GB2476704A

GB2476704A - An elevator safety system

Info

Publication number: GB2476704A
Application number: GB1018278A
Authority: GB
Inventors: Chris Moore; Mark Spencer
Original assignee: ELEVATOR EQUIPMENT Ltd
Current assignee: ELEVATOR EQUIPMENT Ltd
Priority date: 2010-10-29
Filing date: 2010-10-29
Publication date: 2011-07-06
Also published as: GB201018278D0

Abstract

An elevator safety system comprises a buffer 22 secured in use to a sidewall 12 of an elevator shaft 10. The buffer 22 is movable between a retracted position against the sidewall 12, alongside an elevator car 14, to permit unimpeded upward and downward movement of the elevator car, and an extended position in which it prevents downward movement of the elevator car 14 beyond a predetermined distance above a shaft pit floor 28. The system includes a drive arrangement 34 operable to move the buffer 22 between the retracted and extended positions and a controller 42 operable to selectively control the operation of the drive arrangement 34 and positioned such that the drive arrangement 34 can be operated remotely, from outside the elevator shaft 10. The controller may be located outside the shaft or just inside the shaft so that it can be operated from outside the shaft. The buffer preferably comprises a four-bar parallelogram linkage defined by a rigid prop, a pair of links 30, 32 and a frame 24 for mounting to a sidewall of the shaft. The buffer thus has a vertical orientation whether in use, being deployed, or retracted. The drive arrangement 34 may comprise a winch or a geared arrangement.

Description

TITLE

Elevator safety systems

FIELD OF THE INVENTION

The present invention relates to elevator safety systems, and more particularly to an elevator safety system which prevents downward movement of an elevator car into an elevator shaft pit to protect a person working in the shaft pit.

BACKGROUND TO THE iNVENTION

A typical elevator system comprises an elevator shaft, having a shaft pit and a shaft head, and an elevator car which is movable vertically along the elevator shaft between the shaft pit and the shaft head. Movement of the elevator car is typically effected by an electric motor and cable system or by a hydraulic system.

It is sometimes necessary for an operative to carry out maintenance and repair work on an elevator system and this can require the operative to work in the shaft pit underneath a stationary elevator car. Although it is normal to deactivate the electric motor and cable system or the hydraulic system so that the elevator car cannot move downwardly into the shaft pit and thereby trap or crush the operative, it is common to additionally utilise an elevator safety system in the form of a buffer (commonly known as a pit prop) which acts as a back-up safety device to prevent any unexpected downward movement of the elevator car into the shaft pit. Such unexpected movement could, for example, occur due to leakage or compression of hydraulic fluid in a hydraulically operated elevator system.

One type of conventional elevator safety system employs a buffer which must be manually mounted on the floor of the shaft pit by an operative so that the buffer extends upwardly into the elevator shaft, towards the elevator car. A mounting structure needs to be provided on the pit floor to securely mount the buffer in position and this structure can present a trip hazard to an operative working in the shaft pit.

In some conventional elevator safety systems of the above type, an operative is required to enter the shaft pit, below an elevator car, to mount the buffer in the mounting structure on the pit floor. This is potentially very dangerous as the operative could become trapped or crushed in the shaft pit prior to installation of the buffer, in the event of unexpected downward movement of the elevator car. In other conventional elevator safety systems of the above type, an operative is required to lean into the shaft pit, through the lowermost shaft doors, to mount the buffer in the mounting structure on the pit floor. Again, this is dangerous as there is potential for the operative to fall into the shaft pit through the open shaft doors, and possibly sustain a serious injury as a result of such a fall.

There is, therefore, a need for an elevator safety system which overcomes the drawbacks associated with conventional elevator safety systems such as those described above.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided an elevator safety system comprising:-a buffer secured in use to a sidewall of an elevator shaft and movable between: a retracted position in which it lies adjacent the sidewall, alongside an elevator car, to permit unimpeded upward and downward movement of the elevator car along the elevator shaft; and an extended position in which it prevents downward movement of the elevator car beyond a predetermined distance above a pit floor at the base of the elevator shaft; a drive arrangement operable to move the buffer between the retracted and extended positions; and a controller operable to selectively control the operation of the drive arrangement and positioned such that the drive arrangement can be operated remotely, from outside the elevator shaft.

According to a second aspect of the present invention, there is provided a kit of components for an elevator safety system, the kit including the following, or components therefor:-a buffer securable in use to a sidewall of an elevator shaft; a drive arrangement operable in use to move the buffer between a retracted position in which it lies adjacent the sidewall of an elevator shaft and an extended position in which it prevents downward movement of an elevator car along an elevator shaft; and a controller operable to selectively control the operation of the drive arrangement and arranged to be positioned, in use, such that the drive arrangement can be operated remotely, from outside an elevator shaft.

The elevator safety system allows an operative to work safely in the shaft pit, at the bottom of the elevator shaft below the elevator car, without fear of being crushed by the elevator car or trapped in the shaft pit because when the buffer is in the extended position, unexpected downward movement of the elevator car, beyond a predetermined distance above the pit floor of the shaft pit, is prevented. By providing a remotely operable drive arrangement for the buffer and a controller which is positioned so that it can be operated from outside the elevator shaft, the buffer can be moved remotely, under the action of the drive arrangement, from the retracted position to the extended position before an operative enters the shaft pit and from the extended position to the retracted position after an operative has exited the shaft pit.

This ensures that safety is maximised because at no time does the operative need to be present in the shaft pit without the buffer being in the extended position.

Safety is further enhanced because the buffer is secured to the sidewall of the elevator shaft, rather than the pit floor of the shaft pit. This eliminates the requirement to provide a mounting structure on the pit floor and thereby eliminates what could otherwise be a potential trip hazard.

The buffer typically includes lower and upper ends. The aforesaid predetermined distance above the pit floor, beyond which downward movement of the elevator car is prevented, is determined by the vertical height of the buffer, in other words the distance between the lower and upper ends.

The lower end of the buffer may be spaced from the pit floor when the buffer is in the retracted position. The lower end of the buffer may contact the pit floor when the buffer is in the extended position. The contact between the lower end of the buffer and the pit floor when the buffer is in the extended position ensures that unwanted downward movement of the elevator car, along the elevator shaft beyond the aforesaid predetermined distance above the pit floor, is prevented as soon as the elevator car contacts the upper end of the buffer.

The buffer may comprise a rigid elongate prop member. Any suitable prop member may be used provided that it will not buckle if compressed against the pit floor by the weight of an elevator car.

The buffer may have a substantially vertical orientation, in use, in both the retracted and extended positions. This ensures that the buffer can lie generally parallel to the sidewall of the elevator shaft when in the retracted position so that movement of the elevator car through the elevator shaft is not impeded and also ensures that the buffer is in the optimum orientation in the event of unwanted downward movement of the elevator car through the elevator shaft. The orientation of the buffer may remain substantially vertical at all positions between the retracted and extended positions.

The elevator safety system may include a frame which may be mounted on the sidewall of the elevator shaft to secure the buffer to the sidewall of the elevator shaft.

The elevator safety system may include a plurality of link members which may be connected between the frame and the buffer. At least two link members are preferably provided. The link members may permit movement of the buffer between the retracted and extended positions under the action of the drive arrangement.

The frame, the at least two link members and the buffer may act as a four-bar linkage, and more particularly as a parallelogram linkage thereby ensuring that the orientation of the buffer is at all times substantially vertical.

The drive arrangement is typically connected to one of the link members and is operable to move the link member. Movement of the link member by the drive arrangement effects movement of the buffer between the aforesaid retracted and extended positions. The link member thus acts as a driving link.

The drive arrangement may comprise a winch device. The winch device may include a winch cable which may be connected to one of the link members and a motor which may be operable to drive the winch cable. The motor is preferably an electric motor.

The drive arrangement may include one or more pulleys and the winch cable may extend between the motor and link member via the one or more pulleys.

The drive arrangement may include a motor control switch which may be operable to deactivate the motor when the buffer is in the retracted andlor extended positions. The motor control switch may include a contactor which is operated when the buffer is in the retracted and extended positions, operation of the contactor providing said deactivation of the motor.

The controller is preferably positioned in use outside the elevator shaft. The controller could, however, be positioned in use inside the elevator shaft in a position in which it can be operated from outside the elevator shaft by an operative, for example by opening the shaft doors. In the latter case, the shaft doors may only need to be opened by a small amount to permit access to the controller, thus avoiding any possibility of an operative falling into the elevator shaft. The controller could be a wired controller or could be a wireless controller and possibly a portable wireless controller.

DRAWiNGS Figure 1 is a diagrammatic side view of an elevator safety system in which a buffer of the system is in a retracted position; Figure 2 is a diagrammatic front view of the elevator safety system of Figure 1 with the buffer in the retracted position; Figure 3 is a diagrammatic side view of the elevator safety system of Figures 1 and 2 with the buffer in a position between the retracted position and an extended position; and Figure 4 is a diagrammatic side view of the elevator safety system of Figures 1 to 3 with the buffer in the extended position.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings.

Part of a typical elevator system is illustrated in the drawings. The elevator system includes an elevator shaft 10, having sidewalls 12, and an elevator car 14 movable upwardly and downwardly along the elevator shaft 10 in a vertical direction.

The elevator shaft 10 includes a shaft pit 16 at its lower end and a shaft head (not shown) at its upper end. Shaft doors 18, which are the vertically lowest shaft doors in the elevator shaft 16, provide access to the elevator car 14 during normal operation of the elevator system and provide access to the shaft pit 16 when the elevator car 14 is raised to a vertical position above the lowermost shaft doors 18. It will be understood that further shaft doors are provided at a plurality of vertically higher positions along the elevator shaft 10 to allow access to the elevator car 14 from different floors of a building in which the elevator system is installed.

An elevator safety system 20 for use with the elevator system comprises a buffer 22 which is mounted on one of the sidewalls 12 of the elevator shaft 10 by a frame 24.

The frame 24 includes fixing brackets 26 which enable it to be mounted directly on the sidewall 12 using suitable fixings.

The buffer 22 is mounted on the frame 24 by two pairs of link members 30, 32 which enable the buffer 22 to move relative to the frame 24, and hence relative to the -.7-sidewall 12, between a retracted position shown best in Figure 1 and an extended position shown in Figure 4. In the retracted position, the buffer 22 lies flat against the frame 24, and hence adjacent to the sidewall 12, and this enables the elevator car 14 to move freely along the elevator shaft 10 in the vertical direction. In the extended position, the buffer 22 extends into the elevator shaft 10 to limit the downward movement of the elevator car 14 along the elevator shaft 10 and prevent unwanted downward movement of the elevator car 14 beyond a predetermined distance above a pit floor 28 of the shaft pit 16.

The predetermined distance above the pit floor 28, below which the elevator car 14 cannot travel, is determined by the height h of the buffer 22 (see Figure 4), that is the distance between lower and upper ends 22a, 22b of the buffer 22. The height h of the buffer 22 is selected to provide a safe working space for an operative carrying out maintenance and servicing tasks in the shaft pit 16 so that there is no possibility of the operative being crushed or injured by the elevator car 14 when in its lowermost position, in contact with the upper end 22b of the buffer 22. The height h of the buffer 22 is also selected so that the elevator car 14 does not block access to the lowermost shaft doors 18 when in its lowermost position, in contact with the upper end 22b of the buffer 22. This ensures that an operative working in the shaft pit 16 can exit the shaft pit 16, via the shaft doors 18, in the event of unexpected downward movement of the elevator car 14 to its lowermost position in the elevator shaft 10.

The buffer 22 is a generally elongate rigid prop member and maintains a vertical orientation at all times, both in the retracted and extended positions and at all positions therebetween. The lower end 22a of the buffer 22 is spaced from the pit floor 28 when the buffer 22 is in the retracted position and contacts the pit floor 28 when the buffer 22 is in the extended position. Contact between the lower end 22a of the buffer 22 and the pit floor 28 is advantageous when the buffer 22 is in the extended position as it ensures that any unwanted downward movement of the elevator car 14 is halted as soon as the elevator car 14 contacts the upper end 22b of the buffer 22, there being no risk of the buffer 22 itself moving downwardly under the weight of the elevator car 14. The construction of the buffer 22 must, of course, be sufficient to withstand compression or buckling between the pit floor 28 and the elevator car 14 under the weight of the elevator car 14. The buffer 22 is typically constructed from steel and has a box section.

As indicated above, the two pairs of link members 30, 32 allow the buffer 22 to move between the retracted and extended positions. The frame 24, link members 30, 32 and buffer 22 together form a four-bar, parallelogram, linkage. This ensures that the buffer 22 remains at all times parallel to the sidewall 12 of the elevator shaft 10 and, hence, in a vertical orientation.

A drive arrangement 34 in the form of a winch device 36 is operable to move the buffer 22 between the retracted and extended positions. The winch device 36 includes a winch cable 38 which is connected at one end to one of the link members 30 and at the other end to a winding drum connected to an electric motor 40 which forms part of the winch device 38. In the illustrated embodiment, the winch cable 38 is connected between the winding drum and the link member 30 via a pulley 39.

It will be understood that as the winch cable 38 is unwound from the winding drum by operation of the electric motor 40, the link members 30, 32 are able to pivot about the frame 24 in an anti-clockwise direction as viewed in Figures 3 and 4. The buffer 22 is thus able to move from the retracted position to the extended position under its own weight until further movement is prevented by contact of the lower end 22a of the buffer 22 with the pit floor 28. The drive arrangement 34 includes a motor control switch 41 which is operable to deactivate the electric motor 40 when the buffer 22 is in either the retracted position or the extended position. In the illustrated embodiment, the motor control switch 41 includes a contactor which detects the extreme positions of one of the link members 32 when the buffer 22 is in the retracted and extended positions and the motor control switch 41 is, thus, operable to control the operation of the electric motor 40 based on the detected position of the link member 32.

A controller 42 is provided to enable an operative to remotely control the operation of the drive arrangement 34, and specifically the operation of the electric motor 40, from a position outside the elevator shaft 10. In the illustrated embodiment, the controller 42 is mounted outside the elevator shaft 10. The electric motor 40 can, thus, be operated, using the controller 42, by an operative from outside the elevator shaft 10, without needing to open the shaft doors 18. In other, non-illustrated embodiments, the controller 42 could be located inside the elevator shaft 10 in a position in which it can be accessed by an operative from outside the elevator shaft 10.

In use, when it is necessary for an operative to perform service or maintenance tasks in the shaft pit 16, he normally operates the elevator system to raise the elevator car 14 in the elevator shaft 10 to a height above the lowermost shaft doors 18 so that he can enter the shaft pit 16 once the shaft doors 18 have been opened. Prior to opening the shaft doors 18 and entering the shaft pit 16, the operative operates the controller 42 to remotely operate the electric motor 40 of the winch device 36. This remote operation of the electric motor 40 causes the winch cable 38 to unwind, allowing the link members 30, 32 to pivot in an anti-clockwise direction about the frame 24 and thus allowing the buffer 22 to move from the retracted position best shown in Figure 1 to the extended position shown in Figure 4.

The illustrated embodiment of the elevator safety system includes safety switches 44 which deactivate the electric motor and cable system or the hydraulic system that is used to move the elevator car 14 as soon as the buffer 22 is moved from the retracted position. However, as described above, unexpected and unwanted downward movement of the elevator car 14 can sometimes occur even after such deactivation has taken place. The safety switches 44 operate when movement of the buffer 22 from the retracted position is intentional, as the winch cable 38 is unwound from the winding drum by operation of the electric motor 40, or unexpected. Two safety switches are provided for redundancy purposes.

Once the buffer 22 has reached the extended position, the electric motor 40 is deactivated by the motor control switch 41 in the manner described above. The elevator safety system is now fully operational and ensures a safe working environment in the shaft pit 16 due to the fact that the elevator car 14 cannot move -10-along the elevator shaft 10 below the upper end 22b of the buffer 22. The operative can, thus, enter the shaft pit 16, via the shaft doors 18, to carry out any necessary service or maintenance tasks.

After the operative has completed his work in the shaft pit 16, he can exit the shaft pit 16 through the same lowermost shaft doors 18 via which he previously entered the shaft pit 16. The operative can then close the lowermost shaft doors 18 before operating the controller 42 to remotely operate the electric motor 40 of the winch device 36. This remote operation of the electric motor 40 winds the winch cable 38 onto the winding drum and causes the driven link member 30, and hence the other link members, to pivot in a clockwise direction about the frame 24, thus urging the buffer 22 from the extended position shown in Figure 4 to the retracted position best shown in Figure 1. Once the buffer 22 has reached the retracted position, in which it lies adjacent the sidewall 12, the electric motor 40 is deactivated by the motor control switch 41 in the manner described above. Furthermore, the safety switches 44 are operated thereby reactivating the electric motor and cable system or the hydraulic system that is used to move the elevator car 14 so that normal operation of the elevator system can be resumed.

Although embodiments of the invention have been described in the preceding paragraphs with reference to various examples, it should be understood that various modifications may be made to those examples without departing from the scope of the present invention, as claimed.

For example, the electric motor 40 could be positioned above the lowermost link members 30, thus avoiding the need for a pulley 39 between the electric motor 40 and the driven link member 30. The winch cable 38 of the winch device 36 could be connected to one of the uppermost link members 32 rather than one of the lowermost link members 30. A drive arrangement 34 other than a winch device 36 could be used to move the buffer 22 between the retracted and extended positions. For example, a geared arrangement could be used to cause pivotal movement of one of the link members 30, 32 and, hence, to move the buffer 22 between the retracted and extended positions.

Claims

-12 -CLAIMS1. An elevator safety system comprising:-a buffer secured in use to a sidewall of an elevator shaft and movable between: a retracted position in which it lies adjacent the sidewall, alongside an elevator car, to permit unimpeded upward and downward movement of the elevator car along the elevator shaft; and an extended position in which it prevents downward movement of the elevator car beyond a predetermined distance above a pit floor at the base of the elevator shaft; a drive arrangement operable to move the buffer between the retracted and extended positions; and a controller operable to selectively control the operation of the drive arrangement and positioned such that the drive arrangement can be operated remotely, from outside the elevator shaft.
2. An elevator safety system according to claim 1, wherein a lower end of the buffer is spaced from the pit floor when the buffer is in the retracted position.
3. An elevator safety system according to claim 1 or claim 2, wherein a lower end of the buffer contacts the pit floor when the buffer is in the extended position.
4. An elevator safety system according to any preceding claim, wherein the buffer comprises a rigid elongate prop member.
5. An elevator safety system according to any preceding claim, wherein the buffer has a substantially vertical orientation, in use, in both the retracted and extended positions.
6. An elevator safety system according to any preceding claim, wherein the orientation of the buffer is substantially vertical in use at all positions between the retracted and extended positions.

-13 -
7. An elevator safety system according to any preceding claim, wherein the elevator safety system includes a frame mounted on the sidewall of the elevator shaft to secure the buffer to the sidewall of the elevator shaft.
8. An elevator safety system according to claim 7, wherein the elevator safety system includes a plurality of link members connected between the frame and the buffer to permit movement of the buffer between the retracted and extended positions.
9. An elevator safety system according to claim 8, wherein the drive arrangement is connected to one of the link members.
10. An elevator safety system according to any preceding claim, wherein the drive arrangement comprises a winch device.
11. An elevator safety system according to claim 10 when dependent on claim 8 or claim 9, wherein the winch device includes a winch cable connected to one of the link members and a motor operable to drive the winch cable.
12. An elevator safety system according to claim 11, wherein the drive arrangement includes a motor control switch operable to deactivate the motor when the buffer is in the retracted and extended positions.
13. An elevator safety system according to any preceding claim, wherein the controller is positioned in use outside the elevator shaft.
14. A kit of components for an elevator safety system, the kit including the following, or components therefor:-a buffer securable in use to a sidewall of an elevator shaft; a drive arrangement operable in use to move the buffer between a retracted position in which it lies adjacent the sidewall of an elevator shaft and an extended position in which it prevents downward movement of an elevator car along an elevator shaft; and -14 -a controller operable to selectively control the operation of the drive arrangement and arranged to be positioned, in use, such that the drive arrangement can be operated remotely, from outside an elevator shaft.
15. A kit of components for an elevator safety system, wherein the components are as defined in any of claims 1 to 13.
16. An elevator safety system substantially as hereinbefore described with reference to the accompanying drawings.Amendments to the claims have been filed as followsCLAIMSI. An elevator safety system comprising:-a buffer secured in use to a sidewall of an elevator shaft and movable between: a retracted position in which it lies adjacent the sidewall, alongside an elevator car, to permit unimpeded upward and downward movement of the elevator car along the elevator shaft; and an extended position in which it prevents downward movement of the elevator car beyond a predetermined distance above a pit floor at the base of the elevator shaft; a motorised winch device operable to move the buffer between the retracted and extended positions; and a controller operable to selectively control the operation of the motorised winch device and positioned such that the motorised winch device can be operated remotely, from outside the elevator shaft.2. An elevator safety system according to claim I, wherein a lower end of the * : * buffer is spaced from the pit floor when the buffer is in the retracted position.* .*.* * * * :* 3. An elevator safety system according to claim I or claim 2, wherein a lower end of the buffer contacts the pit floor when the buffer is in the extended position.4. An elevator safety system according to any preceding claim, wherein the * : buffer comprises a rigid elongate prop member.5. An elevator safety system according to any preceding claim, wherein the buffer has a substantially vertical orientation, in use, in both the retracted and extended positions.6. An elevator safety system according to any preceding claim, wherein the orientation of the buffer is substantially vertical in use at all positions between the retracted and extended positions.7. An elevator safety system according to any preceding claim, wherein the elevator safety system includes a frame mounted on the sidewall of the elevator shaft to secure the buffer to the sidewall of the elevator shaft.8. An elevator safety system according to claim 7, wherein the elevator safety system includes a plurality of link members connected between the frame and the buffer to permit movement of the buffer between the retracted and extended positions.9. An elevator safety system according to claim 8, wherein the motorised winch device is connected to one of the link members.10. An elevator safety system according to claim 8 or claim 9, wherein the motorised winch device includes a winch cable connected to one of the link members and an electric motor operable to drive the winch cable.11. An elevator safety system according to claim 10, wherein the drive arrangement includes a motor control switch operable to deactivate the electric motor when the buffer is in the retracted and extended positions. 1 * * * S* 20 12. An elevator safety system according to any preceding claim, wherein the controller is positioned in use outside the elevator shaft. * ****13. A kit of components for an elevator safety system, the kit including the following components:-a buffer securable in use to a sidewall of an elevator shaft; a motorised winch device operable in use to move the buffer between a retracted position in which it lies adjacent the sidewall of an elevator shaft and an extended position in which it prevents downward movement of an elevator car along an elevator shaft; and a controller operable to selectively control the operation of the motorised winch device and arranged to be positioned, in use, such that the motorised winch device can be operated remotely, from outside an elevator shaft.14. A kit of components for an elevator safety system, wherein the components are as defined in any of claims 1 to 12.15. An elevator safety system substantially as hereinbefore described with reference to the accompanying drawings.SS..... * .S* **... * S S. ** * S S * S S...S* SS*S* * .