Improvements relating to Dynamo-electric Machines and Electric Motors.
Year: 1889

page_text: Date of Application, 8th Apr., 1889
Complete Specification Left, 7th Jan., 1890--Accepted, 8th Feb., 1890
ΠΡΟΙΣΤΑΙΟΤΑΤ
SPRALDICATION
Improvements relating to Dynamo-electric Machines and
Electric Motors.
I, ALFRED LYSTER SHEPARD, of 8 West Kensington Gardens, in the County
of Middlesex, Electrical Engineer, do hereby declare the nature of this invention
to be as follows:-
My invention relates to dynamo-electric machines and electric motors, and is
designed to afford the means whereby the position of the brushes relatively to the
commutator in a dynamo-electric machine or electric motor will be automatically
regulated to suit varying conditions of the external circuit, so as to ensure the most
efficient working of the machine and to obviate or diminish the liability to sparking.
It is well known that the position of the brushes on the commutator of a
dynamo-electric machine or electric motor requires to be altered (when the current
varies in the external circuit) in accordance with the relative magnetic strength of
the armature and of the field-magnets, so as to keep the brushes in contact with
those strips of the commutator between which the greatest difference of potential exists.
To provide for the automatic movement of the brushes for this purpose, I arrange,
in combination with the brushes and commutator, small auxiliary brushes or feelers ;
these brushes or feelers are mechanically connected to and insulated from the
brushes of the dynamo-electric machine or electric motor and are in circuit either
with the armature or the field-magnet coils of a small supplementary electric motor,
or with any other suitable device for moving the brushes for the purpose above
specified. The said auxiliary brushes or feelers are placed opposite each other in
such a position on the commutator of the dynamo-electric machine or electric motor,
that, when the main brushes are in the position of greatest potential, that is to say,
in the position most favourable to efficient working, the potential in the said auxiliary
brushes or feelers is equal and consequently no current flows in the feeler-circuit.
If, however, the relative strength of the magnetism of the armature and field-magnets
becomes altered, then the point of highest potential on the commutator will change
its position, and the feelers will have a different potential, consequently a current
will flow in the feeler-circuit through the armature or field-magnets of the supple-
mentary electric-motor, thus causing it to turn, in one or the other direction
according as the point of highest potential is in advance of or behind the positive
brush to be shifted. The motions of the 'supplementary electric-motor produced by
the current in the feeler-circuit are transmitted to the brushes of the main
dynamo-electric machine or electric motor by means of a worm and worm-wheel
or other suitable device.
When the armature of the supplementary electric motor is in the feeler-circuit,
the field-magnets are either of the class known as permanent, or are excited from
when the
any convenient source, the polarity always remaining the same;
field-magnets are in the feeler-circuit, the armature current is obtained from any
suitable source and is kept always in the same direction, so that the reversal of the
current in the feeler-circuit causes the reversal of the supplementary motor and
consequently moves the brushes of the main dynamo-electric machine or motor into
the most favourable position; the potential of the feeler-brushes then becoming
equalised, the current in the feeler-circuit ceases to flow, and the supplementary
motor stops.
01
T
Ր A -:1 1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.

page_text: VOLI DIN OF MOITICATION.
Improvements relating to Dynamo-electric Machines and Electric
Motors.
I, ALFRED LYSTER SHEPARD, of 8 West Kensington Gardens, in the County of
Middlesex, Electrical Engineer, do hereby deciare 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 relates to dynamo-electric machines, and electric motors, and is
designed to afford the means whereby the brushes will be automatically adjusted
relatively to the commutator to suit varying conditions of the external circuit, so as
to ensure the most efficient working of the machine and to obviate or diminish the
liability to sparking.
It is well known that, in order to keep the brushes of a dynamo-electric machine
or electric motor in contact with those points on the circumference of the commutator
between which the greatest difference of potential exists, or where there is the least
liability to sparking, it is necessary to alter the position of the brushes on the
commutator when the current varies in the external circuit, in accordance with the
relative magnetic strength of the armature and of the field-magnets.
To provide for the automatic movement or adjustment of the brushes for this
purpose, I arrange, in combination with the brushes and the commutator, small
auxiliary brushes or feelers; these auxiliary brushes or feelers are mechanically
connected to, but electrically insulated from the main brushes of the dynamo-electric
machine or electric motor, and are in circuit either with the armature or the field-
magnet coils of a small supplementary electric-motor, or with an electric device for
controlling any other suitable mechanism for moving or adjusting the brushes for the
purpose above specified.
The auxiliary brushes or feelers are so arranged that, when the main brushes are
in such positions relatively to the commutator as to bear upon those points on the
saine between which the greatest Jifference of potential exists, that is to say, in the
positions most favourable to efficient working of the machine, the said auxiliary
brushes or feelers are so situated on the commutator as to rest on equi-potential points
on the same, consequently no current will flow in the feeler-circuit."
If, however, the relative strength of the magnetism of the armature and field-
magnets becomes altered, then the point of highest potential on the commutator will
change its position, and the feelers will have a different potential, consequently a
current will flow in the feeler-circuit in one or the other direction according to
whether the point of highest potential is in advance of, or behind the positive main
brush of the dynamo-electric machine or electric motor, and the device for adjusting
the brushes will be operated and the brushes moved around the commutator in the
corresponding direction until they are again brought into the most favourable
position.
In the accompanying drawing, I have shown how my said invention may be
conveniently and advantageously carried into practice.
Figure 1 is a sectional elevation showing a commutator and a pair of main
brushes with my auxiliary brushes or feelers applied thereto.
Figure 2 is a similar view showing an electric motor combined with the said feelers
for adjusting the brushes as hereinafter specified.
A is the armature shaft of a dynamo-electric machine or electric-motor. B is the
commutator. C, C are the main brushes, which are attached to arms D fitted to
turn upon the said shaft.
a, a are my auxiliary brushes or feelers, which are attached to arms & secured to,
but insulated from one of the arms D. c, c are the wires or conductors connected
with the said auxiliary brushes or feelers. d is an arm or lever formed with, or
firmly attached to the arms D and provided with a toothed segment e. f is a pinion
fixed upon a shaft f, which is carried in suitable bearings and is connected with any

page_text: convenient means for rotating it in one or the other direction to move the arms D
about the shaft A and thus effect the adjustment of the brushes as may be
required.
Referring to Figure 2, g is a worm-wheel, which is fixed upon the shaft f¹, and
with which is geared a worm on the armature-shaft of a supplementary electric
motor j. The wires or conductors c are shown connected with the brushes of the
said supplementary electric motor. They may, however, be connected with the
field-magnet coils of this motor, if desired.
When the armature of the supplementary electric motor is in the feeler-circuit,
the field-magnets of the said motor may be either permanent magnets or electro-
magnets excited from any convenient source, the polarity always remaining the
same when the field-magnets of this motor are in the feeler-circuit, the armature
current is obtained from any suitable source and is kept always in the same direction.
The reversal of the current in the feeler-circuit will, therefore, cause the reversal of
the supplementary motor and consequently the movement of the main brushes C into
the most favourable position; the potential of the feeler-brushes then becoming
equalized, the current in the feeler-circuit will cease to flow, and the supplementary
motor will stop.
Other suitable devices are, if desired, substituted for the toothed segment, worm
and worm-wheel, for imparting motion from the auxiliary motor to the arms carrying
the brushes to be adjusted. Morcover I sometimes provide suitable gearing driven
by the shaft of the dynamo-electric machine or electric motor to be regulated, for
effecting the adjustment of the brushes, and I connect the wires or conductors of
the feeler-circuit with an electrical device for operating a reversing-clutch or similar
contrivance for stopping, starting and reversing the said adjusting gear.
If desired, instead of attaching both of the auxiliary brushes or feclers to one
of the arms carrying the main brushes, I attach one of the said auxiliary brushes
to each of the said arms.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, 1 wish it understood
that I claim :-
First. The herein described method of providing for the automatic adjust-
ment of the brushes of a dynamo-electric machine or electric motor, for the purpose
above specified, by means of auxiliary brushes or feelers in contact with the
commutator of such machine or motor.
Second. The combination, with a dynamo-electric machine or electric motor, of
auxiliary brushes or feelers in contact with the commutator thereof and movable
with the main brushes about the said commutator, and suitable mechanism controlled
by the current in the feeler-circuit for adjusting the main and auxiliary brushes,
for the purposes above specified.
Third. The combination, with auxiliary brushes or feelers movable with the main
brushes of a dynamo-electric machine or clectric motor about the commutator
thereof, of a supplementary electric motor the armature or field-magnet coils of
which are in the fecler-circuit and the shaft or spindle of which is connected by
suitable gearing with the arms or parts carrying the said main brushes, sub-
stantially as, and for the purposes, above specified.
Fourth. The improved apparatus constructed with the auxiliary brushes or feelers
attached to one of the arms which carry the main brushes of the dynamo-electric
machine or electric motor, substantially as described with reference to the
accompanying drawings and operating as, and for the purpose, above specified.
Dated this 7th day of January 1890.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.