A method and an elevator rope elongation determination system for generating elongation data of an elevator hoisting rope arrangement

Abstract

The invention relates to a method for generating elongation data of an elevator hoisting rope arrangement (112). The method comprises: detecting (210), by a detection device (120) arranged inside an elevator shaft (104), an encounter event between the detection device (120) and a counterweight (106), wherein the encounter event is detected by the detection device (120) by detecting an indicator device (130), when the indicator device (130) coupled with a counterweight (106) passes by the detector device (120) inside an elevator shaft (104); receiving (220), from the detection device (120), detection data representing the detection of the encounter event; obtaining (230) encounter position data of an elevator car (102) representing the position of the elevator car (102) inside the elevator shaft (104) at the moment of the encounter event; and generating (240) elongation data representing the elongation of the elevator hoisting rope arrangement (112) based on the obtained encounter position data. The invention relates also to an elevator rope elongation determination system (101).

Description

[0001] A method and an elevator rope elongation determination system for generating elongation data of an elevator hoisting rope arrangement

[0002] TECHNICAL FIELD

[0003] The invention concerns in general the technical field of elevator systems. Especially the invention concerns elevator hoisting rope arrangements.

[0004] BACKGROUND

[0005] Elevator systems typically comprise elevator rope arrangements, such as an elevator hoisting rope arrangement supporting the elevator car and counterweight. The elevator hoisting rope arrangement is one of typical periodical maintenance checking target of the elevator system. The elevator hoisting rope arrangement is typically elongating during its lifetime and thus the length of the elevator hoisting rope arrangement needs to be adjusted, e.g. shortened, especially in case of longer travel elevator systems. The adjustment of the elevator hoisting rope arrangement may for example be performed during maintenance visits. Moreover, the condition of the elevator hoisting rope arrangement needs to be monitored periodically.

[0006] When the elevator car is at the top floor landing, an unobstructed distance remains between the counterweight buffer or buffers fixed at the bottom of the counterweight and the floor of the elevator shaft pit (or, if the counterweight buffer(s) is (are) fixed at the shaft pit floor, between the counterweight bottom and the counterweight buffer(s)). This distance is referred to as the counterweight overtravel distance and it must exceed a predefined limit value.

[0007] Due to the elongation of the elevator hoisting rope arrangement, the counterweight overtravel distance decreases. Thus, also the counterweight overtravel distance needs to be adjusted. The adjustment of the counterweight overtravel distance may for example be performed by adjusting the length of the elevator hoisting rope arrangement or adjusting the height of the buffer of the counterweight.

[0008] Taking a direct measurement of the counterweight overtravel distance requires access to the pit of the elevator shaft. However, in low pit elevator systems, access into the pit of the elevator shaft may be prevented. Therefore, there is a need to develop further solutions for monitoring the elevator hoisting rope arrangement and / or the counterweight overtravel distance.

[0009] SUMMARY

[0010] The following presents a simplified summary in order to provide basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments of the invention.

[0011] An objective of the invention is to present a method and an elevator rope elongation determination system for generating elongation data of an elevator hoisting rope arrangement. Another objective of the invention is that the method and the elevator rope elongation determination system for generating elongation data of an elevator hoisting rope arrangement enable determination elongation of an elevator hoisting rope arrangement.

[0012] The objectives of the invention are reached by a method and an elevator rope elongation determination system as defined by the respective independent claims.

[0013] According to a first aspect, a method for generating elongation data of an elevator hoisting rope arrangement is provided, wherein the method comprises: detecting, by a detection device arranged inside an elevator shaft, an encounter event between the detection device and a counterweight, wherein the encounter event is detected by the detection device by detecting an indicator device, when the indicator device coupled with a counterweight passes by the detector device inside an elevator shaft; receiving, from the detection device, detection data representing the detection of the encounter event; obtaining encounter position data of an elevator car representing the position of the elevator car inside the elevator shaft at the moment of the encounter event; and generating elongation data representing the elongation of the elevator hoisting rope arrangement based on the obtained encounter position data.

[0014] The elongation data may comprise at least one of the following: an encounter position difference value, an estimate of the elongation of the elevator hoisting rope arrangement, an estimate of a change of a counterweight overtravel distance.

[0015] Generating elongation data may comprise determining an encounter position displacement value by comparing the obtained encounter position data of the elevator car to a reference encounter position of the elevator car.

[0016] If the obtained encounter position data differs from the reference encounter position, the encounter position displacement value may correspond to the difference between the obtained encounter position data and the reference encounter position, or if the obtained encounter position data does not differ from the reference encounter position, the encounter position displacement value may be zero.

[0017] Generating elongation data may further comprise determining an estimate of the elongation of elevator hoisting rope arrangement based on the determined encounter position displacement value and a roping ratio of elevator hoisting rope arrangement.

[0018] Alternatively or in addition, generating elongation data may further comprise determining an estimate of a change of a counterweight overtravel distance based on the determined encounter position displacement value.

[0019] The reference encounter position may be determined during a commissioning of the elevator hoisting rope arrangement.

[0020] The method may further comprise detecting that the elongation data meets a predefined limit, and generating, in response to the detection that the elongation data meets the predefined limit, a maintenance request comprising an instruction to adjust the length of the elevator hoisting rope arrangement.

[0021] The operation of the detection device and the indicator device may be based on a contactless detection technique.

[0022] The contactless detection technique may be one of the following: radio frequency identification (RFID), near field communication (NFC), quick response code (QR code), or reflection -based detection. The elongation data may be generated every time when the indicator device coupled with the counterweight passes by the detector device inside the elevator shaft, or periodically.

[0023] The detector device may be arranged at the elevator car, attached to a wall of the elevator shaft, or attached to a landing door frame inside the elevator shaft.

[0024] The indicator device may be attached to the counterweight or to any part mounted to the counterweight, such as a buffer mount at the counterweight or a counterweight deflection pulley.

[0025] According to a second aspect, an elevator rope elongation determination system for generating elongation data of an elevator hoisting rope arrangement is provided, wherein the system comprises: a detection device arranged inside an elevator shaft; an indicator device coupled with a counterweight; and a computing system communicatively coupled to the detection device, wherein the detection device is configured to detect an encounter event between the detection device and the counterweight, wherein the encounter event is detected by the detection device by detecting the indicator device, when the indicator device coupled with the counterweight passes by the detector device inside the elevator shaft; and wherein computing system is configured to: receive, from the detection device, detection data representing the detection of the encounter event; obtain encounter position data of the elevator car representing the position of the elevator car inside the elevator shaft at the moment of the encounter event; and generate elongation data representing the elongation of the elevator hoisting rope arrangement based on the obtained encounter position data.

[0026] The elongation data may comprise at least one of the following: an encounter position difference value, an estimate of the elongation of the elevator hoisting rope arrangement, an estimate of a change of a counterweight overtravel distance.

[0027] Generating elongation data may comprise that the computing system is configured to determine an encounter position displacement value by comparing the obtained encounter position data of the elevator car to a reference encounter position of the elevator car. If the obtained encounter position data differs from the reference encounter position, the encounter position displacement value may correspond to the difference between the obtained encounter position data and the reference encounter position, or if the obtained encounter position data does not differ from the reference encounter position, the encounter position displacement value may be zero.

[0028] Generating elongation data may further comprise that the computing system is configured to determine an estimate of the elongation of elevator hoisting rope arrangement based on the determined encounter position displacement value and a roping ratio of elevator hoisting rope arrangement.

[0029] Alternatively or in addition, generating the elongation data may further comprise that the computing system is configured to determine an estimate of a change of a counterweight overtravel distance based on the determined encounter position displacement value.

[0030] The reference encounter position may be determined during a commissioning of the elevator hoisting rope arrangement.

[0031] The computing system may further be configured to: detect that the elongation data meets a predefined limit, and generate, in response to the detection that the elongation data meets the predefined limit, a maintenance request comprising an instruction to adjust the length of the elevator hoisting rope arrangement.

[0032] The operation of the detection device and the indicator device may be based on a contactless detection technique.

[0033] The contactless detection technique may be one of the following: radio frequency identification (RFID), near field communication (NFC), quick response code (QR code), or reflection -based detection.

[0034] The elongation data may be generated every time when the indicator device coupled with the counterweight passes by the detector device inside the elevator shaft, or periodically.

[0035] The detector device may be arranged at the elevator car, attached to a wall of the elevator shaft, or attached to a landing door frame inside the elevator shaft. The indicator device may be attached to the counterweight or to any part mounted to the counterweight, such as a buffer mount at the counterweight or a counterweight deflection pulley.

[0036] Various exemplifying and non-limiting embodiments of the invention both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying and non-limiting embodiments when read in connection with the accompanying drawings.

[0037] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of unrecited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of “a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.

[0038] BRIEF DESCRIPTION OF FIGURES

[0039] The embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings.

[0040] Figure 1A illustrates schematically an example of an elevator system, in which an elevator rope elongation determination system may be implemented.

[0041] Figure 1 B illustrates schematically an example of a local computing system implementation of a computing system.

[0042] Figure 1C illustrates schematically an example of a remote computing system implementation of the computing system.

[0043] Figure 1 D illustrates schematically an example of a combined computing system implementation of the computing system.

[0044] Figure 2 illustrates schematically an example of a method for generating elongation data of an elevator hoisting rope arrangement.

[0045] Figure 3 illustrates schematically another example of the method.

[0046] Figure 4A illustrates schematically an example of a reference encounter position of the elevator car. Figure 4B illustrates schematically an example of an encounter position displacement value.

[0047] Figures 5A-5C illustrate schematically simple examples of an estimate of an elongation of the elevator hoisting rope arrangement with different roping ratios.

[0048] Figures 6A-6C illustrate schematically simple examples of an estimate of a change of a counterweight overtravel distance with different roping ratios.

[0049] Figure 7 illustrates schematically an example of components of the computing system.

[0050] DESCRIPTION OF THE EXEMPLIFYING EMBODIMENTS

[0051] Figure 1A illustrates schematically an example of an elevator system 100, in which an elevator rope elongation determination system 101 may be implemented. The elevator system 100 comprises an elevator car 102 configured to travel along an elevator shaft 104 between a plurality of floors (i.e. landings), a counterweight 106, and an elevator control system 108. The elevator system 100 may also form an elevator group, i.e. group of two or more elevator cars 102 each travelling along a separate elevator shaft 104 configured to operate as a unit serving the same landings. The elevator system 100 further comprises a hoisting machinery system configured to drive the elevator car 102 along the elevator shaft 104 between the floors. The elevator hoisting machinery may comprise for example a motor and a traction sheave 110 for lifting the elevator car 102. For illustrative purposes, only the traction sheave 110 is shown in Figure 1A. The elevator car 102, the hoisting machinery and the counterweight 106 are interconnected via an elevator hoisting rope arrangement 112 routed via a plurality of pulleys 114a-114n, and the traction sheave 110. When the traction sheave 110 rotates, the elevator car 102 and the counterweight 106 are moving. The elevator hoisting rope arrangement 112 comprises at least one hoisting rope. The elevator control system 108, e.g. an elevator controller, is configured to at least control the operations of the elevator system 100. The elevator control system 108 may be located inside a machine room 116 (as illustrated in the example of Figure 1A) or at one of the floors. The elevator control system 108 is communicatively coupled to the other entities of the elevator system 100. The communication between the elevator control system 108 and the other entities of the elevator system 100 may be based on one or more known communication technologies, either wired or wireless. The implementation of the elevator control system 108 may be done as a stand-alone control entity or as a distributed control environment between a plurality of stand-alone control entities, such as a plurality of servers, providing distributed control resource. The elevator control system 108 may, for example, comprise one or more elevator controllers. The elevator system 100 may further comprise one or more known elevator related entities, e.g. user interface devices, elevator doors, safety circuit and devices, and / or elevator brakes, etc., which are not shown in Figure 1 A for sake of clarity.

[0052] The elevator system 100 may further comprise the elevator rope elongation determination system 101 or the elevator rope elongation determination system 101 may be associated with the elevator system 100. The elevator rope elongation determination system 101 comprises a detection device 120, an indicator device 130, and a computing system 140. The detection device 120 is arranged inside the elevator shaft 104. For example, the detection device may be arranged, e.g. installed, at the elevator car 102, attached to a wall of the elevator shaft 104, or attached to a landing door frame inside the elevator shaft 104. The indicator device 130 is coupled with the counterweight 106. For example, the indicator device 130 may be attached to the counterweight 106 or to any part mounted to the counterweight 106 (e.g. to a buffer mount at the counterweight 106 or a counterweight deflection pulley 114n). The detection device 120 and the indicator device 130 are positioned such that the detection device 120 can detect the indicator device 130 passing by inside the elevator shaft 104. The detection device 120 may for example be arranged on the rooftop of the elevator car 102 as illustrated in the example of Figure 1A. However, the detection device 120 may also be arranged at any other location inside the elevator shaft 104, e.g. at any other location at the elevator car 102 (e.g. below the elevator car 102 or on the side of the elevator car 102), to the wall of the shaft 104, or to the landing door frame inside the shaft 104, as long as the detection device 120 is capable of detecting the indicator device 130, when the indicator device 130 coupled with the counterweight 106 passes by the detection device 120 inside the elevator shaft 104. The indicator device 130 may for example be attached to the bottom part of the counterweight 106, as illustrated in the example of Figure 1A. However, the indicator device 130 may be attached to any other location of the counterweight 106 or to any part mounted to the counterweight 106 (e.g. to the buffer mount at the counterweight 106 or the counterweight deflection pulley), as long as the detection device 120 is capable of detecting the indicator device 130, when the indicator device 130 coupled with the counterweight 106 passes by the detection device 120 inside elevator shaft 104.

[0053] The implementation of the computing system 140 may be done as a standalone computing entity or as a distributed computing environment between a plurality of stand-alone computing entities, such as a plurality of servers, providing distributed computing resource. The computing system 140 may be a local computing system 140a or a remote computing system 140b. Figure 1 B illustrates schematically an example of the local computing system 140a implementation of the computing system 140. Figure 1 C illustrates schematically an example of the remote computing system 140b implementation of the computing system 140. Alternatively, the computing system 140 may be a combined computing system comprising the local computing system 140a and the remote computing system 140b. Figure 1 D illustrates schematically an example of the combined computing system implementation of the computing system 140. The local computing system 140a may for example comprise one or more computing entities locating in the elevator system 100 or in association with the elevator system 100. For example, the local computing system 140a may be part of the elevator control system 108. Alternatively or in addition, the local computing system 140a may for example be any other computing system that may be arranged in association with the elevator system 100. The remote computing system 140b may for example comprise one or more computing entities located remotely from the elevator system 100. The remote computing system 140b may for example be at least one of the following: a cloud server, a service center, a data center, a remote monitoring system, a remote diagnostic system. Implementation of the computing system 140 at least partly by using the remote computing system 140b enables remote monitoring of the elevator hoisting rope arrangement 112, e.g. remote monitoring of the elongation of the elevator hosting rope arrangement 112. The computing system 140 is communicatively coupled to the detection device 120. The communication between computing system 140 and detection device 120 may be based on one or more known communication technologies, either wired or wireless.

[0054] Next an example of a method for generating elongation data of an elevator hoisting rope arrangement 112 is described by referring to Figure 2. Figure 2 schematically illustrates the method as a flow chart. The method is performed by the rope elongation determination system 101 described above.

[0055] At a step 210, the detection device 120 detects an encounter event between the detection device 120 and the counterweight 106 inside the elevator shaft 104. The encounter event between the detection device 120 and the counterweight 106 represents an event, wherein the detection device 120 and the counterweight 106 encounter each other inside the elevator shaft 104, when the elevator car 120 and the counterweight 106 are driven along the elevator shaft 104. When the detection device 120 is attached at the elevator car 102, the encounter event also represents an event, wherein the elevator car 102 and the counterweight 106 encounter each other inside the elevator shaft 104 when the elevator car 120 and the counterweight 106 are driven along the elevator shaft 104. The encounter event is detected by the detection device 120 by detecting the indicator device 130, when the indicator device 130 coupled with the counterweight 106 passes by the detector device 120 inside the elevator shaft 104. In other words, when the counterweight 106 passes by the detector device 120 inside the elevator shaft 104, the detection device 120 detects the indicator device 130 coupled with the counterweight 106, which indicates that the detection device 120 and the counterweight 106 encounter each other inside the elevator shaft 104. Thus, the detection of the indicator device 130 coupled with the counterweight 106, by the detection device 120, corresponds to the detection of the encounter event between the detector device 120 and the counterweight 106.

[0056] The operation of the detection device 120 and the indicator device 130 may be based on a contactless detection technique. For example, the contactless detection technique may be one of the following: radio frequency identification (RFID), near field communication (NFC), quick response code (QR code), or reflection -based detection. When the RFID is used as the contactless detection technique, the detection device 120 is an RFID reader device and the indicator device 130 is an RFID tag device. The RFID reader detects the RFID tag device, when the RFID tag device coupled with the counterweight 106 passes by the RFID reader device, in order to detect the encounter event. When the NFC is used as the contactless detection technique, the detection device 120 is an NFC reader device and the indicator device 130 is an NFC tag device. The NFC reader device detects the NFC tag device, when the NFC tag device coupled with the counterweight 106 passes by the NFC reader device, in order to detect the encounter event. When the QR code is used as the contactless detection technique, the detection device 120 is a QR code reader device and the indicator device 130 is a QR code. The QR code reader device detects the QR code, when the QR code coupled with the counterweight 106 passes by the QR code reader, in order to detect the encounter event. When the reflection -based detection system is used as the contactless detection technique, the detection device 120 is a device capable of emitting and detecting light (e.g. a laser device) and the indicator device 130 is a light reflecting element (e.g. a mirror or any other reflecting element). The light emitting and detecting device emits light and detects light reflected from the light reflecting element, when light reflecting element coupled with the counterweight 106 passes by the light emitting and detecting device, in order to detect the encounter event.

[0057] At a step 220, the computing system 140 receives from the detection device 120 detection data representing the detection of the encounter event. The detection data may for example comprise an indication of the detection of the encounter event. The detection device 120 provides the detection data to the computing system 140 in response to the detection of the encounter event. The detection device 120 may for example provide the detection data to the computing system 140 instantly after detecting the encounter event. In that case, the computing system 140 may determine the detection time of the encounter event, i.e. the moment of the encounter event, based on the receiving time of the detection data. According to an example, the received detection data may further comprise a time stamp indicating the detection time of the encounter event.

[0058] At a step 230, the computing system 140 obtains encounter position data of the elevator car 102 representing the position of the elevator car 102 inside the elevator shaft 104 at the moment of the encounter event, i.e. the encounter position of the elevator car 102. As the elevator car 102 travels along the elevator shaft 104 in the vertical direction (V), the encounter position of the elevator car 102 is the position of the elevator car 102 inside the elevator shaft 104 in the vertical direction (V). As it is well-known in the field of elevators, the position of the elevator car 102 inside the elevator shaft 104 in the vertical direction (V) can be determined accurately. For example, the elevator system 100 may comprise an absolute positioning system for determining the position of the elevator car 102 inside the elevator shaft 104 in the vertical direction (V). The computing system 140 may thus obtain the encounter position data of the ele- vator car 102 representing the position of the elevator car 102 inside the elevator shaft 104 at the moment of the encounter event, either directly from the absolute positioning system or indirectly via the elevator control system 108, for example. Alternatively, the encounter position data of the elevator car 102 may be based on a time stamp of detection of the elevator car 102 at a known position in the elevator shaft 104, e.g. a door zone indicator of a given landing, the time stamp of the encounter event, the velocity of the elevator car 102 therebetween, and distance calculation thereof. Furthermore, encounter position data may be based on elevator motor encoder data alone or in combination with other position detection means, including those mentioned above.

[0059] At a step 240, the computing system 140 generates elongation data representing the elongation of the elevator hoisting rope arrangement 112 based on the obtained encounter position data of the elevator car 102. In other words, the computing system 140 generates at the step 240 the elongation data representing the elongation of the elevator hoisting rope arrangement 112 based on the position of the elevator car 102 inside the elevator shaft 104 at the moment of the encounter event, i.e. based on the encounter position of the elevator car 102. The elongation data may for example, be used for a condition monitoring of the elevator hoisting rope arrangement 112. The elongation data may comprise at least one of the following: an encounter position displacement value (D), an estimate of the elongation of the elevator hoisting rope arrangement 112 (E), an estimate of a change of a counterweight overtravel distance (ADOT). According to an example, the elongation data may be generated every time when the indicator device 130 coupled with the counterweight 106 passes by the detection device 120 inside the elevator shaft 104. Alternatively, the elongation data may for example be generated periodically, e.g. according to a predefined schedule. For example, the elongation data may be generated predefined times per hour, per day, per week, or per month, etc., e.g. once an hour, once a week, once a month, etc. The condition monitoring of the elevator hoisting rope arrangement 112 enables proactive scheduling of maintenance visits. Moreover, the implementation of the computing system 140 at least partly by using the remote computing system 140b enables remote condition monitoring of the elevator hoisting rope arrangement 112. The condition monitoring of the elevator hoisting rope arrangement 112 may be especially advantageous in case of new type of elevator hoisting rope arrangements, for example but not limited to elevator hoisting rope arrangements with a novel coating. Figure 3 illustrates schematically the step 240, i.e. the step of generating the elongation data, more in detail. The elongation of the elevator hoisting rope arrangement 112 does not have an effect on the determining of the position of the elevator car 102 inside the elevator shaft 104, as the position of the elevator car 102 is determined by the absolute positioning system. Thus, the correct position of the elevator car 102 inside the elevator shaft 104 can still be determined, even when the elevator hoisting rope arrangement 112 has elongated. However, due to the elongation of the elevator hoisting rope arrangement 112, the position of the elevator car 102 inside the elevator shaft 104 at the moment of the encounter event, i.e. the encounter position of the elevator car 102, changes in the vertical direction (V), i.e. moves lower in the vertical direction (V) inside the elevator shaft 104. When a roping ratio of elevator hoisting rope arrangement 112 is known, the estimate of the elongation of the elevator hoisting rope arrangement 112 may be defined based on the change of the encounter position (i.e. the encounter position displacement value (D)) and the roping ratio of the elevator hoisting rope 112 as will be described later in this application.

[0060] At a step 310, the computing system 140 may compare the obtained encounter position data of the elevator car 102 to a reference encounter position (Pref) of the elevator car 102. In other words, at the step 310 the computing system 140 may define whether the obtained encounter position data of the elevator car 102 differs from the reference encounter position of the elevator car 102 (Pref). The reference encounter position (Pref) of the elevator car 102 may be determined during a commissioning of the elevator hoisting rope arrangement 112. The commissioning of the elevator hoisting rope arrangement 112 may for example be performed during commissioning of the elevator system 100. Alternatively, the commissioning of the elevator hoisting rope arrangement 112 may be performed, when the elevator hoisting rope arrangement 112 is replaced with a new elevator hoisting rope arrangement. During the commissioning of the elevator hoisting rope arrangement 112 the length of the elevator hoisting rope arrangement 112 is adjusted to the required length. The elevator hoisting rope arrangement 112 may for example be adjusted so that when the elevator car 102 is at the top floor, counterweight overtravel distance remains between a counterweight buffer(s) fixed at the bottom of the counterweight 106 (e.g. by means of the buffer mount) and the bottom of the elevator shaft 104, i.e. the floor of the elevator shaft pit (or if the counterweight buffer(s) is fixed at the floor of the shaft pit, the counterweight overtravel distance remains between the bottom of the counterweight 106 and the counterweight buffer(s)). As discussed in the background section, in the course of time the elevator hoisting rope arrangement 112 elongates. The elevator hoisting rope arrangement 112 adjusted to the required length is thus considered not elongated elevator hoisting rope arrangement 112, i.e. the elevator hoisting rope arrangement 112 without elongation. During the commissioning of the elevator hoisting rope arrangement 112, after the adjustment of the elevator hoisting rope arrangement 112 to the required length, the reference encounter position (Pref) of the elevator car 102 may be determined similarly as the encounter position of the elevator car 102 discussed at the steps 210-230 above. In other words, during the commissioning of the elevator hoisting rope arrangement 1 12, when the elevator hoisting rope arrangement 112 has not elongated, the position of the elevator car 102 may be obtained at the moment of the encounter event detected by the detection device 120 as discussed above and this obtained position of the elevator car 102 is the reference encounter position (Pref) of the elevator car 102. The reference encounter position (Pref) of the elevator car 102 represents the position of the elevator car 102 at the moment of the encounter event, when the elevator hoisting rope arrangement 112 has not elongated. Figure 4A illustrates schematically an example of the reference encounter position (Pref) of the elevator car 102 with the elevator hoisting rope arrangement 112 without elongation.

[0061] At a step 320, the computing system 140 determines the encounter position displacement value (D) based on the result of the comparison at the step 310. In other words, the computing unit 104 determines at the step 310 the encounter position displacement value (D) by comparing the obtained encounter position data of the elevator car (102) to the reference encounter position of the elevator car (102). If the obtained encounter position data of the elevator car 102 differs from the reference encounter position (Pref) of the elevator car 102, the encounter position displacement value (D) corresponds to the difference between the obtained encounter position data of the elevator car 102 and the reference encounter position (Pref) of the elevator car 102. In other words, the encounter position displacement value (D) may be defined by subtracting the obtained encounter position (Pe) from the reference encounter position (Pref). Alternatively, if the obtained encounter position data of the elevator car 102 does not differ from the reference encounter position (Pref) of the elevator car 102, the encounter position displacement value (D) is zero. When the encounter position displacement value (D) zero, it indicates that the elevator hoisting rope arrangement 112 is not elongated. When the encounter position displacement value (D) is non-zero, it indicates elongation of the elevator hoisting rope arrangement 112. Figure 4B illustrates an example of the encounter position displacement value (D). In the example of Figure 4B due to the elongation of the elevator hoisting rope arrangement 112, the encounter position has been changed by the encounter position displacement value (D), i.e. moved lower by the encounter position displacement value (D) in the vertical direction (V) inside the elevator shaft 104, in comparison to the reference encounter position (Pref). In other words, the obtained encounter position (Pe) is the encounter position displacement value (D) lower in the vertical direction (V) in comparison to the reference encounter position (Pref).

[0062] At a step 330, the computing system 140 may determine the estimate of the elongation of the hoisting rope arrangement 112 (E) based on the encounter position displacement value (D) and a roping ratio of elevator hoisting rope arrangement 112. The roping ratio of the elevator hoisting rope arrangement 112 may for example be 1 :1 , 2:1 , or 4:1 . With 1 :1 roping ratio the speed of the elevator hoisting rope arrangement 112 corresponds to the speed of the elevator car 102. With 2:1 roping ratio the speed of the elevator hoisting rope arrangement 112 is twice as much as the speed of the elevator car 102. With 4:1 roping ratio the speed of the elevator hoisting rope arrangement 112 is four times as much as the speed of the elevator car 102. The estimate of the elongation of the hoisting rope arrangement 112 (E) may for example be defined by using the following equation:

[0063] E = 2n x D, (1 ) wherein n represents the roping ratio n:1 and D is the encounter position displacement value. In the above equation (1 ), it is assumed that that the roping ratio is the same at the side of the elevator car 102 and at the side of the counterweight 106 and that at the encounter position the elevator hoisting rope arrangement 112 is divided approximately 50 / 50 to each side of the traction sheave 110. As the 50 / 50 division of the elevator hoisting rope arrangement 112 to each side of the traction sheave 110 at the encounter position cannot necessarily be realized in every case, the exact elongation of the elevator hoisting rope arrangement 112 cannot be determined in those cases by using the above equation (1). However, although the 50 / 50 division of the elevator hoisting rope arrangement 112 to each side of the traction sheave 110 at the encounter position cannot be realized, the above equation (1 ) provides the estimate of the elongation of the elevator hoisting rope arrangement 112 (E) with sufficient accuracy. Figures 5A-5C illustrate schematically simple examples of the estimate of the elongation of the hoisting rope arrangement 112 with different roping ratios. In the examples of Figures 5A-5C, the elongation of the hoisting rope arrangement 112 is illustrated with dashed lines, wherein the length of each dashed line corresponds to the encounter position displacement value (D). Figure 5A illustrates an example of the estimate of the elongation of the hoisting rope arrangement 112 with 1 :1 roping ratio, when the encounter position displacement value is D. By using the above equation (1 ), the estimate of the elongation of the hoisting rope arrangement 112 (E) is 2D with 1 :1 roping ratio. Figure 5B illustrates an example of the estimate of the elongation of the hoisting rope arrangement 112 with 2:1 roping ratio, when the encounter position displacement value is D. By using the above equation (1 ), the estimate of the elongation of the hoisting rope arrangement 112 (E) is 4D with 2:1 roping ratio. Figure 5C illustrates an example of the estimate of the elongation of the hoisting rope arrangement 112 with 4:1 roping ratio, when the encounter position displacement value is D. By using the above equation (1 ), the estimate of the elongation of the hoisting rope arrangement 112 (E) is 8D with 4:1 roping ratio. According to a non-limiting example, when the encounter position displacement value (D) is 25 millimeters and the roping ratio is 2:1 , the estimate of the elongation of the hoisting rope arrangement (E) is 100 millimeters. The roping ratio of the elevator hosting rope arrangement 112 may for example be prestored to a memory unit 720 of the computing system 140, obtained from a database, or received via a user input.

[0064] Alternatively or in addition, the computing system 140 may determine at a step 340 the estimate of the change of the counterweight overtravel distance (ADOT) based on the encounter position displacement value (D). As described above, during the commissioning of the elevator hoisting rope arrangement 112, the length of the elevator hoisting rope arrangement 112 may be adjusted. As also discussed above, the elevator hoisting rope arrangement 112 may typically be adjusted so that when the elevator car 102 is at the top floor, the counterweight buffer(s) fixed at the bottom of the counterweight 106 is the counterweight overtravel distance from the floor of the elevator shaft pit, or if the coun- terweight buffer(s) is fixed at the floor of the shaft pit, the bottom of the counterweight 106 is the counterweight overtravel distance from the counterweight buffer(s). Due to the elongation of the elevator hoisting rope arrangement 112, the counterweight overtravel distance decreases. Thus, the estimate of the change (i.e. decrease) of the counterweight overtravel distance (ADOT) may be defined based on the encounter position displacement value (D). The roping ratio of the elevator hoisting rope arrangement 112 does not have an effect on the change of the counterweight overtravel distance ( DOT). In other words, the estimate of the change of the counterweight overtravel distance (ADOT) may be determined similarly with all roping ratios. The estimate of the change of the counterweight overtravel distance (ADOT) may for example be defined by using the following equation: DOT= 2 X D, (2) wherein D is the encounter position displacement value. In the above equation (2), it is assumed that that the roping ratio is the same at the side of the elevator car 102 and at the side of the counterweight 106 and that majority of the elevator hoisting rope arrangement 112 is on the side of the counterweight 106, when the elevator car 102 is at the top floor. The exact change of the counterweight overtravel distance cannot necessarily be determined in every case by using the above equation (2). However, the above equation (2) gives the estimate of the change of the counterweight overtravel distance (ADOT) with sufficient accuracy. Figures 6A-6C illustrate schematically simple examples of the estimate of the change of the counterweight overtravel distance (ADOT) with different roping ratios. In the examples of Figures 6A-6C, the elongation of the hoisting rope arrangement 112 is illustrated with the dashed lines, wherein the length of each dashed line corresponds to the encounter position displacement value (D). Because the elongation of the elevator hoisting rope arrangement 112 is in practice entirely at the side of the counterweight 106, the estimate of the change of the counterweight overtravel distance (ADOT) is 2D with all roping ratios. Figure 6A illustrates an example of the estimate of the change of the counterweight overtravel distance (ADOT) with 1 :1 roping ratio, when the encounter position displacement value is D. By using the above equation (2), the estimate of the change of the counterweight overtravel distance (ADOT) is 2D with 1 :1 roping ratio. Figure 6B illustrates an example of the estimate of the change of the counterweight overtravel distance (ADOT) with 2:1 roping ratio, when the encounter position displacement value is D. By using the above equation (2), the estimate of the change of the counterweight overtravel distance (ADOT) is 2D with 2:1 roping ratio. Figure 6C illustrates an example of the estimate of the change of the counterweight overtravel distance ( DOT) with 4:1 roping ratio, when the encounter position displacement value is D. By using the above equation (2), the estimate of the change of the counterweight overtravel distance (ADOT) is 2D with 4:1 roping ratio. According to a nonlimiting example, when the encounter position displacement value (D) is 25 millimeters, the estimate of the change of the counterweight overtravel distance (ADOT) is 50 millimeters. The elevator rope elongation determination system 101 and the method described above enables monitoring of the change of the counterweight overtravel distance (ADOT) without the need to visit the elevator system 100 and to access into the pit of the elevator shaft 104. This is especially advantageous in low pit elevator systems. Moreover, implementation of the computing system 140 at least partly by using the remote computing system 140b enables remote monitoring of the chance of the counterweight overtravel distance (ADOT), which in turn enables proactive scheduling of maintenance visits.

[0065] After generating the elongation data at the step 240, the computing system 140 may further detect at a step 250 whether the elongation data meets a predefined limit. The predefined limit may depend on the elongation data. The predefined limit may for example be a predefined elongation limit. The computing system 140 may compare the estimate of the elongation of the elevator hoisting rope arrangement 112 (E) to the predefined elongation limit to detect whether the estimate of the elongation of the elevator hoisting rope arrangement 112 meets the predefined elongation limit (e.g. exceeds or reaches the predefined elongation limit) at the step 250. Alternatively or in addition, the predefined limit may for example be a predefined displacement limit and the computing system 140 may compare the encounter position displacement value (D) to the predefined displacement limit to detect whether the encounter position displacement value (D) meets the predefined displacement limit (e.g. exceeds or reaches the predefined displacement limit) at the step 250. Alternatively or in addition, the predefined limit may for example be a predefined overtravel distance limit and the computing system 140 may compare the estimate of the change of the counterweight overtravel distance (ADOT) to the predefined overtravel distance limit to detect whether the estimate of the change of the counterweight overtravel distance meets the predefined displacement limit (e.g. reaches the predefined displacement limit or is less than the predefined displacement) at the step 250. The predefined elongation limit may for example be defined based on the length of the elevator hoisting rope arrangement 112 after which the length of the elevator hoisting rope arrangement 112 needs to be adjusted, e.g. shortened, for example according to elevator safety regulations. The predefined displacement limit may then for example be defined based on the predefined elongation limit and the roping ratio of the elevator hoisting rope arrangement 112. The predefined overtravel distance limit may for example be defined based on the predefined displacement limit.

[0066] At a step 260, the computing system 140 may generate a maintenance request in response to a detection at the step 250 that the elongation data meets the predefined limit. The maintenance request may comprise an instruction to adjust, e.g. shorten, the length of the elevator hoisting rope arrangement 112. The maintenance request may for example generated to maintenance personnel. If the predefined limit is the predefined elongation limit, the maintenance request is generated in response to the detection that the estimate of the elongation of the elevator hoisting rope arrangement 112 (E) meets the predefined elongation limit. If the predefined limit is the predefined displacement limit, the maintenance request is generated in response to the detection that the encounter position displacement value (D) meets the predefined displacement limit. If the predefined limit is the predefined overtravel distance limit, the maintenance request is generated in response to the detection that the estimate of the change of the counterweight overtravel distance ( DOT) meets the predefined overtravel distance limit.

[0067] If the computing system 140 is implemented as the local computing system 140a, the local computing system 140a performs all the method steps of the computing system 140 described above. Alternatively, if the computing system 140 is implemented as the remote computing system 140b, the remote computing system 140b performs all the method steps of the computing system 140 described above. Alternatively, if the computing system 140 is implemented as the combined computing system 140 comprising the local computing system 140a and the remote computing system 140b, one or more of the method steps of the computing system 140 described above may be performed by the local computing system 140a and the rest of the method steps of the computing system 140 described above may be performed by the remote computing system 140b. According to a non-limiting example, the local computing system 140a may receive the detection data (step 220), obtain the encounter position data (step 230), and provide the received detection data and the obtained encounter position data to the remote computing system 140b that may then perform the rest of the steps of the method (i.e. step 240 and possibly also steps 250-260). According to another non-limiting example, the local computing system 140a may receive the detection data (step 220), obtain the encounter position data (step 230), generate the elongation data (step 240), and provide the generated elongation data to the remote computing system 140b that may then generate the maintenance request, if the elongation data meets the predefined limit (steps 250 and 260).

[0068] Figure 7 illustrates schematically an example of components of the computing system 140. The computing system 140 may comprise a processing unit 710 comprising one or more processors, the memory unit 720 comprising one or more memories, a communication unit 730 comprising one or more communication devices, and possibly a user interface (III) unit 740. The mentioned elements may be communicatively coupled to each other with e.g. a communication bus. The memory unit 720 may store and maintain portions of a computer program (code) 725, the detection data, the encounter position data of the elevator car 102, the reference encounter position of the elevator car 102, the elongation data, the predefine limit, the roping ratio of the elevator hoisting rope arrangement 112, and any other data. The computer program 725 may comprise instructions which, when the computer program 725 is executed by the processing unit 710 of the computing system 140 may cause the processing unit 710, and thus the computing system 140 to carry out desired tasks, e.g. one or more of the method steps described above. The processing unit 710 may thus be arranged to access the memory unit 720 and retrieve and store any information therefrom and thereto. For sake of clarity, the processor herein refers to any unit suitable for processing information and control the operation of the computing system 140, among other tasks. The operations may also be implemented with a microcontroller solution with embedded software. Similarly, the memory unit 720 is not limited to a certain type of memory only, but any memory type suitable for storing the described pieces of information may be applied in the context of the present invention. The communication unit 730 provides one or more communication interfaces for communication with any other unit, e.g. the detection device 120, the elevator control system 108, one or more databases, and / or with any other unit. The user inter- face unit 740 may comprise one or more input / output (I / O) devices, such as buttons, keyboard, touch screen, microphone, loudspeaker, display and so on, for receiving user input and outputting information. The computer program 725 may be a computer program product that may be comprised in a tangible non- volatile (non-transitory) computer-readable medium bearing the computer program code 725 embodied therein for use with a computer, i.e. the computing system 140.

[0069] The illustrated dimensions and distances in the drawings are not to scale and not comparable to each other; they have been selected only for graphical clari- ty in the drawings.

[0070] The specific examples provided in the description given above should not be construed as limiting the applicability and / or the interpretation of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.

Claims

CLAIMS1 . A method for generating elongation data of an elevator hoisting rope arrangement (112), the method comprises: detecting (210), by a detection device (120) arranged inside an elevator shaft (104), an encounter event between the detection device (120) and a counterweight (106), wherein the encounter event is detected by the detection device (120) by detecting an indicator device (130), when the indicator device (130) coupled with a counterweight (106) passes by the detector device (120) inside an elevator shaft (104); receiving (220), from the detection device (120), detection data representing the detection of the encounter event; obtaining (230) encounter position data of an elevator car (102) representing the position of the elevator car (102) inside the elevator shaft (104) at the moment of the encounter event; and generating (240) elongation data representing the elongation of the elevator hoisting rope arrangement (112) based on the obtained encounter position data.

2. The method according to claim 1 , wherein the elongation data comprises at least one of the following: an encounter position difference value, an estimate of the elongation of the elevator hoisting rope arrangement (112), an estimate of a change of a counterweight overtravel distance.

3. The method according to any of the preceding claims, wherein generating (240) elongation data comprises determining (320) an encounter position displacement value by comparing (310) the obtained encounter position data of the elevator car (102) to a reference encounter position of the elevator car (102).

4. The method according to claim 3, wherein if the obtained encounter position data differs from the reference encounter position, the encounter position displacement value corresponds to the difference between the obtained encounter position data and the reference encounter position, or if the obtained encounter position data does not differ from the reference encounter position, the encounter position displacement value is zero.

5. The method according to any of claims 3 or 4, wherein generating (240) elongation data further comprises determining (330) an estimate of the elongation of elevator hoisting rope arrangement (112) based on the determined encounter position displacement value and a roping ratio of elevator hoisting rope arrangement (112).

6. The method according to any of claims 3 to 5, wherein generating (240) elongation data further comprises determining (340) an estimate of a change of a counterweight overtravel distance based on the determined encounter position displacement value.

7. The method according to any of claims 3 to 6, wherein the reference encounter position is determined during a commissioning of the elevator hoisting rope arrangement (112).

8. The method according to any of the preceding claims, further comprising: detecting (250) that the elongation data meets a predefined limit, and generating (260), in response to the detection that the elongation data meets the predefined limit, a maintenance request comprising an instruction to adjust the length of the elevator hoisting rope arrangement (1 12).

9. The method according to any of the preceding claims, wherein the operation of the detection device (120) and the indicator device (130) is based on a contactless detection technique.

10. The method according to claim 9, wherein the contactless detection technique is one of the following: radio frequency identification (RFID), near field communication (NFC), quick response code (QR code), or reflection -based detection.

11. The method according to any of the preceding claims, wherein the elongation data is generated every time when the indicator device (130) coupled with the counterweight (106) passes by the detector device (120) inside the elevator shaft (104), or periodically.

12. The method according to any of the preceding claims, wherein the detector device (120) is arranged at the elevator car (102), attached to a wall of theelevator shaft (104), or attached to a landing door frame inside the elevator shaft (104).

13. The method according to any of the preceding claims, wherein the indicator device (130) is attached to the counterweight (106) or to any part mounted to the counterweight (106), such as a buffer mount at the counterweight (106) or a counterweight deflection pulley.

14. An elevator rope elongation determination system (101 ) for generating elongation data of an elevator hoisting rope arrangement (112), the system (101 ) comprises: a detection device (120) arranged inside an elevator shaft (104); an indicator device (130) coupled with a counterweight (106); and a computing system (140) communicatively coupled to the detection device (120), wherein the detection device (120) is configured to detect an encounter event between the detection device (120) and the counterweight (106), wherein the encounter event is detected by the detection device (120) by detecting the indicator device (130), when the indicator device (130) coupled with the counterweight (106) passes by the detector device (120) inside the elevator shaft (104); and wherein computing system (140) is configured to: receive, from the detection device (120), detection data representing the detection of the encounter event; obtain encounter position data of the elevator car (102) representing the position of the elevator car (102) inside the elevator shaft (104) at the moment of the encounter event; and generate elongation data representing the elongation of the elevator hoisting rope arrangement (112) based on the obtained encounter position data.

15. The elevator rope elongation determination system (101 ) according to claim 14, wherein the elongation data comprises at least one of the following:an encounter position difference value, an estimate of the elongation of the elevator hoisting rope arrangement (112), an estimate of a change of a counterweight overtravel distance.

16. The elevator rope elongation determination system (101 ) according to any of claims 14 or 15, wherein generating elongation data comprises that the computing system (140) is configured to determine an encounter position displacement value by comparing the obtained encounter position data of the elevator car (102) to a reference encounter position of the elevator car (102).

17. The elevator rope elongation determination system (101 ) according to claim 16, wherein if the obtained encounter position data differs from the reference encounter position, the encounter position displacement value corresponds to the difference between the obtained encounter position data and the reference encounter position, or if the obtained encounter position data does not differ from the reference encounter position, the encounter position displacement value is zero.

18. The elevator rope elongation determination system (101 ) according to any of claims claim 16 or 17, wherein generating elongation data further comprises that the computing system (140) is configured to determine an estimate of the elongation of elevator hoisting rope arrangement (112) based on the determined encounter position displacement value and a roping ratio of elevator hoisting rope arrangement (112).

19. The elevator rope elongation determination system (101 ) according to any of claims 16 to 18, wherein generating the elongation data further comprises that the computing system (140) is configured to determine an estimate of a change of a counterweight overtravel distance based on the determined encounter position displacement value.

20. The elevator rope elongation determination system (101 ) according to any of claims 16 to 19, wherein the reference encounter position is determined during a commissioning of the elevator hoisting rope arrangement (112).

21. The elevator rope elongation determination system (101 ) according to any of claims 14 to 20, wherein the computing system (140) is further configured to:detect that the elongation data meets a predefined limit, and generate, in response to the detection that the elongation data meets the predefined limit, a maintenance request comprising an instruction to adjust the length of the elevator hoisting rope arrangement (112).

22. The elevator rope elongation determination system (101 ) according to any of claims 14 to 21 , wherein the operation of the detection device (120) and the indicator device (130) is based on a contactless detection technique.

23. The elevator rope elongation determination system (101 ) according to claim 22, wherein the contactless detection technique is one of the following: radio frequency identification (RFID), near field communication (NFC), quick response code (QR code), or reflection -based detection.

24. The elevator rope elongation determination system (101 ) according to any of claims 14 to 23, wherein the elongation data is generated every time when the indicator device (130) coupled with the counterweight (106) passes by the detector device (120) inside the elevator shaft (104), or periodically.

25. The elevator rope elongation determination system (101 ) according to any of claims 14 to 24, wherein the detector device (120) is arranged at the elevator car (102), attached to a wall of the elevator shaft (104), or attached to a landing door frame inside the elevator shaft (104).

26. The elevator rope elongation determination system (101 ) according to any of claims 14 to 25, wherein the indicator device (130) is attached to the counterweight (106) or to any part mounted to the counterweight (106), such as a buffer mount at the counterweight (106) or a counterweight deflection pulley.

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