HK1115744B - Elevator safety systems and method of preventing injury to a person thereof - Google Patents

Description

Elevator safety system and method for preventing personnel from being injured

The present invention relates to improvements in elevator safety and in particular to the detection of the unauthorized presence of a person on top of an elevator car.

It is becoming more and more common in elevator installations to provide very little space above the normal travel of the elevator car, since this reduces the construction costs and increases the flexibility available for the construction design. However, there is a risk of injury to work in low-top elevator installations, as the refuge space provided for persons standing on top of the elevator car becomes smaller as the car approaches the uppermost landing. It is therefore necessary to provide a series of safety systems such as retractable balustrades and a dedicated inspection mode for the elevator control that prevents the car from traveling to the top of the hoistway. These measures allow an engineer standing on top of the car to safely conduct an authorized inspection. However, if these safety measures are not all properly taken or are inadvertently or intentionally abused, the risk of injury increases. This may be due to the engineer not adhering to the inspection process under an approved procedure or may be due to unauthorized personnel gaining access to the top of the car.

In view of the above, it is desirable to automatically prevent the elevator car from moving to the uppermost end of its travel if there is a person on top of the car.

Viewed from a first aspect the invention provides an elevator system comprising a hoistway and an elevator car arranged to travel vertically within the hoistway, the hoistway being further provided with a sensing arrangement for detecting the presence of a person on top of the car as the car approaches the top of the hoistway, the elevator system being arranged to restrict further upward movement of the car in the event that a person is detected.

Viewed from a second aspect the invention provides a method of preventing injury to a person standing on top of an elevator car in a low-overhead elevator system, the method comprising detecting the presence of a person on top of the car as the car approaches the top of a hoistway using a device disposed in the hoistway and limiting further upward movement of the car in the event that a person is detected.

Thus, those skilled in the art will appreciate that according to the present invention, when the elevator car moves upward, a person in danger of injury at the top of the hoistway will be detected and the elevator system will limit the upward movement of the car to reduce the danger of injury to that person.

The means for detecting a person on top of the car may be a means that can distinguish between a living person and an inanimate object so that the means does not sense the presence of the car itself during normal operation. For example, the sensing arrangement may comprise a passive infrared sensor for sensing body heat of a person on top of the car. However, the sensing arrangement is preferably adapted to detect the presence of an object at the relevant vertical point of the hoistway.

A point in the hoistway above the normal travel of the elevator may be selected, but in a very low overhead installation this may not provide sufficient distance to safely stop the car without causing injury to the person on top of the car. Thus, according to a preferred embodiment, the sensing point is located within the normal travel of the car and the elevator system is arranged so as to be able to distinguish between a person standing on top of the car and the car itself having traveled to the vertical sensing point during normal operation. Although there are many ways of achieving this, it is preferred to use an existing position reference system to determine the position of the car, and according to the invention, the upward movement of the car is limited only if it is determined by the position reference system that the elevator car is not intended to be at a position that will be detected by the sensing arrangement. One way of achieving the above object is by the sensing arrangement sending a signal to the elevator controller and the elevator controller being arranged to limit the upward movement of the car based on the signal from the sensing arrangement and the position reference system.

Alternatively, the sensing arrangement is activated when the elevator car is moving towards the top of the hoistway but still low enough so that there is still sufficient space between the top of the car and the top of the hoistway to accommodate a person. For example, the sensing arrangement may be activated when the elevator car is at a landing below the uppermost landing. By positioning the sensing arrangement above the position the elevator car was in when it was activated, the sensing arrangement will only detect objects located on top of the car and not the car itself. Of course, if the sensing arrangement is positioned such that the elevator car will pass the sensing arrangement during normal operation, this should not cause the safety system to restrict the car movement. One possibility is to deactivate the sensor with a second position signal. Alternatively, the sensing arrangement may be activated when a time measurement is taken to determine whether the presence of an object is detected before the car itself would be expected to be detected when the elevator car is above the penultimate landing.

Upon detecting that an unauthorized person is located on top of the car, there are a number of possibilities to take action to prevent injury to the person. For example, the elevator controller may immediately prevent any further upward movement of the car by cutting power to the elevator motor and applying a brake. Additionally, or alternatively, a physical security device may be automatically employed.

In a preferred set of embodiments the sensing arrangement comprises means for emitting sensing radiation and means for detecting the emitted radiation to enable detection of the presence of an object in the path of the radiation. The sensing arrangement may be such that radiation reflected back from the body being detected is sensed, but the arrangement is preferably such that the radiation travels through the hoistway to be detected such that sensing of the radiation is interrupted due to the presence of a body at that vertical point in the hoistway. Most preferably, the sensing arrangement comprises a plurality of beams across the hoistway and one or more sensors arranged to detect the beams.

The radiation employed may be of any suitable nature, such as ultrasonic, microwave or visible light, but infrared radiation is preferred because the associated sensors and emitters are relatively readily available and inexpensive while being reliable.

Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

fig. 1 is a front view of a low overhead elevator hoistway showing a hazard situation for a person on top of the car;

fig. 2a and 2b are a front view and a perspective view, respectively, of an elevator system embodying the present invention, showing the actuation of an infra-red curtain (infra-red current);

figures 3a and 3b are front and perspective views, respectively, showing the detection of an unauthorised person on top of the car; and

fig. 4 is a front view of the embodiment of fig. 2 and 3, wherein the car is safely stopped to prevent injury to a person on top of the car.

Fig. 1 shows an elevator car 2 arranged to move vertically within a hoistway 4. It can be seen that when the car 2 is adjacent the uppermost landing 6, there is very little space 7 between the top of the car 2 and the ceiling 8 of the hoistway. In particular, there is no refuge space provided for persons who happen to be on top of the car.

In low-top systems, such as the one shown in the figure, some series of safety measures need to be taken to ensure that the car with a person on top cannot reach the uppermost landing 6. Typically, these systems are associated with certain conditions, such as placing the elevator in a dedicated detection mode or detecting the opening of a hoistway door in an unauthorized manner to indicate the approach of an unauthorized person to the top of the car.

However, it is possible that the detection element is overused (overridden) or that the elevator is not properly placed in the inspection mode. In particular, the door detection system may be abused by an unauthorized user who may then stand on top of the car in the normal mode. As can be seen from fig. 1, this is extremely dangerous and potentially fatal. This can be prevented according to the present invention, which will now be described with reference to fig. 2 to 5.

According to embodiments of the invention described herein, in the uppermost part of the hoistway 2, there is provided an infrared sensor and emitter arrangement comprising an elongate emitter array 10 and a corresponding elongate sensor array 12 disposed horizontally within the elevator hoistway by being attached to respective guide rails 14. In the embodiment shown, the emitter array 10 comprises a plurality of individual emitters that emit infrared beams that traverse the hoistway at a plurality of different angles and are to be sensed by a corresponding plurality of sensors in the sensor array 12 located on the other side of the hoistway. By providing multiple independent emitters and sensors, the likelihood of false detection of, for example, small pieces of debris or flying insects in the hoistway can be reduced. However, it is envisaged that a single beam may be employed which may only traverse the hoistway once or alternatively may be reflected one or more times to provide a greater spatial extent.

It can be seen that the sensor and emitter arrays 10, 12 are disposed at a position approximately one third of the way up the uppermost landing space 6. The sensing arrangements 10, 12 are activated when the elevator car 2 is adjacent a landing 16 below the uppermost landing 6. As can now be seen in connection with fig. 3A and 3B, when the elevator car moves upwards beyond the penultimate landing 16, an unauthorized person 18 on top of the car will block the infrared beam between the emitter array 10 and the sensor array 12, which will be detected by the sensor array 12 as a situation in which the sensor array signal is interrupted. Once this has been detected, further upward movement of the elevator car 2 will be prevented and the brake will be applied. As can be seen in fig. 2A, this means that there remains sufficient space above the top of the car 2 to prevent injury to unauthorized persons 18 located on top of the car. Although not necessary, the system may be arranged so as to require a manual reset, for example by an authorised engineer, before it can resume normal operation.

If there are no unauthorized persons on the car top, the car top itself will eventually block the beam between the emitter array 10 and the sensor array 12 as the car moves up to the uppermost landing 6. However, this does not result in the car halting operation because the Position Reference System (PRS) signal indicates that the car is at a position where it is interrupting the beam as expected.

It will be appreciated by those skilled in the art that various changes and modifications may be made to the described embodiments without departing from the scope of the invention. For example, other means for detecting the presence of a person on top of the car may be provided, such as visible light, ultrasound, microwave or other sensors. In addition, timing signals may be utilized instead of position signals to distinguish between the car and unauthorized persons located on top of the car.

Claims (26)

1. An elevator system, which elevator system comprises a hoistway (4) and an elevator car (2) arranged to travel vertically within the hoistway, which hoistway is further provided with a sensing arrangement (10, 12) for detecting the presence of a person on top of the car when the car approaches the hoistway top (8), which elevator system is arranged so as to restrict the car from further upward movement in the event of detection of a person, characterized in that:

the elevator system is arranged to be able to distinguish between a person standing on top of the car and the car itself which has traveled to a predetermined point during normal operation.

2. The elevator system of claim 1 wherein: the predetermined point is a predetermined vertical point on the hoistway at which the sensing arrangement (10, 12) is adapted to detect the presence of an object.

3. The elevator system of claim 2 wherein: the predetermined vertical point is located within a normal stroke of the elevator car (2).

4. Elevator system according to claim 3, which elevator system is arranged, in use, to determine the position of the car (2) with a position reference system and to limit the upward movement of the car only if it is determined by means of the position reference system that the elevator car is not intended to be at a position that will be detected by the sensing arrangement (10, 12).

5. Elevator system according to claim 4, wherein the sensing arrangement (10, 12) is arranged to send a signal to an elevator controller and the elevator controller is arranged to limit the upward movement of the car (2) based on the signal and the output from the position reference system.

6. Elevator system according to claim 4, wherein the sensing arrangement (10, 12) is arranged such that it is activated when the elevator car (2) is moving towards the top of the hoistway (4) but still low enough such that there is still enough space between the top of the car and the top of the hoistway to accommodate a person.

7. Elevator system according to claim 6, which is arranged such that the sensing arrangement (10, 12) is activated in use when the elevator car is at a landing (16) below the uppermost landing (6).

8. Elevator system according to claim 4, comprising means for generating a position signal for bringing the sensing arrangement (10, 12) into a disabled state when the car (2) is in proximity to the sensing arrangement.

9. Elevator system according to claim 4, comprising means for taking a time measurement when the car (2) has passed a predetermined point, the elevator system being arranged such that the movement of the car is restricted if the sensing arrangement (10, 12) detects the presence of an object before the car itself is expected to be detected.

10. Elevator system according to claim 1, comprising means for immediately preventing any further upward movement of the car (2) upon detection of an unauthorized person being located on top of the car.

11. Elevator system according to claim 1, comprising means for automatically employing a physical safety device upon detection of an unauthorized person being located on top of the car (2).

12. Elevator system according to claim 1, wherein the sensing arrangement comprises means (10) for emitting sensing radiation and means (12) for detecting the emitted radiation to enable detection of the presence of an object in the radiation path.

13. The elevator system according to claim 12, wherein the sensing arrangement (10, 12) is such that the radiation travels substantially horizontally through the hoistway (4).

14. The elevator system according to claim 12 or 13, wherein the sensing arrangement (10, 12) comprises a plurality of beams across the hoistway and one or more sensors (12) arranged to detect the beams.

15. The elevator system of claim 12 or 13, wherein the radiation is substantially infrared radiation.

16. A method of preventing injury to a person standing on top of an elevator car (2) in a low-overhead elevator system, the method comprising detecting the presence of a person on top of the car as the car approaches the top (8) of a hoistway using a sensing arrangement (10, 12) provided in the hoistway and limiting further upward movement of the car in the event that a person is detected, characterized by:

including distinguishing between a person standing on top of the car (2) and the car itself.

17. A method according to claim 16, comprising detecting the presence of an object at a predetermined vertical point of the hoistway (4).

18. The method of claim 16, comprising determining the position of the car (2) with a position reference system, and limiting upward movement of the car only if it is determined by the position reference system that the elevator car is not intended to be at a position to be detected by the sensing arrangement (10, 12).

19. The method of claim 18, comprising sending a signal to an elevator controller that limits upward movement of the car (2) based on the signal and an output from the position reference system.

20. Method according to claim 18, comprising activating the sensing arrangement (10, 12) when the elevator car (2) is moving towards the top of the hoistway (4) but still low enough so that there is still sufficient space between the top of the car and the top of the hoistway where a person can be accommodated.

21. The method according to claim 20, comprising activating the sensing arrangement (10, 12) when the elevator car (2) is at a landing (16) below the uppermost landing (6).

22. The method of claim 18, comprising generating a position signal that causes the sensing arrangement (10, 12) to be in a disabled state when the car (2) approaches the sensing arrangement.

23. A method according to claim 18, comprising making a time measurement when the car (2) has passed a predetermined point, and limiting movement of the car if the sensing arrangement (10, 12) detects the presence of an object before the car itself is expected to be detected.

24. The method of claim 16, comprising preventing any further upward movement of the car (2) immediately upon detection of an unauthorised person being located on top of the car.

25. The method of claim 16, comprising automatically employing a physical safety device upon detecting that an unauthorized person is located on top of the car (2).

26. The method of claim 16, comprising emitting sensing radiation and detecting the emitted radiation thereby detecting the presence of an object in the path of the radiation.