WO2018019665A1 - Elevator suspension member slack detection arrangement - Google Patents

Abstract

A slack detection arrangement (17) for detecting a slack in a suspension member arrangement (11) of an elevator (1) is proposed. The suspension member arrangement (11) comprises at least one suspension member (12) being attached to a fixation structure (19) and suspending a movable component (3) such as an elevator cabin or a counterweight being displaceable in an elevator hoistway (9). The slack detection arrangement comprises a bracket (35), a string (37), a tension force sensor (39) and at least one string actuation lever (41). The bracket (35) is adapted for being attached to the fixation structure (19) to which the suspension member arrangement (11) is attached. The string (37) is arranged such as to extend transverse to and closely neighbouring to the at least one suspension member (12) when the slack detection arrangement (17) is mounted in the elevator (1). One end of the string (37) is attached to the tension force sensor (39). The tension force sensor (39) is attached to the bracket (25) and is adapted for sensing a mechanical tension of the string (37). The string actuation lever (41) is adapted to be attached to the suspension member (12) such as to protrude from the suspension member in a transverse direction and closely neighbouring to the string (37) at an upstream location such that upon any slack occurring in the suspension member (12) the string actuation lever (41) is displaced downstream and thereby pushes onto the string (37) and thereby increases the mechanical tension of the string (37).

Description

ELEVATOR SUSPENSION MEMBER SLACK DETECTION ARRANGEMENT

The present invention relates to an elevator. Particularly, the invention relates to a slack detection arrangement for detecting a slack in a suspension member arrangement of an elevator.

Elevators are typically used for transporting passengers or items in a vertical or inclined direction for example within a building. Therein, an elevator cabin or car accommodating the passengers or items is moved along a hoistway.

In traction-type elevators, the elevator cabin and/or other movable components such as a counterweight are suspended by a suspension member arrangement. Such suspension member arrangement typically comprises several suspension members such as ropes or belts which may carry heavy loads in a suspension direction but which may be bent in a bending direction transverse to such suspension direction. The movable components may then be displaced in the elevator hoistway by displacing the suspension member arrangement. Typically, the suspension members are wound around a traction sheave which may be driven into rotation using a drive engine including for example an electric motor. Ends of the suspension member are typically attached to a fixation structure. Generally, various types of suspension member arrangements are possible. For example, the fixation structure may be attached to the movable component to be suspended, i.e. to the elevator cabin or the counterweight, and ends of the suspension members may be attached to such fixation structure. Alternatively, the fixation structure may be attached to fix points within the elevator hoistway and ends of the suspension members are attached thereto. In the latter case, the suspension members may suspend the movable components for example by being wound around a pulley attached to the movable component.

In traction-type elevators, care has to be taken in order to avoid that single or plural suspension members of the suspension member arrangement are excessively loaded as such excessively loading could result e.g. in damages to the suspension member arrangement. Excessively loading of the suspension members may result from various circumstances or conditions. One of such circumstances or conditions is slack in one or more suspension members. Such slack means that the respective suspension member is not under adequate mechanical tension any more but is relatively "loose".

Slack in single or plural suspension members of a suspension member arrangement may result from different reasons. For example, in a suspension member arrangement comprising multiple suspension members, single suspension members may become slacking due to for example damages at the suspension member itself or at its attachment components attaching the suspension member to the fixation structure. In such scenario, the remaining suspension members have to carry the additional load of the slacking suspension member and may therefore become excessively loaded. In another scenario, the entirety of all suspension members may become slacking due to for example the movable component being stuck within the elevator hoistway while the suspension member arrangement being driven further towards the movable component.

Generally, slacking of a suspension member in a suspension member arrangement indicates a defective condition within the elevator. Accordingly, reliably detecting any slack in the suspension member arrangement may be indispensible in order to avoid hazardous conditions in the elevator.

Various approaches for detecting a slack in a suspension member arrangement of an elevator have been proposed. For example, WO 2011/131574 Al describes monitoring the operation state of suspensions in an elevator system in which slack suspension switches each monitoring a slack of a single suspension member are included in a safety circuit of an elevator system so that actuating at least one of the multiple slack suspension switches interrupts the safety circuit. Alternatively, WO 2013/092163 Al describes an elevator system in which a suspension member comprises a test element, an electric resistance of the test element changing as a result of an elongation of the test element, thereby enabling detection of a load decrease to the suspension member or even slack of the suspension member.

There may be a need for an alternative slack detection arrangement for detecting a slack in a suspension member arrangement of an elevator. Particularly, there may be a need for a slack detection arrangement being applicable to various types of elevators, having a relatively simple construction, being highly reliable and/or being producible at low costs. Furthermore, there may be a need for an elevator comprising such slack detection arrangement.

Such needs may be met with the subject-matter of the independent claims. Advantageous embodiments are defined in the dependent claims and in the following specification.

According to a first aspect of the invention, a slack detection arrangement for detecting a slack in a suspension member arrangement of an elevator is proposed. Therein, the suspension member arrangement comprises at least one suspension member being attached to a fixation structure and suspending a movable component such as e.g. an elevator cabin or a counterweight being displaceable in an elevator hoistway. The slack detection arrangement comprises a bracket, a string, a tension force sensor and at least one string actuation lever. The bracket is adapted for being attached to the fixation structure to which the suspension member arrangement is attached. The string is arranged such as to extend transverse to the at least one suspension member and such as to extend closely neighbouring to the suspension member when the slack detection arrangement is mounted in the elevator. One end of the string is attached to the tension force sensor. The tension force sensor is attached to the bracket and is adapted for sensing a mechanical tension of the string. The string actuation lever is adapted to be attached to the suspension member such as to protrude or extend from the suspension member in a transverse direction and closely neighbouring to the string at an upstream location such that upon any slack occurring in the suspension member, the string actuation lever is displaced downwards and thereby pushes onto the string and thereby increases the mechanical tension of the string.

According to a second aspect, an elevator is proposed to comprise a movable component such as an elevator cabin or a counterweight being displaceable within an elevator hoistway, a suspension member arrangement suspending the movable component and comprising at least one suspension member being attached to a fixation structure and, finally, a slack detection arrangement according to an embodiment of the first aspect of the invention. Therein, the bracket of the slack detection arrangement is fixedly connected to the fixation structure. The string is arranged such as to extend transverse to and closely neighbouring to the at least one suspension member. And the at least one string actuation lever is attached to the at least one suspension member such as to protrude from the suspension member in a transverse direction and closely neighbouring to the string at an upstream location such that upon any slack occurring in the suspension member the string actuation lever is displaced downstream and thereby pushes onto the string and thereby increases the mechanical tension of the string.

Ideas underlying embodiments of the present invention may be interpreted as being based, inter alia and without limiting the scope of the invention, on the following observations and recognitions: Briefly summarized, embodiments of the presented slack detection arrangement enable detecting an excessive slack of one or more suspension members in a suspension member arrangement with a very simple approach. A tension force sensor such as for example a mechanical switch which may be actuated upon applying a mechanical tension force thereto is provided. One end of a string such as for example a Bowden wire is attached to the tension force sensor. The string is tightened preferably such that at least a minimum tension force is applied via the string to the tension force sensor. The tension force sensor may sense the mechanical tension of the string at least qualitatively (but necessarily quantitatively). Particularly, the tension force sensor may detect when the mechanical tension applied by the string temporarily increases. The slack detection arrangement and its string and tension force sensor are adapted and mounted relative to the suspension member arrangement such that the string extends transverse to the suspension member(s) of the suspension member arrangement and in close neighbourhood thereto, i.e. for example with a distance of less than 10 cm, preferably less than 2 cm, to the suspension members. String actuation levers are then attached to the suspension members to be monitored for their slack. Each such string actuation lever is adapted and arranged such as to protrude from the elongate suspension member in a transverse direction and to extend closely neighbouring, i.e. for example at less than 10 cm, preferably less than 2 cm, to the string at an upstream location thereof. In this context, "upstream" relates to a direction of the mechanical tension applied to the suspension member, i.e. downstream is the direction to which the suspension member is displaced when the tension is released. Accordingly, in case the mechanical tension normally applied to each of the suspension members of the suspension member arrangement is released or loosens at least at one of the suspension members and this suspension member gets slacking, the string actuation lever attached thereto will displace in a downstream direction and, due to it being very close to the string, it will push onto the string, thereby deforming or deflecting the string and increasing the mechanical tension of the string. Such increase in mechanical tension is then transferred via the string to the tension force sensor. In other words, the string may act like a tripwire for detecting any displacement of the string actuation lever resulting from displacements of the suspension member to which it is attached, such displacements resulting upon loosening mechanical tension to the suspension member and occurring of substantial slack. Finally, upon detecting a corresponding change in the mechanical tension of the string, the tension force sensor may provide a signal indicating that slack occurred at least at one of the suspension members comprised in the suspension member arrangement. Such signal may be transferred e.g. to an elevator control which may then initiate suitable measures such as stopping an operation of the elevator and/or informing a maintenance service.

According to an embodiment, the suspension member arrangement comprises multiple suspension members, for example two, three, four or five or even more suspension members, each being attached to the fixation structure. The slack detection arrangement then comprises multiple string actuation levers and the string is arranged such as to extend transverse to and closely neighbouring to each of the suspension members. In such configuration, each of the string actuation levers is adapted to be attached to one of the suspension members such as to protrude from the respective suspension member in a transverse direction and closely neighbouring to the string at an upstream location such that upon any slack occurring in the respective suspension member the string actuation lever is displaced downstream and thereby pushes onto the string and thereby increases the mechanical tension of the string.

In other words, the suspension member arrangement of the elevator preferably comprises multiple suspension members which may be monitored for occurring slack at at least one of these suspension members using the proposed slack detection arrangement. Therein, a single string may be arranged such as to cross potential displacement paths of the string actuation levers attached to each of the suspension members. Accordingly, when at least one of the suspension members becomes slack, the string actuation lever attached thereto will move in the downstream direction towards the string and will push onto the string such as to change the mechanical tension applied via the string to the tension force sensor. Thus, the tension force may detect any slack in at least one of the suspension members.

According to an embodiment, the bracket has opposing first and second attachment areas adapted to being arranged at opposing sides of the suspension member arrangement when the slack detection arrangement is mounted in the elevator. A first end of the string is then attached to the first attachment area of the bracket. An opposing second end of the string may be attached to the tension force sensor. The tension force sensor is fixed to the second attachment area of the bracket.

In other words, when the proposed slack detection arrangement is mounted in an elevator, its bracket is attached to the fixation structure and has a first attachment area arranged at one side neighbouring the suspension member arrangement and a second attachment area arranged at an opposite side neighbouring the suspension member arrangement. In such configuration, the string may be arranged transverse to the suspension member arrangement and closely neighbouring the string actuation levers by being fixed with its one end to the first attachment area and with its second end to the second attachment area. However, while the first end of the string may be attached directly to the bracket, the opposite end of the string shall be attached to the tension force sensor which itself is fixed to the second attachment area of the bracket. Accordingly, a simple construction may be provided for arranging the string like a tripwire for the string actuation levers to be displaced upon slack occurring to any of the suspension members.

According to an embodiment, the bracket may comprise a V-shaped structure comprising a central lower part and first and second opposing lateral higher parts. Therein, the central lower part is adapted for being attached to the fixation structure. A first end of the string is fixed to the first lateral higher part and the tension force sensor is fixed to the second lateral higher part.

The V-shaped structure of the bracket may provide for suitably positioning the attachment areas of the bracket. Furthermore, the V-shaped structure may be easily fabricated and/or may provide for sufficient mechanical stiffness of the bracket.

Particularly, a crossbeam may be provided between both lateral higher parts of the V- shaped bracket in order to further stiffen the bracket. According to an embodiment, the bracket may consist of a metal sheet construction. Such metal sheet construction may be composed of one or more metal sheets. Each metal sheet may be provided as a press-bent part which is bent and/or punched into a desired shape or configuration. Two or more of such bent and/ or punched metal sheets may be mechanically interconnected to form the entire metal sheet construction. Interconnections may be releasable using for example screws or may be non-releasable using for example rivets, bolts, weldings or similar means. The metal sheet construction may be light- weighted and/or highly stressable.

According to an embodiment, the bracket may comprise openings which are located and dimensioned such that a portion of one suspension member of the suspension member arrangement may extend through such opening.

In other words, when installed in the elevator, each of a plurality of suspension members may extend through one or more associated ones of the openings in the bracket before for example being mechanically attached with its lower end to the fixation structure.

Accordingly, the suspension members do not only extend adjacent to the bracket carrying the string and the tension force sensor but extend "through" the bracket, i.e. through the openings in the bracket. Thereby, an overall mechanical strength of the bracket may be increased by for example increasing lateral dimensions of the bracket while enabling keeping the string and the tension force sensor close to the suspension members.

Preferably, the bracket may be provided as a standard component for various types of elevators comprising various numbers of suspension members. For such purpose, the bracket may comprise a multiplicity of openings. Particularly, the number of openings may be larger than a maximum number of suspension members of an elevator for which it shall be used. Particularly, the openings may be located such that for each of possible numbers of suspension members, all suspension members may be arranged equidistant to each other and may extend through associated openings in the bracket. For example, a standard bracket usable for various elevators comprising between one and five suspension members may comprise nine openings arranged linearly next to each other at constant distances. According to an embodiment, the tension force sensor is adapted for outputting a slack indicating signal upon sensing a change in the mechanical tension of the string being higher than a predetermined limit change value.

In other words, while the tension force sensor does not need to be adapted for measuring absolute values of mechanical tensions, it should be able to detect when the mechanical tension applied by the string changes by more than a predetermined value. A magnitude of such limit change value may be selected such that the tension force sensor outputs its slack indicating signal upon the string being pushed by more than a predetermined degree in the downstream direction, i.e. towards the fixation structure, by one of the string actuation levers being attached to a suspension member which became slack. Expressed differently, the tension force sensor may have an activation threshold which is selected such that minor changes in mechanical tension applied thereto are ignored but significant changes in mechanical tension resulting from a suspension member becoming slacking are reliably detected.

According to an embodiment, the slack detection arrangement further comprises a string tension limiter. Such string tension limiter may be adapted and arranged such as to limit a mechanical tension applied by the string to the tension force sensor.

In other words, while changes in mechanical tension applied to the string as a result of a suspension member becoming slacking shall be transferred to the tension force sensor preferably in a direct or proportional manner such that the slack is detectable by the tension force sensor, excessive changes in mechanical tension of the string shall be prevented from reaching the tension force sensor. For such purpose, the string tension limiter is provided and may protect the tension force sensor from becoming damaged due to excessive mechanical tensions. The string tension limiter may for example allow force transmission between the string and the tension force sensor in an unlimited manner as long as the forces are lower than a predetermined limit. However, upon exceeding such limit, the string tension limiter may absorb excessive forces thereby preventing them from damaging the tension force sensor.

According to an embodiment, the slack detection arrangement further comprises string support elements which support the string at areas between two neighbouring string actuation levers. Preferably, the string support elements are provided at equidistant positions along an extension direction of the string.

In other words, the string may not only be attached at its end portions e.g. by fixing the end portions to opposing attachment areas of the bracket thereby mechanically tensioning the string, but the string may also be supported at intermediate points in between the end portions. Particularly, multiple string support means may be provided which support the string at various positions in between the string's end portions. These positions may be spaced equidistantly from each other.

Providing such string support element may allow for a same response of the string to any slack at one of the suspension members independent of which suspension member gets loose. In other words, while, in case no string support elements are provided, responses to a slacking suspension member would be different depending on whether the suspension member is close to one of the attachment areas where the string is held fixe or whether the suspension member is close to a centre between such attachment areas, provision of such string elements at areas between neighbouring suspension members will result in same changes occurring in the mechanical tension of the string as a reaction to a string actuation lever pushing onto the string in response to the associated suspension member getting slacking independent of which of the suspension members got slacking.

Accordingly, signals of the tension force sensors may be easier to interpret.

Furthermore, having string support elements supporting the string in areas arranged between two neighbouring string actuation levers may additionally allow clearly detecting whether only one single suspension member got slacking or whether more than one suspension member got slacking. While, without string support elements, an overall mechanical tension change in the string upon two neighbouring suspension members getting slacking is only slightly larger than with only one suspension member getting slacking, having string support elements supporting the string in between neighbouring suspension members will result in an approximately doubling of the mechanical tension change when two suspension members get slacking.

According to an embodiment of the elevator proposed herein, the fixation structure to which the suspension members are attached may be a hitch plate. Such hitch plate may be mechanically attached to the movable component of the elevator, i.e. for example to the counterweight or to the elevator cabin. Such hitch plate is typically used in traction-type elevators for mechanically connecting the suspension members to the cabin and/or the counterweight. It may be advantageous to attach the bracket of the slack detection arrangement to such hitch plate.

Particularly, it may be preferable that the hitch plate is being mechanically attached to the movable component of the elevator in a way such as to be fixedly connected to the movable component in a suspension direction but such as to be rotatable in a plane transverse to the suspension direction.

In other words, the hitch plate to which both the suspension member(s) and the bracket of the slack detection arrangement are attached, may be attached to the elevator cabin or counterweight such that the suspension members may suspend the weight of this movable component. However, in a plane transverse to such suspension direction, the hitch plate shall be rotatable with respect to the movable component. Such rotation capability may enable suitably aligning an orientation of the suspension member arrangement with respect to the movable component.

Particularly, using the rotatable hitch plate, one and the same suspension member arrangement may be used for example for both, counterweights arranged at a rear portion of a hoistway as well as counterweights arranged at a side portion of the hoistway or may even be used for elevator arrangements in which the counterweight is provided in a diagonal arrangement within the hoistway. Accordingly, with the bracket of the slack detection arrangement directly fixed to the rotatable hitch plate, the slack detection arrangement may be easily used in various elevator types with for example various positional arrangements of the counterweight.

According to a specific embodiment, each suspension member comprises an elongate flexible member such as a rope or a belt and further comprises a rigid bar. Therein, one end of the rigid bar is attached to an end of the flexible member and an opposite end of the rigid bar is attached to the fixation structure. In such configuration, the actuation lever is attached to the rigid bar. In other words, the suspension member does not only comprise a belt or rope but such flexible member is attached at its end to a rigid bar which then interconnects the flexible member to the fixation structure. The rigid bar may be for example a threaded bar which may be threaded into screw nuts arranged underneath through-holes through the fixation structure. Accordingly, an overall length of the suspension member may be adjusted by threading the bar into the screw nuts and mechanical tension applied to the suspension member may be adjusted accordingly. Elastic elements such as e.g. springs or an elastomer may be interposed between the screw nuts and an opposing surface of the fixation structure. In such arrangement, it may be preferable to attach the actuation lever to the rigid bar instead of attaching it to the flexible member of the suspension member. Upon loosening mechanical tension to the rigid bar due to a slacking of the flexible member attached thereto, the rigid bar may move downwards and the actuation lever attached thereto may press onto the string of the slack detection arrangement.

It shall be noted that possible features and advantages of embodiments of the invention are described herein partly with respect to a slack detection arrangement and partly with respect to an elevator comprising such slack detection arrangement. One skilled in the art will recognize that the features may be suitably transferred from one embodiment to another and features may be modified, adapted, combined and/ or replaced, etc. in order to come to further embodiments of the invention.

In the following, advantageous embodiments of the invention will be described with reference to the enclosed drawings. However, neither the drawings nor the description shall be interpreted as limiting the invention.

Fig. 1 shows a schematic side view of an elevator according to an embodiment of the present invention.

Fig. 2 shows a perspective view of a slack detection arrangement mounted in an elevator according to an embodiment of the present invention.

Fig. 3 shows an enlarged perspective view of an area A of the slack detection arrangement shown in Fig. 2. The figures are only schematic and not to scale. Same reference signs refer to same or similar features.

Fig. 1 shows an elevator 1 according to an embodiment of the present invention. The elevator 1 comprises movable components 3 such as an elevator cabin 5 and a counterweight 7 which are displaceable within an elevator hoistway 9. The movable components 3 are suspended by a suspension member arrangement 11 comprising a multiplicity of suspension members such as ropes or belts. A first end of the suspension member arrangement 11 is attached to a first fixation structure 19 provided at the counterweight 7. An opposite end of the suspension member arrangement 11 is attached to second fixation structure 29 at a top of the hoistway 9. Coming from the first fixation structure 19 at the counterweight 7, the suspension member arrangement 11 extends towards a drive engine 13 provided at the top of the hoistway 9. The suspension member arrangement 11 is then wound around a traction sheave 15 of the drive engine 13. The suspension member arrangement 11 then extends downwards towards pulleys 27 arranged at a lower side of the elevator cabin 5 and is finally returned towards the second fixation structure 29 at the top of the hoistway 9.

Various other options of suspending the movable components 3 including the elevator cabin 5 and a counterweight 7 exist. For example, in a 1 :1 suspension scenario, the suspension member arrangement 11 may be fixed to a fixation structure 19 which itself is directly fixed to the cabin 5 or to the counterweight 7.

In order to enable measuring of a potential slack occurring in one or more of the suspension members comprised in the suspension member arrangement 11, a slack detection arrangement 17 is provided in the elevator 1. In the example shown in Fig. 1, this slack detection arrangement 17 is arranged on top of the first fixation structure 19 at the counterweight 7. However, in principle, such slack detection arrangement 17 may also be provided at other locations such as for example at the second fixation structure 29 at the top of the hoistway 9. Alternatively, especially in case the suspension member arrangement 11 is implemented in another configuration than the one shown in Fig. 1, the slack detection arrangement could also be provided at for example the elevator cabin 5. Fig. 2 shows an enlarged perspective view onto a slack detection arrangement 17 mounted in an elevator 1 according to an embodiment of the present invention.

In the presented example, the suspension member arrangement 11 comprises five suspension members 12 arranged in a vertical plane and parallel to each other. Each suspension member 12 comprises a belt 31 which is connected via a connector 32 to a rigid bar 33 or rod. Each of the suspension members 12 is attached to the first fixation structure 19 in order to thereby enable suspending the movable component 3, i.e. the elevator cabin 5 or the counterweight 7 (not shown in Fig. 2).

In the example shown, the fixation structure 19 is implemented as a hitch plate 21. The hitch plate 21 comprises through-holes 34 through which ends of the rigid bars 33 of the suspension members 12 extend, the ends of the rigid bars 33 then protruding from a lower surface of the hitch plate 21. By for example screwing screws onto threadings at the ends of the rigid bars 33, the suspension members 12 may be secured at the hitch plate 21 in a tension direction 65 and a mechanical tension acting onto the suspension members 12 may be adjusted. An elastic element such as a spring may be interposed between the screw and the lower surface of the hitch plate. The hitch plate 21 has a shape of a circular disk and extends in a horizontal plane. Side portions of the hitch plate 21 are held by vertical side plates 23. The side plates 23 are mechanically attached to slings 25 fixed to the movable component. The side portions of the hitch plate 21 extend through horizontal slots within the side plates 23. In such configuration, the hitch plate 21 is mechanically attached via the side plates 23 and the slings 25 to the movable component such as to be fixed in the suspension direction 65, i.e. suspension forces applied by the suspension member arrangement 11 may be directly transmitted via the hitch plate 21 to the movable component. However, in a plane transverse to such suspension direction 65, the hitch plate 21 may be rotated, for example about up to 90° or even up to 180°. Such rotation of the hitch plate 21 may be necessary in order to align an orientation of the suspension member arrangement 11 with an orientation of the movable component 3 and its fixation components. The slack detection arrangement 17 is arranged on top of the fixation structure 19, i.e. on top of the hitch plate 21. The slack detection arrangement 17 comprises a bracket 35, a string 37, a tension force sensor 39 and string actuation levers 41.

The string 37 may be formed by a cable or a wire or any other elongate element being substantially inelastic in its longitudinal direction. The string 37 is arranged substantially horizontally between a first attachment area 53 of the bracket 35 arranged at a left side next to the suspension member arrangement 11 and a second attachment area 55 of the bracket 35 arranged at an opposite right side next to the suspension member arrangement

11. Specifically, the string 37 extends in close neighbourhood to the suspension members

12, particularly to the rigid bars 33 of these suspension members 12.

While a portion at or close to the left end of the string 37 is directly attached to the bracket 35 at its first attachment area 53, an opposite end of the string 35 is connected to the tension force sensor 39 arranged at the opposite second attachment area 55 of the bracket 35.

As shown in more detail in Fig. 3, the string actuation levers 41 are attached to the rigid bars 33 of each of the multiple suspension members 12 such as to protrude in a horizontal direction, i.e. transverse to the longitudinal direction of the suspension members 12. Specifically, the string actuation levers 41 are formed by metal sheets which are interposed and held by screws 59 which engage with outer threadings at the rigid bars 33. The screws 59 may be screwed towards each other such as to clamp the interposed string actuation lever 41. Therein, the string actuation lever 41 is positioned slightly above, i.e. upstream, the string 37, for example at a distance of only a few millimetres or a few centimetres, preferably less than 10 cm. In principle, the string actuation levers 41 could even slightly contact the string 37.

In case any slack occurs to one of the suspension members 12, its rigid bar 33 will displace in a downward direction due to the lacking upward-directed forces normally provided by the non-slacking suspension members 12 and their belts 31. The string actuation lever 41 attached to the respective rigid bar 33 will then push down onto the string 37. Due to such action, the tension applied by the string 37 to the tension force sensor 39 will increase. As soon as such applied mechanical tension exceeds a specific value, i.e. when a change in the mechanical tension of the string 37 is sensed to be higher than a predetermined limit change value, the tension force sensor 39 will output a slack indicating signal for example through an interface 67. Such slack indicating signal may then be transmitted for example to an elevator control which may then initiate suitable measures.

In the example shown in Fig. 2 and 3, the bracket 35 has a V-shape comprising a central lower part 47 and first and second opposing lateral higher parts 43, 45 having the first and second attachment areas 53, 55 at their ends. Furthermore, a crossbeam 51 is provided between the higher parts 43, 45. The bracket 35 is provided as a metal sheet construction in which several metal sheets are bent and punched into suitable configurations and are then fixed with respect to each other using for example rivets 63 or other fixation means. The central lower part 47 of the bracket 35 is fixed to the hitch plate 21 by fixation means 49 such as screws.

The bracket 35 comprises multiple openings 61 through which the rigid bars 33 of the suspension members 12 extend towards the hitch plate 21. A number of openings 61 and a positional arrangement of these openings 61 may be chosen such that one and the same bracket 35 may be used as a standard component for various types of elevators 1 having different numbers of suspension members 12. In other words, as shown in the given example, the bracket 35 may have nine openings 61 arranged equidistantly next to each other such that the bracket 35 may be used for suspension member arrangements 11 comprising any number of suspension members 12 between one and five. In the crossbeam-reinforced V-shaped bracket 35, the openings 61 may be provided both in the lower part 47 and the lateral higher parts 43, 45 as well as in the crossbeam 51.

In order to limit the mechanical tension applied by the string 37 to the tension force sensor 39, a string tension limiter 57 is provided. This string tension limiter 57 may be attached for example close to the tension force sensor 39 at the second attachment area 55.

Furthermore, string support elements 69 supporting the string 37 in areas arranged between two neighbouring string actuation levers 41 are provided. Such string support elements 69 extend from the bracket 35, for example from the crossbeam 51, in a direction upwardly towards the string 37 and may locally support the string 37 when it is pushed downwards by one of the string actuation levers 41, while allowing sideways movement or displacement of the string 37.

The slack detection arrangement 17 described herein may be provided as a simple and robust means for detecting any slack in a suspension member arrangement 11. A single arrangement may be used for various elevator configurations having different numbers of suspension members 12 in its suspension member arrangement 11. Furthermore, the fixation structure 19 provided by the hitch plate 21 may be rotatable such that the slack detection arrangement 17 attached thereto may be applied for various configurations in which a movable component 3 such as the counterweight 7 is arranged for example at a rear side, a lateral side or in a diagonal manner within the elevator hoistway 9.

Finally, it should be noted that the term "comprising" does not exclude other elements or steps and the "a" or "an" does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

List of reference signs

1 elevator

3 movable component

5 elevator cabin

7 counterweight

9 hoistway

11 suspension member arrangement

12 suspension members

13 drive engine

15 traction sheave

17 slack detection arrangement

19 fixation structure

21 hitch plate

23 side plate

25 sling

27 pulleys

29 fixation structure

31 belts

32 connectors

33 rigid bars

34 through-holes

35 bracket

37 string

39 tension force sensor

41 string actuation lever

43 first lateral higher part

45 second lateral higher part

47 central lower part

49 screws

51 cross beam

53 first attachment area

55 second attachment area string tension limiter screws

openings rivets

tension direction interface string support element

Claims

Claims:

1. Slack detection arrangement (17) for detecting a slack in a suspension member arrangement (11) of an elevator (1), the suspension member arrangement (11) comprising at least one suspension member (12) being attached to a fixation structure (19) and suspending a movable component (3) being displaceable in an elevator hoistway (9), the slack detection arrangement (17) comprising:

a bracket (35);

a string (37);

a tension force sensor (39); and

at least one string actuation lever (41);

the bracket (35) being adapted for being attached to the fixation structure (19) to which the suspension member arrangement (11) is attached;

the string (37) being arranged such as to extend transverse to and closely neighbouring to the at least one suspension member (12) when the slack detection arrangement (17) is mounted in the elevator (1);

one end of the string (37) being attached to the tension force sensor (39);

the tension force sensor (39) being attached to the bracket (25) and being adapted for sensing a mechanical tension of the string (37);

the string actuation lever (41) being adapted to be attached to the suspension member (12) such as to protrude from the suspension member (12) in a transverse direction and closely neighbouring to the string (37) at an upstream location such that upon any slack occurring in the suspension member (12) the string actuation lever (41) is displaced downstream and thereby pushes onto the string (37) and thereby increases the mechanical tension of the string (37).

2. Slack detection arrangement of claim 1 ,

wherein suspension member arrangement (11) comprises multiple suspension members (12) each being attached to the fixation structure (19);

wherein the slack detection arrangement (17) comprises multiple string actuation levers (41);

wherein the string (37) is arranged such as to extend transverse to and closely neighbouring to each of the suspension members (12);

wherein each of the string actuation levers (41) is adapted to be attached to one of the suspension members (12) such as to protrude from the respective suspension member in a transverse direction and closely neighbouring to the string (37) at an upstream location such that upon any slack occurring in the respective suspension member (12) the string actuation lever (41) is displaced downstream and thereby pushes onto the string (37) and thereby increases the mechanical tension of the string (37).

3. Slack detection arrangement of one of the preceding claims,

wherein the bracket (35) has opposing first and second attachment areas (53, 55) adapted to being arranged at opposing sides of the suspension member arrangement (11) when the slack detection arrangement (17) is mounted in the elevator (1);

wherein a first end of the string (37) is attached to the first attachment area (53) of the bracket (35);

wherein the tension force sensor (39) is fixed to the second attachment area (55) of the bracket (35).

4. Slack detection arrangement of one of the preceding claims,

wherein the bracket (35) comprises a V-shaped structure comprising a central lower part

(47) and first and second opposing lateral higher parts (43, 45);

wherein the central lower part (47) is adapted for being attached to the fixation structure

(19);

wherein a first end of the string (37) is fixed to the first lateral higher part (43);

wherein the tension force sensor (39) is fixed to the second lateral higher part (45).

5. Slack detection arrangement of one of the preceding claims, wherein the bracket

(35) consists of a metal sheet construction.

6. Slack detection arrangement of one of the preceding claims, wherein the bracket (35) comprises openings (61), each opening being located and dimensioned such that a portion of one suspension member (12) of the suspension member arrangement (11) may extend through the opening (61).

7. Slack detection arrangement of one of the preceding claims, wherein the tension force sensor (39) is adapted for outputting a slack indicating signal upon sensing a change in the mechanical tension of the string (37) being higher than a predetermined limit change value.

8. Slack detection arrangement of one of the preceding claims, further comprising a string tension limiter (57) adapted and arranged such as to limit a mechanical tension applied by the string (37) to the tension force sensor (39).

9. Slack detection arrangement of one of the preceding claims, further comprising string support element (69) which support the string (37) at equidistant positions along an extension direction of the string (37).

10. Elevator (1) comprising:

a movable component (3) being displaceable within an elevator hoistway (9);

a suspension member arrangement (11) suspending the movable component (3) and comprising at least one suspension member (12) being attached to a fixation structure (19);

a slack detection arrangement (17) according to one of claims 1 to 8;

the bracket (35) of the slack detection arrangement (17) being fixedly connected to the fixation structure (19);

the string (37) being arranged such as to extend transverse to and closely neighbouring to the at least one suspension member (12);

the at least one string actuation lever (41) being attached to the at least one suspension member (12) such as to protrude from the suspension member in a transverse direction and closely neighbouring to the string (37) at an upstream location such that upon any slack occurring in the suspension member (12) the string actuation lever (41) is displaced downstream and thereby pushes onto the string (37) and thereby increases the mechanical tension of the string (37).

11. Elevator according to claim 10,

wherein the suspension member arrangement (11) comprises multiple suspension members (12) each being fixed to the fixation structure (19);

wherein the slack detection arrangement (17) comprises multiple string actuation levers

(41);

wherein the string (37) is arranged such as to extend transverse to and closely neighbouring to each of the suspension members (12);

wherein each of the string actuation levers (41) is attached to one of the suspension members (12) such as to protrude from the respective suspension member in a transverse direction and closely neighbouring to the string (37) at an upstream location such that upon any slack occurring in the respective suspension member the string actuation lever (41) is displaced downstream and thereby pushes onto the string and thereby increases the mechanical tension of the string (37).

12. Elevator according to one of claims 10 and 11,

wherein the fixation structure (19) is a hitch plate (21) being mechanically attached to the movable component (3) of the elevator (1).

13. Elevator according to claim 12, wherein the hitch plate (21) is mechanically attached to the movable component (3) of the elevator in a way such as to be fixedly connected to the movable component in a suspension direction (65) and such as to be rotatable in a plane transverse to the suspension direction (65).

14. Elevator according to one of claims 10 to 13,

wherein each suspension member (12) comprises an elongate flexible member (31) and furthermore comprises a rigid bar (33), wherein one end of the rigid bar (33) is attached to an end of the flexible member (31) and an opposite end of the rigid bar (33) is being attached to the fixation structure (19);

wherein the string actuation lever (41) is attached to the rigid bar (33).

15. Elevator according to claim 13,

wherein the bracket (35) comprises a V-shaped structure comprising a central lower part

47) and first and second opposing lateral higher parts (43, 45);

wherein the central lower part is attached to the fixation structure (19);

wherein a first end of the string (37) is attached to the first lateral higher part (43); wherein the tension force sensor (39) is attached to the second lateral higher part (45); wherein the bracket (35) consists of a metal sheet construction;

wherein the bracket (35) comprises openings (61) and each one of the suspension members (12) of the suspension member arrangement (11) extends through one of the openings (61);

wherein the tension force sensor (39) is adapted for outputting a slack indicating signal upon sensing a change in the mechanical tension of the string being higher than a predetermined limit change value.