Improvements in Electric Elevators,
Year: 1899

page_text: Date of Application, 22nd Apr., 1899-Accepted, 19th Aug., 1899
[Communicated from abroad by GUSTAF RENNERFELT, of 527, West 34th Street,
New York, United States of America, Electrician.]
Improvements in Electric Elevators,
I, EDWARD HIBBERD JOHNSON, of 527, West 34th Street, New York, United
States of America, but at present residing at The Hotel Cecil, Strand, in the
County of London, Electrician, 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 elevators and has for its objects.
First, improved means whereby the car of an electric elevator may be caused
to stop at the proper time on approaching a floor or landing; Second, improved
means whereby the speed of the car may be properly regulated when the
weight thereof and its load are such as to cause the motor to act as a generator;
and, Third, improved means whereby a retarding force may be automatically
or when the momentary
applied upon the too-sudden starting of the car
acceleration thereof is beyond a normal or stated speed.
A fruitful source of trouble in operating electric elevators lies in the difficulty
of effecting proper stoppages of the car at the right moment. In order to effect
these stoppages with moderate certainty in existing types of electric elevators,
it is customary to employ a single powerful brake applied by a strong spring
which is released when the current is turned off, thereby causing the car to be
brought to rest. With such a device, however, the retarding force of the brake
cannot be varied at the will of the operator; whether the load on the car be heavy
or light, and whether the car be running at high or low speed, the brake when
applied, exerts always the same pressure and all that the operator can do is to
cut off the current a little sooner or a little later, as the case may be, and trust
to chance to allow the brake to slide sufficiently far to cause the car to stop where
it should. The uncertainty of this operation is naturally increased with the
speed of the car and with the absence of friction in the machinery; and it is
also increased by the wearing of the brake shoes, thus rendering necessary a
frequent adjustment of the shoes.
My invention is designed to overcome, as far as possible, the evil effects of
existing types of elevator controlling apparatus, and will be fully understood by
referring to the accompanying drawings, in which,
Figure 1 is a diagrammatic view illustrating all of the electrical circuits and
necessary attachments for accomplishing the objects for which the invention is
devised.
Figure 2 is a transverse sectional view taken through the body of my apparatus
for automatically applying a retarding force in case of a too-sudden starting of
the car or when the acceleration thereof exceeds a definite limit.
Figure 3 is a detail view of the circuit contacts of the apparatus shewn in
Figure 2.
Figure 4 is a diagrammatic view illustrating the means I employ for auto-

page_text: matically regulating the speed of the car when the combined weight of the car
and its load is such as to cause the motor to act as a generator.
Figure 5 is a side elevation thereof as seen looking at Figure 4 from the right
hand toward the left hand side of the drawings, the motor being shown in section
with the circuit connections omitted.
W W represent the current leads or mains running from a dynamo electric
machine, not shown, and W W branch current leads running respectively to the
switching apparatus for controlling the circuits of the armature AR and thence
through the coils of the brake controlling magnet 1) and rheostat F. 10 101 w203
etc., to wo inclusive represent branch conductors running to the push buttons 1*,
2 and 3, electromagnets and switching contacts of the controlling switches LL',
HH, GG, K K', shunt field coil FM and auxiliary brake controlling magnet B,
ratchet controlling magnets Q Q'; the aforesaid push buttons being located in the
moving car. 1-2, 1-2, 1-2, 1-2 are switching contacts for the switches G G¹
and armature AR; 3-3, 3-3, 4-4 4-4 being similar switching contacts for
the switches L L' and K K¹.
A represents the electromagnet which controls the operation of the brake
(not shown) which is applied in the usual manner by a spring when released,
the adjustment of this brake being just sufficient to prevent the car from slipping
under its maximum load. An auxiliary brake which is controlled by the coil
or magnet B is applied when necessary and its retarding force can be varied at the
will of the operator by a rheostat F1 carried on the car and located in the
circuit 100. This rheostat is of sufficient capacity for the small current
necessary for operating the brake controlled by said coil, and the operator can,
by varying its resistance, apply the brake, controlled by the coil B, with more
or less force as he sees fit, so that the same will naturally help him considerably
in making his stoppages and incidentally on other occasions."
An additional source of trouble in an electric elevator service, (especially with
so-called overbalanced cars where the counter-weight is such as to just balance
the car and the mean or average load which it is supposed to carry), lies in the
fact that often a greater speed is attained than is desirable by reason of the motor
being driven as a generator, when the car is carrying a load less than that of the
mean or average load, and with this type of elevators such a condition of affairs
is liable to happen when the car is travelling in either direction, dependent, of
course, upon the load it carries. This excessive speed can occur only when the
armature circuit contains some external resistance, as a pure shunt wound
machine cannot otherwise attain any higher speed than is determined by the
voltage of the circuit. In an elevator service the motor generally starts up with
resistance in the armature circuit, whether the said motor needs the current or
not, and in the latter case excessive speed may be attained before the attendant
has had time to cut the resistance out.
With my improvement illustrated in Figure 1, such abnormally high speed
will never occur, since the starting resistance F is automatically short circuited
whenever the motor happens to act as a generator. The manner in which this is
accomplished is clearly illustrated in the diagram. A rotary armature C (see
also Figures 4 and 5) of fixed polarity is so designed as to rotate a definite distance
by reason of stops ss in one or the other direction through the influence of a
field magnet I) energized by the current passing through the armature AR of
the motor. To obtain a fixed polarity for the rotary armature C, I magnetize it
by passing a current through its commutator brushes and coils from the main
or lead W through the conductors, said current running always in the
same direction. This rotary armature C is suitably connected through a crank b,
linka and lever a¹ to a movable contact E, so that whenever the motor runs as
a generator, and the current in the field magnet I) assumes sufficient strength
in direction opposite to that of the normal direction, the contact E will be moved
so as to short circuit the starting resistance F by bridging the space between
the stationary contacts E¹ and E³, see Figures 1 and 4. When the current passes

page_text: through the field magnet ]) in the proper direction so as to cause the armature AR
of the motor to serve its function as a motor, the rotary armature C causes the
contact E so to move that the starting resistance F will be cut into circuit with
the armature of the motor. Excessive speed caused by the armature AR of the
motor being driven as a generator is thus effectively guarded against. Should
a still lower speed in this case be desired, it can be attained by a simple application
of the auxiliary brake controlled by the coil or magnet and rheostat F' in
the circuit w³ u.
An additional feature of my invention is the manner in which I effect the
closing of first the shunt circuit and afterwards the armature circuit of the
motor. This will be understood by referring to Figure 1, where G is a switch for
both terminals of the armature circuit 1-2, 1-2, and is adapted to be closed by
energizing the coil H in the circuit ca. This coil H is in series relation
with the shunt windings FM of the motor, as shown, and the switch G is so
balanced by a spring or by gravity that the current in the shunt field, and,
consequently, in the coil H must rise to a certain strength before the switch will
be closed. In this manner, I guard against any sudden rush of current through
the armature in a non-excited field. The circuit comprising the coil H and the
shunt field might be closed by a switch operated by a rope, but in the diagram
I have shown a switch K controlled by the coils of an electromagnet located in
a circuit w running to the push button 1 in the elevator car.
The apparatus disclosed in Figures 4 and 5 of the drawings and arranged to
operate, as described, will prevent the motor from attaining any higher than a
predetermined speed, but there still remains the possibility that the acceleration,
or rate of speed increase, may become greater than desirable. It is, of course,
true that the operator can at any time he sees fit apply the auxiliary brake
controlled by the magnet or coil B and thus by adding load upon the motor
check the speed, but it is preferable that such regulation should occur auto-
matically and instantaneously. For this purpose I have devised an additional
apparatus, shown in Figures 2 and 3 of the drawings, consisting of a pulley S and
a fly wheel T, both running loosely on a shaft and joined together by means
of a torsional spring .. The pulley S is driven by a belt from the motor and it is
evident that upon setting this pulley in motion, the spring connecting it to the
fly-wheel T will be deflected to a certain degree depending upon the suddenness
of the start.
26
P is an electrical contact carried by the fly-wheel T, R and R' being additional
contacts carried by the pulley S and so located with relation to the contact P
that when the pulley is revolved in opposite directions with sufficiently great
acceleration, said contact R or R', as the case may be, will be caused to come into
electrical contact with the contact P, it being understood that the relation
between the weight of the fly-wheel T and the torsional spring connecting it to
the pulley S is such that for a predetermined speed of starting, the contacts P
and R or R' will not be brought together. The contact P is connected by proper
circuit connections, as shown, to a vielding contact held against the face of a
conducting ring on the fly-wheel T by a spring 2, which in turn is connected
to the conductor 7, while the contacts Rand R₁ are connected in a similar
manner to a metallic disc carried by the pulley S. Against this pulley rests a
second sliding contact t yieldingly held against said ring by a conducting spring ♬
electrically connected with a conductor. The conductors w and u are con-
nected one to the conductor 6 at a point near the auxiliary brake coil B, and the
conductor 8 is in turn connected to a shunt resistance coil O so that when the
circuit is closed through the contacts P and R or R¹ the auxiliary brake coil B
will be shunted and the brake applied, thereby checking the speed of the car.
Several apparatus of this sort could be used for shunting more or less of the
current, if desired, and thus more or less pressure of the brake caused to be
exerted. Probably one or two of such apparatus however, would be sufficient.
This apparatus which I call an acceleration controller, is not to be confounded

page_text: with speed regulators which are common in the art. This apparatus does not
prevent variation of the speed between any limits, however great. It only
prevents the speed from varying too suddenly. Without affecting the principle
of this apparatus various modifications may be made in its construction. For
instance, the pulley S might be supplied with two fly-wheels, one on each side,
and the fly-wheel could be supplied with a brake for the purpose of making it more
sluggish if this should be found desirable. It should be noted that while this
apparatus prevents a too-sudden starting of the car from a point of rest, it does
not prevent a too-sudden stoppage which I consider a feature of great advantage
since the stopping of a car can, and should, ordinarily be controlled by the operator
alone, without any interference from the automatic regulating mechanism.
The operation of the apparatus as illustrated in the diagram is as follows-
When the car is to be started, say upward, the attendant presses push button 1*
in circuit ww¹ on the left. Current therefore flows, as indicated by the arrows,
through the rotary armature C, (see Figure 4), the coils of the magnet controlling
the switch K, back to the current mains or feeds. A branch circuit is also closed
through the conductor in the direction of the arrows and the coils of the
switch magnet L and the rheostat controlling coil Q. The shunt field FM is now
energized because the switch K is closed, and when the field is strong enough
the armature circuit AR is closed and the brake controlled by the magnet or coil A
released, thus allowing the car to move upward. Should the machine now run
as a generator, the contact E will immediately close by virtue of the shunting
action of the apparatus illustrated in Figures 4 and 5, and already described, and
the car will hence move more slowly.
If it is desired to obtain greater speed the attendant simply presses the push-
button 3* in the circuit 10 2010 thereby energizing the controlling magnet M and
causing it to impart motion to a controlling. arm V3 operatively connected with
the rheostat F, through the various contacts X X X X³ X', thereby cutting out
more or less of the coils of said rheostat. This arm continues to advance so long
as the push-button 3* is held closed or until the maximum speed is attained,
which occurs when it reaches its lower or vertical position and all of the coils
are cut out, as will be apparent on inspection of Figure 1 of the drawings. If it
is desired to maintain the speed of the car constant on ascending, the attendant
simply releases the push-button 3* when the desired speed is reached, in which
event the controlling magnet M will be disconnected and the controlling arm Vs
will be held by the arm J of the solenoid Q. It will also be apparent on
inspection of Figure 1 of the drawings, that should the controlling arm V³ be
moved in either direction to its bottom limit, the circuit will be ruptured as said
arm strikes the weighted switch N, thus limiting the movements of said arm in
opposite directions."
This controlling arm V is held in any desired position of its radial movement
by any well known means, not shown, but controlled by either of the levers J J¹
actuated by the solenoids Q Q in the circuits 101 103, and said means are released,
as will be understood on inspection of Figure 1, by actuating the push-buttons 1*
or 2 in accordance with the direction in which the car is being moved. To stop
the motor, the attendant simply releases the push button 1 in circuit ww¹. The
magnetic switch L will then drop quickly, said magnet having a small time
constant. This will short circuit the winding of the switch H so that the armature
circuit will be broken before the shunt field FM is opened. When the armature
circuit is opened the brake controlled by the coil A is applied by a spring, this
brake having been previously released by the current. Since the car is liable to
move some distance by reason of its momentum the brake, controlled by the
coil B, is now applied in order to stop at the proper place. A switch N is placed
in a suitable location in the circuit 0 for opening the circuit of the coil B
which controls the auxiliary brake, so that its full force will be immediately
applied in case the car should travel beyond its proper limits, the necessary
limit switches being of course previously opened.

page_text: When the push button 1 is released and the motor stopped, the coil Q is
demagnetized and hence the arm J is released, and the arm is restored to its
vertical or normal position with all of the rheostat in circuit ready for starting.
G L K are the duplicates of the switching apparatus GLK and 2 is the
duplicate of the push button 1, said apparatus being designed for moving the car
in a reverse direction, as will be fully understood by noting the circuit relations
through the several switches, the armature AR and shunt field magnet FM, as
seen on the right of the diagram in Figure 1.
Haring now particularly described and ascertained the nature of this
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. In an electric elevator the combination of a brake adapted to be released
automatically by the current, with an auxiliary brake adapted to be applied at
will, and means for varying the retarding force of said auxiliary brake, sub-
stantially as described.
2. In an electric elevator the combination of a resistance in the armature circuit,
with means dependent upon the speed of the motor for short circuiting said
resistance when the motor is driven as a generator by the load, substantially as
described.
3. In an electric elevator the combination with a shunt wound electric motor of
a switch in the armature circuit of said motor and an electromagnet for closing
said switch by the action of the current through it, after the shunt field has
attained a definite strength, substantially as described.
4. In an electric elevator the combination with an electric motor, of the
acceleration controller connected with the motor and with means for checking or
breaking the speed of the car, substantially as and for the purposes described.
5. In an acceleration controller such as that herein described, the combination
of a fly-wheel and a pulley with a torsional spring substantially as and for the
purpose described.
6. An electric motor provided with electromagnetic means for automatically
closing the circuit through the field magnet coils before it is closed through the
armature coils, in combination with additional electromagnetic means for effecting
such closure of the circuit through the armature coils, substantially as described.
7. An electric motor provided with means for closing the circuit through the
field magnet coils before it is closed through the armature coils, in combination
with devices for effecting the closure of the circuit through the armature coils
and means for releasing the said devices, substantially as described.
8. An electric elevator provided with apparatus for controlling the cars sub-
stantially as described with reference to the accompanying drawings.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.