Note: Descriptions are shown in the official language in which they were submitted.
.B~CKGROUND OF TEIE _NVE:NTI:ON
The present invention IS directed to an elevator
driving arrangement .in which a sheave on which the ma:in
cable :Eor suspendiny the cage i~ wound .is dri.ven by an
elect.ric mo-tor through a speed reduc~ion mechani.sm. More
speci.fically, the present invention is dîrected to a dual
motor driving arrangement and the associated control
circuitry for simultaneously energizing both motors or a
single motor depending upon operating condi.tions.
BRIEF DESCRIPTION OF TElE DR~WINGS
Figure 1 is a side view, partly in section, of a
conventional elevator dri.vin~ device.
Figure 2 is a sectional view taken along line
II-II of Figure 1.
Figure 3 is a top plan view, partly in section
of an elevato.r driving device according to the present
invention.
Figure 4 is a schematic circuit diagram showing
the control unit according to the present invention.
Figure 5 is a side elevation view, partly in
section, showing a modified ~orm of a two motor drive
according to t~e present lnvention.
Figure 6 is a schematic circuit diagram showing
a power coverter according to the present invention.
Figure 7 is a detailed circuit dïagram showinq
an operation and direction instruction generating unit and
a frequency and phase sequence instruct;on generating unit
from the circuit of Figure 6?
3l~ 7~
1 Figures 8-13, inclusi.ve, are a number of cJraphs
showing differen-t operati.ng characteristics oE the power
coverter.
In a conventi.onal elevator dri.ving arrangement
as illustrated in Fi~ures 1 and 2, an elevator cage 2 is
adapted to be moved up and down a shaft 1 by means of a
cable 3 which is wound a~out a sheave 8 with the opposite
end of the cable being entrained over the guide sheave 7
for connection to a counter weight 4. The sheave 8 is
mounted on the output shaft 8a of a gear reduction mechan-
ism 12, the input shaft of which is operatively connectedto an electric motor 13. The entire mechanism is mounted
on a mach;nery platform 6 located in an equipment room 5
located directly above the elevator shaft 1. The motor is
controlled by means of a control unit 17 which is operative-
ly connected to the call buttons ;~n a cage and at eachfloor.
The details of the driving arrangement are shown
in Figure 2 wherein the gear reduction mechanism 12 is
shown in cross section. A flywheel 15 and a tachometer
2~ for detecting the speed of the motor 13 are mounted on one
end of the motor shaft while the other end of the motor
sha~t is operatively associated with the brake 14 for
braking the drive shaft of the motor 13. The drive shaft
of the motor 13 is operatively coupled to a h~i.gh speed
drive shaft 11 which ;.s rotatably supported within the gear
reduction unit 12. The high speed s~aft 11 carrïes a worm
which is in operative engagement with an intermed;.ate gear
--2-
1 10 which in turn i.s coupl.ed to a year on the low speed
output shaft 9 of the gear reduction unit 12. The low
speed output shaft is coupled d;~rectly to the shaft 8a
upon which the sheave 8 is mounted~
When the motor 13 is deenergized and the brake
14 applied the shafts; of the speed reduc-tion unit will
also be stopped to prevent the rotation of the sheave 8
and movement of the cage 2 which is suspended ~y the main
cable. When a motor .13 i.s energized by the control unit
17, the brake 14 is released to allow the motor to turn.
In this case, the speed of the motor îs detected by the
tachometer 16 and fed back -to the control unit 17 so that
the motor 13 is rotated at a predetermined speed. A high
speed shaft 11 of the speed reduction unit 12 i.s driven by
the motor 13 to thereby rctate the sheave 8 through the
gearing of the speed reduction unit 1.2 to cause movement of
the cage up or down depending upon the direction of rotation
of the motor .13.
A similar elevat.or drive mechanism uti.lizing a
single electric motor and a single speed reduction unit for
driving the sheave upon wh.ich -the elevator cable is wound
is disclosed in United Kirlgdom Patent
Number 2,076,771, published December 9, 1981 and
assigned to the same assignee as the present application.
In the application, the arrangement of the sheave,
gear reduction unit and electric motor has been modified
with respect to the arrangement shown in Figures 1 and 2
gs7~ f
1 of the present appli.cation to p~oyi.,de a more compac-t arranye-
ment ~hich can more readi.ly be enclose~d in a small équipment
room at the top of the elevator shaft ~h.ile sti.ll providing
easy access to the indî.vidual components for servicing
In the arrangement disclosed in Figures 1 and 2
o:E the present application, and ~n the arrangement disclosed
in the above-identified appl:ication, the use of
a single motor and single gear reduct;on unit under the
control of a single control unit limits the operation of
t]~e elevator with respect to speed and torque. When it is
desired to design an elevator drive mechanism for a cage
having a higher load capacityr it is necessary to provide
a heavy duty speed reduction unit having stronger gears
and shafts and if it i.s desired to vary the speed of the
cage, it is necessary to provide a speed reduct;on unit
having a differen-t gear reduction ratio and possibly vary
tlle design of the motor. ~hen the motor is designed differ-
ently, for example.'with a different number of poles, it
. a:lso becomes necessary to modify the control unit. Thus,
-20 il is necessary to provide a variety of different electric
motors, different control units, and different speed
reduction units so that elevator drive systems can ~e de-
signed to accomodate different speeds and load capacities.
Since a large number of different types of parts are re-
qui.red! it is difficult to achieve savings wh.ich.would
ordinari,ly be achieved with the mass producti.on of identical
components which could be utilized in a larger number of
different capacity systems.
--4--
7~
_MMARY OF T_IE INVE.NTION
The present invent:ion provides a new and improved
elevator driving device which overcomes all of the above-
mentioned difficulties associated with the design of ele~
vator drive systems of dif:Eerent capacities and speeds.
The present invention provides a new and improved
elevator drive mechanï.sm which utili2es a plurality of
electric motors, each of which is designed for use with an
elevator whose cage has a relatively small load capacity,
which may be operated simultaneously for driving an ele-
vator cage having a relatively large load capacity therehy
allowing the mass production of elevator motors of one size.
The present invention provides a new and improved
elevator driving device wherein a plurality of electric
15 motors which are similar to one another in construction
and operation are operable through speed reduction means which
are similar to one another in construction and operation
to drive a single sheave on which the main cable or suspend-
ing cage is wound. Control means are provided for energizing
the motors simultaneously to operate the latter in a par-
allel mode so that controlling the number of electric motors
in use provldes a motor output which is in agreement ~ith
the specification of the elevator. Thus, it is unnecessary
to provide a variety of different electric motors or a
variety of different elevators, thereby making it possible
to produce electric motors for elevators on a large scale
with attendant cost savings.
:il22~4~7~
1 The foregoing and other objects, features, and
advantages of the invention will become more apparen-t frorn
the :Eollowing more detail.ed description of the invention
as illustrated in the accompanying drawings.
DETAILED DESCRIPTI.ON OF THE INVENTION
.. . .,. .~
A first embodiment of the elevator driving
device accordlng to the present ~.nvention is shown in
~22~L~79
Figures 3 and 4 wherein an electric motor 13 and speed
reduction unit 12 are provicLed for driving the sheave 8,
similar to that cLisclosed in the conventional construction
of Figure 2. The first electric motor 13 is a three phase
induction motor operable under the control of a first
control unit 17. A flywheel 15 and tachometer 16 are
provided at one end of the motor shaft and a brake
mechanism 14 is operably associated with the other encL of
the motor shaft.
An identical electric motor and gear reduction
drive unit is provided on the opposite side of the sheave
8 which is a mirror image of the conven-tional mechanism
described above. A second electric motor 23, similar to
the first motor 13, is operably coupled to the high speed
lS input shaft 21 of the speed reduction unit 22 and a low
speed output shaft 19 is operably driven througll the
intermediate gears 20. The low speed output shaft 19 is
arranged symmetrically with respect to the shaft 9 on the
other side of the sheave 8 and both low speed output
shafts 9 and 19 are operably coupled to the shaft 8a for
supporting the sheave 8. A flywheel 25 is mounted on one
end of the mo~or shaft 23 while a break mechanism 24 is
operably associated with the other end of the motor shaft.
A control unit 27 is provided for controlling a~ electric
motor 23 similar to the manner in which the control unit
. -- 7
~L2Zlqt79
17 controls the operation of the motor 13. The control
circuits 17 and 27 are best seen in Figure 4 wherein an
instruction speed generating unit 17a is provided for
controlling the operation speed of an elevator cage 2.
A first variable-voltage, variable-frequency control uni-t
i7v is ~rovided in which, after three-phase alternating
current is converted into direct current, three-phase
alternating current is generated again. The variable-
voltage,variable-frequency ~VVVF) control unit 17b
operates to change the frequency and voltage with aid of
the difference signal between the output signal of the
tachometer 16 and the output signal of the lnstructlon
speed generating unit 17a. A second variable-voltage,
variable-frequency (V WF) control unit 27b is similar to
the first VVVF control unit 17b and is utilized for the
same purpose when applicable.
When the first and second motors 13 and 23 are
de-energized, the first and second speed reduction units
12 and 2Z are stopped by the first and second brake units
14 and 24, respectively, so that the cage will be main-
tained in a stationary position while being suspended by
the main cable 3. When all of the starting conditions
have been satisfied the first and second motors 13 and 53-
are energized by the first and second control units 17
and 27, respectively, while the first and second brake
8 -
~2Z1~7~
units 14 and 24 are released, thereby allowing the cage
to be driven. The speed of the first motor 13 is detected
by the tachometer 16 and is compared with a speed pattern
provided by the instruction speed generating unit 17a so
that a comparison signal is produced. With the aid of
this compariaon signal, the first and second motors 13 ar.d
23 are driven by the first and second VVVF control units
17 and 2?, respectively, to run the cage 2 at a predeter-
mined speed.
When the cage 2 reaches a predetermined posi-
tion, the instruction speed generating unit 17a generates
a speed reduction pattern to reduce the speeds of the
motors 13 and 23 to thereby decelerate the cage 2. When
the cage 2 reaches a stopping point, the first and second
motors 13 and 23 are de-energized and the first and second
brake units 14 and 24 are actuated ~o maintain the cage
in the stopped condition.
In the above-described elevator driving device,
the cage 2 is driven by two electric motors, namely the
first and second motors 13 and 23. Accordingly, it is
unnecessary to provide an electric motor, ~he output of
which is twice that of the first motor 13. The first and
second motors 13 and 23 are three-phase induction motors
and are controlled by the first and second V WF control
units 17b and 27b, respectively. Accordingly, if the
g
~2Z~479
upper limit Gf frequency is changed according to -the rated
speed of the cage 2, the synchronous speed changes with
the frequency whereby the cage 2 can be driven at the
rated speed. Therefore, the sheave 8, the first speed
reduction unit 12, first motor 13, second speed reduction
UiliL 2Z and second motor 23, can be applied to elevaLor~
with dif-ferent rated speeds and they can be manufactured
on a large scale.
The main cable 3 is connected to a central
portion of the cage 2 and accordingly, the sheave 8 must
be arranged in a substantially central position in the
shaft 1, thus limiting the layout of the driving mechanism.
Therefore, the position of the motor is determined by the
necessary location of certain mechanical equipment.
~ccordingly, if the motor is large in capacity, it is
generally large ln size so that it might interfere with
other equipment or the walls of the mechanical equipment
room 5. This interference can be eliminated by the
provision of the above-described elevator driving device
since the space occupled by the motor is decreased by the
employment of two electric motors 13 and 23. By arranging
the first and second motors on opposite sides of the
sheave 8, the space in the machinery equipment room is
more effectively utilized.
In the above-described device, the first and
- 10 -
7~
second speed reduction units 12 and Z2 are comprised of
gears whose axes are in parallel. However, in the embodi-
ment of Figure 5, the speed reduction unit 30 is comprised
of a worm gear 31 which is secured to the low speed shaft
9 for rotation therewith and a pair of worms 32 and 35
engaged therewith and driven by motors 3a arld 36,
respectively~ each of which is provided with a brake unit
34 and 37, respectively. In this embodiment the sheave 8
is driven by the low speed shaft 9 and the worm wheel 31
which in turn is driven by the first and second worms 32
and 35 which in turn are driven by the first and second
motors 33 and 36. Therefore, in this case it is un-
necessary to manufacture separately a large capacity
electrical motor since smaller uniform size motors can be
used which can be manufactured on a large scale. In th~
worm gear arrangement of Figure 5 the vibrations are
substantially reduced relative to the arrangement in
Figure 3 wherein the axes of the gear reduction units are
disposed in parallel to each other. The speed reduction
units may also be manufactured by utilizing conventional
planet rollers ~not shown). Such a gear reduction unit
could be used with a pair of identical low capacity motors
such as used in Figure 5 with a further reduction in
vibration.
In the above-described elevator driving device,
- 11 -
~22~
the firs-t and second motors are three-phase induction
motors. The device was modified to use these DC motors
and DC variable-voltage control units 17 and 27 so that
the speeds of the DC mo-tors are changed by controlling
the voltages, it would then be possible to utilize the
motols and speed reduction units with various eleva~ors
having different cage speeds.
In the above-described device, two electric
motors are used to drive the elevator. However, when the
elevator is substantially under full load the cage 2 is
liable to be accelerated during operation in the downward
direction since the cage 2 is heavier than the counter-
balance weight 4. When the elevator is substantially
under no load, the cage 2 is liable to be accelerated
during operation in the upward direction. Accordingly,
it is unnecessary that the first and second motors 13 and
23 be simultaneously operated and controlled in the same
manner. That is, a method may be employed in which,
depending upon the sta~e of the load and the direction of
the operation of the cage, the second motor 23 is de-
energized so as to be turned by inertia while only the
first motor 13 is energized. Employment o~ this method
results in the economical use of electric power.
The instruction speed generating unit 17a and
the WVF control unit 17b of Figure 4, will be described.
- 12 -
4179
The control unit 27b is similar to the control unit 17b.
The VVVF control unit 17b is shown in Figure 6
wherein the three-phase AC source R, S, and T, lead from
a power transformer TR to diodes 101, 102, and 103 whose
cathodes are connected together and di.odes 10~, 105, and
106, whose anodes are connected togelher. lhe cathodes
of the diodes 104, lOS, and 106, are connected to the
anodes of the diodes 101, 102, and 103, thereby forming a
rectifi.er circuit 107 for obtaining a direct current.
A smoothing capacitor 107A is connected to the
output in rectifier circuit 107 and the collectors of
transistors 108, 109, and 110 are connected to the
positive output terminal of the rectifier circuit 107.
The collectors of transistors llI, 112~ and 113 are
connected respectively to the emi~ters of transistors 108,
109, and 110, while the emitters of transistors 111, 112,
and 113 are connected to the negative output terminal of
the rectifier circuit 107. Diodes 114-119 are connected
in parall.ed to the transistors 109-113, respectively.
The transistors 108-113 and diodes 114-119 form an
inverter circuit for converting direct current into
alternating current for applying three-phase alternating
current to lines U, V, and W, which are connected
respectively to the emitters of transistors 108, 109, and
110.
- 13 -
~l~2Z~79
The electromagnetic contactors 122a, 122b, and
122c, are connected respectively to the lines U, V, and W,
and are also connected to a three-phase induction motor
123 which is coupled through the shaft 123a to a winding
sheave 124. Upon closure of the contactors 122a, 122b,
alld 122c, the inductlon motor is enegerized by ~he
variable-frequency, three-phase current to turn the wind-
ing sheave to thereby move the cage 125 and the counter-
balance weight 126 through the main cable 124A. Control
push button units 125a and 128 are located in the elevator
cage 125, and on each floor 127, respectively.
The instruction speed generating unit 17a is
comprised of an operation and direction instruction
generating unit 129 for providing the operation-direction
and operation-instruction which ~re determined by the
floor call registered by the pwsh button control unit 128
or 125a. The instruction speed generating unit 17a also
includes a frequency and sequence instruction generating
unit 130 which receives the output signal of the operation
and direction instruction generating unit 129 and is
provided with six output terminals which operate
individually and which are connected to the bases of the
transistors 108-113. In response to the output signal
from the operation an-d direction instruction generating
unit 129, the transistors 108-113 are rendered conductive,
- 14 -
1%;2~
thereby applying three-phase alternating current to the
lines U, V, and ~.
The instruction speed generating unit 117a,
which is shown broadly in Figure 6, is shown in greater
detail in Figure 7 and includes a DC positive pole, ~Vcc,
a ~C nega~ive pole, -Vcb, start instruction contact means
131 having one terminal connected to the DC positive pole
for starting the three-phase induction motor 123 upon
being closed, deceleration instruction contact means 132,
having one terminal connected to the DC negative pole
which is adapted to be closed when the cage reaches a pre-
determined position prior to reaching the desired floor
to provide a deceleration instruction, a resistor 133
having one terminal connected to the other terminal of
~he start instruction contact means 131, a resistor 13
having one terminal connected to the other terminal of
the resistor 133 and the other terminal connected to the
other terminal o~ the deceleration instruction contact
means 132, a capacitor 135 having one terminal connected
to the other terminal of the resistor 133 and the other
terminal grounded, and a diode 136 having its anode
grounded while being connected in parallel to a capacitor
135. The start instruction contact means 131, the
deceleration instruction contac~ means 132, resistors 133
and 134, capacitor 135 and diode 136 form a speed instruc-
- 15 -
~2~
tion generating circui-t for providing a voltage a-t one end
of the capacitor as a speed instruction signal Vp. An
upward movement instruction contact means 139 having one
terminal connected to a DC positive pole is closed when
the cage 125 is moved u~pwardly and a downward movement
ins,ruc~ ,rl ~_ontact means 140 having one terminal connected
to the other terminal of the upward movement instruction
contact means 139 and the other terminal grounded is
closed when the cage is moved downwardly. The contact
means 139 and 140 form a direction instruction generating
circuit 141 which provides an output direction instruction
signal Vd. The aforementioned operation direction and
speed instruction generating unit 129 is made up of the
direction and instruction generating circuit 141 and the
speed instru~ting generatillg circuit 137.
The circuit of Figure 7 also includes a pulse
generator 142 for providing a pulse signal 143a having a
number of pulses which correspond to the speed instruction
signal Vp applied thereto. A binary adder/subtractor 144
receives the direction instruction signal Vd through
terminal U/D and the pulse signal 143a through terminal I.
~hen the upward movement instruction contact means 139 is
closed to allow the direction instruction signal Vd to
have the potential of the DC positive pole +Vcc (herein-
after referred to as "a signal H", when applicable) the
- 16 -
~Z21g~79
pulses of the pulse signal 143a are subjected to addition,
whereas when the downward movement ins~ruction contact
means 140 is closed to allow the signal Vd to have a
ground potential (hereinafter referred to as "a signal L",
when applicable), the pulses are subjected to subtraction
so that the first, second, and third bites O~ e ~ ry
number are applied to signal lines 144a, 144d, and 144c,
respectively.
A decoder 145 is operated by the output signal
of the adder/subtracter 144 in such a manner that a signal
H is applied to signal lines 145a-145f, successively,
beginning with the signal line 145a and after the signal
H is applied -to the signal line 145f, the signal line 145a
is selected again for receiving the signal H. The input
of an OR element 146 is connected to signal line 145a anu
145b and the input of OR elements 147-141 are connected
to the signal lines 145b and 145c, 145c and 145d, 145d and
145e, 145e and 145f, and 145f and 145a, respectively.
The output lines 146a-151a of OR elements 146-151 are
connected to the bases of the transistors 108, 113, 109,
111, 110, and 112, respectively.
In the power converter thus constructed three-
phase alternate currents from the three phase AC sources
R, S, and T are subjected to full-wave rectification in
the rectifier circuit 107. Where the smoothing capacitor
~22~'79
107a is no~ connected to the rectifier circuit 107, the
output E7 of the latter is as shown in Figure 8 which is
well known in the art. The output E7 is smoothed by the
capacitor 107a connected to the rectifier circuit 107.
On the other hancl, the time of occurrence of the peak of
the voitage VrS between the three-phase .AC sources R and
S coincides with that of the peak of the output voltage
E7 as shown in Figure 9. In the case of a line current
Ir7 in the three-phase AC source R, the diodes 101 and
105 are rendered conductive with the phase being between
~/3 and 2~/3, the diodes 101 and 106 are rendered
conductive with the phase being between 2~/3 and~, the
diodes 103 and 104 are rendered conductive with the phase
being between ~ /3 and S~/3, and the diodes 102 and 104
are rendered conductive with the phase being between 5ll/3
and 2~. That is, the wave form of the line current Ir7
in the three-phase AC source R is as shown in Figure 9.
The same thing can be said with respect to the remaining
three-phase AC sources S and T.
Assuming the cage 125 is moving upwardly and
stopped at a particular floor, the upward movement instruc-
tion contact means 139 is closed and the direction instruc-
tion signal Vd is applied as the signal H to the adder/
subtractor 144. Upon production of the start instruction,
the electromagnetic contactors 122a-122c are closed while
- 18 -
~;2Z~ 7~
the start instruction contact means 131 is closed so that
-the capacitor 135 is charged through the resistor 133 and
the voltage, mainly the speed instruction signal Vp is
increased as shown in Figure 10. The pulse generator 142
provides output pulse signals 143a, the number o~ which
corresponds to the speed instruction signai Vp. The pulse
signal 143a is subjected to addition in the adder/
subtractor 144. More specifically, as shown in Figure 11,
when the zero pulse signal 143a is inputted at the time
instant tl, the signal lines 144a-144c are at the level L.
~Yhen the first pulse signal 143a is applied, the signal
line 144a is at the level H while the signal lines 144b
and 144c are at the level L. When the second pulse signal
143a is inputted, the signal line 144b is at the level H
and the remaining signal lines are at the level L. When
the third pulse signal 143a is inputted, -the signal lines
144a and 144b are at the level H and the signal line 144c
is at the level L. When the fourth pulse signal 143a is
inputted, the signal line 144c is raised to the level H
and ~he remaining signal lines are set to the level L.
When the ~i~th pulse signal 143a is inputted, the signal
lines 144a and 144c are at the level H while the signal
line 144b is at the level L. When the sixth pulse signal
143a is inputted at the time instant t2, all the signal
lines 144a-144c are set to the level L. Thus, a senary
- 19 -
~22~
counter is formed. When a senary signal is applied to the
decoder 145 in synchronism with the pulse signal 143a the
signal lines 145a-145f are raised to the level H success-
ively as shown in Figure 12. The signal lines 145a-145f
which are raised to the level EI successively are connected
in pairs to the OR elements 146-151, as sllo~ll isl Figure 7.
Accorclingly, a signal H which is twice as long as the
signal H provided on each of the signal lines 145a-145f
is provided on each of the output lines 146a-151a of the
OR elements 146-151 in such a manner that two of the
signal lines 146a-151a are at the level H simultaneously
as shown in Figure 13. The transistors 108-113 are
rendered conductive by the signals H on the signal lines
146a-151a so that three-phase alternating current is
applied to the lines U, ~, and W to energi~e the three-
phase induction motor 123 to thereby move the cage 125
upwardly. As the speed instruction signal Vp is increased,
the interval of the pulse signal 143a is decreased so that
; the frequency of the three-phase alternating current from
the inverter 120 is increased and the three-phase induc-
tion motor 123 is accelerated. When the cage 125 reaches
the deceleration point in t3 seconds as shown in Figure
10, the speed reduction instruction contact 132 is closed
so that the capacitor 135 is dischar~ed through the
resistor 134. Thus, the speed instruction signal Vp is
- 20 -
~221~7g
gradually decreased and finally it becomes zero at the
time instant t4. Accordingly, the interval of the pulse
signal 143a is increased and therefore the frequency of
the three-phase alternating current from the inverter 120
is decreased to decelerate the three-phase induction motor
123. At the time instant t4, ~he speed in~tructioll signal
Vp becomes zero so that the induction motor 123 is stopped.
In the case where the cage 125 is moved downwardly, the
pulse signals 143a from the pulse generator 142 are
subjected to subtraction in the adder/subtractor 144 and
the result of subtraction is applied ~o the signal lines
144a through 144c. The decoder 145 outputs signals to
the signal lines 145a-145f so that the inverter 120
produces the three-pulse alternating current which is
opposite in phase rotation to that in the upward movement
operation. Accordingly, the three-phase induction motor
123 is turned in the opposite direction to move the cage
125 downwardly to the desired floor.
While the invention has been particularly shown
and described with reference to a preferred embodiment
thereof, it ~ill be understood by those in the art that
various changes in form and details may be made therein
without departing from the spirit and scope of the
invention.
- 21 -
