WO1999047447A1

WO1999047447A1 - Safety device for an elevator

Info

Publication number: WO1999047447A1
Application number: PCT/FI1999/000209
Authority: WO
Inventors: Jori Hägg; Timo Syrman; Seppo Ketoviita
Original assignee: Kone Corp
Current assignee: Kone Corp
Priority date: 1998-03-18
Filing date: 1999-03-17
Publication date: 1999-09-23
Anticipated expiration: 2000-09-18
Also published as: FI108124B; FI980594A7; FI980594A0; AU2838699A

Abstract

An elevator safety device for implementing safety clearances required in an elevator shaft according to regulations. The safety device comprises a safety equipment circuit so designed that, when in a first operating position, it will implement normal elevator operation, and when in a second operating position, it will implement inspection drive operation of the elevator; a first buffer arrangement (1) below the elevator car, which can be set up in an operating position in the path of the elevator car to prevent the elevator car from descending beyond a point at a certain distance from the bottom of the pit in the elevator shaft; and a second buffer arrangement (2) below the counterweight, which can be set up in an operating position in the path of the elevator car to prevent the counterweight from descending beyond a point at a certain distance from the bottom of the pit in the elevator shaft and thus to prevent the car from ascending beyond a point at a certain distance from the shaft top.

Description

SAFETY DEVICE FOR AN ELEVATOR

The present invention relates to a safety device for an elevator as defined in the preamble of claim 1.

In the modernisation of elevators in old buildings, problems are often encountered because the safety regulations have changed over the years and the elevator shafts do not have sufficient top and bottom clearances above and below the car as required by current safety regulations. Extending the shaft at the top or bottom is in most cases impossible for constructional reasons or at least so expensive and difficult that an extension is out of the question.

The object of the present invention is to eliminate the drawbacks mentioned above. A specific object of the present invention is to disclose a new type of safety equipment to replace or compensate for insufficient clearances and to guarantee safety clearances as required by safety regulations for personnel working with the elevator.

As for the features characteristic of the invention, reference is made to the claims.

The safety device for an elevator as provided by the invention comprises a safety equipment circuit so designed that, when in a first operating position, it will implement normal elevator operation, and when in a second operating position, it will implement inspection drive operation of the elevator. Moreover, the safety device comprises a first buffer arrangement placed below the elevator car and connected to the safety equipment circuit, which buffer arrangement can be set up in an operating position in the path of the elevator car to prevent movement of the elevator car beyond a certain dis- tance from the bottom of the pit in the elevator shaft, and a second buffer arrangement placed below the counterweight and also connected to the safety equipment circuit, which buffer arrangement can be set up in an operating position in the path of the counterweight to prevent movement of the counterweight beyond a point at a certain distance from the bottom of the pit in the elevator shaft, thus preventing the car from ascending too close to the shaft top.

The buffer can easily be positioned under the car in such a way that the buffer hits to the load-bearing part of the car or to the sling. Thus there is no need to modify the car construction when utilising the solution according to the inven- tion. Similarly the buffer under the counterweight can be positioned to the most suitable place.

Thus, the basic idea of the elevator safety device of the invention is that the elevator comprises a safety equipment circuit that makes it possible to implement inspection drive operation known in itself, but in addition the system is provided with mainly mechanical buffer arrangements at the bottom of the shaft, i.e. below the elevator car and counterweight, to ensure that sufficient safety clearances are main- tained both at the top and at the bottom of the shaft in all possible circumstances.

In an embodiment of the invention, the first and the second buffer arrangements comprise posts mounted with hinge joints on the bottom of the pit of the elevator shaft. When in a horizontal position, the posts allow normal elevator operation, but when raised to an upright position, they prevent the elevator car from descending beyond a point at a certain distance from the shaft bottom. Thus, the posts are turned to their upright position when work has to be done in the shaft pit or on the car top. The posts are provided with buffers, e.g. bodies of slightly elastic polyurethane , placed on the top of the post to damp the impact in the event of a crash.

Both buffer arrangements are preferably provided with limit switches to detect the position of the arrangement or of the posts in the arrangement. The limit switches are connected to the safety equipment circuit e.g. so that they break the safety circuit when the posts are not in their low position. In addition, when the posts are in their upright or operating position, the limit switches for the upright position over- couple the safety device contactors and the limit switches for the low position, thus enabling inspection drive operation.

In a preferred embodiment, the fulcrum of the post hinged on the pit bottom and its centre of gravity when in the upright position are so disposed relative to each other as to ensure that the post will remain upright once it has been turned to the upright position, without requiring any sort of locking devices or latches. This makes the use of the buffers as simple and fast as possible. Of course, the posts can also be provided with suitable latches or other locking devices to guarantee that the posts will remain upright.

The elevator safety device preferably comprises switches mounted on each landing door of the elevator and designed to identify a situation where the door is unlocked with an emergency unlocking key. The switches are connected to the safety equipment circuit, so unlocking a door using an emergency unlocking key results in disabling normal operation of the elevator.

In a preferred embodiment, each door is provided with two mi- croswitches which detect the unlocking of the door with an emergency unlocking key. In this case, an open contact in one of the microswitches is sufficient for detection of an un- locked door, but the safety device can only be reset and normal elevator operation restored if the contacts in both microswitches have been opened.

Moreover, for inspection drive operation from the car top, the car top is provided with parapets of adjustable height. This makes it possible to set up a safety fence of sufficient height as stipulated by regulations on the car top for the time of inspection drive operation. The parapets of adjust- able height are preferably provided with a limit switch identifying their position and connected to the safety equipment circuit. Thus, when the parapets are in their raised position, normal operation of the elevator is disabled and only inspection drive operation is enabled.

The elevator safety device of the invention has significant advantages as compared with prior art. Above all, when elevators in old elevator shafts are being modernised, the safety device of the invention makes it possible to implement safety clearances as stipulated by safety regulations for persons working with the elevator.

In the following, the invention will be described in detail by referring to the attached drawings, wherein

- Fig. 1 presents a diagram representing an elevator safety device assembly according to the invention, and

- Fig. 2 illustrates a post application for use in conjunction with the invention, both in an upright position and in a horizontal position.

A safety device for an elevator as presented in diagrammatic form in Fig. 1 consists of the following components. The safety device 10, provided with relay memory, is equipped with an emergency-stop type push button 11 that locks in the depressed position. The opening contact of the push button is connected to the normal operation signal while the closing contact is connected to the inspection drive signal. Placed in the shaft below the car are buffer arrangements 1 provided with hinged posts 3 which can be raised to an upright position. Both posts are provided with limit switches 4 approved for safety circuit use, designed to identify their position. Similarly, placed below the counterweight in the shaft is a buffer arrangement 2 provided with a hinged post 3 which can be raised to an upright position, which is likewise equipped with a limit switch 5 approved for safety circuit use and ca- pable of identifying the position of the post. The limit switches 4 and 5 are connected to the safety device 10.

Connected to the safety device 10 are also microswitches 8 mounted on the landing doors on each floor. These microswitches connected to the safety device detect the unlocking of the door with an emergency unlocking key 7.

In addition, the safety device presented in the diagram com- prises limit switches 9 approved for safety circuit use, which are connected to parapets mounted on the top of the elevator car to identify their height position. The parapets are capable of telescopic height adjustment and preferably of a two-position type. The limit switches 9 are connected to a junction box 12 placed on the car top. Connected to the same junction box is also an inspection drive unit 13. The junction box 12 is connected via the car cable 14 to the elevator control system 15 and further to the safety device 10.

The elevator safety device presented in the diagram in Fig. 1 is used as follows. When it is necessary to work on the car top, the car is stopped at a place from where a person can get onto the car top and the stop button 16 on the car top is depressed. As a result, data indicating that a landing door has been unlocked with an emergency unlocking key is stored in memory and all electrical operation is disabled. After this, the door on the bottommost floor is opened and the emergency stop type button 11 on the safety device 10 is depressed. This button connects the inspection drive signal and disconnects the normal operation signal. This situation is preserved even in the event of a power failure. A serviceman now enters the shaft pit and raises the posts 3 comprised in the buffer arrangements 1 and 2 into the upright position.

Next, the serviceman goes to the car top and sets the telescopic parapets to the raised position, whereupon the elevator can be operated in inspection drive mode from the car top. The operation switch 17 is turned to an inspection drive position and the required inspection drive operations are carried out as normal. The upright posts 3 in the buffer systems 1 and 2 ensure that the safety clearances will be maintained even in the event of a failure in the electronic in- spection drive operation. For this elevator type, inspection drive from the car top is effected as normal, between the terminal synchronising switches. During inspection drive, all the normal controls and limits are in operation, but if the limits and controls should fail, the upright posts will guar- antee safety clearances according to regulations both at the car top and at the pit bottom.

After the required maintenance operations have been carried out, the safety parapet is returned to its low position and the operation switch 17 is turned to the normal position and the position of the stop button 16 is verified. Next, the serviceman enters the shaft pit and turns the posts 3 to the low position and leaves the pit. After this, while standing on the landing, the serviceman releases button 11 to the nor- mal position. After a few seconds, the normal operation mode of the elevator is restored.

When maintenance work is to be done in the shaft pit, the door of the bottommost floor is opened and the emergency-stop type button 11 on the safety device 10 is depressed. As a result, data indicating that a landing door has been unlocked with an emergency unlocking key is stored in memory and all electrical operation is blocked. After this, the serviceman goes into the shaft pit and raises the posts 3 in the buffer systems 1 and 2 to the upright position. The required normal maintenance operations can now be carried out while a suf^¬ ficient safety clearance in the pit is guaranteed by the posts 3 and the button 11 of the safety device 10. When nor^¬ mal operation of the elevator is to be restored, the service- man turns the posts to their low position and leaves the pit. Next, while standing on the landing, the serviceman releases button 11 to the normal position and closes the door. After a few seconds, the normal operation mode of the elevator is restored.

Fig. 2 presents an embodiment of the posts used in the buffer arrangements in the shaft pit. The buffer arrangement comprises a straight post 3 pivoted at one end by a hinge 6 with a horizontal axis on a knuckle bearing 19 mounted on the shaft bottom 18. The lower end of the post 3 is provided with a small swinging bracket 20 extending transversely to the post and connecting the post 3 via the hinge 6 to the knuckle bearing 19. Therefore, when the post is in the upright position, the centre of gravity of the post is definitely on one side of the joint 6, so the post need not be provided with any locking elements or latches to ensure that it will remain upright. Mounted in conjunction with the post is additionally a limit switch 4 for detecting the position of the post. Moreover, the post 3 is provided with a buffer 21 made of elastic material, e.g. polyurethane , mounted on its top. If the car should crash on the post, the buffer will damp the impact.

In the foregoing, the invention has been described by way of example by the aid of the attached drawings, but different embodiments of the invention are possible within the scope of the inventive idea defined by the claims.

Claims

1. Elevator safety device for implementing safety clearances required m an elevator shaft according to regulations, charac teri se d in that the safety device comprises

- a safety equipment circuit so designed that, when m a first operating position, it will implement normal elevator operation, and when m a second operating position, it will implement inspection drive operation of the elevator, - a first buffer arrangement (1) below the elevator car, which can be set up m an operating position n the path of the elevator car to prevent the elevator car from descending beyond a point at a certain distance from the bottom of the pit in the elevator shaft, and that - the first buffer arrangements (1) comprises a post (3) hinged essentially on the bottom of the pit, said post be^¬ ing capable of being raised to an operating position below the elevator car.

2. Safety device as defined in claim 1, character ised in that it comprises

- a second buffer arrangement (2) oelow the counterweight, which can be set up n an operating position m the path of the elevator counterweight to prevent movement of the coun- terweight beyond a point at a certain distance from the bottom of the pit m the elevator shaft and thus to prevent the car from ascending beyond a point at a certain distance from the shaft top, and that

- the second buffer arrangements (1) comprises a post (3) hinged essentially on the bottom of the pit, said post be^¬ ing capable of being raised to an operating position below the elevator counterweight.

3. Safety device as defined m claim 1 or 2, charac - terised m that the posts (3) are essentially horizontal when they are not m their operating positions.

4. Safety device as defined in any one of claims 1 - 3, char ac t e r i s ed in that the buffer arrangement (1,2) comprises a limit switch (4, 5) identifying its position, said limit switch being connected to the safety equipment circuit to enable inspection drive operation and disable normal operation when the buffer arrangement is in its operating position.

5. Safety device as defined in any one of claims 1 - 5, char ac te ri sed in that the fulcrum (6) and centre of gravity of the post (3) in the upright position of the post are so disposed with respect to each other that, when turned to the upright position, the post remains upright without separate locking devices.

6. Safety device as defined in any one of claims 1 - 5, c har ac te r i s e d in that the buffer arrangement comprises a locking device for locking the post in an upright operating position.

7. Safety device as defined in any one of claims 1 - 6, charac te r i s e d in that the post (3) is provided with a buffer (21), preferably an elastic body of polyurethane , mounted on the top of the post to damp possible impacts.

8. Safety device as defined in any one of claims 1 - 7, charac te r i s ed in that it comprises switches (8) mounted on each landing door of the elevator and designed to identify a situation where the door is unlocked with an emer- gency unlocking key (7) , said switches being connected to the safety equipment circuit.

9. Safety device as defined in any one of claims 1 - 8, c har ac te r i s e d in that the car top is provided with a parapet of adjustable height to achieve a safety fence of sufficient height for inspection drive operation from the car top.

10. Safety device as defined in claim 9, character i sed in that the parapet is provided with a limit switch (9) identifying its position, said switch being connected to the safety equipment circuit to disable normal operation and enable inspection drive operation of the elevator when the parapet is in its raised position.