Improvements in Controlling Apparatus suitable for Use with Electric Motors.
Year: 1899

page_text: Date of Application, 7th June, 1899-Accepted, 19th Aug., 1899
COMPLETE SPECIFICATION.
Improvements in Controlling Apparatus suitable for Use with
Electric Motors.
I, HENRY JOHN WALKER, of Victoria Works, Gateshead-on-Tyne, in the County
of Durham, 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 has reference to electric motor controlling apparatus wherein
resistances and a movable contact maker are so arranged that the latter can be
left stationary on any of the fixed contacts connected to consecutive resistances so
that the resistances can be used not only as starting resistances but also as speed
controlling resistances to admit of the electric motor with which the apparatus is
used being run continuously at any desired speed within the limits of the
particular motor, the construction moreover being such that in the event of the
load on the machine driven by the motor increasing to such an extent as to stop
the motor and remove its back E M F, or reduce its speed and back E M F to a
predetermined amount, a resistance will be automatically inserted in circuit such
as will reduce the potential difference between the terminals of the motor by an
amount corresponding, or approximately so, to that of the back EM F of the
motor removed or reduced by the stoppage or reduction in speed of the motor,
so that the current passing through the stationary or slower moving armature
shall not be such as to injure the armature.
In the accompanying illustrative drawings Fig. 1 is a vertical section on the
line of Fig. 2, and Fig. 2 a plan, showing one construction of apparatus
according to this invention. Fig. 3 shows the apparatus partly in side elevation
and partly in vertical section. Fig. 4 is an elevation at right angles to Fig. 8
showing part of the apparatus. Fig. 5 shows in vertical section and Fig. 6 in
plan, means for operating the contact maker from a point some distance above
the same. Fig. 7 is a diagram of the apparatus and its connections.
Upon a suitable base 1 are fixed two series of insulated contacts 2, 2" arranged
in a circular row and connected to suitable resistances 3, 3" the two series of
contacts being separated by a suitable gap 4 at one side and one series being
adapted for use when the electric motor 5 with which the controlling apparatus is
employed is to run in one direction and the other series when the motor is to
run in the reverse direction, as well understood. 6 and 7 are two insulated metal
rings arranged concentrically one within the other and within the circular row
of fixed contacts 2, 2, and 8 and 8ª are two fixed insulated metal segments
arranged between the ring 7 and the two series of contacts 2, 2ª respectively.
9 and 9 (Fig. 7) are two terminals of which one, viz. 9, is connected to one polo
of a dynamo 10, or other source of electric supply, and to a part ring 11 to which
one end of each of the two series of resistances 3, 3 is connected. The other
terminal 9 is connected to the second pole of the dynamo, or other source of
electric supply, and to the ring 7. 12 and 12 are two terminals that are con-
nected to the segments 8 and 8" respectively and to the ends of the winding

page_text: on the armature of the motor 5. Fixed upon a vertical spindle 13 but insulated
therefrom and from each other are two contacts 14 and 15 made in the form of
bent metal bars and constituting the movable contact maker, these contacts, when
the controlling apparatus is out of use, being in the inoperative positions shown
in dotted lines in Fig. 7. One end 14" of the contact 14 is arranged to rub over
one or the other of the series of the fixed contacts 2 or 2" according to the direction
in which the spindle 13 is turned and the motor is to run, the other end 14 of
the contact being arranged to simultaneously travel in contact with the seg-
ment 8 or 8. One end 15" of the contact 15 is arranged to simultaneously travel
in contact with the segment 8 or 8" and its other end 15b with the ring 7.
As will be seen the arrangement so far described is such that if the contact
maker be moved in the direction of the arrow (Fig. 7) current will pass from one
pole of the electric generator say to the terminal 9, and thence by the part ring 11,
right hand resistances 3, one or other of the fixed contacts 2, movable contact 14,
14", 14, segment 8", terminal 12" to one terminal of the motor armature, returning
to the terminal 12, segment 8, contact 15, 15", 15, ring 7 and terminal 9 and
thence to the other pole of the electric generator, the amount of resistance put
in the armature circuit depending upon the position of the movable contact,
the amount decreasing as the end 14 of the contact approaches the part ring 11
and increasing as it approaches the gap 4. Upon moving the spindle 13 and
contact maker in the opposite direction to the arrow, the direction of the current
through the armature and the direction of rotation of such armature will be
reversed as well understood. To enable the contact maker to be moved in either
direction and to remain stationary in any position into which it is moved and
then released, there is mounted to freely turn upon a reduced portion 13" of the
spindle 13, a hollow spindle 16 to which is fixed two ratchets wheels 17 and 17"
which may, as shown, be made in one piece, the teeth of one wheel being arranged
the reverse way to those of the other wheel. The ratchet wheel 17 engages with
a pawl 19 formed as one arm of a lever pivoted at 19% and the other arm 19 of
which is jointed to the movable core 20 of a solenoid 21. The ratcht 17" engages,
in like manner, with a pawl 19 jointed to the core 20% of a second solenoid 21".
The two solenoids 21, 21 are secured to a carrier 22 fixed to the spindle 13. The
hollow spindle 16 may be extended upward to any convenient height within a
pillar 23 (Fig. 5) and is provided at its upper end with suitable means, such as
a worm wheel 24 gearing with a hand operated worm 24 (Figs. 5 and 6) by which
the spindle with toothed wheels 17, 17" and contact maker can be rotated in
either direction and the latter left in any desired position on the fixed contacts.
The part 13 of the spindle 13 may be extended up through the hollow spindle 16
and be provided at its upper end with a pointer 25 arranged to move over a
dial 26, 26 having divisions corresponding to the positions of the two sets of
fixed contacts 2, 2 so that the pointer will at all times indicate to the operator
the position of the movable contact maker relatively to the two sets of fixed
contacts which may be out of his view.
To the lower end of the spindle 13 is fixed an arm 26 provided with dia-
metrically arranged pins 27 to which are connected two coiled
springs 28, 28", that are connected to holders 29 and serve to resist
rotation of the contact maker in either direction after the same has been moved
through a predetermined angle, say from about the point A on either side of
Fig. 2 onward. For automatically disconnecting the contact maker from the
ratchet wheels one end of each solenoid 21, 21 is connected to a common
conductor 30 (Fig. 7) that is connected through a conductor 31 to the end 15" of
the contact bar 15, the other ends of the two solenoids being respectively con-
nected by conductors 32, 32" to two movable plugs or plungers 33, 33" that are
arranged to make electrical contact with the wide part of the ring 7 when moved
over the same by the rotation of the contact maker and to be disconnected there-
from when brought over the recessed part 7° of such ring. By the arrangement
described it will be seen that the two solenoids, each of which consists of a
few turns of thick wire, form a loop shunt in parallel with the contact maker

page_text: between the ends 15", 15 of the contact bar 15 so that a portion of the current will
flow through one or other of the solenoids as soon as the corresponding plug
or plunger 33 or 33" is brought into contact with the ring 7, instead of the whole
of the current flowing through the contact maker from 15 to 15. 34 is a fine
wire solenoid forming a magnetic blow out adapted to be placed in a shunt
across the two supply mains when the controller is in use for which purpose one
of its ends may conveniently be connected to the conductor 30 by a conductor 35
and its other end to the ring 6 by a conductor 36.
The action of the apparatus is as follows:-On turning the wheel 24, the
movable contact maker passes over the fixed contacts 2 or 2 either to the right
hand or to the left, one side causing rotation of the armature in one direction
and the other rotation the reverse direction. On reaching the part ring 11 the
contact maker can go no further and the motor will be at full speed, all the
resistance being cut out. If the attendant wishes to stop the motor, he would turn
the wheel 24 in the reverse direction and so turn the contact maker back again,
and if he wishes to reverse the direction of rotation of the motor he would
continue in this direction on the other side of the apparatus until the contact
maker again reached the part ring 11 when the motor would be full speed in
the reverse direction, the resistance being again cut quite out. Should however
the current rise beyond the predetermined maximum, the corresponding solenoid
would act and release the ratchet wheel 17 or 17° and the spring 28 or 28" would
then return the contact maker back say to the point A (Fig. 7), beyond which
point the spring has no effect, and insert a suitable resistance in the armature
circuit the pointer 25 indicating to the operator what is going on. If before
the contact maker reached the point A, the motor should go on again and increase
its back EMF and so reduce the current, the solenoid that acted would cease to
hold its pawl out of action and such pawl would then engage with its corre-
sponding ratchet wheel and stop the further backward movement of the contact
maker. The operator seeing this would turn his wheel 24 forward again and so
cut out the inserted resistance and enable the motor to again run at its maximum
speed.
If the motor had been completely stopped however, one or other of the
springs 28, 28 would carry the contact maker back to the point A, and as long as
the motor was at rest the operator could not cut the added resistance out, as the
pawl of the operative solenoid would not engage with its corresponding ratchet
wheel. His only course therefore would be to return the contact maker
to the normal and inoperative position by means of the other ratchet wheel
and pawl. On the contact maker passing the point A towards the
gap 4, the corresponding plug or plunger 33 or 33, (which, ag
before stated, only makes contact with the wide part of the contact
ring 7) will be brought over the recessed part 7 of the ring 7 and thereby be
disconnected from such ring so that no current will then flow in the corresponding
solenoid which' will at once release its pawl, whereupon the operator might try
to return the contact maker to the part ring 11 but he will be unable to pass the
point A unless the excessive load has been removed from the motor, because at
that point the pawl will be again tripped out of gear by the action of the solenoid.
The magnetic blow out 34 serves to prevent the setting up of an arc when the
contact maker leaves the last contact 2 or 2 as it passes into the inoperative
position shown in dotted lines in Fig. 7. For this purpose the poles of the
solenoid are so arranged in proximity to the last contacts 22" that on the circuit
through the controller being broken by the contact maker leaving the last
contact on either side, the effect of the magnetism flowing from one pole to the
other will cause the spark set up by the breaking of the circuit to be blown out.
The speed of backward motion of the movable contact under the action of the
spring 28 or 28", is regulated by a brake consisting it may be of vanes 37 arranged
to rotate in liquid and fixed to a shaft 38 geared to a wheel 39 fast on the
spindle 13.

page_text: Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. Electrical controlling apparatus arranged and operating substantially as
hereinbefore described.
2. Electric motor controlling apparatus arranged so that upon an excessive
load being put upon the electric motor connected therewith so as to reduce
or stop the rotation of the motor armature and thereby reduce its back E MF
below a predetermined amount, or entirely remove such back E M F, a resistance
will be automatically inserted in the armature circuit and prevent undue increase
of the current flowing through the armature winding, substantially as described.
3. In controlling apparatus for electric motors, the combination with the
movable contact maker, and means for operating the same in one direction
by hand and in the opposite direction by a weight or spring, of reversely
arranged ratchet wheels connected to the operating means, pawls connected to
the movable contact maker and adapted to engage with and be driven by one
or other of the ratchet wheels, and solenoids arranged and operating substantially
as described so as to disconnect one or other of the pawls from the corresponding
ratchet wheel and enable the contact maker to be automatically moved into a
position to insert a suitable resistance in the circuit of an electric motor con-
nected with the apparatus, in the event of the back E M F of such motor being
removed or unduly reduced by an excessive load, substantially as described.
4. Electrical controlling apparatus constructed, arranged and operating sub-
stantially as hereinbefore described with reference to the drawings annexed.
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.