each or any
of the polar surfaces of a dynamo in such a manner as to produce one or more gaps in
the magnetic field, parallel to the conductors in the armature, the effect of which is to
produce non-active sections in the armature, and thus enable me to apply additional
or intermediate brushes to the commutator without destructive sparking. The
armature of the dynamo is wound to give twice or more times (according to the
number of slots or divisions which have been made in the polar surfaces) the EM F
required for working, and thus I am able to use conductors of smaller and more con-
venient cross section on, the armature and to employ a larger number of turns, and
so get a satisfactory number of sections on the commutator. The equi-potential
brushes may be connected together. The operator connects his working electrode to
the ordinary brushes in the usual way if he requires the full E M F of which the
machine is capable, or to one of the ordinary and one of the additional or inter-
mediate ones if he requires a smaller EM F; or, if the polar surfaces of the field
magnets have been arranged to allow of more than one pair of additional or inter-
mediate brushes to be applied to the commutator, the working electrodes may be
connected to two pairs of additional or intermediate brushes ;-that is, one electrode
to one pair and one electrode to the other pair.
Dated this 2nd day of October 1889
WILLIAM BROOKS SAYERS.
COMPLETE SPECIFICATION.
Improvements in Dynamo-electric Machines for Electro Plating and
like Work.
I, WILLIAM BROOKS SAYERS Electrical Engineer, of 71 Norroy Road Putney in
the County of Surrey, late of 24 Glycena Road, Lavender Hill, London S.W. 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:
The object of this invention is to facilitate the manufacture of dynamo electric
machines for electro plating and at the same time to produce a more economical
machine and one which shall afford the electro plater increased facilities in the
execution of his work. There are practical difficulties met with in constructing
dynamo machines with either ring or drum armatures capable of delivering a good

page_text: output for the size and cost of the machine at the low pressure or voltage required in
electro plating work. This results from the fact that even when in designing the
machine the coils on the armature and sections of the cominutator have been reduced
to the smallest practicable number the E M F is generally much too high for the
work when the machine is run at a fair speed; also electro platers require a
higher E. M F at the commencement of any piece of work than during the greater
part of the operation.
My invention consists in forming one or more slots or divisions across each or any
of the polar surfaces which are presented to the armature, for the purpose of
producing one or more gaps or positions of diminished intensity in the magnetic field,
in a plane or planes parallel to the axis on which the armature rotates the effect of
which is to produce non-active or nearly non-active sections intermediate between the
points of reversal of the current in the armature and thus enable me to apply inter-
mediate brushes to the commutator without destructive sparking resulting.
The armature of the dynamo may be wound to give twice or more times (according
to the number of divisions or slots which have been made in the polar surfaces) the
maximum EM F required for working, and thus I am able to use conductors of
smaller and more convenient cross section on the armature and to employ a larger
number of turns, and so get a satisfactory number of sections in the commutator.
Brushes on opposite sides of the diameter of commutation, if equi-potential, may be
connected together.
The operator connects his working electrodes to the ordinary brushes in the usual
way if he requires the full E M F of which the machine is capable, or to one of
the ordinary and one of the intermediate ones if he requires a smaller E MF; or,
if the polar surfaces of the magnets have been slotted or divided to allow of more
than one intermediate brush (or more than one pair of same) to be applied to the
commutator, the working electrodes may be connected to two intermediate or pairs
of intermediate brushes; that is, one electrode to one brush or one pair of brushes and
-the other electrode to the other brush or pair of brushes.
The width of the divisions or the width and depth of the slots as the case may be
should be such that the strength of the magnetic field cut by the coil or coils of a
section of the winding when passing them is less than that required to generate a
current in the section when short-circuited under the brush equal in strength to the
armature current. There will then generally be a sparkless position for the inter-
mediate brushes, provided the current flowing in the part of the winding in front of
the brush is greater than the current generated in a section when short-circuited by
the brush in the weakest part of the weakened field in the region of the slots or
divisions in the pole pieces.
In machines having drum armatures the position of the slots or divisions must be
arranged so that the conductors of a section on diametrically opposite sides of the
drum come under them simultaneously.
In machines having ring armatures it is not essential that the divisions or slots on
the two or more polar surfaces should be similarly disposed or equal in number.
Intermediate brushes may be applied to any point on the commutator corresponding
to the position of one of the slots or divisions in the pole pieces.
In order that the said. invention may be fully understood I will now proceed to
.describe the same with reference to the several figures on the annexed sheet of
drawings. The same letters indicate corresponding parts in all the figures.
For the sake of clearness the brushes are shown pressing upon the armature instead
of upon a commutator as would be the case in actual practice. Figures 1, 2 and 3,
represent diagramatically machines constructed according to my invention.
In each case A is the armature; N, S, the field magnet poles; m 1 a division
between the like magnet poles, and m a slot in the magnet poles. Figure 1 shows a
convenient way of carrying out my invention when double magnets are employed.
Instead of uniting the like poles as is ordinarily done when double magnets of this
class are employed and thus forming a single pole piece, 1 leave a gap or dividing
space between them as shown at m 1, m 1.

page_text: If necessary for mechanical reasons, bridges or distance pieces of nou-magnetic
material may be fixed between or across the divisions or gaps m 1, m 1, Figure 1.
g1, 1 are the intermediate brushes which are shown connected together and to one
electrode in the vat represented at ; the other electrode of the vat is connected
to the brush G, and the yat therefore receives an EM F equal to half that
generated by the dynamo. The vai represented at a is connected to the brushes G +
and receives the whole EMF generated.
and G
-
-
Figure 2 illustrates the use of slots in the pole pieces. The ends of the slots are
shown at m, m.
g1, 192, y2, are the intermediate brushes. The vat a receives
the whole EMF generated, the vat about one third, and the vat c about two thirds
of the total E M F generated by the machine.
Figure 3 illustrates a ring arinature machine in which one pole piece has two
slots "m, m, and the other three slots m, m, m; this arrangement enables a larger
variety of different E M Fs to be provided from the same machine than the forms
previously described. Thus the vat a will receive the full E M F generated by the
armature, the vat about one third, the vat e about two thirds, the vat d about one
quarter, the vat e about half and the vat f, about three quarters of the total EM F
generated by the armature.
с
I prefer to make each brush independently adjustable.
When more than one slot or division is made in each pole piece, the number of
intermediate brushes may generally be less than the number of slots, as all the
different volt powers will not generally be required at the same time. The inter-
mediate brushes must be mounted on movable supports so that they may be set to any
desired position corresponding to a slot or division in the pole piece.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is:
1. In a dynamo electric machine, dividing and spacing apart two or more parts of
the magnet poles, intermediate between the points of reversal of polarity, so as to
cause non-active sections, or sections of diminished activity at corresponding points
in the revolving armature and enable intermediate brushes to be applied to the
commutator without causing destructive sparking, as, and
for the purpose,
described.
2. In a dynamo electric machine, forming slots in the polar surfaces so as to cause
non-active sections, or sections of diminished activity at corresponding points in the
revolving armature and enable intermediate brushes to be applied to the commutator
without causing destructive sparking as, and for the purpose described.
3. Applying one or more intermediate brushes to the commutator of a dynamo
electric machine at positions fixed by the positions of slots or divisions in the pole
pieces for the purpose of obtaining therefrom electric currents having only a fraction.
of the volt-power given at the ordinary collecting brushes of the machine as
described and illustrated with reference to Figures 1, 2 and 3 of the accompanying
drawings.