WO2006078081A1

WO2006078081A1 - Rope brake system of elevator by using cam

Info

Publication number: WO2006078081A1
Application number: PCT/KR2005/000185
Authority: WO
Inventors: Si Lark Yeo
Original assignee: Kisan Information System Co., Ltd
Priority date: 2005-01-20
Filing date: 2005-01-20
Publication date: 2006-07-27
Also published as: CN1906111A

Abstract

Disclosed is a rope braking apparatus for an elevator, which operates, by using cams, lining plates for braking rope of the elevator. In the apparatus, at the moment eccentric cams (36) secured to a camshaft (35) are rotated and pass a top dead center, with a trigger lever (34) preventing rotation of the camshaft (35), a state of waiting an emergency brake signal (that is, a normal running state) is maintained. If an emergency situation takes place, as an actuator (32) actuates the trigger lever (34) and compressed springs (38) are returned to their original state, a second movable plate (14) is moved toward a fixed plate (12) to brake the rope of the elevator. At this time, since reverse rotation prevention means is installed in a driving or driven gear (27, 29), a rotation force applied to the eccentric cams (36) is not transmitted to a motor (23).

Description

[DESCRIPTION]

[invention Title]

ROPE BRAKE SYSTEM OF ELEVATOR BY USING CAM

[Technical Field] The present invention relates , in general , to a rope braking apparatus for an elevator, and, more particularly, to a rope braking apparatus for an elevator, which supplements a usual elevator brake operated while an elevator travels at a normal speed, in a manner such that, when the elevator in a stopped state slips on rope or the elevator travels at a speed faster than the normal speed, a movable plate having a brake lining coupled thereto can be actuated to momentarily grip and lock the rope of the elevator, thereby serving as a failsafe auxiliary brake capable of preventing slip of the elevator on the rope and over-speeding of the elevator and capable of ensuring safe operation of the elevator .

[Background Art]

A plurality of rope braking apparatuses for an elevator which are operated . in the same manner as described above have been disclosed in the art . For example, the present applicant has disclosed a rope braking apparatus in

Korean Patent No . 269685 ( laid-open published on January 5, 1999) . This rope braking apparatus comprises a hydraulic pressure generating section . A movable plate having a lining is operated by hydraulic pressure from the hydraulic pressure generating section in response to a signal from a control section of an elevator . The movable plate cooperates with a fixed plate to brake rope of the elevator. The return of the movable plate (that means release of a rope braking state) is affected by the returning force of springs . Korean Utility Model Registration No . 213918 (published on February 15, 2001 ) discloses a similar braking apparatus for an elevator in which a rope braking state is released by a hydraulic force .

However, these conventional rope braking apparatuses suffer from defects in that high costs are incurred to configure the hydraulic pressure generating section . A period from the time at which the movable plate for braking the rope of the elevator starts to operate to the time at which the braking operation is completed is substantially lengthened . Therefore, in order to cope with this problem, it is necessary to separately install a pressure accumulator .

Other rope braking apparatuses for an elevator which use a cam instead of the hydraulic pressure generating section as a power source have been disclosed in the art . In a rope braking apparatus for an elevator disclosed in Korean Patent No. 221960 (laid-open published on April 30, 1998 ) which is owned by the present applicant, an eccentric cam is rotated using a motor, and a movable plate is moved forward or rearward through rotation of the eccentric cam and by a returning force of springs to brake rope of the elevator . Korean Patent Laid-open Publication No . 1998-9086 (laid-open published on April 30, 1998 ) discloses a similar rope braking apparatus for an elevator which operates using an eccentric cam. Nevertheless, these conventional rope braking apparatuses using a cam have a drawback in that, since a power switching device such as a clutch is not provided between a shaft (including a reduction gear) of the motor and a camshaft, although the camshaft must be quickly rotated to operate the movable plate, the motor which is connected in series to the camshaft functions to retard the quick rotation of the camshaft . Consequently, a basic requirement of the rope braking apparatus, that the movable plate must be quickly operated within 200 msec to appropriately brake the rope, cannot be satisfied.

Of course, while this drawback can be solved to some extent by using an electronic clutch, the manufacturing cost is raised due to the installation of the costly electronic clutch, and as the size of the entire rope braking apparatus increases, installation work and maintenance and repair work cannot be easily and conveniently conducted.

Further, as shown in FIG . 22 , in a state in which rope 3 is wound on a traction pulley 5 in a machine room provided with a traction machine, a conventional rope braking apparatus for an elevator is arranged on a rope portion on which an elevator car 1 is installed or on a rope portion on which a counterweight 7 is installed . The reference character A schematically illustrates an installation state of a rope braking apparatus according to the present invention, and the reference character A ' schematically illustrates an installation state of the conventional rope braking apparatus . It is to be readily understood that the conventional rope braking apparatus is likely to interfere with the traction pulley 5. In the conventional rope braking apparatus (as disclosed in Korean Patent No . 221960 and Korean Patent Laid-open Publication No . 1998-9086) , as shown in FIG . 23, cams and a camshaft are disposed in front of a fixed plate 51 , and a movable plate 52 is disposed behind the fixed plate 51. A support plate 56 for supporting springs behind the movable plate 52 is fastened to a housing . As a consequence, in order to place a rope portion between linings of the fixed plate 51 and the movable plate 52 , the support plate 56 must be first disassembled, and then, the springs and the movable plate 52 must be disassembled . Thus, the number of parts which must be disassembled increases . Also, since operation rods interlocked with the cams disposed in front of the fixed plate 51 are secured to the movable plate 52 , the operation rods must also be disassembled, whereby difficulty results when installing the rope braking apparatus in place .

Also, as shown in FIG . 23, because the linings for braking the rope portion are positioned intermediately in the housing, the conventional rope braking apparatus is likely to interfere with the traction pulley 5, whereby installation work cannot help but be performed with difficulty .

[Disclosure] [Technical Problem]

In the present invention, in an unlocking state in which eccentric cams (36) are rotated to compress springs

(38 ) , when an emergency signal is applied, by a returning force of the compressed springs ( 38 ) , a first movable plate

( 13 ) is moved away from a fixed plate ( 12 ) and a second movable plate ( 14 ) is moved toward the fixed plate ( 12 ) , to brake rope of an elevator . In this regard, an obj ect of the present invention is to provide a mechanical brake system wherein, when a camshaft (35 ) is rotated by the returning force of the compressed springs ( 38 ) , a rotation force of the camshaft (35 ) is prevented from being transferred to a motor (23 ) to allow the movable plates ( 13, 14 ) to be quickly operated and to thereby shorten a braking time as much as possible .

Another object of the present invention is to provide a rope braking apparatus which is simplified and miniaturized in its construction when compared to the conventional cam type braking apparatus , to allow elevator installation work to be performed conveniently.

[Technical Solution]

In order to achieve the above objects , according to one aspect of the present invention, there is provided a rope braking apparatus for an elevator comprising : a driving gear (27 ) driven through a shaft of a motor (23) ; a driven gear (29) rotated by the driving gear (27 ) to drive a camshaft (35 ) ; reverse rotation prevention means arranged in the driving gear (27 ) or the driven gear (29 ) ; a trigger lever ( 34 ) operated by an actuator ( 32 ) ; a rotation plate ( 33 ) secured to one end of the camshaft ( 35 ) and having a stepped portion (33a) which is engaged with a latch portion (34a) of the trigger lever (34 ) ; eccentric cams ( 36) secured to the camshaft ( 35 ) to push a first movable plate (13) toward a fixed plate ( 12 ) by virtue of rotation of the camshaft ( 35 ) ; and springs ( 38 ) compressed by movement of the first movable plate ( 13) to generate a returning force . According to another aspect of the present invention, one end of each of a plurality of guide shafts ( 15 ) which can slide in bushings provided through the fixed plate (12) is secured to the first movable plate (13) , and the other end of each of the plurality of guide shafts ( 15 ) is secured to a second movable plate (14 ) . The springs (38 ) are respectively fitted around the guide shafts ( 15) between the fixed plate ( 12 ) and the first movable plate

( 13) . The springs (38) are compressed when the first movable plate (13 ) is moved toward the fixed plate ( 12 ) .

When the force which moved the first movable plate ( 13 ) forwards is removed, a substantially large returning force is applied to the first movable plate ( 13 ) to push the first movable plate ( 13 ) away from the fixed plate ( 12 ) .

[Advantageous Effects]

In the conventional rope braking apparatus, as can be readily seen from FIG . 23, due to the fact that the support plate 56 for supporting the springs behind the movable plate 52 is fastened to the housing, in order to place the rope portion between the linings of the fixed plate 51 and the movable plate 52, the support plate 56 must be first disassembled, and then, the springs and the movable plate

52 must be disassembled . Thus, as the number of parts which must be disassembled increases , difficulty is caused when installing the rope braking apparatus in place . Also, because the linings for braking the rope portion are positioned intermediately in the housing, the conventional rope braking apparatus is likely to interfere with the traction pulley 5 as shown in FIG . 22 , whereby installation work cannot help but be performed with difficulty.

However, in the present invention, the rope braking apparatus comprises a housing 11 which includes a fixed plate 12 and forms a substantially H-shaped frame . A first movable plate 13 and a second movable plate 14 are positioned at both sides of the fixed plate 12 so that the fixed plate 12 is interposed between the first and second movable plates 13 and 14. Bushings are provided through the fixed plate 12 , and guide shafts 15 are movably inserted through the bushings . The first and second movable plates 13 and 14 are respectively bolted to both ends of the guide shafts 15. By this construction, it is possible to design the rope braking apparatus so that linings are positioned maximally rearwards with respect to the housing .

In order to install the rope braking apparatus according to the present invention, constructed as mentioned above, on rope of an elevator, bolts which secured the second movable plate 14 to the guide shaft 15 are removed. Then, after only the second movable plate 14 is disassembled and the rope is placed on the lining, the second movable plate 14 is bolted again to the guide shafts 15. In this way, it is possible to simply install the rope braking apparatus . Also, since interference between the rope braking apparatus and the traction pulley 5 can be minimized, convenience can be significantly improved when performing installation work in situ.

[Description of Drawings]

FIG . 1 is a schematic exploded perspective view illustrating a rope braking apparatus in accordance with a first embodiment of the present invention;

FIG . 2 is a plan view illustrating a normal state in which the rope braking apparatus according to the first embodiment of the present invention is not operated; FIG . 3 is a plan view illustrating a state in which the rope braking apparatus according to the first embodiment of the present invention is operated and rope is braked;

FIG . 4 is a sectional view illustrating a pawl type one-way clutch as reverse rotation prevention means which is applied to the present invention;

FIG . 5 is a sectional view illustrating a roller type one-way clutch as another reverse rotation prevention means which is applied to the present invention; FIG . 6 is a sectional view illustrating an eccentric ball type one-way clutch as still another reverse rotation prevention means which is applied to the present invention;

FIG . 7 is a conceptual view for explaining positions of a top dead center of an eccentric cam, a stepped portion formed on a circumferential outer surface of a rotation plate, and a trigger lever, in the present invention;

FIG . 8 is a sectional view illustrating a relationship between the positions of the stepped portion and the eccentric cam which are secured to a camshaft, in the present invention;

FIG . 9 is a view illustrating a trigger lever using an actuator;

FIG . 10 is a view illustrating another trigger lever using an actuator; FIGs . 11a and lib are views illustrating still another trigger lever using an actuator, wherein FIG . 11a illustrates a state in which the trigger lever prevents the rotation of the camshaft, and FIG . lib illustrates a state in which the camshaft can be freely rotated; FIG . 12 is a schematic explanatory view illustrating a relationship between the stepped portion of the rotation plate and sensing means for sensing a rotational position of the camshaft;

FIG . 13 is a plan view illustrating a variation of the first embodiment of the present invention, in which auxiliary springs are added between a first movable plate and a fixed plate;

FIG . 14 is a perspective view illustrating another variation of the first embodiment of the present invention, in which an idle gear is interposed between a driving gear and a driven gear; FIG . 15 is a sectional view taken along the line A-A of FIG. 14 , illustrating power transmission means and reverse rotation prevention means;

FIGs . 16 through 18 are sectional view illustrating various types of reverse rotation prevention means which can be applied to the variation of FIG . 14 ;

FIG . 19 is a schematic exploded perspective view illustrating a rope braking apparatus in accordance with a second embodiment of the present invention; FIG . 20 is a plan view illustrating a normal state in which the rope braking apparatus according to the second embodiment of the present invention is not operated;

FIG . 21 is a plan view illustrating a state in which the rope braking apparatus according to the second embodiment of the present invention is operated and rope is braked;

FIG . 22 is an explanatory view illustrating an installation position of a rope braking apparatus; and

FIG. 23 is a plan view illustrating a locking section of a conventional cam type rope braking apparatus .

[Best Mode]

Reference should now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components . FIG . 1 is a perspective view illustrating a rope braking apparatus for an elevator in accordance with a first embodiment of the present invention, and FIGs . 2 and 3 are plan views of FIG. 1. A construction of the rope braking apparatus for an elevator according to the first embodiment of the present invention will be described with reference to FIGs . 1 through 3.

The rope braking apparatus includes a housing in which left and right plates 11 are integrally secured to both ends of a fixed plate 12 to form a substantially H- shaped frame .

The rope braking apparatus further includes a locking section . The locking section comprises guide shafts 15 movably inserted through the fixed plate 12, a first movable plate 13 and a second movable plate 14 secured to both ends of the guide shafts 15, and springs 38 fitted around the guide shafts 15 between the fixed plate 12 and the first movable plate 13 to accumulate a returning force when the first movable plate 13 is moved toward the fixed plate 12.

The rope braking apparatus further includes an operating section for operating the first movable plate 13. The operating section comprises a camshaft 35 having eccentric cams 36 secured thereto and rotatably fitted through left and right plates 11 , driving means (a motor) 23 for rotating the camshaft 35, power transmission means for transmitting the rotation force of the driving means 23 to the camshaft 35, and reverse rotation prevention means for transmitting the rotation force of the driving means to the camshaft 35 and preventing a rotation force generated in the camshaft 35 from being backwardly transmitted to the driving means 23.

In one form of the power transmission means which can be applied to the present invention, in order to decrease the rotational speed of the motor 23 and obtain a large torque, a reduction gear 23a can be additionally provided . In another form of the power transmission means , a gear ratio between the driving gear 27 and the driven gear 29 can be appropriately adjusted . As a method of adjusting a gear ratio between the driving gear 27 and the driven gear 29, by interposing an idle gear 28 between the driving gear 27 and the driven gear 29, it is possible to obtain a great reduction ratio . FIG. 14 illustrates a variation of the first embodiment of the present invention which adopts the idle gear 28, and FIG . 15 is a sectional view taken along the line A-A of FIG . 14 , illustrating power transmission means and reverse rotation prevention means shown in FIG . 14.

While all component elements of the present invention are important, reverse rotation prevention means is regarded as a particularly important component element among them. The reverse rotation prevention means is installed in the driving gear 27 or the driven gear 29, so that, at the moment and immediately after the eccentric cam 36 passes a top dead center, a rotation force applied to the camshaft 35 by a returning force of the springs 38 is prevented from being transmitted to the driving means 23. FIGs . 4 through 6 illustrate preferred examples of the reverse rotation prevention means installed in the driving gear 27 in the case of the rope braking apparatus shown in FIG . 1 in which the camshaft 35 is rotated in a counterclockwise direction . FIG . 4 illustrates a pawl type one-way clutch which is constructed in a manner such that a rotating body 27a is formed integrally with a shaft of the motor 23 and is defined with pawl receiving grooves, a circumferential inner surface of the driving gear 27 is defined with pawl engagement grooves, and pawls 26b are respectively inserted into the pawl receiving grooves to be capable of being engaged with the pawl engagement grooves . Therefore, while a clockwise rotation force of the shaft of the motor 23 is transmitted to the driving gear 27 , in the case that a clockwise rotation force which is greater the clockwise rotation force of the motor 23 is generated in the driving gear 27, the clockwise rotation force of the driving gear 27 is prevented from being transmitted to the shaft of the motor 23. FIG. 5 illustrates another example of the reverse rotation prevention apparatus which comprises a roller type cam clutch . The reference numeral 26a of FIG . 5 designates teeth which are formed on a circumferential outer surface of a rotating body 27a rotated integrally with the shaft of the motor 23 in the clockwise direction, and the reference numeral 26c designates rollers which roll between the rotating body 27a and the circumferential inner surface of the driving gear 27.

FIG . 6 illustrates still another example of the reverse rotation prevention apparatus which comprises an eccentric ball type cam clutch . In FIG . 6, the reference numeral 26d designates eccentric balls which roll between a rotating body 27a and the circumferential inner surface of the driving gear 27. As can be readily seen from FIG. 6, each eccentric ball 26d has a portion which increases linearly in its radius of curvature .

The reverse rotation prevention means comprises oneway clutches which are well known in the art of mechanical engineering . Thus, although detailed description of their structures is omitted, a person skilled in the art will readily understand those structures .

FIG . 7 illustrates a state in which the eccentric cams 36 formed on the camshaft 35 maximally push the first movable plate 13 (that is , a state in which the top dead center of each eccentric cam 36 is brought into contact with the first movable plate 13 ) . In this state, the springs 38 are maximally compressed . The state is shown in FIG . 2 as a plan view.

In this state, as the rotation force of the driving means 23 is continuously transmitted to the camshaft 35, at the moment the eccentric cams 36 pass the top dead center, by the returning force of the springs 38 , the first movable plate 13 is willing to momentarily move away from the fixed plate 12 , and the camshaft 35 is willing to rotate at a very high speed in a counterclockwise direction . As an essential feature of the present invention, the rotation of the camshaft 35 is suspended at this very time, and the rotation force of the camshaft 35 is accumulated to be used to brake the rope of the elevator upon occurrence of an emergency situation . Hence, a positional relationship between the top dead center of the eccentric cam 36 and a stepped portion 33a which is formed on the circumferential outer surface of a rotation plate 33 is regarded as another important feature of the present invention .

In the present invention, the position of the stepped portion 33a which is formed on the circumferential outer surface of the rotation plate 33 is determined as shown in FIG . 8. That is to say, it is preferred that the stepped portion 33a be formed at a position which is immediately after the top dead center of the eccentric cams 36 secured to the camshaft 35. Concretely speaking, it is preferred that, when viewed from a rotation center of the camshaft 35, the stepped portion 33a of the rotation plate 33 be formed at a position which is rotated from the top dead center of the eccentric cam 36 by about 0.2°~15° (that is, 0.2° < α < 15°) in a rotating direction of the camshaft 35. When viewed from the rotation center of the camshaft 35, until immediately before the eccentric cams 36 pass the top dead center, the springs 38 apply a force for hindering the rotation of the camshaft 35. However, after the eccentric cams 36 pass the top dead center, the returning force of the springs 38 acts as a force for accelerating the rotation of the camshaft 35. At this moment (that is , immediately after the top dead center) , a latch portion 34a of a trigger lever 34 must be engaged with the stepped portion 33a of the rotation plate 33 to prevent the camshaft 35 from being rotated, using a minimum necessary force . Thus, the position of the top dead center of the eccentric cams 36 and the position of the stepped portion 33a of the rotation plate 33 are important .

Next, a trigger mechanism of the present invention will be described . The trigger lever 34 is structured to be engaged with the stepped portion 33a of the rotation plate 33. The latch portion 34a is formed at one end of the trigger lever 34 , and an actuator 32 for actuating the trigger lever 34 is connected to the other end of the trigger lever 34. The trigger lever 34 is rotatably installed to the housing by a hinge pin P at a middle portion thereof . The actuator 32 is fastened to the housing to rotate the trigger lever 34 about the hinge pin P within a predetermined angle .

Various examples of the trigger lever 34 which can be applied to the present invention are shown in FIGs . 9 through 11. The actuator 32 comprises a solenoid type element which functions to pivot the trigger lever 34. The actuator 32 is constructed in a manner such that the trigger lever 34 which is rotated about the hinge pin P through extension and retreat of a plunger 32a prevents or allows the rotation of the rotation plate 33. That is to say, in a normal operation state of the elevator, the plunger 32a is extended out of the actuator 32 by current supply to a solenoid to push the trigger lever 34 upwards, and in the case that an emergency signal is applied (or current is not supplied) to the actuator 32, the operation of the solenoid is interrupted, and the . plunger is retracted into the actuator 32 (Depending upon a configuration of the trigger mechanism, a solenoid can be used in a manner such that the plunger 32a is extended out of the actuator 32 when the operation of the solenoid is interrupted) . As a preferred embodiment for minimizing frictional resistance when the latch portion 34a of the trigger lever 34 is brought into contact with the stepped portion 33a of the rotation plate 33, the latch portion 34a of the trigger lever 34- is provided with a rotation roller 34b. FIG. 9 illustrates an example of the trigger lever 34 which is bent several times to be operable by a small force. In FIG. 10, the trigger lever 34 is formed in the shape of a straight lever to be rotated about the hinge pin P through operation of the solenoid to thereby pivot the latch portion 34a . The examples of the trigger lever shown in FIGs . 9 and 10 were explained on the assumption that the camshaft 35, that is, the rotation plate 33, is rotated in the counterclockwise direction .

FIGs . 11a and lib illustrate still another example of the trigger lever 34 according to the present invention . A pair of levers 34 and 31 having different hinge points P2 and P3 are combined to allow the latch portion 34a to be engaged with the stepped portion 33a of the rotation plate 33. A roller 31a is installed on one end of the second lever 31 to reduce frictional resistance when the second lever 31 is brought into contact with the first lever 34. The example of the trigger lever shown in FIGs . 11a and lib was explained on the assumption that the camshaft 35, that is, the rotation plate 33, is rotated in the clockwise direction .

FIG. 12 is a view for explaining a construction of sensing means for precisely sensing a rotational position of the rotation plate 33, that is, the camshaft 35, based on the example of the trigger lever shown in FIGs . 11a and lib. In FIG . 12 , a position sensing disc 33b which is formed with a stepped portion 33c is integrated with the rotation plate 33 and the camshaft 35, so that, when a switch 30a projecting from a sensor 30 is brought into contact with the stepped portion 33c, power supply to the motor 23 is interrupted and the actuator 32 is operated to allow the trigger lever 34 to be engaged with the stepped portion 33a of the rotation plate 33. At this time, immediately after the stepped portion 33c formed on the position sensing disc 33b is brought into contact with the switch 30a, the latch portion 34b of the trigger lever 34 must be engaged with the stepped portion 33a .

Hereafter, operation of the rope braking apparatus for an elevator according to the first embodiment of the present invention, constructed as mentioned above, will be described.

FIG. 3 illustrates a state in which the eccentric cams 36 do not push the first movable plate 13. In this state, since the first movable plate 13 is moved forwards (toward the position where the motor is installed) by the springs 38, a lining lβb of the second movable plate 14 which is integrally locked to the first movable plate 13 by the plurality of guide shafts 15 is moved toward and brought into tight contact with a lining lβb of the fixed plate 12 to brake the rope of the elevator . In this way, the rope braking apparatus according to the present invention operates .

In order to release the emergency braking state and return to the normal operating state of the elevator, first, by driving the motor 23, the camshaft 35 is rotated through the driving gear 27 and the driven gear 29.

At this time, when assuming that the shaft of the motor 23 is set to rotate in the clockwise direction and the reverse rotation prevention means is provided in the driving gear 27 , the reverse rotation prevention means according to the present invention must be installed as shown in FIGs . 4 through 6 in a manner such that the rotation force transmitted from the camshaft 35 is not transmitted to the shaft of the motor 23.

When assuming that the reverse rotation prevention means according to the present invention is provided in the driven gear 29, the reverse rotation prevention means must be installed in a direction shown in FIGs . 16 through 18

(which is opposite to that shown in FIGs . 4 through 6) .

FIGs . 16 through 18 are sectional views taken along the line B-B of FIG . 15 and illustrate an installation direction of the reverse rotation prevention means in the case that the idle gear 28 is interposed between the driving gear 27 and the driven gear 29. In this case, the reverse rotation prevention means is installed in the same direction as in the case that the reverse rotation prevention means is installed in the driven gear 29 in the power transmission means composed only of the driving gear 27 and the driven gear 29. As shown in FIG . 15 , the idle gear 28 is composed of a pair of gears 28a and 28b which have a common axis and possess different diameters . The reverse rotation prevention means 26 is installed between the gears 28a and 28b .

The rotation force of the motor 23 is changed through the reduction gear 23a to a large rotation force having a low speed and rotates the driving gear 27 through the pawl 26b configured as aforementioned above . The rotation of the driving gear 27 rotates the driven gear 29 and the camshaft

35 in the counterclockwise direction . If the eccentric cams

36 are rotated, a rounded surface of each eccentric cam 36 gradually pushes the first movable plate 13 to compress the springs 38 , and the first movable plate 13 is moved toward the fixed plate 12 while compressing the springs 38. At this time, since the second movable plate 14 is locked integrally to the first movable plate 13 through the guide shafts 15, the second movable plate 14 is also moved rearward. Accordingly, as a gap between the linings 16a and 16b which brake the rope of the elevator gradually increases , the elevator can be returned to its normal operation state . During this procedure, because the actuator 32 pushes the plunger 32a upward, the roller 34b which is provided to the distal end of the latch portion 34a of the trigger lever 34 slides on the circumferential outer surface of the rotation plate 33 while being brought into tight contact therewith .

As the motor continuously rotates, the eccentric cam 36 which comes into contact with the first movable plate 13 approaches the top dead center of its rounded surface . At the time the eccentric cam 36 passes the top dead center, the eccentric cam 36 receives a rotational moment by the returning force of the springs 38 , whereby the eccentric cam 36 is willing to rotate continuously irrespective of driving of the motor 23. At this moment, the motor 23 is stopped in response to a signal from the position sensing sensor 30. At the moment the camshaft 35 is willing to continuously rotate in spite of the stopped state of the motor 23 , the latch portion 34a of the trigger lever 34 is engaged with the stepped portion 33a of the rotation plate

33 which is secured to one end of the camshaft 35. In a state in which the latch portion 34a of the trigger lever

34 is engaged with the stepped portion 33a of the rotation plate 33 to prevent the rotation plate 33 from being further rotated, the elevator is normally operated and is maintained in a standby state for receiving an emergency signal . FIG . 2 illustrates this state m a plan view .

As shown in FIG . 8 , because the stepped portion 33a of the rotation plate 33 is formed immediately after the top dead center of the eccentric cam 36, at the moment the eccentric cam 36 which comes into contact with the first movable plate 13 passes the top dead center, the latch portion 34a of the trigger lever 34 , which slides on the circumferential outer surface of the rotation plate 33 while being brought into tight contact therewith, is engaged with the stepped portion 33a of the rotation plate 33 to suppress the rotation of the camshaft 35 (against the returning force of the springs 38 ) . Here, signal indicative of the position of the eccentric cam 36 or the position of the camshaft 35 (that is , a signal which recognizes a position immediately after the top dead center) is obtained by the sensor 30 for sensing the rotated position of the camshaft 35. FIGs . 11a and lib illustrate a preferred construction for sensing the rotated position of the camshaft 35. Through the above-described procedure, the rope braking apparatus for an elevator according to the present invention is completely returned to its normal operating state and enters a standby state for receiving an input of a signal for emergency operation . Since the latch portion 34a for preventing the rotation of the rotation plate 33 must be constructed to sufficiently endure the returning force of the springs 38 , the latch portion 34a should be designed to have a sufficient strength . In this regard, it can be envisaged to increase a diameter of the rotation plate 33 which is secured to one end of the camshaft 35, to thereby decrease a load applied to the latch portion 34a and the stepped portion 33a .

While the elevator returns to the normal operating state, if the trigger lever 34 cannot stop the rotation of the rotation plate 33 at the moment the eccentric cam 36 passes the top dead center, a problem is caused in that the rotational moment of the eccentric cam 36 which is induced by the returning force of the compressed springs 38 applies a force to rotate the camshaft 35, the motor 23 is rotated by the rotation of the camshaft 35, and the first movable plate 13 and the second movable plate 14 are moved to brake the rope again . Accordingly, in the present invention, the position where the stepped portion 33a of the rotation plate 33 is formed and the operation of the trigger lever 34 are regarded as important factors .

At the moment the eccentric cam 36 passes the top dead center, in order to ensure that the compressed springs 38 are quickly returned toward their original state, it is preferred that the eccentric cam 36 be formed to have a radius of curvature which abruptly decreases immediately after the top dead center . However, an elliptical cam or a circular cam can be applied to the present invention . In the case of the asymmetrical cam as shown in FIGs . 7 and 8 , which is other than a symmetrical elliptical cam or a symmetrical circular cam, a configuration of the eccentric cam must be changed depending upon a rotating direction of the camshaft 35.

Moreover, as in the case of the roller 34b of the latch portion 34a, in order to minimize frictional resistance while the fist movable plate 13 is brought into contact with the eccentric cams 36, it is preferred that the first movable plate 13 be provided with rollers 37 at positions where the first movable plate 13 comes into contact with the eccentric cams 36. The rollers 37 can be installed directly on the first movable plate 13 or can be installed on the first movable plate 13 by way of mounting brackets fastened to the first movable plate 13 as shown in FIG . 7.

Next, a procedure in which an emergency signal is applied and the rope braking apparatus according to the present invention operates will be described .

If an emergency braking signal is applied from the elevator controller to the rope braking apparatus according to the present invention (or power supply is interrupted) , the actuator 32 rotates the trigger lever 34 about the hinge pin P to disengage the latch portion 34a of the trigger lever 34 from the stepped portion 33a of the rotation plate 33. If the latch portion 34a is disengaged, the camshaft 35 which is formed integrally with the rotation plate 33 is rotated in the counterclockwise direction by the returning force of the compressed springs 38. Then, the first movable plate 13 and the second movable plate 14 are moved forwards by the returning force of the springs 38 , and the two linings 16a and 16b are brought into tight contact with each other to quickly brake the rope . FIG . 3 is a plan view illustrating a state in which the rope braking apparatus according to the present invention is operated to brake the rope .

A speed and a force at and by which the two linings 16a and 16b are brought into tight contact with each other when the second movable plate 14 is moved toward the fixed plate 12 is determined depending upon a compression force of the springs 38 which are fitted around the guide shafts 15. In other words, by adjusting a spring constant of the springs 38 , it is possible to change a braking force of the linings 16a and 16b . In a variation of the first embodiment of the present invention for increasing a speed at which the two linings 16a and 16b are brought into tight contact with each other, as shown in FIG . 13, by adding auxiliary springs 38a between the first movable plate 13 and the fixed plate 12 , it is possible to reinforce a compression force of the springs 38 which are fitted around the guide shafts 15.

At this time, an important feature of the present invention which is distinguished from the conventional art is that the reverse rotation prevention means a s installed in the power transmission means to prevent the rotational force of the camshaft 35 from being transmitted to the motor 23 through the power transmission means upon release of the trigger lever 34. Namely, in the present invention, if the camshaft 35 is rotated in the counterclockwise direction, the driven gear 29 is also rotated in the counterclockwise direction, and the driving gear 27 which is meshed with the driven gear 29 is rotated in the clockwise direction . In this regard, due to the presence of the reverse rotation prevention means according to the present invention as shown in FIGs . 4 through 6, the rotational force of the driving gear 27 is not transmitted to the rotating body 27a which is formed integrally with the shaft of the motor 23, and instead, the driving gear 27 is idly rotated so as not to transmit the rotational force to the motor 23. In the case that the shaft of the motor 23 and the camshaft 35 are connected only by the power transmission means , due to the presence of the motor 23 , the rotation of the camshaft 35 is retarded. Therefore, as the returning speed of the compressed springs 38 decreases , a braking time of the linings lβa and 16b can increases . However, in the present invention, due to the fact the reverse rotation prevention means is installed in the power transmission means, the motor 23 can be prevented from being damaged, and a braking time of the linings l βa and 16b can be significantly shortened . In this regard, referring to the conventional rope braking apparatus using eccentric cams (as disclosed in Korean Patent No . 221960 and Korean Patent Laid-open Publication No . 1998-9086) , when the camshaft is rotated by a rotational moment which acts on the camshaft by the returning force of the springs , the rotat ional force is backwardly transmitted to the motor to adversely affect the rope braking operation .

Hereinbelow, a second embodiment of the present invention wi ll be described .

I n the second embodiment of the present invention, as a provision for increasing the ret urning force of the springs 33 , a plurality of springs 38a are additionall y provided to the first movabl e plate 13. While the first movabJ e plate 13 of the fu st embodiment has a flat plate- shaped configuration, the second embodiment of the present invention as shown in FIG. 19 is bas i cally di stinguished from the first embodiment m that the fi r=t movable plate 13 is def ined with pockets Ua for accommodating the springs 38 and the auxiliary springs iod . Each pocket 13a is opened toward the fixed plate 12 and extends away from the fixed plate 12. The springs 38 and the auxiliary springs 38a are supported between the boti oms of the pockets 13a and the fixed piate 12.

Further, as an additional component element, the rope braking apparatus may have a reinforci ng plate 13b for preventing deformation of the first movable p Late 13. The reinforcing plate 13b j s secured to the project. ons of the first movable plate 13, in which the pockets 13a are respectively defined . In this case that the reinforcing plate 13b is additionally provided to the first movable plate 13, it is necessary to define in the reinforcing plate 13b through-holes 13c for preventing interference between the reinforcing plate 13b and the eccentric cams 36.

FIG . 20 illustrates a state in which the eccentric cams 36 secured to the camshaft 35 maximally push the first movable plate 13 (that is, a state in which the top dead center of each eccentric cam 36 comes into contact with the first movable plate 13) , and FIG . 21 illustrates a state in which the first movable plate 13 is maximally pushed away from the fixed plate 12 by the returning force of the springs 38. From FIGs . 20 and 21, it is to be readily understood that the through-holes 13c are defined through the reinforcing plate 13b to prevent interference between the eccentric cams 36 and the reinforcing plate 13b .

While it was described in the first embodiment that the driving means (motor) 23 is positioned opposite the brake linings 16a and 16b, in the second embodiment of the present invention, a plate 11a is horizontally installed above the housing 11 and the fixed plate 12 , and the driving means 23 is fixed to the plate 11a . By installing the driving means 23 above the housing, the entire configuration of the rope braking apparatus , when assembled, can be conveniently installed, and it is possible to place the rope braking apparatus in a narrow space .

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications , additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims .

Claims

[CLAIMS!

[Claim l]

A rope braking apparatus for an elevator, including a power transmission section for transmitting to a locking section a rotation force generated by a motor (23 ) fastened to a housing, an operating section for braking and releasing rope by power transmitted, and the locking section having a fixed plate ( 12 ) secured to the housing and a first movable plate ( 13) , the rope braking apparatus being operated in response to a signal from an elevator controller to brake the rope wound on a traction pulley in a machine room having a traction machine, wherein the power transmission section comprises the motor (23 ) , a driving gear (27 ) driven by the motor (23 ) through a reduction gear (23a ) , a driven gear (29) rotated by the driving gear (27 ) to drive a camshaft (35) , and reverse rotation prevention means disposed in the driving gear (27 ) for preventing a rotation force generated by the camshaft ( 35 ) from being transmitted to a shaft of the motor (23) ; the locking section comprises guide shafts ( 15 ) movably inserted through the fixed plate ( 12 ) secured to the housing, the first movable plate ( 13 ) and a second movable plate ( 14 ) respectively secured to both ends of the guide shafts ( 15) , and springs ( 38 ) fitted around the guide shafts (15 ) between the fixed plate ( 12 ) and the first movable plate to accumulate a pressing force when the first movable plate ( 13 ) is moved toward the fixed plate ( 12 ) ; and the operating section comprises a trigger lever ( 34 ) actuated by an actuator (32 ) , a rotation plate (33) secured to one end of the camshaft ( 35 ) and having a stepped portion ( 33a) with which a latch portion ( 34a) of the trigger lever (34 ) is engaged, and eccentric cams (36 ) secured to the camshaft ( 35 ) to push the first movable plate ( 13) by rotation of the camshaft ( 35) , the springs ( 38 ) being compressed by movement of the first movable plate ( 13 ) to generate a returning force .

[Claim 21

The rope braking apparatus according to claim 1 , wherein the first movable plate ( 13) is defined with pockets ( 13a ) for accommodating the springs (38 ) and auxiliary springs ( 38a) , the pockets ( 13a ) being opened toward the fixed plate ( 12 ) and extending away from the fixed plate ( 12 ) , and the springs (38 ) and the auxiliary springs ( 38a) being supported between bottoms of the pockets ( 13a ) and the fixed plate ( 12 ) .

[Claim 3]

The rope braking apparatus according to claims 1 or 2 , wherein, when viewed from a rotation center of the camshaft ( 35 ) , the stepped portion ( 33a) of the rotation plate (33 ) is formed at a position which is rotated from a top dead center of the eccentric cam (36 ) by about 0.2°~15° in a rotation direction of the camshaft ( 35 ) .

[Claim 4 ] The rope braking apparatus according to claims 1 or 2 , wherein a signal indicative of a position of the eccentric cam (36) or the camshaft ( 35 ) (a signal for recognizing whether or not the eccentric cam (36) reaches the top dead center) is obtained by a sensor (30 ) for sensing a rotated position of the rotation plate ( 33 ) which is integrated with the camshaft ( 35) , to control the motor (23 ) and the actuator ( 32 ) .

[Claim 5]

The rope braking apparatus according to claims 1 or 2 , wherein the latch portion ( 34a) of the trigger lever

( 34 ) is provided with a rotation roller ( 34b) for minimizing frictional resistance when brought into contact with the stepped portion (33a) of the rotation plate ( 33 ) .

[Claim β] The rope braking apparatus according to claims 1 or 2 , wherein the first movable plate ( 13) is provided with rollers (37 ) for minimizing frictional resistance when brought into contact with the eccentric cams ( 36 ) . ΪClaim 7]

The rope braking apparatus according to claims 1 or 2 , wherein the reverse rotation prevention means comprises a rotating body (27a) which is formed integrally with the shaft of the motor (23) and is defined with pawl receiving grooves , a circumferential inner surface of the driving gear (27 ) which is defined with pawl engagement grooves , and pawls (26b) which are respectively inserted into the pawl receiving grooves to be capable of being engaged with the pawl engagement grooves , whereby the reverse rotation prevention means serves as a pawl type one-way clutch so that, at the moment and immediately after the eccentric cam ( 36 ) passes the top dead center, a rotation force of the camshaft ( 35 ) which is generated by application of the returning force of the springs (38 ) to the camshaft (35 ) is prevented from being transmitted to the shaft of the motor (23) .

ΪClaim 8]

The rope braking apparatus according to claims 1 or 2 , wherein the reverse rotation prevention means comprises a rotating body (27a) which is rotated integrally with the shaft of the motor (23) in a clockwise direction and is formed with teeth on a circumferential outer surface thereof, and rollers (26c) which are respectively inserted into the grooves defined between the teeth and roll between the rotating body (27a) and a circumferential inner surface of the driving gear (27 ) , whereby the reverse rotation prevention means serves as a roller type one-way clutch .

[Claim 9]

The rope braking apparatus according to claims 1 or 2 , wherein the reverse rotation prevention means comprises eccentric balls ( 26d) each of which has a portion having a linearly increasing radius of curvature and rolls between a rotating body (27a) and a circumferential inner surface of the driving gear (27 ) , whereby the reverse rotation preventi on means serves as an eccentric ball type one-way clutch .

[Claim 10l The rope braking apparatus according to claims 1 or

2, wherein an idle gear (28 ) is interposed between the driving gear (27 ) and the driven gear (29) , and the reverse rotation prevention means is installed in the idle gear

( 28 ) .

[Claim ll]

The rope braking apparatus according to claim 2 , wherein a reinforcing plate ( 13b) for preventing deformation of the first movable plate ( 13 ) is secured to projections of the first movable plate ( 13 ) in which the pockets ( 13a) are respectively defined.

[Claim 12]

The rope braking apparatus according to claim 11 , wherein through-holes ( 13c) for preventing interference between the reinforcing plate ( 13b) and the eccentric cams ( 36) are defined through the reinforcing plate ( 13b) .