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Патент USA US2137075

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Nov. 15,1938.
Filed Sept. 17, 1936
4 Sheets-Sheet l
Nov. 1-5, 1938.
“Filed Sept. 17/1936
4 Sheets-Sheet 2
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Nov. 15, 1938.
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Filed Sept. 17,_ 1936
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Nov. 15, 1938.
Filed Sept. 17, 1936
4 Sheets-Sheet 4
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Patented Nov. 15, 1938
Alexander Albert Chubb, Coventry, England, as
signor to The General Electric Company
Limited, London, England
Application September 17, 1936, Serial No. 101,221
In Great Britain September 18, 1935
11 Claims.
(or. rite-+152)
This invention relates to electro-magnetic sys
tems of lift control, and has for its object the
provision of means whereby the levelling of the
lift at a floor is rendered substantially independ
5 ent of the load carried in the lift car.
As is well known, lift driving motors operated
from alternating current supplies do not easily
afford a wide range of speed control. Thus, for
_’ example, the ‘pole changing type of machine,
w though it enables a certain set of speeds to be
obtained, does not easily permit a smooth change
from one speed to another. This smooth change
is essential in the case of a motor operating a
u lift, preferably during acceleration as well as
1*’ during deceleration.
According, therefore, to the present invention,
a lift driving motor operated by alternating cur
rent functions in conjunction with an eddy cur
rent brake, the extent of energization of the
brake being dependent on the load. in the lift,
this load being measured by the time taken for
the lift to pass between certain predetermined
points during the decelerational period.
In one embodiment of the present invention,
n1‘ an alternating current induction motor driving
a lift is started in either direction by means of
the normal slip-ring method.
When decelera
tion on approaching a ?oor is required, the max
“ imum value of eddy current braking is applied,
‘in and soon afterwards resistance is inserted in the
rotor circuit of the motor, this causing the car
to decelerate. It should here be noted that the
value of the resistance in the rotor circuit is con
V stant for all loads.
After a short period of deceleration the lift
is timed in its passage between‘ two ?xed points
in the lift shaft.
If the load in the lift is one
helping the motor to drive, the passage of the
car between the points is rapid.
Conversely, if the load is a hindering one, the
lift’s passage is relatively slow. According to the
time taken by the lift in this passage between
the said two points, resistance is inserted in the
slightly greater creeping speed with a hindering
load than with a helping one.
The sequence of operations is governed by
means of one or more inductor relays situated
on the lift car, co-o-perating with a sequence
switch of the step-by-step'variety, the contact
banks of which are interconnected with various
controlling relays. The timing of the lift is per
formed by a further step-by-step switch which
during the timing period rotates at a ?xed rate.v
The points between which the lift is timed are
marked by inductor plates situated in the lift
shaft at places reached and. passed by the lift
prior to its arrival at any required floor. Con
nections between the inductor relay and the sec0nd or timing switch are such that passage of
one plate initiates switch stepping and passage
of another’ plate arrests switch motion.
The »
switch contact banks are connected to resistances
which are inserted between a transformer and 20
a recti?er supplying the eddy current brake mag
net ?eld coils, variations in the switch position
causing variations in the current ?owing through
the braking ?eld.
One arrangement in accordance with the in 25
vention will now be described by way of example
with reference to the accompanying diagram~
matic drawings, of which Figures 1 and 1A com—
bined show a circuit diagram of the electrical
connections of the gear and Figures 2 and 2A
show a “code” diagram for the readier under
standing of Figures 1 and 1A.
In the drawings, the lift motor comprises a,
stator ST connected through contactor contacts
to the three-phase supply mains, and a rotor 30
R0 connected through slip rings to starting re
sistances. An eddy-current brake EB and a fric
tion brake BK operate on the motor shaft, and
this shaft is arranged to drive the lift carriage
LC through any suitable form of gearing. The
eddy-current brake EB is energized through the
recti?er RA from the transform-er TR, and the
friction brake is removed from the driving shaft
when its coil is energized through the recti~
M ?eld circuit of the brake, so that in the case of c ?er RC.
" a helping load, nearly full energizaticn is main.
Two step-by-step switches of a known type and
tained, whereas for a hindering load the brak
as used in telephone systems are used in the con~
ing is reduced. By this means, the lift reaches trolling circuit. These switches comprise mag
the required floor level at approximately the same nets A and B and contact banks A1, A2, A3 and
B1, B2,‘ B; respectively. The switch A
used 50
50 creeping speed whatever the load, and can there
' ‘ fore be stopped at the floor with great accuracy
as a sequence controller, and the switch B acts
as a timing device to measure time taken by the
by a further friction brake employed for the pur
pose. If necessary, a slight “over-compounding” lift to pass between fixed points in the shaft.
It is proposed to describe the operation of
may be effected by suitable choice of resistance‘
.55 values so that the lift arrives at a floor with the system by means of a typical traverse of
the lift.
The control mechanism is shown as
being hand-operated, the switches CSU and CSD
being operable by hand from the lift car. Clo
sure of switch CSU causes the lift to travel up,
and CSD causes the lift to travel down. When
ever the starting handle is moved away from the
normal “o?” position, contact CS is broken, no
matter what direction of travel is required. All
apparatus is shown in a normal position, i. 0.
10 one in which the apparatus rests when the lift is
at a floor and all the gates are closed.
these conditions the relay GL is operated, since
its circuit includes the emergency stop button
ES and the gate locks GA GB and (30. Its con
tacts are shown in operated positions.
Assuming that the lift operator closes contact
CSU (and consequently opens contact CS), a
circuit is completed from the positive of con
tact 911, via contacts rm, v3, n1, CSU, UL the
upper limit switch, which is normally closed and
ddi to relay UD which operates.
udl prevents false operation of the relay DD
which drives the lift in the opposite direction.
udz locks UD operated, so that it is not re
25 leased when contact us opens later.
udg prepares to operate relay C.
U614 opens a self-interrupting circuit of the
switch magnet A.
uds operates the gate lock catch RCR and
30 prepares a locking and operating potential for
other relays later.
through bank A2.
Relay SC is also operated
ude breaks a self-interrupting circuit for the
switch magnet B.
14617 and lLds apply current to the stator wind
ings ST and to the brake magnet BK.
801 and so: short-circuit resistances in the
rotor circuit used for deceleration.
8C3 prepares to operate relays V and VA.
On removal of the friction brake BK from the
driving shaft, the lift commences to move, a
large starting current being induced in the wind~
switch, being of the reverse drive type, does not
yet take a step.
c2 operates relay EC from uds via bank A3.
801 locks relay EC operated to M15.
(202 applies full potential to the eddy-current
brake EB via the recti?er RA from the ?rst
contact of the switch bank B3 and the trans
former TR.
Release of relay C on passage of the ?rst plate
de-energizes the driving magnet A, and the
switch takes a step forward. The current in the.
eddy-current brake begins to rise, causing a pro
gressive deceleration against the drive of the
motor. This must not, however, be continued
for long, as the motor would proceed to draw a
large over-load current from the supply. An
other plate is now passed by the relay Y, and
on operation and release of relay C for the sec
ond time, the switch reaches the third contact
in its banks. Wiper A2 breaks the connection 20
to relay SC and this relay releases.
s01 and $02 open short circuits across resist
ances in the rotor circuit.
so; releases relays V and VA.
in and 122 open short circuits on further re
sistance in the rotor circuit, and both stator
and rotor currents are reduced to a value appre
ciably below that of starting, so that the motor
drives the lift against the eddy-'cmrent brake
with only a very reduced effort.
The lift is now allowed to decelerate for a short
space until the effect of the load in the lift is ap
preciable. Another plate is now passed by relay
Y, and C operates for a third time. Closure of
contact 02 operates relay M through wiper A3.
m1 locks relay M operated.
m2 applies positive from udt via bank B1 to
the switch magnet B and the relay N, operating
The contact 111 of relay N performs a. function 40
which will be described later. Operation of the
immediately its contact cs1 operating relay VA
magnet B opens the interrupter contacts db and
relay S operates in series with the resistance X.
Contact .91 now releases magnet B and the switch
takes a step, closing the contacts db and short 45
circuiting relay S which also releases. This cy
from positive on contact 303. Contact var locks
VA operated, contact 'UCLz prepares to operate re
tinues, the switch (wipers of B1, B2, B3) being
ings of the rotor R0. A potential derived from
a rotor winding is applied via transformer and
45 the recti?er RB to the relay VS, which operates
cle of mutual interruption between S and B con
lay V later, and contact Dds reduces the current
driven at a uniform and predetermined rate over
through relay VS. As the rotor speed increases,
its contacts. The wiper of B3 in moving over its
bank inserts resistance in the circuit of the eddy
current brake, reducing its effectiveness progres
the rotor currents decrease, so that after a short
interval the potential applied to VS is reduced
to such an extent that this relay releases. Con
tact 2731 now operates relay V, the contacts 121
of which short circuit resistances in the
rotor circuit and the machine runs up to full
The lift continues to travel in the shaft until
60 some distance ahead of the floor at which it is
required to stop. At this point, the switch CSU
is opened, and the contact CS closes. Nothing
happens until an inductor plate in the shaft is
passed, which operates relay Z momentarily,
relay UD being held operated by its contact mix.
This inductor relay Z, in closing contact Z1
momentarily operates relay PS.
ps1 locks relay PS operated to Ztds.
ps2 prepares an operating path for relay C.
A series of plates is now passed by the induc
tor relay Y, each plate operating the relay mo
mentarily. Each of these operations pulls up
and releases relay C. When the ?rst of this se
ries of plates is encountered, relay C operates.
01 energizes the switch magnet A but the
This condition continues until a further plate
is pased by relay Y. The time of transit between 55
the plates is naturally dependent on the load in
the lift, since if this load is a helping one, the
passage of the lift between the plates is fairly
rapid. If on the other hand, the load is a hin
dering one, the passage between the plates is
longer than normal, and this passage time deter
mines the extent of travel of the switch B. If
the load is a helping one the brake energization
must be large in order to cause adequate speed
reduction, and conversely if the load is a hindering 65
one, considerably less braking is required. As
suming that the load is a helping one, then the
switch B takes a few steps only, inserting a small
amount of resistnace in the circuit of the brake
EB. The second timing plate is then passed by 70
the inductor Y, and operation of relay C causes
the application of potential from contact 02 via
bank A3 and contact on to the second coil of re
lay M, short-circuiting it. Release of the relay
cuts the circuit of the self-interrupting cycle of 75
S and B at contact 1212, and the switch B re
trol of devices which register calls in combina
mains positioned for the remainder of the lift’s
travel. Release of relay C allows the magnet A
to de-energize and step the switch to the ?fth
The lift now decelerates under the in?uence
ment of the lift, these causing suitable opera
tion or closure of the contacts CSU, CSD and CS.
These call storage and car following devices
tion with a further- device which follows the move
are well-known in the art, and are not de~
load in the lift. If necessary, the effect of “over
scribed in further detail as they form no part
of the present invention, though it is to be
compounding” can be obtained so that the lift
understood that the scope of the ‘said invention '
of a braking force which is proportional to the
10 when it reaches a distance of a few inches from
the floor at which it is required to stop, has a
slower creeping speed with a helping load than
with a hindering load. This enables more accu
rate levelling to be made with the friction brake
15 BK than if exactly the same speed is reached
during deceleration independently of the load.
When a point a few inches ahead of the re
quired floor is reached, the last plate is en
countered by the inductor Y, and C is energized
20 for the last time. Contact 01 energizes the mag
net A and 02 operates the relay NR.
n11 releases relay UD.
udq and uds tie-energizes the stator and both
brakes, causing the friction brake BR to be ap
25 plied to its sheave and stop the lift at the floor.
11,114 completes a self-interrupting circuit for
the magnet A through its interrupter contact dot.
is intended to cover all obvious modi?cations of 10
control of the lift such as that described.
Finally, although in the drawings the bank B3
is shown connected directly to the controlling re
sistances, it might be necessary to arrange that
the switch operated a number of contactors which 15
in turn switch the resistances in or out of circuit.
I claim:
1. In a lift control system for serving a plu
rality of floors, a motor for driving the lift, con
trol means, relays operated by the control means 20
for effecting operation of‘ the motor for up and
down travel of the lift, an eddy~current brake ar
ranged to control deceleration of the motor for
stopping the lift at a floor, and means including
variable resistance controlled by the speed of the 25
lift when approaching‘ the floor at which the lift
is to stop for varying the effect of said eddy-cur
uds releases the gate latch relay RCR, and also ‘ rent brake during deceleration, the arrangement
being such that with a helping load in the lift
relays EC, NR and PS.
uds completes a self-interrupting circuit for the speed is greater and the amount of resistance
the relay S and magnet B, and holds relay N inserted is less than with a hindering load when
the speed is less and more resistance is inserted.
2. In a lift control system for serving a plu
udz breaks the holding circuit of relay UD.
uds opens the circuit of C, previously broken rality of floors, a motor for driving the lift, con
trol means, relays operated by the control means
35 by ps2.
01 de-energizes the magnet A, and enables the for effecting operation of the motor for up and
down travel of the lift, an eddy-current brake ar
switch to step to its ?rst contact by self-inter
ruption, when the stepping circuit is broken by ranged to control deceleration of the motor for
stopping the lift at a ?oor, resistance for con
wiper A1 and the switch stops.
The relay S and magnet B from positive through trolling the current to the eddy-current brake 40
while the motor is decelerating, the speed of the
bank B2 interrupt each others’ circuits as pre
viously described, stepping the switch B until its motor during deceleration being controlled by the
wiper B2 rests on the ?rst contact, when the load in the lift, and means controlled by the lift
stepping circuit is broken. During this time, re~ for varying said resistance according to the speed
45 lay N is held operated, and its contact in pre
vents operation of either of the driving relays
UD or DD, so that the lift cannot be started until
this timing switch B has reached a zero position,
when the relay N releases.
In the meantime, the gate is opened, and one
of the gate contacts GA-GC releases relay GL
the contacts 911 and 912 of. this relay preventing
operation of either of the driving relays or of
relay C until reclosure of the gates.
From the foregoing it will be seen that a meas
urement of the load in the lift has been effected
by measuring the time taken by it to pass be
tween two ?xed points or plates in the shaft.
During normal travel from one floor to a dis
tant one, both inductor relays Y and Z are op
erated by the passage of plates in the shaft, but
their contacts are prevented from causing any ac
tion by the open condition of contacts ps2 and
CS, until the handle of the driving switch has
65 been returned to normal by the lift attendant,
so that the deceleration process can only be
commenced after this action has been performed
by the operator.
Although my invention has been described in
70 connection with a manually operated lift, it
should be understood that it is easily applicable
to one in which automatic operation combined
with call storage is effected. The only adapta
tion necessary to ful?l these conditions is that
75 of putting the relays UD and DD under the con
of the lift during‘ deceleration.
3. In a lift control system for serving a plu
rality of floors, a motor for driving the lift, con
trol means, relays operated by the control means
for effecting operation of the motor for up and
down travel of the lift, an eddy-current brake ar 50
ranged to control deceleration of the motor for
stopping the lift at a floor, a circuit including a
tapped resistance for controlling current to the
eddy-current brake, switching means cooperating
with said tapped resistance for varying‘ the resist 55
ance in said eddy-current circuit according to
the speed of the lift during deceleration, said de
celeration speed being determined by the load in
the lift, and a relay operated by the lift for con
trolling‘ operation of said switching means.
4. A lift control system as in claim 3 wherein
said relay operated by the lift is arranged to be
operated by an inductor relay during deceleration
of the motor, said inductor relay being operated
by inductor plates which are passed by the lift.
5. In a lift control system for serving a plu
rality of floors, a motor for driving the lift, con
trol means, relays operated by the control means
for effecting operation of the motor for up and
down travel of the lift, an eddy-current brake 70
arranged to control deceleration of the motor for
stopping the lift at a floor, a circuit including a
tapped resistance for controlling current to the
eddy-current brake, a step-by-step switch coop
erating with the tappings of said resistance for 75
varying the resistance in said eddy-current cir~
cuit, automatic impulsing means for stepping said
switch at a ?xed rate during deceleration and re
lay means controlled by the lift for starting and
stopping the stepping of said automatic impuls
ing means when the lift reaches prearranged dis
tances from the floor at which it is to stop.
6. A lift control system as in claim 5 wherein
an inductor plate relay arranged to be operated
10 during deceleration by a plurality of inductor
plates controls the starting and stopping of said
automatic impulsing means.
‘7. A lift control system as in claim 5 wherein a
,step-by-step sequence switch is arranged to start
and stop operation of said automatic impulsing
means, and a relay arranged to be actuated by
the lift controls the stepping of said sequence
8. In a lift control system for serving a plu
rality of ?oors, an alternating current motor for
driving the lift, resistance coils in the rotor cir
cuits of the motor, control means having an off
position, relays arranged to be energized by op
eration of the control means for effecting opera
tion of the motor for up and down travel of the
lift, an eddy-current brake for controlling the
motor during deceleration, a sequence relay ar
ranged to be operated by the lift while travelling
to a stop at a floor, and only when said control
g means is in its off position, for controlling opera
tion of said brake, sequence step-by-step switch
ing means controlled by said last named relay,
relays controlled by said sequence switching
means and operating contacts for short circuit
ing and inserting said rotor resistances, the ar
rangement being such that said resistances are
short-circuited at normal speed of the motor and
inserted during deceleration when said eddy-cur
rent brake is operated and an inductor plate re
lay arranged to cooperate with a plurality of in
ductor plates in sequence for operating said se
quence relay.
9. A lift control system as in claim 8 wherein
additional lift inductor plate operated relay
means controlled by said control means and op
erable only when the latter is in its oil” position
is provided for preparing an operating circuit for
said sequence relay.
10. A lift control system as in claim 8 wherein
a tapped resistance is provided for controlling
current to said eddy-current brake and an auto
matically stepping switch for controlling inser
tion of said resistance is provided, the starting
and stopping of which is arranged to be con
trolled by said sequence relay.
11. A lift control system as in claim 8 wherein
there is provided an electromagnetically oper
ated holding brake cooperating with the motor
shaft, said brake being arranged to be released
upon e?ecting operation of the motor by ener
gization of said up and down relays and to be
come effective to stop and hold the motor when ,0
said relays are deenergized.
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