Patent ID: 12252376

DETAILED DESCRIPTION

The solution presented below provides a solution to release safety gears of an elevator car or counterweight in a rescue situation.

FIG.1illustrates a method for releasing safety gears of an elevator car of an elevator system according to an example embodiment.

The method may be applied in an elevator system comprising a stalling detector coupled to compensation roping associated with the elevator car and counterweight and configured to detect an increased rope tension. At100a stalling indication from the stalling detector is prevented during the rescue operation, and at102the elevator car is moved in order to release the safety gears. The movement may be provided by elevator machinery configured to move the elevator car in an elevator shaft. Alternatively, the movement may be provided by manually pulling the elevator car down with the compensation roping.

FIG.2Aillustrates an elevator system211comprising a stalling detector200according to an example embodiment. The elevator system211may be implemented with ropings202,207of any reeving factor, such as 2:1 or 1:1.

The elevator system211comprises a counterweight208and elevator machinery configured to move an elevator car206in an elevator shaft. The machinery may comprise, for example, a motor and a traction sheave210for lifting the elevator car206. For illustrative purposes, only the traction sheave210is shown inFIG.2A. The elevator car206, the machinery and the counterweight208are interconnected via hoisting roping207routed via a plurality of pulleys201,203A,204A,209and a sheave210.

The compensation roping202is used in conjunction with the hoisting roping207to cancel the varying imbalance between the elevator car206and counterweight sides of the elevator car206caused by the imbalance of the weight of the hoisting roping207, especially in extreme positions of the elevator car206and the counterweight208. The compensation roping202may be suspended below the elevator car206and the counterweight208. The compensation roping202may comprise a plurality of pulleys201,203B,204B,205. The ropings202,207may be implemented with any known solution, such as steel ropes, belts, polyurethane coated ropes, high friction ropes made with special grease, or cogged belts.

The elevator system211further comprises a stalling detector200. The stalling detector200may comprise a monitoring device (not shown inFIG.2A). The monitoring device may be coupled with the compensation roping202of the elevator system211. The monitoring device may be configured to detect changes in rope tension which indicate abnormality in the movements of the elevator car206or the counterweight208. For example, the monitoring device may detect when the rope tension exceeds a predetermined threshold. Alternatively, the monitoring device may be configured to detect any change in the rope tension and/or position of the stalling detector200.

The changes in the rope tension may be detected, for example, with a force sensor. Alternatively, the changes in the rope tension may be detected with a sensor configured to detect changes in position of the stalling detector200. Alternatively, the sensor may be configured to detect tension force or force applied in response to the pulley resisting the upward movement. In an example embodiment, the stalling detector200may be configured in the diverting pulley201of the compensation roping202. The diverting pulley201may be either fixed or movable, such as a tensioning pulley. Alternatively, the stalling detector200may be configured in at least one of the car pulleys203,204. The stalling detector200may also be configured in different locations in the elevator system211, for example, in connection with the compensation roping202. The stalling detector200may be configured to detect movement of the pulley associated with the stalling detector200. The movement may be essentially orthogonal with respect to the rotating axle of the pulley. The stalling detector200may comprise a switch, which opens in response to the detected abnormal movement or tension and shuts down the machinery and applies machinery brakes. In an example embodiment, the stalling detector200may move a predetermined distance before the switch is triggered.

The stalling detector200may be coupled to a fixed support. For example, one possible option is to arrange the stalling detector200at any of the rope termination points212,213, for example, as a force sensor. Alternatively, the stalling detector200may be movable such that it is arranged to move in response to an increased tension on the compensation roping202. Further, the stalling detector200may be arranged to be movable only for a predetermined distance. For example, when releasing the elevator car206from safety gear gripping by moving the counterweight upwards, the movement is also induced via the compensation roping202to the diverting pulley201comprising the stalling detector200. In a normal operation, the diverting pulley201may stay still, that is, it does not move up or down, and the pulley201may only have rotating motion. When the diverting pulley201is fixed, or if it may move only a limited distance, its restricted upward motion indicates a higher tension in the compensating roping202. The stalling detector200configured to the diverting pulley201may detect the increased tension and the stalling detector200may cause the elevator machinery to stop and machinery brakes to activate. The detection may be performed, for example, by a force sensor or by a switch activated by the movement of the diverting pulley201. For example, the diverting pulley201may move and physically contact the switch when a certain amount of movement has been reached. The elevator car206may remain inoperable until the stalling detection condition is reset by a service person.

FIG.2Billustrates a rescue method for releasing safety gears of an elevator car206according to an example embodiment. The elevator system211illustrated inFIG.2Bcorresponds to the elevator system211ofFIG.2A.

In the exemplary situation presented inFIG.2B, the safety gears (not shown inFIG.2B) have engaged in response to the elevator car206overspeeding in the upward direction. The safety gears may be bi-directional safety gears. In order to carry out a rescue operation and disengage the safety gear, the elevator car206needs to be moved downwards. An attempted downward movement of the elevator car206may cause strain to the compensation roping202which is detected by the stalling detector200. Therefore, the elevator car206may not move downwards using the motor, which is shut down in response to the stalling detection.

The rescue operation may be enabled by preventing a stalling indication from the stalling detector200during a rescue operation. In an example embodiment, the stalling detector200may be set to a rescue mode. In another example embodiment, the stalling detector200may be locked in place mechanically or electromechanically. In the rescue mode, the operation of the stalling detector200may be deactivated. Hence, while in the rescue mode, the pulley associated with the stalling detector200may still rotate although the position of the pulley may not change in the rescue mode. In another example embodiment, the stalling detector200may be configured such that it can move, for example, vertically for a predetermined distance before stalling detection indication. For example, a detection switch may be positioned such that it detects movement of the stalling detector only after the stalling detector has reached a preset moving limit distance. By preventing or deferring the stalling detection, the movement of the elevator car206is not prevented during the rescue operation. Therefore, the elevator may be able to drive itself out from the gripping situation in either direction.

In another example embodiment, the stalling indication may be bypassed electrically. In another example embodiment, the stalling indication signal may be registered but ignored by a computer program running in an apparatus, for example, an elevator safety controller. In other words, the elevator safety controller may obtain the stalling indication from the stalling detector, and override the stalling indication during the rescue operation. Further, in an example embodiment, the elevator safety controller may be configured to monitor the stalling detector so that the elevator car cannot be taken into normal use when the stalling detector is locked or set to the rescue mode.

The stalling detector200may be set to the rescue mode or locked manually or automatically. A supervision may be needed for locking the stalling detector200so that the elevator car206cannot be taken into normal use when the stalling detector200is locked or in the rescue mode. When the elevator pit is not accessible for a service man, it may be useful that the setting or locking and moving operations may be performed remotely.

If the elevator car206is stuck very heavily in the upwards direction, the rescue may be performed by pulling the elevator car206downwards using the compensation roping202. The pulling may be performed, for example, with a separate tool, such as a hoist, or by moving the elevator with the machinery. The manual pulling may require opening of the machinery brakes, and therefore the activation of the stalling detector200may need to be prevented also in this case. The elevator car206may be released from the safety gear engagement, for example, by pulling downwards from a rescue point214as illustrated with an associated arrow inFIG.2A.

In the next sections, some examples of possible implementation forms of the stalling detector are described in detail. The arrangements enable preventing the stalling detection during a rescue operation by restricting the movement of the stalling detector. The restricted movement may prevent the stalling detector from detecting the increased tension of the compensation roping when the tension is caused by the rescue operation.

FIGS.3and4illustrate a stalling detector300,400arranged to have a restricted movement according to example embodiments. The example e embodiments enable preventing a stalling indication from the stalling detector during a rescue operation by a restricting movement of the stalling detector300,400. The restricted movement may prevent the stalling detector to detect the increased tension of the compensation roping when the tension is caused by the rescue operation.

The stalling detector300,400may be coupled to compensation roping302,402of an elevator system. The stalling detector300,400may comprise a monitoring device, such as a switch or sensor, to trigger safety functions in response to increased strain of the compensation roping302,402. The stalling detector300,400may be coupled, for example, to a diverting pulley303,404of the compensation roping302,402.

The stalling detector300,400may be arranged such that it may allow some vertical movement before stalling detection by a sensor or a switch. In an example embodiment, the stalling detector300may be implemented with a swing arm301, as illustrated inFIG.3. The swing arm301may be configured to suspend the stalling detector300from a shaft wall or floor of the elevator pit such that a restricted movement is allowed for the stalling detector300. For example, the swing arm301may be arranged to enable movement of the stalling detector300for a predetermined distance A before the switch is activated. Because the arrangement allows the stalling detector300to move for the predetermined distance A, the switch is not immediately triggered when the tension of the compensation roping302increases. This is because the stalling detector300,400may not detect a force exceeding a threshold limit as the diverting pulley/stalling detector300moves in response to the induced force. When the predetermined distance A is reached, the diverting pulley303may stop moving and a stalling indication may be provided by the stalling detector300. In an example embodiment, the movement of the stalling detector300or the diverting pulley303may be restricted or the stalling detector300or diverting pulley303may be locked in place in order to prevent the stalling indication from the stalling detector300during the rescue operation. The locking may be implemented, for example, with at least one of electromechanical and electrical means. In another example embodiment, the stalling detector300may be set in a rescue mode that prevents the stalling indication from the stalling detector300during the rescue operation.

FIG.4illustrates another possible implementation of a support structure for the stalling detector400according to an example embodiment. InFIG.4, the stalling detector400and the associated pulley may be arranged in a casing401. The casing401may comprise one or more weight or spring elements403to maintain a suitable tension in the compensation roping402. When the tension of the compensation roping402increases and a lifting force is applied to the pulley, the stalling detector400and the support structure401start to move upwards. In other words, the stalling detector and the associated pulley may be vertically movable. The stalling detector400may be configured such that only after the vertical movement exceeds a predetermined distance B, the stalling detector400provides a stalling indication. As discussed relating toFIG.3, in an example embodiment, the movement of the stalling detector400or the diverting pulley404may be restricted or the stalling detector400or diverting pulley404may be locked in place in order to prevent the stalling indication from the stalling detector400during the rescue operation. The locking may be implemented, for with example, at least one of electromechanical and electrical means. In another example embodiment, the stalling detector400may be set in a rescue mode that prevents the stalling indication from the stalling detector400during the rescue operation.

InFIGS.3and4, the allowed movement is illustrated as distances A, B between the arrows. The distances A, B may be measured from the center of the stalling detector300,400at a starting position corresponding to the location of the stalling detector300,400and the associated pulley in a normal operation (left side ofFIGS.3and4) to the center of the stalling detector300,400at a second position during an abnormal operation (right side ofFIGS.3and4). The stalling detector300,400may move from the starting position to the second position in response to an increased tension of the compensation roping402. The stalling detector300,400may move a predetermined distance A, B before indicating stalling detection or a monitoring device does not trigger the switch during the rescue operation, while still being capable of detecting situations where the safety functions need to be activated. For example, when the elevator car is moved during the rescue operation, a movement within the predetermined distance A, B may be enough to disengage the safety gears.

Although the embodiments and examples above discuss the elevator car and its associated safety gear, the same principles apply also to the counterweight of the elevator and to the safety gear associated with the counterweight.

Although two examples were illustrated for arranging the stalling detector with a limited movement, also other arrangements are possible. Further, although a diverting pulley was used as an example with which the stalling detector may be associated, any pulley of the compensation roping of the elevator system or a rope termination point may be used instead.

While there have been shown and described and pointed out fundamental novel features as applied to preferred embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices and methods described may be made by those skilled in the art without departing from the spirit of the disclosure. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the disclosure. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiments may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. Furthermore, in the claims means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.

The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole, in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that the disclosed aspects/embodiments may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the disclosure.