Improvements connected with Electric Motors and Electric Elevator Apparatus.
Year: 1892

page_text: Date of Application, 8th Jan., 1892-Accepted, 20th Feb.. 1892
COMPLETE SPECIFICATION.
Improvements connected with Electric Motors and Electric Elevator
Apparatus.
A communication from abroad by OTIS BROTHERS & Co., of 38, Park Row, New
York, in the United States of America, Manufacturers.
We, AMERICAN ELEVATOR COMPANY (Incorporated) of 4 Queen Victoria
Street, in the City of London, Manufacturers, 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 improvements connected with electric motors and
electric elevators and more especially to means whereby an electric elevator may
be readily operated at different speeds in connection with ordinary systems of
distribution of electricity.
In operating electric elevators, it is very desirable to provide means whereby
the speed of the elevator may be regulated as it approaches the various landings,
as it is generally desirable to slacken the speed before the landing is reached in
order that the stop may be made without jar or jolt.
It is further desirable in the use of electric elevators, to provide means whereby
the speed of the elevator may be regulated for the purpose of inspection, which is
done periodically, and in inspecting the guides and ropes for instance of the
elevator, it is necessary that it be driven at a moderate speed, so that defects or
irregularities may be discovered. This regulation of the speed of a motor for an
electric elevator has hitherto been accomplished by interposing the resistance to
the current passing through the motor, and it has been found that when a motor is
driven at a slow speed for instance on the whole trip up or down in the course of
inspection of the parts or otherwise, this resistance becomes overheated, and the
safety of the rheostat is endangered and a large amount of current is wasted.
In order to overcome these objections, and avoid this wasteful method, and to
provide means whereby the speed of the motor may be easily regulated, and the
inotor used with the common systems of distribution, the motor and its connections
are arranged that it is adapted to make use of the different pressures or potentials
of the ordinary multiple wire system, by which most of the incandescent light
stations distribute their current, in a manner to avoid wasting the current and the
consequent danger from overheating the resistances. The invention in the present
instance is shewn as applied to what is known as the three wire system of
distribution, as that is the most common system in use, though
other systems wherein more distributing wires are used by simply extending the
may be applied to
principles of the invention in a manner well understood by those skilled in the art.
In the accompanying drawings
Figure 1 is a general view of an electric motor and its attachments and connections
adapted for operating an elevator.
Figure 2, is an enlarged diagrammatic view representing the arrangement of
circuits in connection with the three wire system.
It is well known that the lifting capacity of an electrical elevator depends upon
he torque or tangential force of the motor. This depends again in a motor with a
given armature upon the strength of the magnetic field and the quantity of
urrent flowing through the armature. If, now, the strength of the field is kept
he same, and also the quantity or amperes of the current passing through the
rmature, the motor will be able to lift the full load, but with a speed varying,
pproximately proportionate to the pressure or voltage of the current passing'
hrough the armature.
This fact is made use of to vary the speed of the electric motor of an electric

page_text: elevator in connection with the three or other multiple wire system of distribution,
and the parts and connections are so arranged that the current passing through the
armature of the motor may be derived from the outside or main conducting wire of
the system in which case the full current passes through the armature of the motor,
with a pressure corresponding to the pressure of the main line and the motor will
run at its maximum speed, or the armature of the motor may derive its current from
the neutral wire of the system, in which case the armature of the motor will be
driven by a current under a voltage corresponding to that of the neutral wire.
To illustrate this principle, it may be assumed that the difference of potential
between the outside or main distributing wires of a three wire system is 240 volts,
while the difference of potential between either one of the outside or main
distributing wire and the neutral wire of the system is 120 volts. The motor and
its connections are so arranged that the armature may be operated by a current
from either the outside wires or the neutral wire of the system, and thereby the
voltage of the current will be changed to correspond with its source, and
consequently, the speed of the motor and the elevator operated thereby will be
changed in accordance therewith. In carrying out the invention, a shunt motor is
made use of.
It is not deemed necessary to refer specifically to the details of the motor and
elevator as shown in the accompanying drawing as their operation is well understood
by those skilled in the art, it being sufficient to say that A, is the winding drum
upon which the rope B, is wound and unwound to raise and lower the car B', the
rope passing over suitable sheaves B2. The drum A, is supported upon a shaft A¹,
which is mounted in suitable bearings on a base plate A2, and this drum is operated
for instance by a worm wheel on the shaft C, meshing with a suitable worm gear on
the shaft A. The shaft C is driven by an electric motor D, the armature D', of
which is fixed to the shaft C.
The current supplied to the electric motor is controlled by a suitable switch
device S, whereby the motor may be started, stopped, reversed and otherwise
controlled in a manner readily understood. This switch device S, is shown as
being operated by a segmental lever arm E, which in turn is connected to a sliding
rod F. This in turn is connected by a segmental arm G, to a pinion G¹, on the
shaft A', and this pinion is adapted to be operated from the car or other position
by means of a band rope H, there being a lever or other well known mechanical or
electrical device on the car adapted for this purpose.
The switch device is arranged so that the current may be turned on to the motor
in such a manner as to cause the armature of the motor to rotate in either direction,
and to avoid the danger of injuring or burning the motor, the current is first
admitted to the field coils to excite the field magnet, and, is then gradually
admitted to the armature circuit until a sufficient amount of current is passing
through the motor, the resistance devices connected with the switch operating to
prevent the current passing with its full force directly to the armature, before the
motor has attained a speed sufficient to create the requisite counter clectro motive
force. It is not deemed necessary to describe in detail the construction and
arrangement of the switch device for carrying out this part of the operation, as it is
well known, and many and various devices may be used for this purpose.
drawings is illustrated a conventional and well known form of switch.
In the
Referring more particularly to Figure 2, X X represent two or more dynamo
electric generators connected up in series and P and M, represent the main feeding
circuit, plus and minus of the system, while N, represents the neutral wire of the
system, which is connected between the dynamo machines. In said diagram 1,
represents the binding post to which one, (we may say the plus leading wire) is
connected and 2, the binding post of the machine to which the minus leading wire
is connected, while 3, is the binding post to which the neutral wire of the system is
connected. From the binding post 1, the circuit passes to the segment, of the
switch, and from this point, the circuit 5, leads to the field magnet coils 6, of
the motor, and from thence a circuit 7, leads directly to the minus binding post 2,

page_text: and thence to the main line wire. It will thus be seen that the field magnet is
always excited under those conditions by the full pressure or potential of the
current from the outside or main leading wires, and a constant field of force is
provided whenever the motor is in operative connection, and in the instance
assumed, there is a current of 240 volts passing through the field magnet coils.
The switch arm S', is provided with conducting pieces 8 and 9, which are adapted
to connect the inner segments of the switch 4, and 10, respectively with their outer
segments 11 and 12. The segment 11, is made up of a series of resistance devices
connected in the usual way, so that the direction of rotation of the armature may
be controlled and the current admitted to the armature in either direction through
a series of resistances in the manner before intimated.
While the field of the motor has thus far been described as being connected to
the leading or main wires of the system to maintain a constant field, it is evident
that a constant field could be maintained at a less voltage by connecting the field
magnet coils with the neutral wire of the system, the resistances of the field magnet
coils being properly proportioned and such an arrangement is indicated by the dotted
line N but it is preferred as a general thing to excite the field from the leading
wires of the system.
In order that the speed of the motor may be varied under these conditions
independently of the resistances in the main switch, the armature circuit is so
arranged that the armature coils may be excited either by a current from the main
leading wires of the system under the full voltage, or by a current from one of the
main wires of the system, and the neutral wire by a current of a less voltage. In
order to do this an additional series of resistances O, is provided having brushes 20,
and 30 operated by solenoids 21, 31, respectively, or their equivalents, and
controlled by a cam 40, or other device which is adapted to be mounted as a matter
of convenience upon the shaft of the switch arm S', so as to move in unison there-
with and to control by suitable connections, as the ievers 50 and 60, the solenoids 21
and 31. In the drawing, these are shown displayed for the sake of clearness, it
being understood that the cam 40, will move in harmony with the switch arm S¹.
When the switch arm S¹, is in the position shown in full lines Figure 2, no current
is passing through the armature, but when it is turned towards the position shown
in dotted lines, the current passes from the segment 4, through the bridge piece 8,
to one of the sectors of the segment 11, thence through the resistance coils to the
line 13, to the brush 14, through the armature out by the brush 15, and by the
wire 16, to the outer segment 12. From thence it passes by the bridge piece 9, to
the inner segment 10, and by the conductor 17, to the central block 18, of the
resistance device O.
Meanwhile the cam 40, has rotated with the arm S¹, and the lever 60, has been
moved, so as to cause the brush 30, which has meanwhile normally rested on the
contact piece 19, which is unconnected with the circuit to pass to a contact 32.
The armature circuit is completed by passing through the resistances between the
blocks 18 and 32, and thence by the brush 30, the solenoid 31, and the neutral
wire N. By this time we assume that the switch arm has been moved to a position
so that the roller 61, of the lever 60, occupies the space 41, of the cam 40, and the
lever 60, and its connected brush 30, are free to move under the influence of
the weight 62, controlled by the solenoid 31. It will be evident that as soon as the
motor generates a sufficient counter electro-motive force to counteract or balance
the attractive force of the current passing through the solenoid 31, the weight 62,
will move the brush 30, on to the contact 18, cutting out all intermediate resistances
between said contact and the brush. The armature thereby operates under a
current of the voltage or pressure between one of the main leading wires and the
neutral wire of the system, and as before stated, this voltage being assumed to
be 120 volts, the motor operates at its reduced speed.
If, then, it is desired to operate the motor, at its full speed, the operator moves
the switch arm S', further on the segment 11, and consequently rotates the cam 40
to a greater degree, so that the lever 50, which so far has been stationary is operated

page_text: by the cam in a manner to cause the brush 20, to pass from the bearing piece 22,
which is out of circuit, on to one of the contacts 23, which is connected to the
central contact 18, through a series of resistances.
By this time it is assumed that the roller 51, has reached a portion of the cam
indicated at 42, wherein the lever 50, is free to move under the influence of the
weight 52, controlled by the solenoid 21. This connects the armature circuit with
the minus leading wire 7, of the system. Under these conditions, the armature
circuit for the moment is connected between the main leading wires having a
difference of potential, assumed in the present instance of 240 volts. An excessive
current for the moment passes through the contact 18, and the intermediate
resistances, and contact 23, to the brush 20, and solenoid 21, into the minus leading
wire 7, but this energizes the coil of the solenoid 31, which immediately operates to
withdraw the brush 30, from the contact 18, on to the contact 19, breaking the
circuit of the neutral wire, and allowing the armature to be energized by a current
of the full voltage between the main leading wires when the motor will run at full
speed.
In order to insure this action in addition to the solenoid 31, the cam portion 41
is so formed that when the arm S¹, is moved to its extreme position, the
lever 60, will be forcibly operated to withdraw the brush 30, and allow the motor
to operate under the full force of the current. This brush is then held in position
by the cam, so that it cannot return to the contact 18, if perchance, the current
through the solenoid 31 should be insufficient to support the weight and hold the
brush in its unmoved position.
Under these conditions, it will be seen that when the motor is running at full
speed, and it is desired to stop or reverse the motor, the parts will operate under the
influence of the cam, and the solenoid in the reverse order. Thus as soon as the
cam is moved sufficiently, the lever 50 is operated to forcibly move the brush 20,
from the contact 18, to the contact 22, breaking the circuit, and if perchance, the
brush 30, during this operation bears upon the contact 32, it is immediately
removed by the cam, as it assumes its normal or central position, and the motion is
stopped.
From this construction it will be seen that while a constant field of force of the
motor may be maintained, the pressure current in the armature may be varied, so as
to vary the speed at which the motor runs, that is to say, the current of the
armature may be maintained by the difference of potential between the main feeding
wires of the system, or the difference of potential between one of the main
feeding wires and the neutral wire, and the change may be made by the operator
moving the switch from the cage.
It is evident that instead of operating the brushes 20, and 30, automatically in
the manner described, through the medium of the cam, either one or both of the
brushes may be permanently fixed in position, so that the motor will run under
either one or the other varying currents, the cam being disconnected from one or
the other of the brushes, and the brush secured in position.
It is further evident that instead of the solenoids 21 and 31, for operating the
brushes, other means may be substituted which will accomplish the same result,
although the automatic means of operation heretofore described is preferred.
Having now particularly described and ascertained the nature of our said
invention which has been communicated to us from abroad by our foreign
correspondents and in what manner the same is to be performed we declare that
what we claim is :-
1. The combination with a multiple wire system of electrical distribution, of a
shunt motor, and means for connecting said motor to said system to vary the speed
of the motor, substantially as described.
2. In an electric elevator apparatus, the combination with a multiple wire system
of electrical distribution, of a shunt motor, connections between the field magnet
coils of the motor and the wires of the system, and mechanism substantially as

page_text: described for connecting the armature of the motor to the various wires or
system to alter the speed of the motor, substantially as described.
GILO
3. In an electric elevator apparatus, the combination with a multiple wire system
of electrical distribution, of a shunt motor, the field magnet coils of which are
connected to have a constant field of force, and means for connecting the armature
to the main leading wires, or to the main and noutral wire for varying the speed of
the motor, substantially as described.
4. In an electric elevator apparatus, the combination with a multiple wire system
of electrical distribution, of a shunt motor, the field magnet coils of which are
connected to produce a constant field of force, a switch device, and means for
automatically connecting the armature circuit to the leading wires of the system to
vary the speed of the motor, substantially as described.
5. In an electric elevator apparatus, the combination with a multiple wire system
of electrical distribution, and a shunt motor, the field magnet coils of which are
connected to produce a constant field of force, of a switch controlling the circuit of
the motor, and a resistance device and means for automatically controlling said
resistance device whereby the speed of the motor may be varied, substantially as
described.
6. In an electric élevator apparatus, the combination with a multiple wire system
of electrical distribution, a shunt motor, the field magnet coils of which are
connected to produce a constant field of force, of a switch, a cam controlled by the
switch, a resistance device controlled by the cam for regulating the speed of
the motor, substantially as described.
7. In an electric elevator apparatus, the combination with a multiple wire system
of electrical distribution, a shunt motor, the field magnet coils of which are
connected to produce a constant field of force, of a switch device controlling the
circuit to the armature, a cam controlled by said device, a resistance device
controlled by the cam, and solenoids connected in the circuits for regulating the
operation of the cam, substantially as described.
8. In an electric elevator apparatus, the combination with a multiple wire system
of electrical distribution, a shunt motor, the field magnet coils of which are
connected to produce a constant field of force, of a switch device controlling the
circuit to the armature, a cam controlled by the switch device, the resistance device
controlled by the cam, brushes bearing on said resistance device, a solenoid in one
of the main leading wires, and a solenoid in the neutral wire, substantially as
described.
1
LT180
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Agent for the Applicants.