WO2007020320A1

WO2007020320A1 - Method and appliance for increasing the useful area of an elevator car

Info

Publication number: WO2007020320A1
Application number: PCT/FI2006/000235
Authority: WO
Inventors: Teuvo VÄNTÄNEN; Håkan BÄRNEMAN; Carsten Wermter
Original assignee: Kone Corporation
Priority date: 2005-08-16
Filing date: 2006-07-03
Publication date: 2007-02-22
Also published as: EP1915312A1; EP1915312A4; FI118731B; ES2405617T3; FI20050828A; FI20050828A0; EP1915312B1

Abstract

The invention relates to a method and an appliance for increasing the useful area of an elevator car (2). The elevator car (2) is fitted to travel in the elevator shaft (1) controlled by the control system (11) along guide rails (6) in essentially the vertical direction, and the weight of the load of the elevator car (2) is monitored with a load- measuring device (4) and overspeed of the elevator car (2) is monitored with an overspeed governor (12). According to the invention a change of status of the elevator car (2) is monitored when it is at the landing and when the status exceeds a predefined limit value the elevator car (2) is locked in its position in the landing zone.

Description

METHOD AND APPLIANCE FOR INCREASING THE USEFUL AREA OF AN ELEVATOR CAR

The present invention relates to a method as defined in the preamble of claim 1 and an appliance as defined in the preamble of claim 7 for increasing the useful area of an elevator car.

Generally a weight limit is set for elevator cars, especially in traction sheave elevators, which the combined weight of the car and the load may not exceed for safety reasons. If the weight limit is exceeded and an overload enters the elevator car, the friction between the hoisting ropes of the elevator and the rope grooves of the traction sheave is not necessarily sufficient to keep the elevator car in its position, and instead in an overload situation the elevator car can start moving downwards from the landing. Such undesired movement, which is also called creeping, causes hazards to passengers and according to the regulations is not permitted.

Overload protectors are used to prevent an overload in elevators, which measure the load of the elevator car and in an overload situation prevent the starting of the elevator motor, keep the brakes of the elevator locked and report with different signaling devices that there is an overload in the elevator. In this case the elevator car cannot resume normal drive before the overload situation is removed. One problem, however, is the creeping mentioned earlier, where the hoisting ropes of a traction sheave elevator slip on the traction sheave as it is kept in its position by the brake and the elevator car moves downwards causing hazardous situations.

In addition to measuring the overload and in order to prevent any creeping, prior-art elevator cars are dimensioned for the sake of safety so that the maximum amount of the load that fits in the elevator car is such that the combined weight of the elevator and the load probably does not exceed the weight limit - i.e. the area of the elevator car is linked to the rated load of the elevator. One drawback of this solution is that since the area of the car must be restricted because of the weight limit, these types of elevators cannot convey loads that because of their size take up a lot of space but are relatively light.

Mechanical locking devices for an elevator car, i.e. anti- creeping devices, which lock the elevator car in its position either against the guide rail, the hoisting rope of the elevator or some other suitable point by means of a latch, safety gear or additional brake so that the elevator car cannot move downwards, are also prior-art in technical terms. In hydraulic elevators solutions are often used in which the elevator car is mechanically gripped to be supported by the elevator shaft owing to an oil leak or to an unintended reduction in the oil volume of the hoisting cylinder for some other reason. Different mechanical locking devices are used e.g. in goods elevators, in which case e.g. a forklift truck can drive into the elevator car during loading and unloading. These locking devices can often be switched on and off separately, with e.g. a push-button for this purpose, thus they are not applicable as such for normal passenger elevator use.

The purpose of the present invention is to eliminate the aforementioned drawbacks and to achieve a dependable, low-cost method and an operationally reliable appliance for increasing the useful area of an elevator car, particularly for use with traction sheave elevators, which will enable the use of elevator cars with a volume that is greater than normal despite the weight limit. A particular aim of the invention is a safe method to permit a large area for transportation in relation to the load-bearing capacity of the elevator. The method according to the invention is characterized by what is disclosed in the characterization part of claim 1. Likewise the appliance according to the invention is characterized by what is disclosed in the characterization part of claim 7. Other embodiments of the invention are characterized by what is disclosed in the other claims. Some inventive embodiments are also discussed in the descriptive section of the present application. The inventive content of the application can also be defined differently than in the claims presented below. The inventive content may also consist of several separate inventions, especially if the invention is considered in the light of expressions or implicit sub-tasks or from the point of view of advantages or categories of advantages achieved. In this case, some of the attributes contained in the claims below may be superfluous from the point of view of separate inventive concepts . Likewise the different details presented in connection with each embodiment can also be applied in other embodiments .

In the following the method and appliance according to the invention will be referred to by the common name of the solution according to the invention. One advantage of the solution according to the invention is the possibility to construct large elevator cars also although the weight limit otherwise set for the cars would be low. An elevator car can thus be constructed that is larger than the normal volume corresponding to the rated load, in which case goods of a rather large size but light in weight can be transported in the elevator, such as e.g. furniture or children's prams. Another advantage is that the structures of the car can be lighter than in elevator cars with the same volume that comply with the standards because the car of an elevator dimensioned for a lighter load needs to bear a smaller load and stresses than the maximum load according to the standards . A load- bearing capacity that is dimensioned smaller with respect to the area also results in a saving in energy. In traction sheave elevators with counterweight a lighter load also means savings in costs owing to the smaller counterweight and a smaller counterweight may also result in a saving in the space occupied by the elevator shaft. A further advantage is that a smaller motor and control unit for the motor can be used, in which case the manufacturing and operating costs of the elevator are lower than a corresponding prior-art elevator. Smaller fuses can be used with a smaller motor and control unit and the electrical connection cable is smaller. For example a 5000 kg car dimensioned in its area according to prior art can be used in the solution according to the invention as a 4000 kg car, in which case all the regulating elements can be dimensioned according to a 4000 kg car, but achieving the clearance of a 5000 kg car as a benefit. The invention is especially suitable for use in connection with an elevator without counterweight.

The invention can be implemented by constructing a control for the existing brake devices or safety gear devices of the elevator car, which is activated to stop the elevator car when the elevator car is at the floor level if the elevator car unintentionally, e.g. with the doors open, moves a greater distance than the pre-set distance. When the elevator car is controlled to move, said control for keeping the elevator car in the proximity of the landing is switched off. The control can be based on at least partly the load information of the elevator or can be fully independent of the load information. One method to implement the invention is to achieve gripping of the elevator car resulting from an unintended downward movement of the elevator car by stopping the overspeed governor or the rope of the overspeed governor if it moves e.g. more than the distance permitted beforehand when the elevator car is at the landing. Stopping of the overspeed governor can be effected by e.g. adding a prevention means to the overspeed governor, which always activates during the time the elevator car is stopped and which by means of a detent or impediment or some other means stops the rotation of the overspeed governor if the elevator car tries to move for a longer distance than that permitted beforehand. Likewise, stopping the rope of the overspeed governor can be effected e.g. by fitting a brake device that acts on the overspeed governor, which always activates during the time the elevator car is stopped and which restrains the rope of the overspeed governor from moving more than the distance permitted beforehand. In the following, the invention will be described in more detail by the aid of one example of its embodiment with reference to the attached drawings, wherein

Fig. 1 presents a diagrammatic and simplified side view of an elevator shaft, in which the elevator car has stopped normally at the floor level,

Fig. 2 presents a diagrammatic view of the most important mechanisms of the solution according to the invention and their connection to each other and

Fig. 3 presents a diagrammatic side view of a solution according to another embodiment of the invention, in which a speed governor is used as an aid.

In order to understand the invention, the appliance according to the invention and the operation of the appliance will be explained first.

Fig. 1 presents in diagrammatic and simplified form a traction sheave elevator applicable to one concept according to the invention, which comprises at least an elevator hoisting machine 6 with its hoisting motor, a traction sheave 7, a counterweight 9, an elevator control system 11 and an elevator car 2 that moves in essentially the vertical direction along guide rails 3, said elevator car being suspended by means of hoisting ropes 8 such that as the hoisting ropes 8 rotate around the traction sheave 7 the elevator car 2 obtains its movement as a result of the friction between the traction sheave 7 and the hoisting ropes 8. In addition the elevator car 2 is equipped with a load-measuring device 4, e.g. with a load-weighing device, which measures the combined weight of the elevator car and the load in the elevator car. The load- measuring device 4 according to the invention is used as a measuring device that monitors a change in the status of the elevator car 2 when it is at the landing, said change in status being in this case a change in the load of the elevator car. The load-measuring device that monitors a change in the status of the elevator car 2 will be referred to below also with the reference number 4.

An elevator applicable to the concept of the invention also includes a sliding inhibitor 5, which locks the elevator car in its position such that the hoisting ropes 8 of the elevator cannot slip a dangerously long distance on the traction sheave

7. The sliding inhibitor 5 can be any prior-art anti-creeping device whatsoever. It can be e.g. a mechanical catch, a guide rail brake or a rope brake, which locks directly onto the hoisting ropes 8 of the elevator.

Fig. 2 presents a diagrammatic view of the most important mechanisms of the solution according to figure 1 and their connection to each other. The load-measuring device 4 is connected to the elevator car 2 and measures the combined weight of the elevator car and the load, or at least the weight of the load. The load-measuring device 4 is connected to the control unit 10 of the sliding inhibitor 5, said control unit 10 also being connected to the sliding inhibitor 5 as well as to the control system 11 of the elevator.

The anti-creeping device used in the solution according to the invention can also be a rope brake 14 according to figure 3 , which locks the rope 13 of the overspeed governor 12 in its position, or a device for preventing or braking the rotation of the rope wheel of the overspeed governor 12 , in which case when the elevator car 2 moves downwards a little distance when at the landing the rope 13 of the overspeed governor activates the safety gear 5a of the elevator and thereby prevents the elevator car 2 sliding downwards when the elevator car 2 at the landing has moved more than the pre-set travel distance. In this case the sliding inhibitor 5 acts as a mechanism that stops the rope 13 of the overspeed governor, which therefore can comprise e.g. a rope brake 14 and a safety gear 5a. The rope brake 14 is connected to the control unit 10, which is further connected to the control system 11 of the elevator. In this case the measuring device 4a that monitors a change in the status of the elevator car 2 is a measuring device that monitors and measures the distance the elevator car travels when at the landing or the position of the elevator car when at the landing, in which case therefore the change in the status of the elevator car 2 is the distance traveled by the elevator car when at the landing or a change in the position of the elevator car when at the landing. The measuring device 4a can be e.g. an element that measures the rotational movement of the overspeed governor 12 , which calculates the distance traveled by the elevator car 2 based on the rotational movement. The measuring device 4a can just as well measure the distance traveled by the rope 13 of the overspeed governor or directly the distance traveled by the elevator car, in which case the measuring device is connected to e.g. the elevator car 2. The measuring device 4a can also be a position sensor at the landing, which measures the position of the elevator car 8 when at the landing. Many other structural and positional solutions for the measuring device 4a are also possible.

From the viewpoint of the basic concept of the invention, irrespective of the embodiment, an important feature is to allow the elevator car a certain free movement, of at least the amount of the normal vertical movement resulting from loading of the elevator car, via the structure or operation of the inhibitor itself and/or the structure or operation of the system controlling its operation. The free movement allowance can be somewhat greater than that required for loading, e.g. covering the zone of that specific floor level in which the doors of the elevator car are permitted to open or being some other pre-set permitted travel distance of the elevator car.

With the method according to the invention the useful area of the elevator car 2 can be increased owing to the fact that a change in the status of the elevator car 2 when at the landing is actively monitored and when the status exceeds a pre-defined limit value the elevator car 2 is locked in its position in the landing zone. In one embodiment of the invention the combined weight of the elevator car 2 and the load in it is the change of status monitored by the load-measuring device 4 and if the weight exceeds the permitted weight limit, the creeping - i.e. sliding downwards - of the elevator car is prevented by locking the elevator car 2 in its position with the sliding inhibitor 5. Thus if the combined weight of the elevator car 2 and the load in the car exceeds the weight limit specified for the elevator car, the load-measuring device 4 functioning as the measuring device monitoring the status of the elevator car informs the control unit 10 of the sliding inhibitor 5 of the exceeding of the weight limit, which for its part locks the guide rail brake functioning as the sliding inhibitor 5 in the case according to the embodiment, and therefore the elevator car 2 cannot slide downwards. The control unit 10 of the sliding inhibitor 5 also notifies this fact to the control system 11 of the elevator, which keeps the operating brake of the elevator locked and does not start the elevator because of the overload and announces the overload with e.g. a buzzer.

In another embodiment of the invention a corresponding safety function is achieved by monitoring a change in the status of the elevator car 2 by measuring the downward movement of the elevator car or the position of the elevator car with the measuring device 4a, and the sliding downwards of the elevator car 2 is prevented when a certain, pre-defined creeping distance of the elevator car 2 is exceeded by locking the elevator car 2 in its position with a sliding inhibitor fitted to act in connection with the overspeed governor 12, which comprises in addition to the overspeed governor 12 at least the rope 13 of the overspeed governor, the rope brake 14 acting on the rope 13 of the overspeed governor and the safety gear 5a connected to the elevator car 2, which stops the elevator car 2 when the rope 13 of the overspeed governor stops or slows its speed in relation to the speed of the elevator car. When the elevator car 2 is locked in its position for the aforementioned reasons, the elevator car 2 is not released for movement before the overload or other reason causing the sliding has been removed. When the reason causing the sliding has been removed, the guide rail brake that is the inhibitor 5 is opened or the safety gear 5a is released and information is given to the control system 11 of the elevator that elevator operation can again be permitted.

It is obvious to the person skilled in the art that the invention is not limited solely to the example described above, but that it may be varied within the scope of the claims presented below. Thus, for example, the sliding inhibitor 5 can instead of a guide rail brake be some other type of device for preventing creeping of the elevator car 2 , such as e.g. the aforementioned catch, rope brake or safety gear.

It is also obvious to the person skilled in the art that the aforementioned control unit of the sliding inhibitor does not necessarily need to be separate but can be directly integrated into the control system of the elevator.

Claims

1. Method for increasing the useful area of an elevator car (2), wherein the elevator car (2) is fitted to travel in the elevator shaft (1) controlled by the control system (11) along guide rails (3) in essentially the vertical direction, characterized in that a change in the status of the elevator car (2) when at the landing is monitored and when the change of status exceeds a pre-defined limit value the elevator car (2) is locked in its position in the landing zone.

2. Method according to claim 1, characterized in that the weight of the load of the elevator car (2) is monitored with a load-weighing device (4) and overspeed of the elevator car is monitored with an overspeed governor (12) .

3. Method according to claim 1 or 2 , characterized in that the downward movement of the elevator car (2) is monitored as a change in the status of the elevator car (2) when it is at the landing and the downward movement is prevented by means of an essentially mechanical sliding inhibitor (5, 5a, 12, 13, 14) when the elevator car (2) has moved a greater distance than the pre-set distance.

4. Method according to claim 1 or 2 , characterized in that the load of the elevator car (2) when at the landing is monitored as a change of status of the elevator car (2) and based on the load information obtained from the load-measuring device (4) the elevator car (2) is locked in its position by means of an essentially mechanical sliding inhibitor (5, 5a, 12, 13, 14) when the load information exceeds the permitted weight limit.

5. Method according to any of the preceding claims, characterized in that monitoring of the change of status of the elevator car (2) is activated to be on in conjunction with the arrival of the elevator car at the floor level and in that monitoring of the change of status of the elevator car (2) is switched off in conjunction with the departure of the elevator car from the floor level.

6. Method according to any of the preceding claims, characterized in that the mechanical locking of the elevator car (2) is released based on the load information obtained from the load-measuring device (4) when the overload is removed and information about the removal of the overload is also transmitted to the control system (11) of the elevator.

7. Appliance for increasing the useful area of an elevator car (2), said elevator car (2) being fitted to travel in the elevator shaft (1) controlled by the control system (11) along guide rails (6) in essentially the vertical direction, characterized in that the appliance comprises at least a measuring device (4, 4a) monitoring a change of status of the elevator car (2) and a sliding inhibitor (5, 5a, 12, 13, 14), which is fitted to lock the elevator car (2) in its position in the landing zone if the measuring device (4, 4a) monitoring a change of status detects a change of status of the elevator car (2) exceeding a pre-defined limit value.

8. Appliance according to claim 7 , characterized in that the weight of the load of the elevator car (2) is arranged to be monitored by a load-measuring device (4) , which is connected to the control system (11) of the elevator and overspeed of the elevator car is arranged to be monitored by an overspeed governor (12) .

9. Appliance according to claim 7 or 8 , characterized in that the measuring device monitoring a change of status of the elevator car (2) is a measuring device (4a) that measures the travel distance or position of the elevator car, and in that a sliding inhibitor (5, 5a, 12, 13, 14) is fitted to lock the elevator car (2) in its position if the travel distance of the elevator car at the landing has exceeded a pre-defined distance.

10. Appliance according to claim 7 or 8, characterized in that the measuring device monitoring a change of status of the elevator car (2) is a load-measuring device (4) acting as a load-weighing device of the elevator car, and in that a sliding inhibitor (5, 5a, 12, 13, 14) is fitted to lock the elevator car (2) in its position if the load information obtained from the load-measuring device (4) is greater than the permitted weight limit .

11. Appliance according to claim 7, 8, 9 or 10, characterized in that the appliance comprises a control unit (10) of a sliding inhibitor (5, 5a, 12, 13, 14), said control unit being separate or integrated into the control system (11) of the elevator, to which control unit (10) it is arranged that measuring information from the measuring device (4, 4a) monitoring a change of status of the elevator car (2) is led, and from which control unit (10) control information is arranged to be led onwards to the sliding inhibitor (5, 5a, 12, 13, 14) for locking the elevator car (2) in its position and for releasing the locking of the elevator car (2) when the overload has been removed.

12. Appliance according to any of claims 7-11, characterized in that a sliding inhibitor (5, 5a, 12, 13, 14) is fitted to lock the elevator car (2) in its position essentially mechanically, and that the sliding inhibitor (5) is preferably a guide rail brake, a rope brake gripping the hoisting ropes

(3) of the elevator, a catch, a rope brake (14) that grips the rope (13) of the overspeed governor of the elevator and that activates the safety gear (5a) of the elevator or a corresponding essentially mechanical locking appliance, which is fitted to keep the elevator car (2) in its position in the landing zone when the weight of the load exceeds the permitted weight limit and/or the elevator car moves more than the permitted distance at the landing.

13. Appliance according to any of the preceding claims (7-12) , characterized in that monitoring of a change of status of the elevator car (2) is fitted to be on only during the time that the elevator car is at the floor level.

14. Appliance according to any of the preceding claims (7-13), characterized in that the elevator car (2) is of greater volume than the standard volume corresponding to the rated load.