ELEVATOR BRAKE RELEASE MONITORING

Abstract

Brake release sensors for an elevator can be replaced by an arrangement wherein the brake release is determined from the force caused by the brake. This is achieved by providing measuring device for measuring the weight of an elevator car between the brake and the motor body so that the weight of the elevator car is measured only when the brake is on.

Claims

1. A method for detecting release of a brake of an elevator, which method comprises: using a measuring device for measuring weight of an elevator car from a rotating shaft of part a traction sheave of said elevator when the brake of said elevator is closed; generating a brake release signal; receiving a value from said measuring device; comparing said received value to a reference value; and detecting a brake failure when said received value deviates from said reference value.

2. The method according to claim 1, the method further comprises transmitting an error message as a response to said detected failure.

3. The method according to claim 1, the method further comprises moving said elevator to the next floor responsive to detecting the brake failure.

4. The method according to claim 1, wherein the method further comprises preventing use of said elevator after detecting a brake failure.

5. The method according to claim 1, wherein said reference value is the value that corresponds with the situation wherein said measuring device is unloaded.

6. The method according to claim 5, wherein said value is zero.

7. The method according to claim 1, wherein determining said reference value by driving the elevator to both directions and accepting the value indicated by the measurement device as a reference value when the measurement device indicates same value to both directions.

8. A computer program for a computing device comprising code adapted to cause the method according to claim 1 when executed on a data-processing system.

9. An apparatus comprising: processor; at least one memory; wherein the apparatus is configured to perform the method according to claim 1.

10. An elevator system comprising at least one elevator comprising the apparatus according to claim 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:

[0013] FIG. 1 is a block diagram of an example embodiment of the present invention,

[0014] FIG. 2 is a flow chart of a method according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0015] Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

[0016] In FIG. 1 a block diagram of an arrangement according to the present invention. In the embodiment of FIG. 1 an elevator car 10 is operated by using a hoisting rope 11 which is arranged to a traction sheave 12, which is operated by the hoisting machine 13. The elevator car 10 transports passengers according to given calls. The hoisting machine of the embodiment is controlled by a controller 16 that is connected to the hoisting machine 13. For example, when the controller receives a call, directly or indirectly, from the elevator car, it will instruct the hoisting machine to move the elevator to the called floor. When the elevator is not moving it will be kept in its position by a break 14. The break is typically magnetic so that an electromagnetic force is used to keep the brake released during the movement of the elevator car. When the elevator car stops the brake closes when the electromagnetic force is turned off. In the embodiment of figure a weighing device 15 is arranged between the brake 14 and traction sheave 12 so that the weighing device 15 is able to measure the weight of the elevator car when the brake 14 is in closed position. The present invention is not limited to any brake or hoisting machine type but any hoisting machine and brake type can be used, provided that they can be configured in a manner that the weight of the elevator car is measured only when the brake is in closed position. Examples of suitable brake, measuring device and hoisting machine are given, for example, in WO2013/182742 A1 mentioned above.

[0017] In the embodiment according to FIG. 1 hoisting machine 13, weighing device 15 and brake 14 are connected to the controller 16. In the figure a separate connection between each of the components is disclosed, however, it is possible that the arrangement comprises a further controller at the vicinity of the hoisting machine or hoisting arrangement and the information is then transmitted further to the controller. Conventionally the weighing device 15 has been used for providing a smooth start for elevator ride by estimating the force needed from the weight of the elevator car. A further use has been to detect possible overload situations when the elevator car is too heavy. When the elevator is overloaded the operation of the elevator should be prevented for security reasons. In other words, conventionally the weighing device has been used between the rides when the elevator car is stationary in a floor waiting for a next call or having a stop in a floor when the elevator rides have been called to a plurality of destinations.

[0018] When the arrangement of FIG. 1 is operated the controller 16 receives calls and schedules the movement of the elevator car 10. During the operation it may receive indications from and can send instructions to the elevator car 10, hoisting machine 13, brake 14 and weighing device 15. According to the embodiment of FIG. 1 the release of the brake 14 can be detected using, for example, a method discussed below with regard FIG. 2. In the method the controller 16 detects or receives an indication that the brake release signal has been generated and/or the elevator is moving. At the same time it will continue receiving data from weighing device 15. When the brake 14 and weighing device 15 are configured as discussed above, there should not be any load to be measured if the brake 14 is released completely. If the weighing device, however, indicates a value different to the value without load it might be an indication of a brake failure. The different value is caused by dragging brake.

[0019] The controller 16 further includes at least one processor 17 and at least one memory 18 for storing and executing computer programs and related data. Furthermore, the controller 16 may include other components that are not shown in the figure, for example, data communications connection if the controller is located at a remote site so that the data can be received and instructions transmitted through this data communication connection.

[0020] In FIG. 2 a method according to the present invention is disclosed. The method is initiated by generating brake release signal, step 20. For example, if the controller 16 of FIG. 1 is responsible for monitoring and instructing the operation of the elevator system, the brake release signal may be an internal message within the software framework operating the elevator. Thus, when the software component responsible for instructing brake release sends an instruction for brake release it simultaneously sends message to monitoring component that the brake has been released. As a response to the brake release signal the brake is released, or if the brake is defect, at least tried to release.

[0021] The monitoring component receives values from the weight measuring device, step 21. When the brake is in closed position the monitoring means receive the weight of the elevator car. When the brake is released the value received should be zero if the weighing device is calibrated to show zero when there is no load. The received value is compared to a reference value, step 22. It is important to understand that the weighing device does not necessarily show zero when there is no load but may deviate from zero. This offset value may be determined by monitoring the values that the weighing device provides and if it is the same value to both elevator operating directions the value can be considered as an offset from zero and used as a reference value. If the measured value deviates from this reference value, there may be a brake problem and it is detected, step 24. Correspondingly, if the reference value cannot be determined, i.e., the weighing device shows different values to different directions, there may be a brake problem.

[0022] After detecting the brake problem different actions may be taken. For example, the elevator may be brought to the next floor and stopped there. The operation of that elevator may be prevented and a maintenance call may be launched.

[0023] The above mentioned method may be implemented as computer software which is executed in a computing device, such as the controller 16 of FIG. 1. When the software is executed in a computing device it is configured to perform the above described inventive method. The software is embodied on a computer readable medium so that it can be provided to the computing device, such as the controller 16 of FIG. 1.

[0024] As stated above, the components of the exemplary embodiments can include computer readable medium or memories for holding instructions programmed according to the teachings of the present inventions and for holding data structures, tables, records, and/or other data described herein. Computer readable medium can include any suitable medium that participates in providing instructions to a processor for execution. Common forms of computer-readable media can include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other suitable magnetic medium, a CD-ROM, CD±R, CD±RW, DVD, DVD-RAM, DVD±RW, DVD±R, HD DVD, HD DVD-R, HD DVD-RW, HD DVD-RAM, Blu-ray Disc, any other suitable optical medium, a RAM, a PROM, an EPROM, a FLASH-EPROM, any other suitable memory chip or cartridge, or any other suitable medium from which a computer can read.

[0025] It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above; instead they may vary within the scope of the claims.