Safety arrangement of an elevator and method of its operation

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a safety arrangement of an elevator and a method of operation for monitoring and recognizing the safety spaces above and beneath an elevator car in its shaft especially during maintenance work.

BACKGROUND OF THE INVENTION

[0002] Persons that enter a hoistway, such as elevator mechanics and building maintenance personnel may suffer serious and fatal accidents when the elevator moves towards the overhead or the pit where the person could stumble on something in case the movement of the car underruns the dimensions for a free movement of the person. Such accidents can also occur in the sudden movement of the elevator. This problem is aggravated in systems in which there is no machine room but the hoisting machine and/or the controller are located in the pit or overhead construction. As architects continue to try to reduce the size of the overhead and the depth of the pit, the problem becomes even worse. The same is true when modernizing the elevators of old buildings since problems are often encountered when the headrooms and bottom clearances in the elevator shaft above and below the car are not large enough to meet the requirements of modern safety regulations. Extending the shaft upwards or downwards is in most cases impossible in terms of construction engineering or at least so expensive and difficult that it is not viable. One goal in new buildings is to save space in the elevator shaft. This is done by dimensioning the headrooms and bottom clearances in the elevator shaft to be as small as possible. In this case there is no longer adequate safety space for personnel protection above and below the elevator car for a serviceman working in the elevator shaft or on the roof of the elevator car.

[0003] Prior art solutions are known for example from JPH09124247 A and JPH0891729 A, the latter disclosing a safety device for the work on an elevator car being equipped with an approach detecting switch which is installed at the top end of a pole extensible/contractible pipe erected at the top part of an elevator car. The switch outputs an approach detection signal by detecting an elevator shaft top part which signal in turn operates a buzzer to issue an alarm. Further, document JP2001080835 A proposes to install sensors at the upper and bottom part of an elevator car. A portable device is arranged under an emblem of a worker's uniform, wherein an alarm is triggered at the uniform site in case the elevator car reaches the uppermost or lowermost landing and an emergency stop of the elevator car is accomplished.

AIM OF THE INVENTION

[0004] The object of the invention is to propose a safety solution for preventing danger for maintenance stuff working in the shaft of an elevator.

SUMMARY OF THE INVENTION

[0005] The above object is achieved by a safety arrangement according to claim 1. A respective method of operating a safety device is disclosed in claim 6, while a software program executing such method is subject of claim 12. Advantageous embodiments are disclosed in the respective subclaims.

[0006] Basic idea of the invention is to create an elevator safety arrangement and a method for its operation that makes it possible to implement an inspection drive operation known in itself, but in addition provides the maintenance stuff about the dimensions of the safety clearances at the top and at the bottom of the shaft in all possible circumstances of a car position.

[0007] To this end, the safety arrangement makes use of a measurement system of an elevator facility which delivers data for a conclusion of where an elevator car is positioned within an elevator shaft. Based on these position data, the safety arrangement is configured to trigger an alert signal when specific predetermined positions of the car are reached or bypassed. These specific positions can be stored in a memory of the safety arrangement or in a memory of the drive system of the elevator facility. Even the same control board for storing these positions and for triggering an alert signal can be used, which is provided for the normal elevator operation, like handling elevator call information, sending control commands to a car door operator, etc. During initiation of the elevator installation, a setup run is done to learn the elevator car position in the shaft. This is based on some movement signal, such as tachometer, motor encoder, car encoder of floor position sensor. After the setup run, the elevator control software knows the car position and therefrom a processor can conclude also the distance from elevator hoistway ends or the movement ends of the track of the car. Later then the distance can be determined by the elevator control software from the movement signal. Therewith, the elevator facility knows the position of the lift in resolution of one mm (from encoder) or in resolution of floor (lifts without encoder). In case of encoder lifts the warning distance could be defined in mm resolution by parameter. In case of no encoder the warning could be activated e.g. after the second top most floor has been bypassed when running upwards or after the second floor when running downwards.

[0008] Alternatively, the safety arrangement comprises a data processor setting the position-data in relation to the distances from the circumference of the elevator car to the uppermost end and/or to the lowermost end of the track of the car which endings limit the car movement, respectively. As a further alternative, said distance data are calculated by a processor of the existing elevator facility and are then forwarded to the safety arrangement. In case a predetermined distance is underrun and therewith the risk of hitting the stuff's head becomes real an audible alert signal is issued.

[0009] European Guideline EN81-20 requires lifts to have lamp and buzzers to indicate when door bypass switches are in use alerting for example a maintenance mode. The same lamp and buzzer are now to be used for informing the maintenance stuff about forthcoming obstacles. According to the invention the service technician is warned in advance about the risk of hitting his head to the ceiling when being on top of the car during a pit inspection operation or when being on the bottom of the shaft and the car is in short distance above him.

[0010] According to a preferred embodiment, the higher the audible issued tone-signal frequency is. It is also possible according to another alternative that it is the signal pattern changing in dependency of the distance being underrun. This can mean that it is the time interval between successive tones is becoming shorter when said distance is underrun more and more. At least, the above two items of changing the tone-signal frequency and the signal pattern can be combined.

[0011] As said, the same buzzer which is used to indicate a door bypassing can be used. Alternatively, any buzzer in the lift car, on top of lift car or in the well could be used. The indication could be implemented also with an ACU device, meaning that the audible alert signal is a voice output informing about the underrun distance by spoken words. Therewith, a speech warning like "Watch your head!" could be issued.

[0012] In a further view, the inventors have found out to suitably use a so-called reverse alarm radar for realizing the above object to inform the maintenance stuff about distances underrun when working in the elevator shaft. Those reverse alarm radar systems are implemented in prior art at the rear part of a car to inform the driver about remaining space when reversing the motor vehicle. In the most cases said radar systems do use an ultrasonic measuring method. To this end, an ultrasonic distance measuring inductor is disposed at the rear end of the automobile's bumper between two lateral corners of the automobile body for calculation of the lateral distance between an obstacle and the lateral corners of the automobile body. A system like this has been adapted for installation at the elevator car's site as well as on the shaft site to trigger a warning signal for the maintenance stuff when the working space becomes too small. The technical concept of this embodiment includes an emitter and sensor technology by means of which the car position relative to the upper and/or lower track ends (shaft wall(s)) is monitored. Additionally, the radar system also monitors and recognizes any obstacle which can be detected within a specific distance from the circumference-walls of the elevator car.

Claims

1. Safety arrangement of an elevator facility comprising a measurement system delivering data for a conclusion of where an elevator car is positioned within an elevator shaft,
characterized in that the safety arrangement is configured to issue an audible alert signal being triggered in dependency of the position data of the car.

2. Safety arrangement according to claim 1,
characterized in that the safety arrangement handles data indicating distances from the circumference of the elevator car to the uppermost end and/or to the lowermost end of the track of the car limiting its movement, respectively, wherein the audible alert signal is issued in case a predetermined distance is underrun by the car.

3. Safety arrangement according to one of the preceding claims,
characterized in that the character of the audible alert signal is set in dependency of the car position or the amount of the underrun actual distance.

4. Safety arrangement according to claim 3,
characterized in that the smaller the remaining distance is, the higher is the frequency of the issued alert signal.

5. Safety arrangement according to any of the preceding claims,
characterized in that the audible alert signal is a voice output informing about the underrun distance by spoken words.

6. Method of operating a safety arrangement of an elevator facility according to claim 1,
wherein the measurement system of the elevator facility delivers data to the safety arrangement about positions of the car within the elevator shaft, and
the safety arrangement issues an audible alert signal being triggered in dependency of the position data of the car.

7. Method according to claim 6,
characterized in that the safety arrangement receives or creates data indicating the distances from the circumference of the elevator car to the uppermost end and to the lowermost end of the track of the car limiting its movement, respectively, wherein an audible alert signal is issued in case a predetermined distance is underrun.

8. Method according to one of claims 6 or 7,
characterized in that the character of the audible alert signal is set in dependency of the position data or the amount of the underrun distance.

9. Method according to claim 8,
characterized in that the smaller the remaining distance is, the higher is the frequency of the issued alert signal.

10. Method according to one of claims 6 to 9,
characterized in that the audible alert signal is a voice output informing about a danger in spoken words.

11. Method according to claim 10,
characterized in that the voice output issues spoken information about the position of the car or the underrun distance.

12. Software program executing the method according to one of claims 6 to 11 when run on a data processor.