Improvements in the Control of Electromotors.
Year: 1895

page_text: Date of Application (in United Kingdom), 22nd Feb., 1895
Complete Specification Left, 22nd Feb., 1895-Accepted, 21st Mar., 1896
Improvements in the Control of Electromotors.
I, ELMER AMBROSE SPERRY, a citizen of the United States residing at Cleveland,
in the County of Cuyahoga, and State of Ohio, do hereby declare the nature of
my 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 a system and apparatus for control of electric machines,
and consists in arrangement of certain details of the electric machine and
construction of certain parts, such as commutator brushes, devices for controlling
the movement thereof, and mechanism for the current control of such electric
machine, ali of which are fully described and especially pointed out in the claims
hereto annexed.
In electric machines where the inducing capacity at start greatly exceeds the
normal or where such capacity is reduced for increasing speed, &c., it has been
found that for the best results at the time of changing the inducing capacity
certain changes should be made in the position of the commutator brushes, owing
for instance to the shifting of the so-called neutral point upon the commutator.
The present invention relates to an automatic method of securing this change, and
when the motor is running in either direction. It has been found that when
such machine is used as a motor a large economy in current consumption can be
effected in starting. Also, that during excessive loads or during the time of heavy
acceleration it is not desirable to alter the inductive capacity or lower the capacity
of the motor for generating counter electro motive force at constant speed, and
certain automatic devices are introduced to prevent the alteration except when the
conditions will permit, for instance, when the motor is used to propel a car on
a level track with not too high degree of acceleration.
In the accompanying drawings,
Figure 1 illustrates a diagrammatic elevation of the controller;
Fig. 2 a diagrammatic view of the motor with commutator brush operating
device;
Fig. 3 a detail of the automatic stop.
Like letters and numerals of reference indicate similar parts throughout the
several views.
The electric machine or motor A, is provided with a commutator B, and
brushes a, mounted upon a yoke revolving around the axis B of the motor in
any suitable manner as by means of the toothed rack a' and co-operating toothed
lever a fulcrummed at b, and furnished with a centralizing spring B co-operating
with pin b'. A link C, connects the top of the lever a" with the solenoid Ci

page_text: which is shown in circuit with the field magnets 1), indicated in dotted lines.
The core of the solenoid is supplied with a coil (" grounded at one end on the
link C and supplied at the other by wire 4, which may include a resistance R¹.
The circuit through the motor is from reversing switch E, wire 5, fields, DD,
wire 6, solenoid &, back to reversing switch E by wire 7. The armature circuits
are completed through the brushes a a and conductors 8 and 9. In the controller F.
the main moving part is shown as in the form of a lever L pivoted at Li
and supplied with a handle or lever H, which slides along the guide G, shown
in section in Fig. 3, the handle being furnished with a guide L" form a part
thereof. A stationary portion G' of the controller which may form a part of
the guide or seguient G, serves to guide the stop S, Fig. 3, a portion only
of which is shown in Fig. 1. A moving weight W, is shown as hung on the
rod W¹ from the point P forming a pendulum, the motion of which is communicated
to the stop S, by bell crank lever K pivoted at K', and link K".
The circuits through the apparatus may be traced as follows: When the electric
machine is used as a motor, the source of current supply may be illustrated by the
trolley T, and wire 10 to the switch S' which may he actuated by the finger I
forming a part of the lever L. The current from this point flows on wire 11 to
contact m, through the resistance R to the moving contact e, upon the lever L,
through either one of two groups of contacts indicated by mm, &c., and nn, &c.
The current at this point passes wire 8, commutator B, wire 9, contact e¹,
contact J, contact J, switch E, wire 7, field D), wire 5, contact J, stationary
contact el, wire 12 to ground G As the lever L, is moved farther to the left
the contact e, finally reaches the contact n¹ when all the resistance R is cut out.
If stop S will permit, a still further movement is made whereupon the contact m¹
is reached, and simultaneously with it the contact e¹ reaches the contact f,
whereupon some of the current which has reached the ground through field D,
and wire 12, now flows over wire 4 through resistance R₁ to the ground by wire 13
which connects with wire 12 as shown. As the switch S' is thrown to and fro in its
well known movement simultaneously with the switch E and the reversal of the
field D, the contact O is covered, and the wire 11 is in this manner connected
with wire 14, which connects with wire 12, in the well known way and may
include the brake or other actuated device X.
Having described the invention, its mode of operation will readily be understood
as follows: Supposing the controller F, to be attached to a car, the horizontal
arrow in Fig. 3, will represent the forward direction of movement of the car.
The inertia of the weight W, will in this case cause the weight to move to the
left. The motion being imparted to the stop S, it will rise and occupy the position
shown by S and thus prevent the lever L from passing. It will also be seen
that when upon a gradit the weight W, hanging from pivot P, will always tend
to assume a vertical position. When the car rises upon the grade its vertical
position will be in line of the double-headed arrow, and it will occasion the
same lifting of the stop S. When the contact et reaches contact f, the field D,
is shunted to a more or less extent, and the inducing capacity of the electric
machine is thereby decreased, but simultaneously with such decrease means are
adopted for decreasing the current supply consisting in resistance R, more of
which is now included by. the contacts m and n, being placed in connection with
the moving contact e. This decrease in inductive capacity may be accomplished
in various ways, as for instance, by introducing extra self-induction in the circuit
where an alternating current motor is used. The machine when used as a motor
in connection with the controller, may be used for electric brake, as is well
known in the art, through the devices shown in connection with the switch S¹
and finger I. The finger I together with. the handle H may serve to adjust
the switch S' at the end of each stroke of the handle as is also well known
in the art. The devices shown in Fig. 2 for automatically causing a change
in the movement of the brushes of the electric machine A, when its inducing
capacity is reduced, may operate in either direction in which the machine may

page_text: he rotating at the time, and in this case a solenoid is placed in the circuit
of that portion of the electric machine, which is reversed when the speed is
changed, which determines the direction that the brushes shall take when altered
as to position. To further effect this change in direction the core of the solenoid
may be separately energized, as by coil (which may constitute the entire
resistance R', Fig. 1, or an extra resistance shown at R¹ Fig. 2 may be added.
In this case the solenoid will be seen to be inactive and dormant until the circuit
through contact and wire 4 is closed, whereupon the solenoid at once acts.
Many of the functions in the invention may be performed by devices differing
considerably in construction from those shown and described without departing
from the spirit of the invention, and while it is designed to use all the above
features in connection with each other, yet it is obvious that some may be used
without the others, and the invention extends to such use.
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. The combination, with a motor, of a current supply, means for gradually
increasing the current in the motor circuit from such supply, up to some
predetermined point, means for then decreasing the counter electro motive force
at constant speed of such motor and simultaneously decreasing the current flowing
in the motor circuit from said supply as compared with that flowing previous to
said change in the counter electro force, and means whereby the current in the
motor circuit may be gradually increased from this point.
2. The combination with a motor, of a current supply, a resistance in the motor
circuit, means for gradually decreasing such resistance, up to some predetermined.
point, means for then more or less suddenly decreasing the counter electro motive
force at constant speed of the motor, and simultaneously increasing the resistance in
the motor circuit, and means whereby the said resistance may then be again gradually
decreased from this point.
3. The combination, with a motor, of a controller for such motor, a contact-
controlled variable resistance in the circuit of the motor, additional contacts
operated by the controller at a predetermined point for decreasing the counter
electro motive force of the motor at constant speed, resistance contacts simultaneously
operated by the controller for inserting resistance in the motor circuit, additional
contacts connected with such resistance whereby same may be afterward gradually
removed from the circuit, substantially for the purpose specified.
4. The combination, with a motor having field magnets, of a current supply, means
for gradually increasing the current in the notor circuit from such supply, means
at some predetermined point during said increase for decreasing the magnetism in
said field of the motor, and simultaneously decreasing the current flowing in the
motor circuit from such supply as compared with that flowing previous to said
change in magnetism, and means whereby the current in the motor circuit may be
gradually increased from this point.
5. The combination, with a motor having field magnets and a shunt for said
magnets, of a current supply, means for gradually increasing the current in the
motor circuit from such supply, up to some predetermined point, means for then
closing said shunt, and simultaneously decreasing the current flowing in the motor
circuit from such supply as compared with that flowing previous to the closing
of the field shunt, and means whereby the current in the motor circuit may be
gradually increased from this point.
6. In an electric machine, movable brushes for such machine, means for
changing the inducing capacity of the machine at constant speed, in combination
with a device for simultaneously shifting said brushes.
7. In an electric machine capable of rotating in either direction, a commutator,
movable brushes for such machine, means for changing the inducing capacity
of the machine at constant speed, in combination with a device for simultaneously

page_text: shifting said brushes in either one or the other direction around the commutator
dependent upon the direction of rotation of the machine.
8. In an electric machine, movable brushes for such .machine, means for changing
the inducing capacity of the machine at constant speed, in combination with
a device in the circuit of the machine for simultaneously shifting the said
brushes.
9. In an electric machine having a field magnet, a shunt for such field in
whole or in part, movable brushes for the machine, means for closing said
shunt, in combination with a device in circuit with said shunt for simultaneously
shifting the brushes.
10. In a controller for an electric machine, a moving part of said controller,
and a pendulum-actuated stop for the moving part.
11. In a controller mounted
controller, a weight mounted to
of the machine, a stop for said
the weight and the stop.
upon a moving machine, a moving part of such
move in a plane parallel to the plane of movement
moving part, and mechanical connection between
12. In a controller for a motor, a moving element of the controller, means
connected with the controller for decreasing the inducing capacity of such motor
at a predetermined point in the movement of said moving part, and a stop for
such controller so located as to arrest the moving part in its excursion just
before reaching the aforesaid means.
13. In a controller for a motor, a moving element of the controller, means
connected with the controller for decreasing the inducing capacity of such motor
at a predetermined point in the movement of said moving part, and an automatic
stop for such controller so located as to arrest the moving part in its excursion
just before reaching the aforesaid means.
14. On a moving vehicle arranged to ascend grades, a motor controller having
a moving part for such vehicle, a stop arranged to arrest the action of the
controller at some predetermined point in its excursion, and means called into
action by the angle of gradit upon which the vehicle may stand for actuating
such stop.
Dated this 21st day of February 1895