WO2021254596A1

WO2021254596A1 - People mover

Info

Publication number: WO2021254596A1
Application number: PCT/EP2020/066536
Authority: WO
Inventors: Simo Mäkimattila
Original assignee: Kone Corporation
Priority date: 2020-06-16
Filing date: 2020-06-16
Publication date: 2021-12-23

Abstract

The invention relates to a people mover, comprising conveying elements (2), such as steps or pallets, each of the conveying elements (2) comprising guide rollers (2a-2d) and a tread member (3) with a tread surface (3a) on which a person can stand; and plurality of elongated guide rails (4a-4d) for guiding and supporting the guide rollers (2a-2d) of the conveying elements (1); and a monitoring system comprising a monitoring unit for monitoring loads sensed by one or more load sensors (6a-6d); and one or more load sensors (6a-6d) mounted on one or more of said guide rails (4a-4d) for sensing load exerted by a guide roller (2a-2d) on the guide rail (4a-4d) in question. Each said load sensor (6a-6d) is a pressure film sensor mounted on top of a portion (7) of a guide rail (4a-4d), and arranged to be run over by guide rollers (2a-2d) of the conveying elements (1) guided by the guide rail (4a-4d) in question.

Description

PEOPLE MOVER

FIELD OF THE INVENTION

[0001] The invention relates to monitoring of a people mover, such as an escalator, an autowalk or a moving ramp. BACKGROUND OF THE INVENTION

[0002] Escalators, auto walks and moving ramps are people movers, each of which typically comprises an endless band of conveying elements, such as steps or pallets for supporting the load to be transported, i.e. a person. The conveying element typically comprises rollers and a tread member with a tread surface on which a person can stand. The conventional people movers furthermore comprise elongated guide rails for guiding and supporting the rollers of the conveying elements. Said elongated guide rails typically comprise two first side guide rails for guiding and supporting the rollers of the conveying elements located on a first side of the conveying elements, and two second side guide rail for guiding and supporting the rollers of the conveying elements located on a second side of the conveying elements. The relative positioning of the guide rails can be used to control the tilt angle of the conveying element, whereby the people mover can comprise sections of different inclinations. The conveying elements are typically connected to each other by a chain on one or both sides of each step. It is typical that on one or both sides of each step, one roller of the step is coupled with a chain link. Thereby the chain becomes guided by the guide rollers as well.

[0003] People movers are typically equipped with a monitoring system for monitoring and ensuring safe operation thereof. The monitoring system can comprise a monitoring unit comprising electronic processing means such as a computer including microprocessors. The monitoring is typically implemented by aid of a sensing means connected with the monitoring unit. The people mover often comprises several different functions and components that are monitored by the sensing means. Much of the monitoring is needed for ensuring safety of the people and that the system is working as intended. Monitoring can also be useful for obtaining various pieces of information that can be useful for other purposes, such as for retrieving information for estimating need of maintenance and/or for retrieving information for making the operation more efficient and economical and/or for retrieving information of traffic and/or passenger behaviour. Said sensing means typically comprise sensors that serve as the means by which the monitoring unit obtains first-hand information of the people mover.

[0004] It has been noticed that monitoring arrangements of prior art have not been able to provide a sensing arrangement which is simple yet efficient and can be used for detecting various problem situations of a people mover. Such problems have been in providing a simple and reliable sensor arrangement enabling one or more of detecting missing roller, detecting step misalignment, detecting uneven wear of rollers, detecting roller surface peel-off. Load state of a conveyor element such as a step has also not been very simple and efficient.

BRIEF DESCRIPTION OF THE INVENTION

[0005] The object of the invention is to introduce a new people mover improved in terms of the monitoring abilities thereof. An object is to introduce a solution by which one or more of the above defined problems of prior art and/or problems discussed or implied elsewhere in the description can be solved. An object is particularly to introduce a solution which can simply yet efficiently be used for detecting various problem situations of a people mover, such as detecting missing roller, detecting step misalignment, detecting uneven wear of rollers, detecting roller surface peel-off or detecting chain stretch, or generally detecting if any thing has changed so that relative positioning of rollers of the people mover has changed, for instance. An object is particularly to introduce a solution which can simply yet efficiently be used for detecting the load state of a conveyor element of a people mover.

[0006] An object is also to introduce a solution which can simply yet efficiently be used for retrieving information of the people mover which information can be used for various alternative purposes. The information can be used for analyzing traffic and/or passenger behaviour, ensuring safety of the people mover operation, for control and analysis of the people flow, or for estimating the need of maintenance. [0007] It is brought forward a new people mover, comprising conveying elements, such as steps or pallets, each of the conveying elements comprising guide rollers and a tread member with a tread surface on which a person can stand; and plurality of elongated guide rails for guiding and supporting the guide rollers of the conveying elements; and a monitoring system comprising a monitoring unit for monitoring loads sensed by one or more load sensors; and one or more load sensors mounted on one or more of said guide rails for sensing load exerted by a guide roller on the guide rail in question. Each said load sensor is a pressure film sensor mounted on top of a portion of a guide rail, and arranged to be run over by guide rollers of the conveying elements guided by the guide rail in question.

[0008] With this solution one or more of the above-mentioned objects can be achieved.

[0009] Preferable further details of the people mover are introduced in the following, which further details can be combined with the people mover individually or in any combination.

[0010] In a preferred embodiment, the monitoring unit is configured to analyze electrical signals received from the one or more load sensors.

[0011] In a preferred embodiment, the signals are electric current signals.

[0012] In a preferred embodiment, each said pressure film sensor is coupled in a circuit one or more electrical properties of which are configured to be measured by the monitoring unit, said properties preferably including at least current.

[0013] In a preferred embodiment, the monitoring unit preferably comprises an electronic processing means, such as one or more microprocessors for example. The monitoring unit may comprise a computer comprising said electronic processing means.

[0014] In a preferred embodiment, each said load sensor is positioned such that it is between the portion of the guide rail and a guide roller when the guide roller runs over it. [0015] In a preferred embodiment, each said load sensor is arranged to be compressed between the portion of the guide rail and a guide roller when the guide roller runs over it.

[0016] In a preferred embodiment, each said pressure film sensor is a piezoresistive sensor comprising piezoresistive material.

[0017] In a preferred embodiment, each said pressure film sensor comprises superposed layers including a first conductor layer and a second conductor layer and a semiconductor layer between them.

[0018] In a preferred embodiment, the first conductor layer forms a first electrode of the sensor and the second conductor layer forms a second electrode of the sensor.

[0019] In a preferred embodiment, each said semiconductor layer comprises piezoresistive material.

[0020] In a preferred embodiment, the monitoring unit is configured to determine whether signals received from one or more of the load sensors fulfil one or more predefined criteria indicating a dangerous situation and to perform one or more predefined actions if one or more predefined criteria indicating a dangerous situation are fulfilled.

[0021] In a preferred embodiment, the monitoring unit is configured to stop movement of the conveying elements or send a signal to a remote monitoring center if one or more predefined criteria indicating a dangerous situation are fulfilled.

[0022] In a preferred embodiment, said determining comprises detecting peaks of signals received from one or more load sensors of one or more guide rails and comparing values of said peaks with a reference value such as an upper limit value. This enables efficient way to detect and react to a load of a roller, which load is incorrect in the prevailing situation or dangerous, such as in particular overload.

[0023] In a preferred embodiment, the one or more predefined criteria indicating a dangerous situation include that a value of a peak exceeds an upper limit value. [0024] In a preferred embodiment, said determining comprises detecting peaks of signals received from a load sensor of a guide rail and comparing frequency of said peaks with a reference frequency. The reference frequency can preferably be a frequency obtained from a list associating a frequency for the prevailing drive speed or a frequency determined earlier. The aforementioned frequency determined earlier can be a frequency determined based on detected peaks of signals received from said same load sensor, for example. The list or the reference frequency can be retrieved from a memory into which it/they have been stored earlier. Comparison of the detected frequency with a reference frequency makes it possible to detect if rollers or the whole conveyor element are incorrectly positioned or even missing, or if any other thing has changed so that relative positioning of the rollers has changed (e.g. due to excessive chain stretch) and to react to it appropriately.

[0025] In a preferred embodiment, the one or more predefined criteria indicating a dangerous situation include that a frequency of detected peaks differs from the reference frequency.

[0026] In a preferred embodiment, said determining comprises detecting peaks of signals received from a load sensor of a first side guide rail and peaks of signals received from a load sensor of a second side guide rail; and determining time differences between the peaks of signals received from a load sensor of a first side guide rail and peaks of signals received from a load sensor of a second side guide rail; and comparing each time difference with a reference. This protocol makes it possible to detect a time difference indicating a misalignment situation of a conveyor element and to react to it appropriately. This is because a time difference of rollers of different sides of the conveyor element is dependent on alignment of the conveyor element. Too small or great determined difference may also indicate some other problem such as a missing roller for instance. The reference is preferably a time difference obtained from a list associating a time difference for the prevailing drive speed of the people mover or a time difference determined earlier such as for some other pair of rollers e.g. for rollers of a preceding conveyor element. The one or more predefined criteria indicating a dangerous situation preferably include that a time difference differs from the reference. [0027] In a preferred embodiment, the one or more predefined criteria indicating a dangerous situation include that a determined time difference differs from the reference.

[0028] In a preferred embodiment, said plurality of elongated guide rails comprises a first side guide rail preferably two of them, for guiding and supporting the guide rollers of the conveying elements located on a first side of the conveying elements, and a second side guide rail preferably two of them, for guiding and supporting the guide rollers of the conveying elements located on a second side of the conveying elements, said first and second side being opposite sides of the conveying elements in width direction of the people mover.

[0029] In a preferred embodiment, said guide rollers of a conveying element comprise a roller, preferably two of them located on a first side of the conveying element and a roller, preferably two of them located on a second side of the conveying element.

[0030] In a preferred embodiment, the monitoring unit is arranged to calculate the total load of an individual conveying element based on signals of load sensors of different guide rails.

[0031] In a preferred embodiment, the elongated guide rails for guiding and supporting the guide rollers of the conveying elements are made of metal.

[0032] In a preferred embodiment, the people mover is an escalator, an autowalk or a moving ramp.

[0033] In a preferred embodiment, the length of one or more of said pressure film sensors is at least equal to or longer than the circumference of a guide roller arranged to run over the pressure film sensor in question. The dimensions defined allow that the full circumference of a guide roller will be able to produce pressure on the film sensor during the same rollover. Based on the signal generated it is simple to deduce the size of the roller in question for the purpose of comparing whether the diameter of the roller in question has changed or not. Such changing typically occurs due to wear in time. In this case, said determining whether signals received from one or more of the load sensors fulfil one or more predefined criteria indicating a dangerous situation preferably comprises determining from signals received a value indicating a diameter, a radius or a circumference of a guide roller, and preferably moreover comparing this value with a reference value, such as a lower limit value. Then, preferably the one or more predefined criteria indicating a dangerous situation include that the value indicating a diameter, a radius or a circumference of a guide roller is below a lower limit value.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In the following, the present invention will be described in more detail by way of example and with reference to the attached drawings, in which

Figure 1 illustrates a people mover according to an embodiment.

Figure 2 illustrates partially the people mover of Figure 1 as viewed in normal direction of a guide rail.

Figure 3 illustrates a block diagram of the monitoring system.

Figure 4 illustrates a sensor, a guide rail and a roller as viewed in longitudinal direction of a guide rail.

Figure 5 illustrates a sensor and a guide rail as viewed in in normal direction of a guide rail.

Figure 6 illustrates the guide rail and a pressure film sensor mounted on top of a portion of the guide rail as viewed in width direction.

Figure 7 illustrates the guide rail and a pressure film sensor mounted on top of a portion of the guide rail as viewed in width direction when a roller runs over it. Figure 8 illustrates an exploded view of a preferred embodiment of a pressure film sensor of the monitoring arrangement.

Figure 9 illustrates further preferred details of a sensor and a guide rail as viewed in in normal direction of a guide rail.

The foregoing aspects, features and advantages of the invention will be apparent from the drawings and the detailed description related thereto. DETAILED DESCRIPTION

[0035] Figure 1 illustrates a people mover 1 comprising an endless band of conveying elements 2, in particular steps, each of the conveying elements 2 comprising guide rollers 2a-2d and a tread member 3 with a tread surface 3a on which a person can stand. The people mover 2 moreover comprises a plurality of elongated guide rails 4a-4d for guiding and supporting the rollers 2a-2d of the conveying elements 2. Figure 2 illustrates a conveying element 2 and the guide rails 4a-4d as seen in normal direction of the guide rails 4a-4d. For the sake of clarity, only small length of the guide rails 4a-4d and only one conveying element 2 is illustrated. The broken line illustrates the direction in which the conveying elements 2 are successively positioned. The arrow shows the direction of movement of the conveying elements 2 corresponding to longitudinal direction L of the guide rails 4a-4d. The successive conveying elements 2 are preferably connected to each other by at least one chain, as it is common in conventional people movers, for example. The people mover can be arranged to apply force for moving the conveying elements 2 by an electric motor connected with the aforementioned chain(s), for instance.

[0036] Said plurality of elongated guide rails 4a-4d comprises two first side guide rails 4a, 4b for guiding and supporting the guide rollers 2a, 2b of the conveying elements 1 located on a first side of the conveying elements 2, and two second side guide rails 4a, 4b for guiding and supporting the guide rollers 2c, 2d of the conveying elements 2 located on a second side of the conveying elements 1, said first and second side being opposite sides of the conveying elements 2 in width direction W of the people mover, which width direction W is horizontal direction and orthogonal to longitudinal direction L of the guide rails 4a-4d, and thereby also orthogonal to the direction L in which the conveying elements 1 are movable.

[0037] The people mover further comprises a monitoring system 5;6a-6d comprising load sensors 6a-6d mounted on said guide rails 4a-4d for sensing load exerted by a guide roller 2a-2d on the guide rail 4a-4d in question, as well as a monitoring unit 5 for monitoring loads sensed by load sensors 6a-6d. The monitoring unit 5 preferably comprises an electronic processing means, such as one or more microprocessors for example. The monitoring unit 5 may comprise a computer comprising said electronic processing means.

[0038] Each said load sensor 6a-6d is a pressure film sensor mounted on top of a portion 7 of a guide rail 4a-4d, and arranged to be run over by guide rollers 2a-2d of the conveying elements 2 guided by the guide rail 4a-4d in question. Such a sensor is simple to install, reliable in use, and outputs signals the strength of which is proportional to a load exerted by a roller thereon. Installation thereof does not necessitate guide rail machining or modification, whereby it is simple to install, also as an add-on feature. It is also simple to replace in case it breaks. Figure 4 illustrates a guide roller 2a-2d when its running over a pressure film sensor mounted on top of a portion 7 of a guide rail 4a-4d. The sensor being a film sensor means that it is film shaped, which means that it the thickness thereof is substantially smaller than width or length thereof. The thickness of the pressure film sensor is preferably less than 0.5 mm, most preferably less than 0.3 mm. Thus, it is simple to install to be smoothly run over by a roller without necessity to machine a deep recess for it in the guide rail section 7. The area (width * length) of the film sensor as viewed in thickness direction is preferably more than 1 cm2, more preferably more than 2 cm2, more preferably more than 3 cm2. Preferably both the width and length thereof are at least 1 cm. Each of these specifications related to length and/or width facilitates that a roller is likely to run over the sensor such that the whole area of the roller via which support force is transmitted to the roller fits overlaps with the sensor area, and the whole load of the roller is exerted on the sensor. Thereby an accurate signal proportional to the load exerted by the roller is outputted by the sensor.

[0039] The people mover is more specifically such that the monitoring unit 5 is configured to analyze electrical signals received from the load sensors 6a-6d. The load sensors 6a-6d are for this purpose preferably connected with the monitoring unit 5, in particular such that the monitoring unit 5 can receive signals from the load sensors 6a-6d. This is illustrated in Figure 5.

[0040] Each said load sensor 6a-6d is positioned such that it is between the portion 7 of the guide rail and a guide roller 2a-2d when the guide roller 2a-2d runs over it, as illustrated in Figure 4. Each said load sensor 6a-6d is particularly arranged to be compressed between the portion 7 of the guide rail and a guide roller 2a-2d when the guide roller 2a-2d runs over it. Figure 5 illustrates a guide rail 4a-4d and a pressure film sensor mounted on top of a portion 7 of the guide rail 4a-4d. The area between broken lines bl illustrated in Figure 5 illustrates the path of the roller running along the guide rail 4a-4d.

[0041] The pressure film sensor 6a-6d is preferably a piezoresistive sensor comprising piezoresistive material. Electrical conductivity of the piezoresistive sensor 6a-6d changes when the surface pressure thereof changes. Preferably, the monitoring unit 5 is configured to monitor each pressure film sensor 6a-6d by analyzing electrical signals of a circuit comprising the pressure film sensor 6a-6d in question. Preferably, the circuit comprises a source of electrical current. In such a case, the signals are electric current signals.

[0042] The one or more electrical properties preferably include current and/or voltage.

[0043] Figure 6 illustrates the guide rail 4a-4d and a pressure film sensor 6a-

6d mounted on top of a portion 7 of the guide rail 4a-4d as viewed in width direction W. Figure 7 illustrates the guide rail 4a-4d and a pressure film sensor 6a-6d mounted on top of a portion 7 of the guide rail 4a-4d as viewed in width direction W when a roller 2a-2d runs over it.

[0044] Each said pressure film sensor 6a-6d comprises superposed layers 8-10 including a first conductor layer 8 and a second conductor layer 9 and a semiconductor layer 10 between them. In the preferred embodiment, said semiconductor layer 10 comprises piezoresistive material.

[0045] As illustrated in Figure 7, the pressure film sensor 6a-6d is arranged to be compressed between the portion of the guide rail 7 on top of which it is mounted and a guide roller 2a-2d when the guide roller 2a-2d is over it. [0046] The first conductor layer 8 forms a first electrode of the sensor 6a-6ds and the second conductor layer 9 forms a second electrode of the sensor 6a-6d. Figure 4 illustrates electrical terminals connected to the electrodes, which terminals can be electrically connected with the monitoring unit 5.

[0047] The compression causes a detectable change in the electrical conductivity of semiconductor layer 10 and thereby in electrical conductivity of the superposed layers. This is particularly due to that when the guide roller 2a-2d is over the pressure film sensor 6a-6d, the compression causes the pressure film sensor 6a- 6d slightly to deform. This deformation under compression is illustrated as reduction of thickness thereof. When the semiconductor layer comprises piezoresistive material, the conductivity increases under said compression.

[0048] As mentioned, preferably the monitoring unit 5 is configured to monitor each pressure film sensor 6a-6d by analyzing electrical signals of a circuit comprising the pressure film sensor 6a-6d in question. Preferably, the circuit comprises a source of electrical current. In such a case, the signals are electric current signals. The pressure film sensor 6a-6d is then coupled into a circuit one or more electrical properties of which are configured to be measured by the monitoring unit 5, said properties preferably including at least current.

[0049] The monitoring unit 5 is preferably configured to determine whether signals received from one or more of the load sensors 6a-6d fulfil one or more predefined criteria indicating a dangerous situation and to perform one or more predefined actions if one or more predefined criteria indicating a dangerous situation are fulfilled. Further, the monitoring unit 5 is preferably configured to stop movement of the conveying elements 2 or send a signal to a remote monitoring center if one or more predefined criteria indicating a dangerous situation are fulfilled.

[0050] Preferably, said determining comprises detecting peaks of signals received from load sensors 6a-6d of guide rails 4a-4d and comparing values of said peaks with a reference value such as an upper limit value. Then, the one or more predefined criteria indicating a dangerous situation include that a value of a peak exceeds an upper limit value. Hereby, an overload situation can be detected and reacted to. This could prevent a dangerous situation from progressing, e.g. when an object being wedged between moving parts of the people mover. This kind of a situation is relevant particularly in proximity of a comb plate of the people mover. When implementing the solution to prevent this kind of situation, the load sensors 6a- 6d should be provided on guide rail section that is located in proximity of a comb plate of the people mover 1.

[0051] Preferably, said determining comprises detecting peaks of signals received from a load sensor 6a-6d of a guide rail 4a-4d and comparing frequency of said peaks with a reference frequency. Then, the one or more predefined criteria indicating a dangerous situation include that a frequency of detected peaks differs from the reference frequency. The reference frequency may in this case be a frequency obtained from a list associating a frequency for the prevailing drive speed. Alternatively, the reference frequency may be a frequency determined earlier. The aforementioned frequency determined earlier can be a frequency determined based on detected peaks of signals received from said same load sensor, for example. In these cases, the comparison would advantageously reveal if any thing has changed so that relative positioning of the rollers has changed. For example, then the comparison would reveal if a chain connecting the steps of the people mover has in time stretched, or if a roller is missing, for example. The list or the reference frequency can be retrieved from a memory into which it/they have been stored earlier.

[0052] Preferably, said determining comprises detecting peaks of signals received from a load sensor 6a;6b of a first side guide rail 4a;4b and peaks of signals received from a load sensor 6c;6d of a second side guide rail 4a;4b; and determining time differences between the peaks of signals received from a load sensor 6a;6b of a first side guide rail 4a;4b and peaks of signals received from a load sensor 6c;6d of a second side guide rail 4a;4b; and comparing each time difference with a reference. The reference may in this case be a time difference obtained from a list associating a time difference for the prevailing drive speed or a time difference determined earlier e.g. for rollers of a preceding conveyor element. The list or the reference, such as the time difference determined earlier, can be retrieved from a memory into which it/they have been stored earlier. Then, the one or more predefined criteria indicating a dangerous situation include that a time difference differs from the reference. This protocol makes it possible to detect a time difference indicating a misalignment situation of a conveyor element and to react to it appropriately. This is because a time difference of rollers of different sides of the conveyor element 2 is dependent on alignment of the conveyor element 2.

[0053] Preferably, the monitoring unit 5 is arranged to calculate the total load of an individual conveying element 2 based on signals of load sensors of different guide rails 4a-4d.

[0054] Figure 8 illustrates an exploded view of a preferred kind of pressure film sensor 6a-6d. In the preferred embodiment illustrated, the pressure film sensor 6a-6d has been manufactured by interposing two similar members A and B, each comprising a flexible substrate sheet 8a;9a on which a conductor metal 8b;9b is spread, preferably in the form of an array of metal conductors, to form a conductor layer 9. Accordingly, the conductor layer 8,9 here comprises a flexible substrate sheet 8a;9a and an array of metal conductors spread thereon. The flexible substrate sheet 8a;9a might not be necessary. Each member A, B comprises piezoresistive material 10a; 10b spread against the conductor metal 8b;9b. In Figure 8, the members A and B are placed such that piezoresistive material side 10a;10b of the members A,B face towards each other. The piezoresistive materials 10a; 10b of the members A,B form together the piezoresistive material layer 10 of the sensor when the members A,B are against each other. The piezoresistive materials 10a; 10b can be regarded as sub layers of the piezoresistive material layer 10. An electrical terminal 8c;9c is connected with the conductor metal 8b;9b of each member A,B.

[0055] Figure 9 illustrates a guide rail 4a-4d and a pressure film sensor mounted on top of a portion 7 of the guide rail 4a-4d, as well as a roller 2a-2d. The area between broken lines bl illustrated in Figure 9 illustrates the path of the roller running along the guide rail 4a-4d. This embodiment is otherwise similar to that of Figure 5 but in this embodiment, the length 1 of a pressure film sensor 6a-6d, in particular as measured in direction L, at least equal to but, preferably longer (as illustrated] than the circumference of a guide roller 2a-2d arranged to run over the pressure film sensor 6a-6d in question. The circumference of a guide roller 2a-2d can be measured by measuring or calculated C=Pi times diameter, wherein C is the circumference. All or some of the pressure film sensors 6a-6d of the embodiments of Figures 1-8 could be dimensioned long as defined above. The dimensions defined allow that the full circumference of a guide roller 2a-2d will be able to produce pressure on the film sensor during the same rollover. Based on the signal generated it is simple to deduce the size of the roller in question for the purpose of comparing whether the diameter of the roller in question has changed or not. Such changing typically occurs due to wear in time. In this case, said determining whether signals received from one or more of the load sensors 6a-6d fulfil one or more predefined criteria indicating a dangerous situation preferably comprises determining from signals received a value indicating a diameter, a radius or a circumference of a guide roller, and preferably further comparing this value with a reference value, such as a lower limit value. This is merely one preferred example how the change could be revealed and reacted to. Then, preferably the one or more predefined criteria indicating a dangerous situation include that the value indicating a diameter, a radius or a circumference of a guide roller is below a lower limit value.

[0056] As mentioned, the width direction W is horizontal direction and orthogonal to longitudinal direction L of the guide rails 4a-4d, and thereby also orthogonal to the direction L in which the conveying elements 1 are movable. In the Figures, also direction N is showed, which is the normal direction, and orthogonal to both the width direction W and longitudinal direction L of the guide rails 4a-4d. The longitudinal direction L of the guide rails 4a-4d can be horizontal but this is not necessary, because the guide rail might be at inclination relative to horizontal plane, such that the longitudinal axis thereof is at an angle relative to horizontal plane. This may be the case if the people mover is a moving ramp or an escalator which comprises an inclined portion.

[0057] It is to be understood that the above description and the accompanying

Figures are only intended to teach the best way known to the inventors to make and use the invention. It will be apparent to a person skilled in the art that the inventive concept can be implemented in various ways. The above-described embodiments of the invention may thus be modified or varied, without departing from the invention, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that the invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. A people mover, comprising conveying elements (2), such as steps or pallets, each of the conveying elements (2) comprising guide rollers (2a-2d) and a tread member (3) with a tread surface (3a) on which a person can stand; and plurality of elongated guide rails (4a-4d) for guiding and supporting the guide rollers (2a-2d) of the conveying elements (1); and a monitoring system (5;6a-6d) comprising a monitoring unit (5) for monitoring loads sensed by one or more load sensors (6a-6d); and one or more load sensors (6a-6d) mounted on one or more of said guide rails (4a-4d) for sensing load exerted by a guide roller (2a-2d) on the guide rail (4a-4d) in question, characterized in that each said load sensor (6a-6d) is a pressure film sensor mounted on top of a portion (7) of a guide rail (4a-4d), and arranged to be run over by guide rollers (2a-2d) of the conveying elements (1) guided by the guide rail (4a-4d) in question.

2. A people mover according to claim 1, characterized in that the monitoring unit (5) is configured to analyze electrical signals received from the one or more load sensors (6a-6d).

3. A people mover according to any of the preceding claims, characterized in that the signals are electric current signals

4. A people mover according to any of the preceding claims, characterized in that each said load sensor (6a-6d) is positioned such that it is between the portion (7) of the guide rail and a guide roller (2a-2d) when the guide roller

(2a-2d) runs over it.

5. A people mover according to any of the preceding claims, characterized in that each said load sensor (6a-6d) is arranged to be compressed between the portion (7) of the guide rail and a guide roller (2a-2d) when the guide roller (2a-2d) runs over it.

6. A people mover according to any of the preceding claims, characterized in that each said pressure film sensor (6a-6d) is a piezoresistive sensor comprising piezoresistive material.

7. A people mover according to any of the preceding claims, characterized in that each said pressure film sensor (6a-6d) comprises superposed layers (8-10) including a first conductor layer (8) and a second conductor layer (9) and a semiconductor layer (10) between them.

8. A people mover according to any of the preceding claims, characterized in that the first conductor layer (8) forms a first electrode of the sensor (6a- 6d) and the second conductor layer (9) forms a second electrode of the sensor (6a-6d).

9. A people mover according to any of the preceding claims, characterized in that each said semiconductor layer (10) comprises piezoresistive material.

10. A people mover according to any of the preceding claims, characterized in that the monitoring unit (5) is configured to determine whether signals received from one or more of the load sensors (6a-6d) fulfil one or more predefined criteria indicating a dangerous situation and to perform one or more predefined actions if one or more predefined criteria indicating a dangerous situation are fulfilled.

11. A people mover according to any of the preceding claims, characterized in that the monitoring unit (5) is configured to stop movement of the conveying elements (2) or send a signal to a remote monitoring center if one or more predefined criteria indicating a dangerous situation are fulfilled.

12. A people mover according to any of the preceding claims 10-11, characterized that said determining comprises detecting peaks of signals received from one or more load sensors (6a-6d) of one or more guide rails (4a-4d) and comparing values of said peaks with a reference value such as an upper limit value, and preferably the one or more predefined criteria indicating a dangerous situation include that a value of a peak exceeds an upper limit value; and/or detecting peaks of signals received from a load sensor (6a-6d) of a guide rail (4a-4d) and comparing frequency of said peaks with a reference frequency, and preferably the one or more predefined criteria indicating a dangerous situation include that a frequency of detected peaks differs from the reference frequency; and/or detecting peaks of signals received from a load sensor (6a;6b) of a first side guide rail (4a;4b) and peaks of signals received from a load sensor (66c;6d) of a second side guide rail (4a;4b); and determining time differences between the peaks of signals received from a load sensor (6a;6b) of a first side guide rail (4a;4b) and peaks of signals received from a load sensor (66c;6d) of a second side guide rail (4a;4b); and comparing each time difference with a reference, and preferably the one or more predefined criteria indicating a dangerous situation include that a determined time difference differs from the reference.

13. A people mover according to any of the preceding claims, characterized in that said plurality of elongated guide rails (4a-4d) comprises a first side guide rail (4a, 4b) preferably two of them (4a, 4b), for guiding and supporting the guide rollers (2a, 2b) of the conveying elements (2) located on a first side of the conveying elements (2), and a second side guide rail (4c, 4d) preferably two of them, for guiding and supporting the guide rollers (2c, 2d) of the conveying elements (2) located on a second side of the conveying elements (2), said first and second side being opposite sides of the conveying elements (2) in width direction (W) of the people mover (1).

14. A people mover according to any of the preceding claims, characterized in that said guide rollers (2a-2d) of a conveying element (2) comprise a roller, preferably two of them (2a, 2b) located on a first side of the conveying element (2) and a roller, preferably two of them (2c, 2d) located on a second side of the conveying element (2).

15. A people mover according to any of the preceding claims, characterized in that the monitoring unit (5) is arranged to calculate the total load of an individual conveying element (2) based on signals of load sensors (6a-6d) of different guide rails (4a-4d).

16. A people mover according to any of the preceding claims, characterized in that the length (1) of one or more of said pressure film sensors (6a-6d) is at least equal to or longer than the circumference of a guide roller (2a-2d) arranged to run over the pressure film sensor (6a-6d) in question.