Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
This invention relates to a hoisting machine for
elevators which causes a cage to ascend and descend through a
main rope.
In an elevator wherein a cage is caused to ascend and
descend by a main rope, the cage is driven by the frictional force
between the sheave and the main rope of a hoisting machine.
Consequently, both the driving force of an electric motor
for driving the sheave and the braking force of a brake for re-
straining the sheave are limited to a range within which the main
rope and the sheave do not slide In the case where a great driv-
ing and braking force is required, therefore, a sheave having a
large outside diameter has been used for increasing the area of
contact between the sheave and the main rope so as to produce
a required frictional force.
BRIEF DESCRIP~ION OF THE DRAWINGS
Figures 1 and 2 show a conventional elevator, in which
Figure 1 is a vertical sectional view of a hoistwayl while Figure
2 is a side view of a hoisting machine;
Figures 3 to 5 show an embodiment of this invention,
in which Figure 3 is a front view of a hoisting machine, Figure
4 is a side view thereof, and Figure 5 is a detailed view of
essential portions;
Figures 6 to 8 show another embodiment of this invention,
in which Figure 6 is a front view of a hoisting machine, Figure
7 is a sectional view taken along line VII-VII in Figure 6, and
Figure 8 is a diagram of a control circuit;
Figure 9 is a side view showing a sheave round which
a main rope is wound by two turns;
Figure 10 is a view showing still another embodiment
of this invention; and
Figure 11 is a side view showing a sheave round which
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a main rope is wound by three turns.
Referr.ing to the Figures, numeral 1 designates a
hoistway, and numeral 2 a cage which ascends and descends along
the hoistway 1. Numeral 3 designates a main rope, one end of
which is connected to the cage 2, and the other end of which
has a balance weight 4 connected thereto. A machine room 5 is
defined in the top part of the hoistway 1. A supporting beam
6 is installed on the floor of the machine room S, while a
machine bed 7 is disposed in a
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manner to stride across this supporting beam 6 and the
wall of the machine room 5. A rotary shaft 11 is carried
by supporting legs 12. A sheave 13 is mounted substantially
centrally on the rotary shaft 11, and has the main rope 3
wound round it. A brake wheel 14 is mounted on the rotary
shaft 11 in adjacency to the sheave 13. A pair of brake
shoes lS grip the brake wheel 14 so as to restrain the
sheave 13. A pair of brake arms 16 are supported by pins 16a
and cause the brake shoes 15 to grip and release the brake
wheel 14. Brake springs 17 press the brake arms 16 to
actuate the brake shoes 15 so as to grip the brake wheel 14,
and a brake coil 18 moves the brake arms 16 agalnst the
brake springs 17 when electrically energized, to actuate
the brake shoes 15 so as to release the brake wheel 14.
The aforementioned brake wheel 14, brake shoes 15J brake
arms 16, brake springs 17 and brake coil 18 constitute
a brake 18A. An electric motor 19 is dispo~ed oppos.ite
to the brake wheel 14 with the sheave ].3 intervening
therebetween, and drives the rotary shaft 11. A deflector
wheel 20 is mounted on the machine bed 7, and it guides
the main rope 3, wound round the sheave 13, to a position
directly over the balance weight 4.
In the hoisting machine for the elevator constructed
as described above, when both the electric motor 19 and
the brake coil 18 are deenergized, the brake shoes lS ~rip
the brake wheel 14 to restrain the sheave 13 and to stop
the cage 2. On the other hand, when both the brake coil
18 and the electric motor 19 are energized, the brake wheel
14 is released, and the sheave 13 is driven by the electric
motor 19, so that the main rope 3 moves to raise or lower the
cage 2.
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Since, in the elevator hoisting machine stated
above, the braXe wheel 14, sheave 13 and motor 19 are
mounted on the rotary shaft 11 in a queue, the rotary
shaft 11 becomes longO In addition, since the sheave 13
is located substantially in the middle of the rotary shaft
11 to support the weights of the cage 2 and the balance
weight 4/ a thick rotary shaft 11 is required which increases
the cost of the hoisting machine.
The driving torque of the electric motor 19 is
limited to values with which the cage 2 can be accelerated
and decelerated without spoiling a confortable ride. In
contrast, the braking force is determined from the viewpoint
of safety, and it requires a value with which the cage
can be stopped suddenly even if the confortable ride is
not maintained. In the elevator wherein the cage 2 is
driven by the frictional force between the main rope 3 and
the sheave 13, even when the sheave 13 is suddenly stopped
by strongly pressing the brake shoes 15 against the brake
wheel 14, the cage 2 cannot be suddenly stopped because
the main rope 3 slides with respect to the sheave. In
order to prevent the main rope 3 from sliding relative to
the sheave 13, therefore, a method has heretofore been
adopted in which the diameter of the sheave 13 is enlarged
to increase the area of contact with the main rope 3. When
the diameter of the sheave 13 becomes largel the rotational
frequency thereof for operating the cage 2 lowers. This
has led to the drawback that the electric motor 19 ~nevitably
becomes large in size and high in cost.
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This invention has been made in view of the above draw-
back, and has for i-ts object to provide a hoisting machine for
elevators in which a main rope for suspending a cage is wound
round a sheave~ the case is raised and lowered by driving the
sheave with an electric motor, a braking force is genera-ted by
frictionally applying brake shoes to the main rope, and -the cage
is restrained by the braking force, whereby, even when the sheave
has a small diameter, a required braking force is generated, and
the rotational frequency of the sheave is raised, to render the
size of the electric motor smaller.
Another object of this invention is to provide a
hoisting machine for elevators in which a rotor core is held in
magne-tic engagement wi-th a stator core outside the stator core,
the resulting structure is supported by a frame, this frame is
formed with grooves so as -to construct a sheave, and a main rope
is wound round -the sheave by three or more -turns, whereby a
frictional force is increased wi-thou-t enlarging the external
shape of the hoisting machine to generate a required braking
force.
Accordingly, therefore the present invention provides
a hois-ting machine for an elevator wherein a cage is caused to
ascend and descend by -the use of a main rope, comprising: (a) a
sheave around which the main rope suspending -the cage is wound
and which frictionally drives the main rope; (b) an electric
motor connected to said sheave, providing said sheave with a
rotational motion; and (c) a brake including a brake member and brake
linings mounted adjacent the sheave and main rope, said braking
member comprising a common braking member having curved brake
linings on the surface thereof for substantial]y simultaneously
imparting a braking force to both the main rope in sliding com-
pression and the outer surface of the sheave, thereby to stop -the
running of the cage.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figures 3 to 6 show an embodiment of this invention.
First, in Figures 3 and 4, the same sy-mbols as in Figures 1 and
2 deno-te the same or corresponding parts, and they shall be
omitted from the description. Symbol 20a denotes a first de-
flector wheel which guides the main rope 3 so as to be wound round
the sheave 13, while symbol 20b denotes a second deflector wheel
which guides the main rope 3 from the first deflector wheel 20a
to the balance weight 4. A pair of brake shoes 30 grip the outer
peripheral surface of the sheave 13 so as to restrain the rota-
tion thereof, and they also touch the main rope 3 in i~s part
wound in the sheave 13, so as to directly restrain the main rope.
A pair of brake arms 31 are pivoted through pins 31a to a base 32
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to which the supporting legs 12 are ~ixed, so as to turn
about the pins, and they cause the brake shoes 30 to grip
and release the sheave 13.
The brake show 30 is shown in Figure 5 in more
detail. Numeral 40 designates a metallic retainer which
is arcuately curved in conformity with the sheave 13,
while numeral 41 designates a brake lining which is
stuck on the concave surface of the metallic retainer 40
and which comes into contact with the outer peripheral
surface of the sheave 13. Recesses ~la are formed in
the concave surface of the brake lining 41, and come
into frictional contact with the main rope 3.
The hoisting machine fo.r the elevator constructed
as stated above operates similarly to the prior-art example
shown in Figures 1 and 2. When the brake shoes 30 grip
the sheave 13 and the main rope 3, the cage 2 is restrained.
In addition, when the brake shoes 30 release the sheave 13
and the main rope 3, the cage 2 .is allowed to ascend and
descend.
According to the embodiment, the brake shoes 30
grip the sheave 13, so that the brake wheel can be dispensed
with, and the rotary shaft 11 shortens correspondinglyD
Moreover, the brake shoes 30 directly restrain the main
rope 3, so that even when the frictional force between
the sheave 13 and the main rope 3 is not a surfficient
value, a yreat braking force can be exerted to suddenly
stop the cage 2.
Figures 6 to 8 show another embodiment of this
invention.
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In a hoisting machine of the type wherein a shaft
rotates, the shaft is apt to thicken because a load
concentrates near the middle part thereof. Therefore,
a hoisting machine of the so-called outer rotor type
wherein a shaft is fixed, a stator core is mounted thereon,
and a rotor core is disposed around the outer periphery
of the stator core so as to drive a sheave, has been
proposed and disclosed in the Japanese Utility Model
Application Laid-Open No. 52-32870. The embodiment of
Figures 6 and 7 is the hoisting machine o the outer
rotor type. In the figures, the same symbols as in
Figures 3 and 4 denote the same or corresponding parts.
Numeral 51 designates a base, and numeral 5~ a pair of
supporting legs which are erected on and fixed to the
base 51. A stationary shaft 53 is supported with both
its ends fixed to the supporting legs 52. A stator core
54 is fixed to the middle part of the stationary shaft 53.
Shown at numeral 55 i5 a primary winding which is wound
around the stator core 54 and to which a three-phase A. C.
voltage is applied. A pair of disc-like brackets 56 are
turnably mounted on the end parts of the stationary shaft
53 through bearings 56a. A sheave 57 is constructed of
a cylindrical frame which has both its ends held in
engagement with the brackets 56 and which is formed with
a plurality of grooves 57a in its outer peripheral surface,
the main rope 3 being wound in each groove 57a over
substantially half of the circumference of the sheave.
A brake wheel 58 is protrusively disposed on one end of
the sheave 57 over thle whole circumference thereof. Numeral
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59 indicates a cylindrical rotor core which is fixedly
disposed on the inner surface of the sheave 57 and in which
the stator core 54 is loosely inserted. The rotor core 59
constitutes a three-phase induction motor 100 in magnetic
engagement with the stator core 54. A pair of brake shoes
60 grip or release the brake wheel 58 as well as the part
of the main rope 3 wound round the sheave 57. A pair of
metallic retainers 51 constitute the brake shoes 60, and
have their arcuately~curved concave surfaces opposed to the
sheave 57. First brake linings 61a similarly constitute
the brake shoes 60, and are stuck on the concave surfaces
of the metallic retainers 61. They grip or release the
main rope 3 wound round the sheave 57. Second brake linings
61b similarly constitute the brake shoes 60, and are stuck
on the concave surfaces of the metallic retainers 61. They
grip or release the brake wheel 58, A pair of brake arms
62 are pivoted to the base 51 through pins 62a so as to
turn. Numeral 63 indicates brake springs, and numeral 64
a brake coil which is mounted on the supporting legs 52
through arms 64a. The brake wheel 58, brake shoes 60,
metallic retainers 61, first brake linings 61a, second brake
linings 61b, brake arms 62, brake springs 63 and brake coil
64 constitute a brake 64A, which functions in the same
manner as in the embodiment of Figures 3 to 6. Shown at
numeral 65 is a deflector wheel which is turnably mounted
on the machine bed 7, and which guides the main rope 3 to
the balance weight 4 after reciprocating winding the main
rope 3 between it and the sheave 57.
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Figure 8 is a diagram of a control circuit for the
hoisting machine shown in Figures 6 and 7. In Figure 8,
the same symbols as in Figures 6 and 7 denote the same
or corresponding parts. Numeral 71 designates a three-
phase A.C. power source. A converter for power running 72
is constructed of thyristors and is connected to the three-
phase A.C. power source 71 so as to convert alternating
current into direct current by full-wave rectification,
while a converter for regenerative braking 73 is similarly
constructed of thyristors and is connected in inverse
parallel relationship to the power running converter 72 so
as to convert direct current into alternating current. A
capacitor 74 is connected across the positive pole and
negative pole of the power running converter 72. Numeral
75 indicates an inverter of the well-known PWM type which
is formed of a parallel circuit consisting of a transistor
and a diode, and which is connected across both the terminals
of the capacitor 74. The inverter 75 changes direct current
into alternating current of variable voltage and variable
frequency and supplies the latter to the primary winding 55
of the stator core 54, and it also changes alternating
current into direct current when the primary winding 55
has produced regenerative electric power. A tachometers
76 senses the velocity of the cage 2 from the rotational
frequency of the sheave 57. A velocity pattern generator
77 generates a velocity curve for operating t~e cage 2.
Comparison means 78 compares the actual velocity signal of
the tachometer 76 with the velocity pattern signal of the -
velocity pattern generator 77. Control means 79 alternatively
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controls the power running converter 72 and the regenerative
braking converter 73 on the basis of the reuslt of the
comparison of the comparison means 78, and it also controls
the inverter 75 . R~1nning means 80 issues a start c~mm~nd
signal and a stop command signal 50 as to energize the
brake coil 64 and the velocity pattern generator 77.
In the hoisting machine for the elevator constructed
as stated above, the main rope 3 and the sheave 57 are
normally restrained by the brake shoes 60. When the start
command signal is produced from the running means ~0, the
brake coil 64 is energized. Then, the sheave 57 is xeleased,
while at the same time, the velocity pattern generator 77
produces the velocity pattern signal. The control means 79
actuates the power running converter 72 or the regenerative
braking converter 73 in accordance with the result of the
comparison of the velocity pattern signal with the actual
velocity signal of the tachometer 76, and it also actuates the
inverter 75 to generate the alternating current of variable
voltage and variable frequency and to energize the primary
winding 55. Upon the energization of the primar~ winding
55, the rotor core 59 rotates to drive the sheave 57~ The
main rope 3 is driven by its friction with the sheave 57,
to rise and lower the cage 2. In a case where the velocity
pattern signal of the velocity pattern generator 77 is
greater than the actual velocity signal of the tachometer 76
due to the unbalanced load between the cage 2 and the balance
weight 3, the control means 79 actuates the power running
converter 72 and the inverter 75 to feed the primary winding
55 with ~.C. power, and to rotate the rotor core 59 as the
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three-phase induction motor. Conversely, in a case where
the actual velocity s.ignal is greater than the velocity
pattern signal, the primary winding 55 generates regenerative
power. The control means 79 actuates the inverter 75 so as
to invert the regenerative power into direct current, and
it also actuates the regenerative braking converter 73
so as to return the regenerative power to the three phase
AoC~ power source 71. When the cage 2 has reached a
pr~determined distance on this side of a destination floor,
the inverter 75 gradually lowers the voltage and the frequency
to decelerate the rotor core 59. When the destination
floor has been reached, the brake coil 64 is deenergized,
and the brake shoes 60 grip the main rope 3 as well as
the brake wheel 58. The main rope 3 is restrained directly
by the hrake shoes 60 and through the brake wheel 58 as
well as the sheave 57, thereby to stop the cage 2.
Also in the embodiment shown in Figures 6 to 8,
the main rope 3 is directly restrained by the brake shoes
60, so that a great braking torque can be generated to
suddenly stop the cage 2.
In addition, the sheave 57 is placed around the
outer p~riphery of the rotor core 59, and the brake shoes 60
are exerted on the main rope 3 wound round thQ sheave 57.
Therefore, when the embodiment is compared with the prior-
art machine wherein the electric motor, the sheave and the
brake wheel are arranged in a queue, the length in the
direction of the stationary shaft 53 decreases, and the
machine .room 5 can be made smaller.
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Moreover, the sheave 57 has an axial length which
is required as the frame for supporting the rotor core
59. Usually, the axial length is a length enough to
~ind the main rope 3 in the manner to reciprocate between
the sheave 57 and the deflector wheel 65 by a plurality
of turns. Owing to such winding of the plurality of turns,
the area of contact is increased, and the frictional force
is increased, so that when the brake wheel 58 is strongly
pressed by the brake shoes 60, it does not slide, and the
cage 2 can be suddenly stopped. In consequence, the
diameter of the sheave 57 can be reduced to raise the
rotational frequency thereof, so that the hoisting machine
can be made smaller in size.
Although, in the embodiment of Figures 6 to 8,
the stator core 54 and the rotor core 59 have been described
as constituting the inauction motor, even a D.C. motor
can achieve the intended purpose.
The brake shoes 60 are not so restricted as to
slidingly compress the main rope 3 in its part wound
round the sheave 57, but they may slidingly compress
the main rope 3 directly as well, and the place of the
compression is not especially limited.
As set forth above, according to this invention,
a main rope for suspending a cage is wound round a sheave,
the cage is raised and lowered by driving the sheave with
an electric motor, a braking force is generated by friction-
ally applying brake shoes to the sheave and the main rope,
and the cage i9 restrained by the braking force, so that
even when the braking force is increased, the main rope
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and the sheave do not slide. This brings ~orth the effect
that the electric motor can be made small in size by reducin~
the diameter of the sheave to raise the rotational frequency
thereof.
Figure 9 illustrates a concrete example o~ the
relationship between the diameter d of each element of the
main rope 3 wound around the sheave 13 and the pitch D of
the main rope 3 on the sheave 13. In the case where the
element of the main rope 3 has a diameter d = 12 millimeters,
the pitch is set at D = 16 millimeters.
Usually, the elements of the main rope 3 are used
in a number of 3 to 6. Assuming now that the 6 elements
are used~ the axial width W2 of the sheave 13 becomes:
W2 = 6 (elements) x 2 (turns) x 16 + 12
= 204 millimeters ......... (1)
On the other hand, the axial width of the electric motor 19
is about 1000 millimeters in case of a gearless elevator
which is often used. Accordingly, an axial length width of
the motor 19 and the sheave 13 combined becomes about
1200 millimeters,
In contrast, when the main rope 3 is wound round
the sheave 13 by 3 turns, the width W3 of the sheave 13
becomes:
W3 = 6 (elements) x 3 (turns) x 16 + 12
= 300 millimeters ~....(2)
Thus, the width W3 increases by about 100 millimeters as
compared with the width W2. Accordingly, when the main
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rope 3 is wound by 3 turns, the rotary shaft 11 must be
thickened from the standpoint of strength, resulting
in a high cost. Moreover, in case of installing the
hoisting machine, interferences with the other equipment
and the machine room 5 are apt to occur, and many restrictions
in layout are involved.
Therefore, the number of turns by which the main
rope 3 is wound round the sheave 13 has heretofore been
limited to 2.
However, such limit is freed from the outer
rotor type hoisting machine as shown in Figures 6 and 7.
There will now be described an embodiment in which the main
rope is wound by 3 turns.
Referring to Figure 10, a large number of grooves
57a are formed in the outer peripheral surface of a sheave
57 constructed of the frame 57b of an electric motor, and
the main rope 3 is wound in the grooves 57a by three turns
in such a mAnner that each groove receives the main rope
over substantially half of the circumference thereo.
In the embodiment illustrated in Figures 13 and
11, the sheave 57 is provided in a part of the frame 57b
which has ~ size necessary for functioning as the electric
motor. As stated before, the frame 57b is about 1000
millimeters long in the gearless elevator often used. On
the other hand, assuming the diameter d of each of the
elements of the main rope 3 to be 12 millimeters, the axial
width W3 of the sheave 57 round which the main rope 3 is
wound by three turns is given from Equation (2) as follows:
W3 = 300 millimeters
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Accordingl~, the width of the frame 57b of the electric
motor is greater than the width W3 of the sheave 57, so
that the main rope 3 can be changed from the 2-turn winding
into the 3-turn winding without increasing the axial length
of the whole hoisting machine. Further, as understood from
Equations (2~ and (3), when the number of turns is increased
by one, the width of the sheave 57 increases by about 100
millimeters, whereas according to this embodiment, the main
rope 3 can be wound up to eight turns or so without incr~asing
the external ~;n~ions of the electric motor. By selecting
an appropriate number of turns, the frictional force can ~e
adjusted, and the cage 2 can be stopped by exerting a
braking force as needed.
Although, in the above embodiment, the sheave has
been described as the frame of tle motor directly formed
with the grooves, the intended purpose can be achieved
even when a cylindrical or arcuate sheave as a separate
member is prepared and is attached to the outer periphery
of the frame.
As set forth above, according to this embodiment,
a hollow rotor core is mounted inside a cylindrical frame
and is turnably supported, a stator core is loosely inserted
inside the rotor core so as to be in magnetic engagem~nt
therewith, thus to construct an electric motor for rotating
the frame located outside, grooves are formed in a part of
the frame so as to construct a sheave, a deflector wheel
is disposed in a position opposing to the sheave, a main
rope for suspending a cage and a balance weiyht is wound
round the sheave and the deflector wheel, and the main
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rope is tensed so that the number of turns thereof wound
round the sheave may become at least three. This brings
forth the effects that the frictional force between the
main rope and the sheave can be increased without changing
the external dimensions of the electric motor and that
a high cost can be suppressed.
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