IMPROVE- MENTS IN DYNAMO-ELECTRIC MACHINES
Year: 1886

page_text: Date of Application, 13th Mar., 1886
Complete Left, 13th Dec., 1886
Complete Accepted, 4th Feb., 1887.
I, WILSON HARTNELL, of Benson's Buildings, Park Row, Leeds, in the County of
York, Electrical Engineer, do hereby declare the nature of my invention for IMPROVE-
MENTS IN DYNAMO-ELECTRIC MACHINES, to be as follows:-
My invention has special reference to Commutators and their Brushes.
In making a Commutator a plan pretty generally in vogue is to build it up in a
number of segments with a layer of insulating material between each; the whole
forming a practically solid mass.
Another plan often adopted is to fix the segments, at the required distances apart,
upon an insulated central core-
e-in this case, also, the whole may be said to be a solid
mass.
These and other modes of building up a commutator into a practically solid mass,
give only a minimum tendency to cool when any heat arises, and consequently a not
unusual occurrence, towards the end of a long run, is a heated commutator: such
heating being accompanied by "sparking," causing serious damage, in many cases, to
the turned surface of the commutator, and also to the brushes in contact therewith."
Further damage also appears to proceed from the insulating material working out,
or wearing out, above the turned surface in contact with the brushes.
The object of my invention is to avoid this heating & "sparking," and thus prolong
the lives both of the commutator and brushes. In some cases, also, the cost of the
manufacture of the commutator will be reduced by the use of a less quantity of
insulating material.
I accomplish my object as follows I make my commutator to ventilate or fan
itself,-arranging for the air to enter and depart-as far as circumstances allow-in a
similar manner to that in an ordinary centrifugal fan; and the action of this air tends
to keep the commutator cool.
Of course any particular shape of commutator will require a particular treatment
according to the mode and form in which it is constructed, so that I cannot describe
every plan in which my invention may be put into practice, but the following modes
will be a sufficient guide for any not mentioned.
In the case of commutators built up in a number of segments, each separated by an

page_text: insulating layer, and held together by end flanges or discs ;, I arrange that an internal
air space surrounding the axis be left, the inlet holes into which may be made in the
sides of the end discs, or arranged between the spokes of such end supports'; or inlet
holes may be made in and through the shaft itself. The egress spaces are provided, by
preference, on the turned outer surface swept by the brushes, and may be arranged in
a variety of ways as follows:-
In some cases the insulating material may be inserted at each end only and may be
omitted entirely over the whole width acted upon by the brushes. (This also enables
me to use any class of insulating material that is found convenient, and leaves the
brushes free from any disturbances which might arise from the working up of the
insulating material).
Or, portions of the insulating material may be here and there omitted; or grooves
may be cut in the metallic segments, or small holes may be drilled through them after
the whole has been fitted together.
In order to assist in getting hold of the air, and in discharging it, a few of the
segments may be arranged to project further than the others into the internal air
space, and thus form-as it were-internal fan blades.
From all this it will be seen that if the commutator be built up so as to form a drum
with a comparatively large interior air space, more satisfactory results may be obtained.
In some arrangements of Dynamos the revolutions of the Armature may be suffi-
cient to draw air, longitudinally, through the interior space, such air being drawn
through the inlet holes before mentioned; no egress holes being required on the
periphery, sufficient ventilation being obtained without them. Internal spiral blades
may be of service in this case.
•
The segments may also be arranged to assist in throwing out the air that would
lodge between them in the spaces where the insulating material has been omitted-by
making them inclined, or curved-like fan blades; this, in cases where the radial
arrangement did not prove sufficiently effective.
In some cases the segments may be so shaped that the longitudinal spaces between
them are waved, zizzaged, or slightly spiral, to prevent any approach to a blow as the
brushes pass from segment to segment.
Whatever may be the form of segment adopted there is nothing to prevent their
ends in between which the insulating material is introduced from being made just
as at present.
Referring next to that class of commutator which has its segments fixed on a solid
insulated central cone. I propose to make these in this way; two or more discs of
insulating material are mounted on an axis-and the metal bars or segments are fixed
on their periphery. Air may be admitted either through holes in the sides of the
discs or in and through the shaft, as before mentioned. The egress of the air would
be permitted through the spaces between the segments.
Another form of commutator may be made by building up segments so as to take
the form of a single disc having a rim extended to suit the width of the brushes. The
disc may be central or otherwise compared with the centre of its rim. The boss of
such a disc may be made to brace together by end flanges as usual, and the layers of
insulating material may be introduced at the boss-and either run right through to the
rim, or stop short at any required point, leaving the rim with open air spaces between
each segment. The outer rim may be made as thick as desired for "turning up"
purposes, and on the inner side of the projecting rim certain of the segments may have
wings projecting out further than the others by way of catching the air and throwing
it out. The air may be thrown out on the periphery either through the spaces left by
omitting the insulating material-or through hole or grooves arranged for the purpose
in the segments or off at the sides if found more convenient. .
From what has been explained it will be seen that any metallic dust that might
otherwise accumulate in the grooves between any two segments will, in this class of
ventilating commutator be thrown or blown out. The spaces arranged between any
one open segment and the next must of course be large enough to prevent "sparking
across.

page_text: In building up one of my commutators with open spaces between the segments it is
simply necessary to provide open sided insulating supports. These may consist of
rings of insulating material with recesses provided for the reception of the segments,
and thus the cost of manufacture may be reduced. If these insulating rings are
placed at the ends of the segments they may be backed up by plates and drawn
together by bolts or other such device-the end plates and rings having the necessary
side openings.
In the matter of Brushes: To further avoid "sparking" through unskilful attend-
ance I feed them forward on or through a fixed guide, and thus present a constant
angle to the face of the commutator, so that the brush requires no refitting.
I specially arrange this guide of mine so that whilst the brush is free to move
forward under the influence of a spring, or other force, it is automatically held from
moving backwards. I accomplish this by means of a gripping lever in connection
with a spring or other such device.
A variation of this plan whilst automatically gripping the brush leaves it free to
move only at such times as the gripping lever is freed by the attendant.
The gripping lever may take the form of a cam; or any tendency to a backward
motion may be resisted by a wedge (or an equivalent cam) which follows up the
forward motion of the brush, with or without a gripping lever.
WILLIAM SNOWDON,
9, Beckett's Bank Chambers, Leeds, Yorkshire,
Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Dynamo-electric Machines.
I, WILSON HARTNELL, of Benson's Buildings, Park Row, Leeds, in the County of
York, 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 :-
My invention has special reference to Commutators and their Brushes.
In making a Commutator a plan pretty generally in vogue is to build it up in a
number of segments with a layer of insulating material between each; the whole
forming a practically solid mass.
Another plan often adopted is to fix the segments, at the required distances apart,
upon an insulated central core-in this case, also, the whole may be said to be a solid
mass.
These and other modes of building up a commutator into a practically solid mass,
give only a minimum tendency to cool when any heat arises, and consequently a not
unusual occurrence, towards the end of a long run, is a heated commutator: such
heating being accompanied by "sparking" causing serious damage in many cases, to
the turned surface of the commutator, and also to the brushes in contact therewith.
Further damage also appears to proceed from the insulating material working out,
or wearing out, above the turned surface in contact with the brushes.
The object of my invention is to avoid this heating and "sparking" and thus
prolong the lives both of the commutator and brushes. In some cases, also, the cost
of the manufacture of the commutator will be reduced by the use of a less quantity of
insulating material.
I accomplish my object as follows:-I make my commutator to ventilate or fan
itself, arranging for the air to enter and depart-as far as circumstances allow-in a
similar manner to that in an ordinary centrifugal fan and the action of this air tends
to keep the commutator cool.
Of course any particular shape of commutator will require a particular treatment
according to the mode and form in which it is constructed, so that I cannot describe
every plan in which my invention may be put into practice, but the following modes
will be a sufficient guide for any not mentioned.
In order to fully explain myself I have annexed four sheets of drawings. The same
letters refer to the same parts or their equivalents throughout. Certain concentric
arrows denote the directions of revolution-whilst the other arrows show the direction
of the currents of air. Insulating material is denoted by dotted ground work.
Figs. 1, 13, 15 and 17 are longitudinal sections through various forms of my
dynamos; Fig. 9 is a longitudinal view on a smaller scale; Figs. 6, 7, 8, 14, and 16,
are transverse sections through various forms of the same; and Figs. 2, 3, 4, 5, 10, 11,
12, & 18 are views of the surfaces of the segments A of the Dynamos swept by
the brushes some partly in section. Figs. 19 & 20 and 21 & 22, are side and end

page_text: sectional Elevations of certain of my Brush Feeders; whilst 23, 24, 25, & 26 are side
sectional Elevations of other variations.
In the case of commutators built up in a number of segments A, each separated by
an insulating layer, and held together by end flanges or discs, I arrange that an
internal air space B, surrounding the axis C be left, the inlet holes into which may be
made in the sides of the end discs D, or arranged between the spokes of such end
supports; or inlet holes may be made in and through the shaft itself-see Fig. 1
which is shown with both arrangements, although one only would be required.
The egress spaces are provided, by preference, in the turned outer surface swept by
the brushes, and may be arranged in a variety of ways as follows
-
In some cases the insulating material may be inserted at each end only and may be
omitted entirely over the whole width acted upon by the brushes-Figs. 1 & 2. (This
also enables me to use any class of insulating material that is found convenient, and
leaves the brushes free from any disturbances which might arise from the working up
or out of the insulating material.)
Or, portions of the insulating material may be here and there omitted-Fig. 3; or
grooves may be cut in the metallic segment-Fig. 4; or small holes may be drilled
through them before or after the whole has been fitted together-Fig. 5.
In order to assist in getting hold of the air, and in discharging it, a few of the
segments may be arranged to project further than the others into the internal air
space, and thus form-as it were-internal fan blades-see Figs. 7 & 8.
From all this it will be seen that if the commutator be built up so as to form a
drum with a comparatively large interior air space B, more satisfactory results may be
obtained.
In some arrangements of Dynamos the revolutions of the Armature may be suffi-
cient to draw air, longitudinally, through the interior space, such air be drawn through
the inlet holes before mentioned; no egress holes being required on the periphery,
sufficient ventilation being obtained without them. Internal spiral blades may be of
service in this case, as shown in Fig. 9. The segments may also be arranged to assist
in throwing out the air that would lodge between them in the spaces where the
insulating material has been omitted-by making them inclined or curved-like fan
blades, see Fig. 8 which shows inclined blades-curved blades may be arranged in a
similar way this, in cases where the radial arrangement did not prove sufficiently
effective.
In some cases the segments may be so shaped that the longitudinal spaces between
them are waved, Fig. 10; zizzaged, Fig. 11; or slightly spiral, Fig. 12; to prevent
any approach to a blow as the brushes pass from segment to segment.
Whatever may be the form of segment adopted there is nothing to prevent their ends
-in between which the insulating material is introduced-from being made just as at
present.
Referring next to that class of commutator which has its segments fixed on a solid
insulated central core. I propose to make them in this way, see Figs. 13 & 14; two
or more discs D), of insulating material are mounted on an axis C, and the metal bars
or segments A are fixed on their periphery. Air may be admitted either through
holes in the sides of the discs or in and through the shaft, as before mentioned. The
egress of air would be permitted through the spaces between the segments, as shown
by the arrows.
Another form of commutator may be made by building up segments so as to take
the form of a single disc, Figs. 15 and 16, having a rim A extended to suit the width
0 of the brushes. The disc E may be central or otherwise-compared with the centre
of its rim. The boss of such a disc may be made to brace together by end flanges D', D',
as usual, and the layers of insulating material may be introduced at the boss, and
either run right through to the rim, or stop short at any required point, leaving the rim
with air
open spaces between each segment. The outer rim may be made as thick as
5 desired for "turning up" purposes, and on the inner side of the projecting rim certain
of the segments may have wings projecting out further than the others, sec dotted
lines F, Fig. 15, by way of catching the air and throwing it out.. The air may be

page_text: thrown out on the periphery either through the spaces left by omitting the insulating
material as shown by the arrow, Fig. 15, or through holes or grooves arranged for the
purpose in the segments similar to Figs. 4 and 5-or off at the sides if found more
convenient.
From what has been explained it will be seen that any metallic dust that might
otherwise accumulate in the grooves between any two segments will, in this class of
ventilating commutator, be thrown or blown out. The spaces arranged between any
one open segment and the next must of course be large enough to prevent "sparking"
across.
57
In building up one of my commutators with open spaces between the segments it is
simply necessary to provide open-sided insulating supports. These, see Figs. 17 & 18
may consist of. rings of insulating material with recesses provided for the reception of
the segments, and thus the cost of manufacture may be reduced. If these insulating
rings G, Figs. 17 & 18, are placed at the ends of the segments they may be backed up
by plates D, D, and drawn together by bolts or other such device H-the end plates
and rings having the necessary side openings.
In the matter of Brushes: To further avoid "sparking” through unskilled attend-
ance I feed them forward, see Figs. 19 to 26, on or through a fixed guide K, and thus
present a constant angle to the face of the Commutator A, so that the brush requires
no refitting. I specially arrange this guide of mine so that whilst the brush L is free
to move forward under the influence of a spring N, or other force it is automatically
held from moving backwards. I accomplish this by means of a gripping lever 0, or
its equivalent, in connection with a spring or other such device.
A variation of this plan whilst automatically gripping the brush leaves it free to
move only at such times as the gripping lever is freed by the attendant, see Fig. 25.
The gripping lever may take the form of a cam, Figs. 19 & 20, or any tendency to
a backward motion may be resisted by a wedge, Fig. 24, (or an equivalent cam) which
follows up the forward motion of the brush, with or without a gripping lever.
In Figs. 19 & 20 the brush L ("split" in this case) is shown mounted in a
brush slide L', being fixed therein by the screw L. The whole is freely drawn
towards the commutator A by the tension spring N which can be adjusted by means of
a screw & nut. The gripping cam O, however, is pressed round by a coiled spring, O¹,
in the direction necessary to grip the brush slide whenever any backward motion is
attempted. If it be wished to hold the brush back, for examining purposes, the cam O,
which is a double one, may be brought over by hand (against its spring) and its
nose O may be wedged against the slide, and thus all will be held back until again
released.
Figs. 21 & 22 have an action equivalent to the last, except that O takes the form of
a gripping lever which is actuated by the same spring (N) that moves the brush slide
forward. The Holding-back device is put into action by releasing the gripping lever
and then drawing the brush slide back & letting the toe O' of the lever fall into one of
the teeth in the rack above it.
In Fig. 23 the "gripper" takes the form of a wedge mounted on a friction pulley.
The spring N is in compression and is adjusted by the double nuts N¹. As the brush
wears these nuts may be adjusted anywhere along the rod Nº.
In Fig. 24 the Gripping Wedge O is drawn by the spring N and thus the brush is
moved forward. The angle of the wedge must be arranged so that no backward
motion of the brush is permitted. The nuts N' are for adjustment on the Rod N²,
The screw K and its spring and key are merely to steady the brush.
Fig. 25. The forward action is the same as in Fig. 23, but the gripping lever is a t
detached one and is released by the attendant.
Fig. 26 has a tension spring N. actuating a gripping roller O. The Holding-back
device when put into gear first thrusts back the roller O & then fits into the
catch Q¹.
Any of the fixed guides K may be attached to the usual cross-bars P of a dynamo 5
―or other such convenient fitting.
I do not pretend to have exhausted the modes in which my improvements may be

page_text: put into practice my object being to show the principle of the improvements which
are directed towards reducing the wear and tear on the commutator and brushes by
keeping the working surfaces cooler and in truer contact.
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 :-
1. Improvements in Dynamo-Electric Machines consisting, firstly, of the novel
method of building up a Ventilating Commutator, with the object and for the purpose
set forth which novel method is shown carried into effect in and by the arrangements
described herein and shown on the drawings.
2. Improvements in Dynamo-Electric Machines consisting, secondly, of the novel
application of a Non-return Gripping Action fitted to brushes arranged with a forward
feed, with the object and for the purpose set forth-which novel application is shown
curried into effect in and by the arrangements described herein and shown on the
drawings.
3. The Ventilating Commutators built up substantially as described herein and as
shown on the drawings, with the object and for the purpose set forth.
4. The Non-return Gripping Action brush arrangements, substantially as described
herein and as shown on the drawings, with the object and for the purpose set forth.
5. The Combination of a Ventilating Commutator and a Brush having a forward
feed fitted with my Non-return Gripping Action-substantially as described herein,
and as shown on the drawings, with the object and for the purpose set forth.
WM. SNOWDON,
9, Beckett's Bank Chambers, Leeds, Yorkshire,
Agent for the Applicant.