Emergency stop device for elevator

Abstract: An elevator apparatus comprising a moving cage (2) capable of ascending and descending along a guide rail (5, 6) in an elevator shaft (1), a drive unit (9) for moving the moving cage (2) up and down, and an emergency stop device (20) adapted emergently to stop the moving cage (2) when the cage descends at an extraordinary speed, the emergency stop device (20) including an emergency stop mechanism (14) provided at the lower end portion of the moving cage (2) and adapted to engage the guide rail (5, 6), thereby emergently stopping the moving cage (2), a link mechanism (28) provided at the lower end portion of the moving cage (2) so as to be located close to the emergency stop mechanism (14) and adapted to actuate the emergency stop mechanism (14) on receiving an external input, and a speed detector (23) for detecting the descent of the moving cage (2) at the extraordinary speed and applying the external input to the link mechanism correspondingly.

Description: The present invention relates to an elevator provided with an emergency stop device. A conventional elevator apparatus comprises an elevator shaft, formed extending vertically in a building, and a machine room, which is located right over the shaft and stores a prime mover and the like. This elevator apparatus further comprises a sheave located in the shaft and driven by means of the prime mover, a moving cage disposed in the shaft and connected to one lower end of a rope that is wound on the sheave, and a counterweight connected to the other lower end of the rope and balanced with the cage. The cage is moved up and down by rotating the sheave in the machine room. The moving cage and the counterweight are guided by means of guide rails arranged in the elevator shaft. US 2 581 297 discloses an elevator according to the preamble of claim 1. With the increase of high-rise buildings, the operating speed of elevators is becoming higher and higher, thus requiring a satisfactory safe measure. To cope with this, the conventional elevator apparatus is provided with an emergency stop device that can stop the moving cage safely and securely in case the cage suddenly descends at a speed higher than its rated speed for any reason. The emergency stop device comprises a governor, a rope passed through the governor and adapted to be restricted in motion when the moving cage descends at a speed higher than its rated speed, and a stop mechanism attached to the cage and capable of braking and stopping the cage. The stop device further comprises a link mechanism, which connects the rope and the stop mechanism and actuates the stop mechanism through the medium of the relative movements of the rope and the cage when the rope is restricted in motion. The emergency stop mechanism, which is located at the lower end portion of the moving cage, includes a holding member having a V-shaped slit gradually spreading downward and a stopper member slidable in the slit. The emergency stop device brakes the moving cage in a manner such that the stopper member moves up to cause each guide rail to be held tight in the slit of the holding member by an wedge effect. The link mechanism includes a driving lever, which is attached to the upper part of the moving cage and fixed to the rope extending from the governor, and a lift rod connecting the driving lever and the slit member of the stop mechanism. The lift rod extends long in the height direction of the cage, and serves to pull up the slit member of the stop mechanism at the lower end of the cage, thereby actuating the stop mechanism. Further, the link mechanism is provided with a limit switch, which detects the actuation of the link mechanism and outputs a winding machine stop command signal. Once the limit switch detects a shift of the driving lever and delivers the stop command signal to a control device, it continues to output the command signal. In canceling an emergency stop state and rerunning the elevator apparatus, the guide rail is released from the hold in the slit by means of the stopper member by, for example, pulling up the moving cage, whereby the restraint on the ascent and descent of the cage by the emergency stop device is removed. An operator gets on the moving cage and directly restores the limit switch to its initial state, thereby enabling the elevator apparatus to be rerun. In the conventional elevator apparatus described above, the link mechanism is attached to the upper end portion of the moving cage, so that a relatively long member is used as the lift rod for connecting the stopper member of each emergency stop device and the driving lever. It is difficult, therefore, to keep the lift mechanism in an assembled state when it is shipped from the factory. Thus, the lift mechanism must be assembled during construction work in the building. Since the elevator shaft is relatively narrow, assembling the link mechanism in the building requires much time and labor. Since the lift rod is a relatively long member, moreover, each link mechanism must be subjected to fine adjustment as it is assembled, in order to secure normal operation. Thus, the construction work entails high costs. If the link mechanism is attached to the lower end portion of the moving cage with the lift rod shortened so that the mechanism can be in the assembled state as it is shipped from the factory, furthermore, the limit switch must be also attached to the lower end portion of the cage. If the limit switch is attached to the lower end portion of the moving cage, it is difficult for the operator to restore the limit switch directly to the initial state in rerunning the elevator apparatus after once actuating the emergency stop device to restrain the cage from ascending or descending. Thus, the elevator apparatus cannot be rerun with ease. Accordingly, a first object of the present invention is to provide an elevator apparatus capable of reduction in the costs of construction and the like. A second object of the invention is to provide an elevator apparatus capable of being easily rerun after an emergency stop device is once actuated to restrain a moving cage from ascending or descending. According to the present invention, there is provided an elevator apparatus comprising a moving cage capable of ascending and descending along a guide rail in an elevator shaft, a drive unit for moving the moving cage up and down, and an emergency stop device adapted emergently to stop the moving cage when the cage descends at an extraordinary speed. The emergency stop device includes an emergency stop mechanism provided at the lower end portion of the moving cage and adapted to engage the guide rail, thereby emergently stopping the moving cage, a link mechanism provided at the lower end portion of the moving cage so as to be located close to the emergency stop mechanism and adapted to actuate the emergency stop mechanism on receiving an external input, and a speed detector for detecting the descent of the moving cage at the extraordinary speed and applying the external input to the link mechanism correspondingly. In an aspect of the invention, the speed detector includes a rope, connected to the link mechanism and capable of normally moving at the same speed as the moving cage, and a rope binding mechanism adapted to bind the rope when the moving cage descends at the extraordinary speed. In another aspect of the invention, the drive unit and the second detector are fixed to a guide rail in the elevator shaft. In still another aspect of the invention, the emergency stop device further includes a detector located close to the link mechanism and used to detect the operation of the link mechanism for emergently stopping the moving cage, drive unit operation prohibiting means for prohibiting the operation of the drive unit in accordance with the result of detection by the detector, and operation prohibition canceling means for canceling the prohibition on the operation of the drive unit by the drive unit operation prohibiting means. In this case, the operation prohibition canceling means may be located at the upper end portion of the moving cage or in a position accessible to an elevator hall. In another aspect of the invention, the emergency stop device further includes a connecting member having one end connected to the link mechanism and the other end connected to the rope, the one end of the connecting member extending downward along the rope and the other end upward. In a further aspect of the invention, the emergency stop mechanism is provided at each of two opposite side portions of the moving cage, and the link mechanism includes a driving lever for actuating one emergency stop mechanism and a driven lever for actuating the other emergency stop mechanism, the driving and driven levers being connected to each other by means of a connecting rod. Preferably, in this case, the link mechanism includes a guide member for allowing the connecting rod only to move in the axial direction thereof. Preferably, moreover, the link mechanism includes an urging member attached to the connecting rod and capable of urging the driving lever and the driven lever in the direction to cancel an emergency stop state. This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features. The invention can be more fully under stood from the following detailed description when taken in conjunction with the accompanying drawings, in which: FIG. 1A is a schematic view showing an elevator according to an embodiment of the present invention; FIG. 1B is a front view showing the lower end portion of a moving cage; FIG. 2 is a view showing an arrangement of an elevator apparatus according to a first embodiment of the invention; FIG. 3 is a side view showing the principal part of the elevator apparatus according to the first embodiment; FIG. 4 is a side view showing a limit switch according to the first embodiment; FIG. 5 is a side view showing an emergency stop device according to the first embodiment; FIG. 6 is a side view showing the way the emergency stop device shown in FIG. 5 operates; FIG. 7 is a side view showing the principal part of an elevator apparatus according to a second embodiment of the invention; and FIG. 8 is a side view showing the principal part of a modification of the elevator apparatus according to the second embodiment. Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Referring first to FIG. 1A, there will be described the general construction of a machine-room-less elevator. In an elevator shaft 1 provided in a building, a moving cage 2 and a counterweight 3 are suspended and balanced by means of a rope 4. Guide rails 5 and 6 for vertically guiding the moving cage 2 are arranged on the right- and left-hand sides, respectively, of the shaft 1, while counterweight guide rails 7 and 8 for guiding the counterweight 3 for up-and-down motion are arranged behind the left-hand guide rail 6. On the left-hand side of the upper part of the interior of the elevator shaft 1, a drive unit 9 (a winding device or traction machine) is set in a narrow space between an inner wall of the shaft 1 and a side wall of the moving cage 2. The drive unit 9, which is fixed to the guide rails 6 and 7, can wind up the rope 4, thereby relatively moving the cage 2 and the counterweight 3 up and down. The drive unit 9 may be fixed to the guide rails 7 or 8. Thus, one end portion of the rope 4, which is wound up by the drive unit 9, is fixed to a rope hitch 10 that is attached to the upper end portion of the guide rail 5, while the other end portion is fixed to a rope hitch 11 that is attached to the upper end portion of the counterweight guide rail 8. The middle portion of the rope 4 is passed around a lower sheave 12 that is attached to the lower part of the moving cage 2, extends through the drive unit 9, and is then passed around a counterweight sheave 13 that is attached to the upper part of the counterweight 3. As shown in FIG. 1B, emergency stop mechanisms 14 are provided on the bottom portion of the cage 2. The mechanisms 14 serve to stop the moving cage 2 safely and securely in case the cage 2 suddenly falls at a speed higher than its rated speed for any reason. As described in detail later, the mechanisms 14 brake and compulsorily stop the cage 2 in a manner such that stopper members are driven like wedges between the cage 2 and the guide rail 6. Referring now to FIG. 2, there will be described an arrangement of an emergency stop device 20 that includes the emergency stop mechanisms 14. The emergency stop device 20 comprises a governor 23 held on the guide rails 5 or 6 for the moving cage 2 by means of a bracket or the like in the elevator shaft 1, an endless rope 24 passed around a sheave 22 of the governor 23, a tensioner 25 attached to the lower end of the rope 24 and capable of applying a predetermined tension to the rope 24. The device 20 further comprises a link mechanism 28, which is attached to the lower end portion of the cage 2 and connects the rope 24 and the emergency stop mechanisms 14, and a limit switch 29 for detecting a stop state by the operation of the link mechanism 28. As the moving cage 2 ascends or descends, the rope 24, which is connected to the cage 2 by means of the link mechanism 28, moves at the same speed as the cage 2, whereupon the sheave 22 of the governor 23 rotates. If the cage 2 descends at an extraordinary speed from any cause, however, the governor 23 is actuated to restrain the action of the rope 24. Thereupon, one end portion of the link mechanism 28 is pulled up relatively, so that the emergency stop mechanisms 14 are actuated. FIGS. 5 and 6 are enlarged views showing one of the emergency stop mechanisms 14. The emergency stop mechanism 14 includes a holding member 33, which is attached to a support base 31 on the lower end of the moving cage 2 and has a V-shaped slit 33a that opens downward. The guide rail 5 (or 6) is passed through the slit 33a of the member 33. A stopper member 34 is interposed between the slit 33a and the guide rail 5 so that the moving cage 2 is braked on the rail 5 by an wedge effect. The stopper member 34 is held by a support member 35 shown in FIG. 5. Braking action is caused by pulling up the support member 35 by means of the link mechanism 28. As shown in FIGS. 2 and 3, on the other hand, the link mechanism 28 comprises a driving lever 41 for actuating the one emergency stop mechanism 14 that is fixed to the rope 24, a driven lever 42 for actuating the other emergency stop mechanism 14 that is connected to the lever 41 by means of a connecting rod 43, and relatively short connecting members 44 connecting the levers 41 and 42 and the respective support members 35 of the two emergency stop mechanisms 14. The driving lever 41 and the driven lever 42 are rockable in the vertical direction around points A and B, respectively. The connecting rod 43, which connects the levers 41 and 42, are allowed only to move in its axial direction by a guide member 45 that is fixed to the support base 31. Inserted in the axial middle portion of the rod 43, moreover, is a spring 46 for urging the levers 41 and 42 to lower the connecting members 44 (in the direction not to actuate the emergency stop mechanisms 14). As shown in FIG. 4, the limit switch 29, which is attached to the link mechanism 28, includes a switch body 51 and a contact 52 that can project from and draw back into the body 51. In an initial state, the contact 52 projects from the switch body 51. The limit switch 29 is mounted on the support base 31 in a manner such that the contact 52 touches the driving lever 41 in the initial state. As the lever 41 rocks, the contact 52 of the switch 29 projects from or draws back into the switch body 51. The limit switch 29 is connected to a control device 21 shown in FIG. 2. When the contact 52 recedes for a predetermined displacement or further, the switch 29 delivers a stop command signal for the drive unit 9 to the control device 21. Preferably, the predetermined displacement of the contact 52 by which the switch 29 outputs the stop command signal should be a displacement obtained immediately before the stopper member 34 comes into contact with the inner surface of the slit 33a of the holding member 33 (see FIG. 6). The limit switch 29 ceases to deliver the stop command signal when the stopper member 34 is moved away from the inner surface of the slit 33a toward the region under the moving cage 2 after the switch 29 once delivers the stop command signal to the control device 21 as the driving lever 41 is shifted. Preferably, the limit switch 29 should be provided with display means, such as an illuminant 53 shown in FIG. 4 that glows as it delivers the stop command signal. In this case, an operator or the like can easily visually determine whether or not the stop command signal is delivered from the switch 29. On the other hand, the control device 21 is a processing element provided with a microprocessor or the like, and serves to control the whole elevator apparatus. The control device 21 comprises a drive unit stop command section 54 for stopping the drive unit 9 and a drive unit operation prohibiting section 55 for maintaining the stop state of the drive unit 9. The command section 54 disconnects the drive unit 9 from the power supply in response to the stop command signal from the limit switch 29. Once the command section 54 cuts off the power supply, prohibiting section 55 maintains the resulting state. Thus, even when the limit switch 29 ceases to deliver the stop command signal, the prohibiting section 55 keeps the drive unit 9 disconnected from the power supply and stopped until the reset switch 18 is operated. When the operator operates the reset switch 18 (drive unit operation prohibition canceling means) to apply a canceling command signal to the input of the control device 21, the device 21 supplies electric power to the drive unit 9, thereby enabling the elevator apparatus to be rerun. The following is a summary of processes for rerunning the elevator apparatus. First, the moving cage 2 is pulled up, for example, to release the guide rail 5 from the hold between the stopper member 34 and the slit 33a, thereby removing the restraint of the emergency stop mechanism 14 on the up-and-down motion of the cage 2. When the mechanism 14 is released in this manner, the contact 52 of the limit switch 29 is restored to its initial state, so that the switch 29 ceases to deliver the stop command signal. In this state, however, the drive unit 9 is disabled by the action of the prohibiting section 55. Thereupon, the operator carries out various inspections and then operates the reset switch 18 to enable rerun of the drive unit 9. The switch 18 is set on a control panel in the door box of a hall door 47 on the uppermost floor, for example. An advantage of the present invention arranged in this manner is that the limit switch 29 ceases to deliver the stop command signal as an emergency stop state is canceled by pulling up the moving cage 2, for example, so that the elevator apparatus can be rerun with ease although the emergency stop mechanisms 14 and the link mechanism 28 are provided at the lower end portion of the cage 2. Since the link mechanism 28 can be located at the lower end portion of the moving cage 2, moreover, it can be in an assembled state when it is shipped from the factory. Thus, the costs of construction work can be lowered. The limit switch 29 delivers the stop command signal immediately before the emergency stop mechanisms 14 restrain the moving cage 2 from moving. If the mechanisms 14 operate wrongly due to vibration attributable to ascent or descent of the cage 2, for example, the drive unit 9 can be prevented from being actuated to loosen the rope 24 that suspends the cage 2 or to cause the rope 24 to slip out of a traction sheave of the drive unit 9. Since the connecting rod 43 that connects the two emergency stop mechanisms 14 is guided in axial slide by the guide member 45, moreover, the mechanisms 14 can securely operate in associated with each other. FIGS. 7 and 8 show a second embodiment of the invention. In FIGS. 1 to 8, like reference numerals refer to the same components throughout the several views. According to the present embodiment, as shown in FIGS. 7 and 8, a driving lever 41 of a link mechanism 28 is connected to a governor rope 24 by means of an extension lever 60. The lever 60 is a belt-shaped plate, one end portion 60a of which is rockably connected to the driving lever 41, and the other end portion 60b of which extends above the one end portion 60a and is rockably connected to the rope 24 in a position higher than the position of connection with the lever 41. Preferably, the extension lever 60 should be connected to the governor rope 24 by means of a first connecting portion 61 at the other end portion 60b and a second connecting portion 62 at the central portion, as shown in FIG. 7. The first and second connecting portions 61 and 62 connect the lever 60 and the rope 24 for rocking motion. According to the present embodiment, the driving lever 41 of the link mechanism 28 is connected to the governor rope 24 by means of the extension lever 60 that extends vertically from the lever 41. Accordingly, a space 49 between the moving cage 2 at its bottom dead center and the floor surface of the elevator shaft 1 can be restricted. Thus, the depth of a pit for the shaft 1 can be reduced, so that the costs of construction of the elevator apparatus can be restrained from increasing. In the case where the extension lever 60 and the governor rope 24 are connected to each other by means of the first and second connecting portions 61 and 62 that are rockable, as shown in FIG. 7, the lever 60 can be prevented from falling so that wrong operation of the emergency stop device is securely restrained if the lever 60 is urged to fall by a tension on the rope 24 and the mass of the lever 60, as shown in FIG. 8.

Claims: An elevator apparatus comprising: (a) a drive unit (9) for ascending or descending a cage (2) along a guide rail (5,6) in an elevator shaft (1); (b) a speed detector (23) for detecting the descending speed of the cage (2); (c) an emergency stop mechanism (14) provided under said cage (2) for engaging said guide rail (5,6) to urgently stop said cage (2); (d) a link mechanism (28) provided under said cage (2) for actuating said emergency stop mechanism (14) when said speed detector (23) descends at an extraordinary high speed; (e) a limit switch (29), located close to said link mechanism, for detecting the operation of said link mechanism (28) for urgently stopping said cage (2) and outputting a stop signal; and (f) means (21, 54) for prohibiting the operation of said drive unit (9) when the limit switch (29) outputs the stop signal; characterized in that : (g) said prohibiting means has means (55) that keeps prohibition of the operation of said drive unit (9) once the limit switch (29) outputs the stop signal; (h) and that there is a reset switch (18) for cancelling the prohibition of the operation of said drive unit (9). The elevator apparatus as in claim 1 wherein said speed detector (23) comprises: a rope (24) connected to said link mechanism and capable of normally moving at the same speed as said cage (2); and a rope binding mechanism (23) configured to bind said rope when said cage descends at the extraordinary speed. The elevator apparatus as in claim 1 and wherein said drive unit (9) is fixed to the guide rail (5,6). The elevator apparatus as in claim 1 and wherein said speed detector (23) is fixed to the guide rail. The elevator apparatus as in claim 1 and wherein said reset switch (18) is located in a position accessible to an elevator hall. The elevator apparatus as in claim 1 and wherein said limit switch (29) comprises: a display (53) for displaying the establishment of an emergency stop state by said emergency stop mechanism (14). The elevator apparatus as in claim 1 further comprising: a connecting member (60) having one end connected to said link mechanism (28) and another end connected to said rope (24), the one end of said connecting member extending downward along said rope and said another end extending upward. The elevator apparatus as in claim 1 further comprising: a pair of said emergency stop mechanisms (14) provided at each of two opposite side portions of said cage (2); and wherein said link mechanism (28) comprises: a driving lever (41) for actuating one emergency stop mechanism (14); a driven lever (42) for actuating the other emergency stop mechanism (14); and a connecting rod (43) which connects said driving lever to said driven lever. The elevator apparatus as in claim 8 wherein said link mechanism (28) comprises: a guide member (45) for restricting movement of said connecting rod only to an axial direction of the connecting rod. The elevator apparatus of claim 8 wherein said link mechanism (28) comprises: an urging member (46) attached to said connecting rod for urging said driving lever (41) and said driven lever (42) in a direction to cancel an emergency stop state.

Inventors: SASAKI HIROTADA, SASAKI, HIROTADA, Sasaki, Hirotada, Intellectual Property Division
Applicants: TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA
Application year: 1999
Main classification: B66B5
IPC codes: B66B5, B66B1