Technical Field
[0001] The present invention relates to an electromagnetic brake device provided in a traction
machine of an elevator.
Background Art
[0002] Patent Literature 1 described below discloses an electromagnetic brake device provided
in a traction machine of an elevator.
[0003] In the electromagnetic brake device described in Patent Literature 1, a rotary body
which rotates in response to the rotation of a driving sheave is provided in the traction
machine. The electromagnetic brake device pushes a braking piece against the rotary
body with the force of a spring, generating a force for holding a car at a standstill
(hereinafter also referred to simply as "a standstill retentive force"). On the other
hand, during the ascent and descent of a car, in the electromagnetic brake device,
attraction which resists the force of the spring is caused to be generated from an
electromagnet, isolating the braking piece from the rotary body.
[0004] In an elevator, a great force is necessary for holding a car at a standstill. For
this reason, the electromagnetic brake device described in Patent Literature 1 has
the problem that, when the braking piece collides with the rotary body, that is, each
time the car stops, a large noise is generated.
[0005] Patent Literature 2 described below discloses a technique for reducing the collision
noise generated when the electromagnetic brake device operates.
[0006] Specifically, in the electromagnetic brake device described in Patent Literature
2, two springs are used to generate the standstill retentive force. In the case where
the standstill retentive force is generated, the braking piece is pushed against the
rotary body by operating first the spring of a larger pushing force.
Citation List
Patent Literature
Summary of Invention
Technical Problem
[0008] The electromagnetic brake device described in Patent Literature 1 has the problem
that because the spring of a larger pushing force is operated first in holding the
car at a standstill, it is impossible to sufficiently reduce the above-described collision
noise.
[0009] The present invention was made to solve the problem described above and an object
of the invention is to provide an electromagnetic brake device for an elevator which
can substantially reduce the noise generated when a braking piece collides with a
rotary body.
Solution to Problem
[0010] The invention is defined by claim 1.
[0011] An electromagnetic brake device for an elevator of the present invention is a device
which holds a car of an elevator at a standstill by pushing a braking piece against
a rotary body rotating in response to the rotation of a driving sheave of an elevator
traction machine. The electromagnetic brake device comprises a first movable iron
piece which is provided with the braking piece, the braking piece being disposed in
such a manner as to be opposed to the rotary body, a second movable iron piece which
is disposed on the side opposite to the braking piece with respect to the first movable
iron piece, a first elastic body having a prescribed pushing force, which is provided
between the first movable iron piece and the second movable iron piece, a second elastic
body which pushes the second movable iron piece against the first movable iron piece
side with a prescribed pushing force stronger than the pushing force of the first
elastic body, and an electromagnet which attracts the second movable iron piece against
the pushing force of the second elastic body and causes the second movable iron piece
to attract the first movable iron piece against the pushing force of the first elastic
body.
Advantageous Effect of Invention
[0012] With the electromagnetic brake device for an elevator of the present invention, it
becomes possible to substantially reduce the noise generated when a braking piece
collides with a rotary body.
Brief Description of Drawings
[0013]
Figure 1 is a diagram showing the general configuration of an elevator.
Figure 2 is a rear view showing a traction machine provided with an electromagnetic
brake device for an elevator in a first embodiment according to the present invention.
Figure 3 is a view taken along the A-A line of Figure 2.
Figure 4 is an enlarged view of the part C of Figure 1.
Figure 5 is a diagram to explain the operation of the electromagnetic brake device
for an elevator in the first embodiment according to the present invention.
Figure 6 is a diagram to explain the operation of the electromagnetic brake device
for an elevator in the first embodiment according to the present invention.
Figure 7 is a diagram to explain the operation of the electromagnetic brake device
for an elevator in the first embodiment according to the present invention.
Description of Embodiment
[0014] The present invention will be described in more detail with reference to the accompanying
drawings. Incidentally, in each of the drawings, like numerals refer to like or corresponding
parts and redundant descriptions of these parts are appropriately simplified or omitted.
First embodiment
[0015] Figure 1 is a diagram showing the general configuration of an elevator.
[0016] In Figure 1, reference numeral 1 denotes a shaft of an elevator, reference numeral
2 denotes a car of the elevator, and reference numeral 3 denotes a counterweight.
The car 2 and the counterweight 3 are suspended by a main rope 4 in a well bucket
manner in the shaft 1.
[0017] Reference numeral 5 denotes a thin-type traction machine provided in the upper space
in the shaft 1. The traction machine 5 constitutes a driving device which drives the
car 2. A driving sheave 6 is provided on the traction machine 5 in such a manner as
to be rotatable in both directions. Part of the main rope 4 is wound on the driving
sheave 6. Because the main rope 4 moves longitudinally in response to the rotation
of the driving sheave 6, the car 2 ascends and descends in the shaft 1 according to
the moving direction of the main rope 4.
[0018] In the figure, reference numeral 7 denotes a guide rail for guiding the ascent and
descent of the car 2, and reference numeral 8 denotes a governor for detecting a prescribed
overspeed condition.
[0019] While the car 2 of the elevator stops in a hall 9, in the traction machine 5 a prescribed
standstill retentive force is generated by an electromagnetic brake device 10 (not
shown in Figure 1).
[0020] Hereinafter, referring also to Figures 2 to 4, a concrete description will be given
of each configuration of the traction machine 5 and the electromagnetic brake device
10 provided in this traction machine 5.
[0021] Figure 2 is a rear view showing the traction machine provided with the electromagnetic
brake device for an elevator in a first embodiment according to the present invention,
Figure 3 is a view taken along the A-A line of Figure 2, and Figure 4 is an enlarged
view of the part C of Figure 1. Figure 2 shows a view taken along the B-B line of
Figure 3.
[0022] Reference numeral 11 denotes a frame which constitutes the framework of the traction
machine 5. The driving sheave 6 is rotatably provided in the frame 11 via a bearing.
Reference numeral 12 denotes a rotary body provided integrally with the driving sheave
6. The rotary body 12 rotates in response to the rotation of the driving sheave 6.
[0023] A cylindrical part 13 in the shape of a short (a short width) cylinder is formed
in part of the rotary body 12. The cylindrical part 13 has the same axis of rotation
as the driving sheave 6, and is disposed in the interior of the frame 11. The cylindrical
part 13 is supported by the frame 11 via other portions of the rotary body 12. A rotor
iron core 14 is provided on an outer circumferential surface 13a of the cylindrical
part 13.
[0024] Reference numeral 15 denotes a stator which constitutes the main part of the electric
motor. The stator 15 is provided on an inner circumferential surface of the frame
11 in such a manner as to be opposed to the rotor iron core 14.
[0025] The electromagnetic brake device 10 generates the force for holding the car 2 at
a standstill by pushing a braking piece 16 against the rotary body 12. During the
ascent and descent of the car 2, the electromagnetic brake device 10 separates the
braking piece 16 from the rotary body 12 and releases the standstill retentive force.
In the traction machine 5 shown in Figure 2, the electromagnetic brake device 10 is
provided on both sides of the rotary body 12. In this case, the electromagnetic brake
device 10 prevents the rotation of the rotary body 12 by pushing the braking piece
16 against the outer circumferential surface 13a of the cylindrical part 13 from the
sides.
[0026] In this embodiment, the outer circumferential surface 13a of the cylindrical part
13 functions as a braking surface for generating the standstill retentive force. The
operating direction of the electromagnetic brake device 10, Le, the direction in which
the braking piece 16 operates when the braking piece 16 comes into contact with the
rotary body 12 {the braking surface) and moves away from the rotary body 12 (the braking
surface), is a horizontal direction.
[0027] In addition to the braking piece 16, a field 17, a coil 18, a movable piece (an iron
piece) 19, a spring (an elastic body) 20, a movable piece (an iron piece) 21, and
an elastic body 22 constitute the main part of the electromagnetic brake device 10.
[0028] The field 17 and the coil 18 constitute an electromagnet. That is, an electromagnetic
force is generated in the field 17 by applying a voltage to the coil 18. An opening
11a is formed on both side portions of the frame 11. The field 17 is placed onto the
frame 11 in such a manner as to cover the opening 11a from outside and is attached
to the frame 11 by bolts 23. The coil 18 is provided in the field 17 in such a manner
that the axis thereof faces the above-described operating direction.
[0029] The movable piece 19 is supported by the field 17 in such a manner as to be able
to move in the operating direction in a prescribed range. The movable piece 19 is
disposed on the rotary body 12 side of the field 17 so that one side surface thereof
is opposed to the field 17. That is, the movable piece 19 is attached to the field
17 in such a manner as to approach the rotary body 12 and move away from the rotary
body 12.
[0030] The spring 20 is intended for use in pushing the movable piece 19 with a prescribed
pushing force in the direction in which the movable piece 19 moves away from the field
17 in the operating direction. That is, the movable piece 19 is constantly pushed
by the spring 20 to the rotary body 12 side. The spring 20 is provided in the field
17 and the tip portion thereof is connected to the one side surface of the movable
piece 19.
[0031] The movable piece 21 is supported by the movable piece 19 in such a manner as to
be able to move in the operating direction in a prescribed range. The movable piece
21 is disposed on the rotary body 12 side of the movable piece 19 so that one side
surface thereof is opposed to the other side surface of the movable piece 19. The
braking piece 16 is provided on the other side surface of the movable piece 21 (the
surface facing the side opposite to the one side surface) and is disposed so as to
be opposed to the outer circumferential surface 13a of the cylindrical part 13. That
is, the movable piece 19 is disposed on the side opposite to the braking piece 16
with respect to the movable piece 21, and the braking piece 16, the movable piece
21, the movable piece 19, and the electromagnet (the field 17) are disposed in series
outside the rotary body 12 and in the operating direction.
[0032] The elastic body 22 is provided between the other side surface of the movable piece
19 and the one side surface of the movable piece 21. The elastic body 22 is a member
formed from rubber, spring and the like, and is provided so as to expand and contract
in the above-described operating direction in the same manner as the spring 20. The
elastic body 22 has a prescribed pushing force weaker than the pushing force of the
spring 20. The elastic body 22 causes a force to apply in the operating direction
so that the movable piece 19 and the movable piece 21 move away from each other with
the pushing force thereof. The spring 20 pushes the movable piece 19 to the movable
piece 21 side with a prescribed pushing force stronger than the pushing force of the
elastic body 22.
[0033] As shown in detail in Figure 4, the movable piece 19 is a member, for example, having
a section in the shape of the letter C, which is open on the rotary body 12 side.
That is, in the movable piece 19, a concavity is formed on the other side surface
opposed to the movable piece 21. The movable piece 21 is configured in such a manner
that when the elastic body 22 contracts, the whole is disposed in the concavity of
the movable piece 19.
[0034] Next, referring also to Figures 5 to 7, a concrete description will be given of the
operation of the electromagnetic brake device 10 having the above-described configuration.
Figures 5 to 7 are diagrams to explain the operation of the electromagnetic brake
device for an elevator in the first embodiment according to the present invention.
[0035] Figure 5 shows the condition of the electromagnetic brake device 10 acting when the
car 2 is running in the shaft 1. During a run of the car 2, a prescribed voltage is
applied to the coil 18. For this reason, electromagnetic attraction Phil is generated
between the field 17 and the movable piece 19, and the field 17 attracts the movable
piece 19 against the pushing force Fkl of the spring 20. That is, the electromagnetic
attraction lis set at a prescribed magnitude capable of overcoming the pushing force
Fk1 of the spring 20.
[0036] Because of the application of the voltage to the coil 18, prescribed electromagnetic
attraction Fm2 is generated also between the movable piece 19 and the movable piece
21. Although the electromagnetic attraction Fm2 is weaker than the electromagnetic
attraction Fm1, the electromagnetic attraction Fm2 is set at a prescribed magnitude
capable of overcoming the pushing force Fk2 (< Fk1) of the elastic body 22. For this
reason, the movable piece 19 attracts the movable piece 21 against the pushing force
Fk2 of the elastic body 22.
[0037] At this time, the movable piece 19 is attracted to the field 17 side, for example,
until the one side surface thereof comes into contact with the field 17. This configuration
can be realized, for example, by fitting the spring 20 in such a manner that the spring
20 can be disposed in the interior of the field 17. When the elastic body 22 is compressed,
the movable piece 21 approaches the movable piece 19 and is disposed in the concavity
of the movable piece 19.
[0038] As a result of this, a prescribed gap is formed between the braking piece 16 and
the outer circumferential surface 13a of the cylindrical part 13, and the car 2 becomes
capable of ascending and descending.
[0039] When the car 2 stops at any of the halls 9, a braking instruction is outputted from
a prescribed control apparatus (not shown in Figures). Upon receipt of the braking
instruction, the electromagnetic brake device II) performs prescribed processing for
reducing the voltage of the coil 18 by demagnetizing. As a result of this, the current
flowing through the coil 18 decreases gradually, and the electromagnetic attractions
Fm1 and Fm2 become small gradually.
[0040] When the current flowing through the coil 18 decreases to a given value I1, the electromagnetic
attraction Fm2 becomes smaller than the pushing force Fk2 of the elastic body 22.
Then, the movable piece 21 is moved by the pushing force Fk2 of the elastic body 22
to the rotary body 12 side, and the braking piece 16 collides with the outer circumferential
surface 13a of the cylindrical part 13. Because the movable piece 19 is disposed in
a position close to the field 17, the electromagnetic attraction Fm1 lis larger than
the electromagnetic attraction Fm2. For this reason, even when the current value of
the coil 18 has decreased to I1, the electromagnetic attraction Fm1 is larger than
the pushing force Fk1 of the spring 20, and the movable piece 19 remains in tight
contact with the field 17.
[0041] Figure 6 shows the condition in which the current value of the coil 18 has decreased
to I1. The elastic body 22 has a prescribed amount of elongation capable of bringing
the braking piece 16 into contact with the rotary body 12, with the movable piece
19 kept in tight contact with the field 17.
[0042] When time further elapses from the condition of Figure 6 and the current flowing
through the coil 18 decreases to a given value I2 (<I1), the electromagnetic attraction
Fm1 becomes smaller than the pushing force Fk1 of the spring 20. Then, the movable
piece 19 is moved by the pushing force Fk1 of the spring 20 to the rotary body 12
(the movable piece 21) side, and the elastic body 22 is compressed. As a result of
this, the pushing force Fk1 of the spring 20 acts on the braking piece 16 via the
movable piece 19, the elastic body 22, and the movable piece 21, and the braking piece
16 is pushed against the outer circumferential surface 13a of the cylindrical part
13 with a prescribed force necessary for standstill holding of the car 2.
[0043] Figure 7 shows the condition in which the current value of the coil 18 has decreased
to I2.
[0044] With the electromagnetic brake device 10 having the above-described configuration,
it is possible to reduce the noise generated when the car 2 stops at the hall 9.
[0045] That is, in the electromagnetic brake device 10, when a braking instruction is outputted
from the control apparatus, first, the movable piece 21 moves to the rotary body 12
side and the braking piece 16 collides with the cylindrical part 13. At this time,
because the spring 20 of a large pushing force remains compressed, only the small
pushing force of the elastic body 22 acts on the braking piece 16. That is, it is
possible to control the energy during the collision of the braking piece 16 with the
rotary body 12 to restrict to small values and the noise generated at this time can
be substantially reduced.
[0046] In the electromagnetic brake device 10, after the braking piece 16 is brought into
contact with the outer circumferential surface 13a of the cylindrical part 13, the
braking piece 16 is pushed against the rotary body 12 with a large pushing force of
the spring 20. For this reason, it is possible to generate a stable standstill retentive
force after the above-described noise is prevented.
[0047] In order to generate a prescribed standstill retentive force, it is necessary that
the movable piece 19 be moved by the spring 20 to the rotary body 12 side and that
the pushingforce of the spring 20 be caused to act on the braking piece 16. Because
in this electromagnetic brake device 10 the elastic body 22 is provided between the
movable pieces 19 and 21, it is possible to absorb the impact by the movement of the
movable piece 19 by using the elastic body 22 and it becomes possible to reduce the
collision noise of the movable piece 19 without the need to provide a new buffer material
and the like.
[0048] Although in this embodiment the case where the thin-type traction machine 5 is provided
in the shaft 1 was described as an example, the configuration and disposition of the
traction machine 5 are not limited to this. The disposition and operating direction
of the electromagnetic brake device 10 are not limited to the above description, either.
The electromagnetic brake device 10 may be disposed on the inner side of the rotary
body 12 and the operating direction of the electromagnetic brake device 10 may be
set in the axial direction of the rotary body 12. Even in the case of such configurations,
it is possible to produce the same effect as described above.
Industrial Applicability
[0049] The electromagnetic brake device according to the present invention can be applied
to an electromagnetic brake device installed in a traction machine of an elevator.
Reference Signs List
[0050]
1 shaft
2 car
3 counterweight
4 main rope
5 traction machine
6 driving sheave
7 guide rail
8 governor
9 hall
10 electromagnetic brake device
11 frame
11a opening
12 rotary body
13 cylindrical part
13a outer circumferential surface
14 rotor iron core
15 stator
16 braking piece
17 field
18 coil
19, 21 movable piece
20 spring
22 elastic body
23 bolt
1. An electromagnetic brake device (10) for an elevator which holds a car (2) of an elevator
at a standstill by pushing a braking piece (16) against a rotary body (12) rotating
in response to the rotation of a driving sheave (6) of an elevator traction machine
(5), comprising:
a first movable iron piece (21) to which the braking piece (16) is connected, the
braking piece (16) being disposed between the first movable iron piece (21) and the
rotary body (12) in such a manner as to be opposed to the rotary body (12), wherein
a prescribed gap is formed between the braking piece (16) and the rotary body (12)
in a condition of the electromagnetic brake device (10) acting when the car (2) is
running in a shaft (1) of the elevator;
a second movable iron piece (19) which is disposed on the side opposite to the braking
piece (16) with respect to the first movable iron piece (21);
a first elastic body (22) having a prescribed pushing force, which is provided between
the first movable iron piece (21) and the second movable iron piece (19);
a second elastic body (20) which pushes the second movable iron piece (19) against
the first movable iron piece (21) side with a prescribed pushing force stronger than
the pushing force of the first elastic body (22); and
an electromagnet (17, 18) which attracts the second movable iron piece (19) against
the pushing force of the second elastic body (20) and causes the second movable iron
piece (19) to attract the first movable iron piece (21) against the pushing force
of the first elastic body (22).
2. The electromagnetic brake device for an elevator according to claim 1, wherein
the first movable iron piece (21), the second movable iron piece (19), and the electromagnet
are disposed in series in an operating direction in which the braking piece (16) contacts
the rotary body (12) and moves away from the rotary body (12), and
the first elastic body (22) and the second elastic body (20) are disposed in such
a manner as to expand and contract in the operating direction.
3. The electromagnetic brake device for an elevator according to claim 1 or 2, wherein
the first movable iron piece (21) is moved by the pushing force of the first elastic
body (22) when the voltage of a coil (18) constituting the electromagnet is reduced
by demagnetizing, whereby the braking piece (16) comes into contact with the rotary
body (12), and
thereafter the second movable iron piece (19) is moved by the pushing force of the
second elastic body (20), whereby the pushing force of the second elastic body (20)
acts on the braking piece (16).
4. The electromagnetic brake device for an elevator according to claim 1 or 2, wherein
a concavity is formed on a surface of the second movable iron piece (19) which is
opposed to the first movable iron piece (21), and
the first movable iron piece (21) is disposed in the concavity when attracted by the
electromagnet on the second movable iron piece (19).
1. Elektromagnetische Bremsvorrichtung (10) für einen Aufzug, die eine Kabine (2) eines
Aufzugs in einem Stillstand hält, indem ein Bremsstück (16) gegen einen Rotationskörper
(12) gedrückt wird, der sich in Reaktion auf die Drehung einer Antriebsscheibe (6)
einer Aufzugszugmaschine (5) dreht, aufweisend:
ein erstes bewegliches Eisenstück (21), mit dem das Bremsstück (16) verbunden ist,
wobei das Bremsstück (16) zwischen dem ersten beweglichen Eisenstück (21) und dem
Rotationskörper (12) derart angeordnet ist, dass es dem Rotationskörper (12) gegenüberliegt,
wobei ein vorgeschriebener Spalt zwischen dem Bremsstück (16) und dem Rotationskörper
(12) in einem Zustand der elektromagnetischen Bremsvorrichtung (10) ausgebildet wird,
der wirkt, wenn die Kabine (2) in einem Schacht (1) des Aufzugs fährt;
ein zweites bewegliches Eisenstück (19), das auf der zum Bremsstück (16) in Bezug
auf das erste bewegliche Eisenstück (21) gegenüberliegenden Seite angeordnet ist;
ein erster elastischer Körper (22), der eine vorgeschriebene Schubkraft aufweist und
der zwischen dem ersten beweglichen Eisenstück (21) und dem zweiten beweglichen Eisenstück
(19) vorgesehen ist;
ein zweiter elastischer Körper (20), der das zweite bewegliche Eisenstück (19) gegen
eine Seite des ersten beweglichen Eisenstücks (21) mit einer vorgeschriebenen Schubkraft
drückt, die stärker als die Schubkraft des ersten elastischen Körpers (22) ist; und
einen Elektromagneten (17, 18), der das zweite bewegliche Eisenstück (19) gegen die
Schubkraft des zweiten elastischen Körpers (20) anzieht und der das zweite bewegliche
Eisenstück (19) dazu veranlasst, das erste bewegliche Eisenstück (21) gegen die Schubkraft
des ersten elastischen Körpers (22) anzuziehen.
2. Elektromagnetische Bremsvorrichtung für einen Aufzug nach Anspruch 1, wobei
das erste bewegliche Eisenstück (21), das zweite bewegliche Eisenstück (19) und der
Elektromagnet in einer Reihe in einer Betriebsrichtung angeordnet sind, in welcher
das Bremsstück (16) den Rotationskörper (12) berührt und sich von dem Rotationskörper
(12) weg bewegt, und
der erste elastische Körper (22) und der zweite elastische Körper (20) auf eine derartige
Weise angeordnet sind, dass sie sich in der Betriebsrichtung ausbreiten und zusammenziehen.
3. Elektromagnetische Bremsvorrichtung für einen Aufzug nach Anspruch 1 oder 2, wobei
das erste bewegliche Eisenstück (21) durch die Schubkraft des ersten elastischen Körpers
(22) bewegt wird, wenn die Spannung einer Spule (18), die den Elektromagneten bildet,
durch ein Entmagnetisieren verringert wird, wodurch das Bremsstück (16) mit dem Rotationskörper
(12) in Kontakt kommt, und
das zweite bewegliche Eisenstück (19) danach durch die Schubkraft des zweiten elastischen
Körpers (20) bewegt wird, wodurch die Schubkraft des zweiten elastischen Körpers (20)
auf das Bremsstück (16) wirkt.
4. Elektromagnetische Bremsvorrichtung für einen Aufzug nach Anspruch 1 oder 2, wobei
eine Aushöhlung an einer Fläche des zweiten beweglichen Eisenstücks (19) ausgebildet
ist, die dem ersten beweglichen Eisenstück (21) gegenüberliegt, und
das erste bewegliche Eisenstück (21) in der Aushöhlung angeordnet ist, wenn es durch
den Elektromagneten auf das zweite bewegliche Eisenstück (19) gezogen wird.
1. Dispositif de frein électromagnétique (10) pour un ascenseur, qui maintient une cabine
(2) d'un ascenseur à l'arrêt en poussant une pièce de freinage (16) contre un corps
rotatif (12) tournant en réponse à la rotation d'une poulie motrice (6) d'une machine
de traction pour ascenseur (5), comprenant :
une première pièce de fer mobile (21) à laquelle la pièce de freinage (16) est reliée,
la pièce de freinage (16) étant disposée entre la première pièce de fer mobile (21)
et le corps rotatif (12) de manière à être opposée au corps rotatif (12), un espace
prescrit étant formé entre la pièce de freinage (16) et le corps rotatif (12) dans
un état du dispositif de frein électromagnétique (10) agissant lorsque la cabine (2)
fonctionne dans une cage (1) de l'ascenseur ;
une seconde pièce de fer mobile (19) qui est disposée du côté opposé à la pièce de
freinage (16) par rapport à la première pièce de fer mobile (21) ;
un premier corps élastique (22) ayant une force de poussée prescrite, qui est prévu
entre la première pièce de fer mobile (21) et la seconde pièce de fer mobile (19)
;
un second corps élastique (20) qui pousse la deuxième pièce de fer mobile (19) contre
le premier côté de la première pièce de fer mobile (21) avec une force de poussée
prescrite plus forte que la force de poussée du premier corps élastique (22) ; et
un électroaimant (17, 18) qui attire la seconde pièce de fer mobile (19) à l'encontre
de la force de poussée du deuxième corps élastique (20) et amène la seconde pièce
de fer mobile (19) à attirer la première pièce de fer mobile (21) à l'encontre de
la force de poussée du premier corps élastique (22).
2. Dispositif de frein électromagnétique pour un ascenseur selon la revendication 1,
la première pièce de fer mobile (21), la seconde pièce de fer mobile (19) et l'électroaimant
étant disposés en série dans une direction de fonctionnement dans laquelle la pièce
de freinage (16) est en contact avec le corps rotatif (12) et s'écarte du corps rotatif
(12), et
le premier corps élastique (22) et le second corps élastique (20) étant disposés de
manière à se dilater et se contracter dans la direction de fonctionnement.
3. Dispositif de frein électromagnétique pour un ascenseur selon la revendication 1 ou
2, la première pièce de fer mobile (21) étant déplacée par la force de poussée du
premier corps élastique (22) lorsque la tension d'une bobine (18) constituant l'électroaimant
est réduite par démagnétisation, la pièce de freinage (16) venant en contact avec
le corps rotatif (12), et
la seconde pièce de fer mobile (19) étant ensuite déplacée par la force de poussée
du second corps élastique (20), la force de poussée du second corps élastique (20)
agissant ainsi sur la pièce de freinage (16).
4. Dispositif de frein électromagnétique pour un ascenseur selon la revendication 1 ou
2,
une concavité étant formée sur une surface de la seconde pièce de fer mobile (19)
qui est opposée à la première pièce de fer mobile (21), et
la première pièce de fer mobile (21) étant disposée dans la concavité lorsqu'elle
est attirée par l'électroaimant sur la seconde pièce de fer mobile (19).