Improvements in Portable Hand Dynamos parts of which Improve. ments are applicable to Small Power Dynamos-and-Motors_for_ other purposes.
Year: 1899

page_text: Date of Application, 25th Jan.. 1899
Comalato Concifnation L oft 24th Oct 1890 Accented 13th Jan. 1900
Complete Specification Loft, 24th Oct
1899 Accepted 13th Jan. 1900
PROVISIONAL SPECIFICATION.
Improvements in Portable Hand Dynamos parts of which Improve.
ments are applicable to Small Power Dynamos-and-Motors_for_
other purposes.
We, EVERSHED & VIGNOLES LTD., of Woodfield Works, Harrow Road, London,
W., Electrical Engineers, and SYDNEY EVERSHED, of the same address, Electrical
Engineer, do hereby declare the nature of this invention to be as follows:
-
Our invention relates to portable hand dynamos used for testing purposes and
is applicable in parts to small power dynamos and motors, exploders for firing
electric fuses, the small motors used in some forms of electric supply meters,
and the like.
According to our invention a hand dynamo for testing purposes (hereinafter
called a hand dynamo) may have an armature preferably of the drum type
mounted on an axle and driven at a high speed by means of a winch handle
through the aid of suitable gearing. The machine may be shunt wound or
series wound but we prefer to use permanent magnets to provide the necessary
induction when the required output is small, and so dispense with any field
winding. We build the armature core of soft iron discs having a ring of holes
or slots on their periphery to receive the winding. The armature may have
either a drum or a ring winding, but where it is desired to obtain the maximum
electromotive force with the minimum number of turns of wire we prefer to wind
as many diametrical coils as a suitable number of holes in the core will allow
and connect each coil to one of a series of two part commutators fixed alongside
one another on the axle; there being thus as many two part commutators as
there are coils.
The insulated segments of the commutator are in the form of deep and narrow
rings having radial slots cut through at opposite points of a diameter to insulate
the two segments from each other. The brushes are thin elastic metal discs
adapted to rotate with their edges rolling in contact against one or both sides of
the commutator rings or 'segments. For this purpose the brush discs are
mounted on axles pivotted in fixed centres. We prefer to mount two discs
"brush." The corresponding
side by side on the same axle to constitute one
commutator ring runs with its peripheral edge between the peripheral edges
of the discs, the periphery of the ring overlapping that of the discs by a small
amount. The ring then serves to rotate the brush discs and good electrical
connection is maintained between them by the elasticity of the discs. One of
these pairs of discs is required on each side of each separate two part commutator.
The series of "brushes" or pairs of discs are connected together so that the
coils on the armature are all in series thus giving double the electromotive force
which would be obtained from the ordinary drum winding and usual multiple
segment commutator. The frictional resistance of our commutator and brush
discs is very small and may be reduced to almost any desired amount by the use
of discs of large diameter and the reduction of the overlap between the discs and

page_text: commutator rings. When the overlap is made too small however the contact
between the discs and ring tends to become entirely a rolling contact which does
not provide such a certain electrical connection as one in which there is a small
amount of rubbing or slip between the surfaces. Hence we prefer to adjust
the discs so that their edges overlap the rings by a sufficient amount to ensure
some slip taking place at all points in contact at a greater and at a less radius
than the rolling or pitch lines of the brush discs and rings.
In order to still further reduce the friction of our hand dynamo we provide
roller bearings for the armature axle. These bearings are made by boring out
the standards or plummer blocks to a larger diameter than the journals they
are to carry and inserting between the journal and the bearing a number of
little rollers made from drawn steel rod. Rollers may be applied to the bear-
ings carrying the axles of the gearing which serves to connect the winch handle
with the armature axle. As an alternative we may use ball bearings for the
same purpose.
We fix our hand dynamo inside a wood or light metal case and according to
our invention the winch handle is attached to its axle in such a manner as will
allow it to be turned back into a recess in the outside of the case when the dynamo
is not in use. For this purpose the handle is fixed to its axle by means of a
pin working in a hole in the latter and acting as a centre on which the handle
can be turned in a plane at right angles to the plane of revolution of the
handle when the machine is in use. In order that the handle may be held
rigidly in position when in use we fix a spring clip on the axle between the
handle and the case and provide a knob or catch on the back of the handle which
engages in the clip when the handle is brought into its working position.
In addition to a pair of terminals on the outside of the case of our dynamo
we may have a convenient length of twin flexible cord coiled on a spring drum
fixed inside the lid of the case. The conductors in the flexible cord are in
electrical connection with the terminals of the dynamo and the outer end of the
cord is provided with terminals adapted for making connection with any parti-
cular instrument with which the dynamo is to be used. When the machine is
not in use the spring drum draws in the cord until the terminals at its outer end
are brought within a recess in the outside of the case adapted to receive them.
Thus when the dynamo is not in use neither the handle nor the cord or its
terminals project beyond the surface of the case, so that the machine is readily
portable.
Our hand dynamo is well adapted for all kinds of testing work and is
particularly applicable where a high electromotive force is required for testing.
It is also well adapted as an exploder for firing electric fuses and detonators.
Our elastic roller brushes are applicable to dynamos and motors generally and
particularly to small machines in which brush friction is usually a large propor-
tion of the frictional and other losses. When it is desired to apply our elastic
roller brushes to machines having the ordinary type of commutator we modify
the arrangement of the brush discs so that they may roll on the cylindrical sur-
face of the commutator and have a sufficient surface in contact therewith. For
example, we mount the brush discs on axles adapted to cause the brush discs to
rotate on axes lying in the same plane as the rotational axis of the commutator
but not parallel thereto. In this manner the discs are brought into contact
with the commutator at an angle which allows the elasticity of the discs to come
into play. This modification of our elastic roller brush is particularly applicable
to the commutators of motor meters. The current traversing the commutator
of such meters is usually very small and therefore easily carried by means of one
brush disc on each side of the commutator, and hence the brush friction may be
reduced to an insignificant amount.
The necessary electrical connection between our brush discs and the terminals
of the machine to which they are fitted is secured by means of metal springs
preferably arranged to press in an axial direction on one or both ends of the

page_text: axle to which the discs are attached. When a brush axle is pivotted in a metal
bearing the contact between pivot and bearing affords an additional path for the
current flowing between the brushes and the terminals of the machine.
Our brush discs are made from thin hard-rolled brass sheet or other metal of
suitable elasticity and conductivity. In applying our roller brushes to a motor-
meter we prefer to use platinum or iridio-platinum for the brush dises in order
to avoid oxidation.
10 low of Jonver 1800
Improvements in Portable Hand Dynamos parts of which Improve-
ments are applicable to Small Power Dynamos and Motors for.
other purposes.
We, EVERSHED AND VIGNOLES LIMITED, a Corporate body, of Woodfield Works,
Harrow Road, London, W., Electrical Engineer, and SYDNEY EVERSHED, of the
same address, 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:-
This invention relates to portable hand dynamos used for testing purposes
and is applicable in parts to small power dynamos and motors, exploders for
firing electric fuses, the small motors used in some forms of electric supply
meters, and the like.
According to our invention a hand dynamo for testing purposes (hereinafter
called a hand dynamo) may have an armature preferably of the drum type,
mounted on an axle, and driven at a high speed by means of a winch handle
through suitable gearing.
The machine may be either shunt wound or series wound, but, we prefer to
use permanent magnets to provide the necessary induction when the required out-
put is small, and so dispense with field winding.
We build the armature core of soft iron discs having a ring of holes or slots
on their periphery to receive the winding.
The armature may have either a drum or ring winding, but where it is
desired to obtain the maximum electro-motive force with the minimum number
of turns of wires, we prefer to wind as many diametrical coils, as a suitable
number of holes in the core will allow, and connect each coil to one of a series of
two part commutators fixed alongside one another on the axle; there being thus
as many two part commutators as there are coils, as hereinafter more particularly
described.
And in order that our invention may be the better understood we will now
proceed to describe the same with reference to the drawings hereto annexed and
to the letters and figures marked thereon.
Fig. 1 is a plan of the box with the lid open containing the dynamo in the
body of the box, and the winch handle ready for operation issuing therefrom, and
the connection device in the inside of the lid.
Fig. 2 is a double broken cross-section through the lid and connecting device
on the lines X X.

page_text: Fig. 3 is a cross-section through the body of the box on the line Y Y.
Figs. 4 & 5 are outside elevations of each end of the closed box.
Figs. 6, & 7, are a side and end elevation of the collapsible winch handle
turned over and Fig. 8 is a plan of the same.
Fig. 9 is a diagram of the connections from the armature through the com-
mutator and brushes.
Figs. 10 & 11 are a longitudinal section and an end view of the double disc-
brush.
Fig. 12 is a part longitudinal section through the commutator.
Fig. 13 is a perspective elevation of a modified rotary disc brush, and a multi-
sectional commutator, for ordinary drum or gramme winding.
A is the armature of a dynamo which is preferably of the drum type and B is
a permanent magnet or magnets providing the necessary induction when the
required output is small but equivalently if desired the dynamo may be shunt
or series wound.
To obtain maximum electromotive force with the minimum number of turns
of wire, as many diametrical coils are wound upon the armature as a convenient
number of holes in the periphery of a core of soft iron discs will admit of and
each coil is connected to one of a series of two part commutator rings C fixed
alongside one another, and insulated one from the other upon the axle a of the
dynamo.
There are thus as many commutator rings C as there are coils. This is seen
in the diagram of armature and commutator connections in Fig. 9 in which all
the disc brushes, but the extremes, are connected in pairs so that the coils on
the armature are all in series, thus giving double the electromotive force which
could be obtained from the ordinary drum winding and usual multiple segment
commutator.
The metallic commutator rings C are in the form of deep and narrow washers
having radial slots e cut through at opposite points of a diameter to insulate the
segments C from one another, the segments C are mounted upon a sleeve of
insulating material D (Fig. 12) and have distance pieces of insulating material d
between them, the whole being gripped together so that the segments C are
firmly held, by a nut E screwed home on the metal headed sleeve e.
The brushes F (Figs. 1, 3, & 10) are formed from two adjacent discs of thin
metal such as copper. They may be corrugated in concentric rings to give
strength as regards lateral bending with elasticity from the centre. Two such
discs are securely pressed together upon a metal spindle f by means of a metal
collar and a set screw f3 all mounted by pin bearings in a standard bracket f¹.
As seen in the diagram Fig. 9 in Figs. 10 & 11, and in the plan Fig. 1, the
end brushes to terminals are single, whilst the other brushes are in duplicate
and form bridges between adjoining commutator segments C, all the supporting
brackets f being mounted on an insulating base f+ Fig. 3 and therefore insulated
from one another.
The frictional resistance of these brushes to the commutator is very small,
and may be reduced to any desired amount by increase of the diameter of the
disc brushes and by the reduction of the overlap of the two combined disc brushes
upon the commutator segment, between them, until this contact becomes almost
a rolling contact without rub, a certain small amount of overlap, and consequent
rubbing between the discs and segments is however valuable to burnish and keep
clean the surfaces in contact.
In order to still further reduce the frictional resistance of this hand dynamo
the axis a of the armature is mounted in ball or roller bearings in the plummer
blocks a al of any known or convenient form of construction, and such ball or
roller bearings may be also applied to the bearings g g of the axles of the double
speed gearing G, G, from the driving winch handle H to the armature A.
The whole of the dynamo and connections are fixed in the body and lid of a
box J, preferably of wood, the connections between the terminals of the dynamo,

page_text: and the special spring drum connection K in the lid (hereinafter more fully
described) being made through the hinges jj of the box; and the exterior of
the box and lid is provided with recesses j,, (Figs. 4 and 5), one for the
reception of the winch handle H when folded up, and the other for the reception of
a double terminal piece L adapted to engage with two set screws or any other
instrument or line wire and connected through the spring drum K to the terminals
of the dynamo. The drum K is free to rotate upon a central spindle and is con-
trolled by a spiral spring k, which causes the drum to normally wind upon its
periphery a flexible cord connection so as to bring up the double terminal L
into the recess of the box lid. One of the wires from the inner lap of cord
connection is brought through the body of the drum formed of insulating
material Fig. 2 to an outer periphery of metal which makes constant
rubbing connection by the spring with one terminal of the dynamo. The
other wire of the flexible cord goes to the bottom metal base of the drum K
and connects through the contact piece with the other terminal of the dynamo.
A spring pressed pawl catch M Fig. 2 is let into the lid_of_the_box engaging_
into a hole or holes on the under face of the drum K so that when the terminal L
is pulled out to any desired distance the drum K is held from recoiling by the
catch pawl M until the latter is released by a push button m when the flexible
cord is rewound on the drum, and the terminal L rests in its recess j'. The
winch handle H is shown in Figs. 4, 6, & 8 turned over with the handle towards
and entering a hole in the box, the handle pivotting upon a pin h in the sleeve h¹
pinned to the axle a of the dynamo. When the handle is required for use it
is brought out of its recess and turned outwards through 180° on its pivot until
a knob detent h² engages in an eye of two spring arms of the sleeve h¹. The
handle is then engaged with the sleeve h¹ clear of the box and will serve to rotate
the dynamo. When an ordinary drum or gramme winding A Fig. 13 with
multi-sectional commutator is desired to be used, a commutator C¹ consisting of
naked wires mounted in insulating collets d' and rotary disc brushes e¹ as shown
in Fig. 13 may be used, the obliquity of the axis of the single disc brush relatively
to the axis of the commutator allowing the elasticity of the brush disc e¹ to
come into play. This modification is particularly applicable to motor meters
when the current is small and is easily carried by one brush disc on each side
of the commutator. This hand dynamo is well adapted for all kinds of testing
work, particularly where a high electro motive force is required for testing or
for firing electric fuses, and detonators or for similar work, when a hand
generator is applicable.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is:-
1st. A hand driven electric dynamo, contained in a portable box, without
projecting terminals, or hand winch when not in use. The dynamo having its
armature coils connected in series by a multi ring commutator and rotary paired
and single brushes, making elastic rolling contact with the commutator seg-
mental rings; the axis of the armature, and, if desired the hand gearing axles
being mounted in ball or roller bearings to constitute a test dynamo of high
electro motive force, with minimum resistance to rotation, substantially as
described,
2nd. In combination, an armature revolving in a magnetic field; a com-
mutator upon the axis of said armature consisting of divided ring segments
insulated from one another, and from the axis; connections to said segmental
rings from coils of said armature; and elastic disc brushes adapted to rotate on a
supported spindle; such discs being in pairs adapted to embrace and elastically
press upon the commutator segments between them substantially as described.
3rd. A rotary brush disc, consisting of two thin metal discs, concentrically

page_text: corrugated, in combination with a metal flanged sleeve upon a central pin axis
and a metal collar pressing said discs together.
4th. A rotary brush disc on an axis oblique to the armature spindle in com-
bination with a lantern multi-section commutator substantially as described in
relation to Fig. 13.
5th. The combination with an armature revolving in a magnetic field of a
commutator having divided and insulated ring segments as many in number as
there are coils on the armature; connections from each coil individually to each
of the pair of segments of one ring; a single rotary brush making contact with
each of the end segment rings for the terminals of the armature; and double
bridge disc brushes connecting adjacent ring segments; so that all the armature
coils are in series substantially as and for the purposes described.
6th. In combination with a hand driven dynamo, a box enclosing same,
recesses in the thickness of the walls of the said box one about the issue of the
winch handle, and one about the issue of the connections; a winch handle on
the armature spindle, adapted to pivot on the end of the spindle, and to fold
over into one of the said recesses with handle inwards; and a spring recoil
connecting device,, having a double terminal bridge adapted to be with drawn
into one of the said recesses when not in use substantially as described.
7th. In combination, a dynamo enclosed in a box and lid; a spring recoil
drum fitted in said lid; connections from the terminals of the dynamo through
the hinges of the box to an insulated peripheral metallic ring on said drum,
and to lower metallic plate and base respectively; a check pawl engaging into
holes on the said drum; a flexible connector containing two insulated wires,
connected respectively to said peripheral metallic ring and base, wound about
said drum; and a double head at end of said flexible connector where it issues
from the side of the lid, substantially as and for the purposes described.
8th. In combination, a dynamo; a sleeve carrying two spring arms pinned
to the extremity of the armature spindle or an axle geared therewith; a winch
handle pivotted transversely to said sleeve; and a knob detent, from under
side of said winch handle, adapted to engage into said spring arms with the
handle outwards, and on release permitting the handle arm to be turned over
with the handle inwards, substantially as and for the purposes described.
Dated this 24th day of October 1800
FELL & JAMES,
Agents for the Applicants,
1, Queen Victoria Street, London, E.C..