Handrail tension monitoring device for passenger transit systems

Abstract

The present invention relates to a handrail tension monitoring device (41) for a passenger transport system (1) designed as a moving walkway or escalator. The handrail tension monitoring device (41) comprises at least a distance sensor (34) and a signal processing unit (47). A measurement signal (M) detected by the distance sensor (34) can be processed and evaluated in the signal processing unit (47). In the signal processing unit (47), a vibration frequency (f) of a scanned handrail (15) of the passenger transport system (1) can be determined from a signal curve (MV) of the measurement signal (M). The vibration frequency can be compared with at least one lower threshold (US) and / or upper threshold (OS). An alarm signal (Z) is generated if the lower threshold (US) is not reached, and a warning signal (W) is generated if the upper threshold (OS) is exceeded.

Description

[Technical Field]

[0001] The present invention relates to a continuous conveying passenger transport system that can be walked on and is designed as an escalator or moving walkway. [Background technology]

[0002] Escalators and moving walkways are used to transport passengers standing on step units, such as treads or pallets, within a building or structure.

[0003] Escalators or moving walkways have moving handrails on both sides. These are used to allow passengers to hold on to one of the escalator's or moving walkway's handrails to maintain balance and avoid falling. For example, passengers may lose their balance if they are unexpectedly pushed by another passenger or if the escalator or moving walkway suddenly stops. The transitions in escalators between the horizontal travel sections in the entrance and exit areas and the inclined travel section between them also pose a particular risk of falling when the steps move perpendicular to each other and passengers on the upper steps place their toes only on the edge of the step.

[0004] However, it must be ensured that the handrail moves as synchronously as possible with the step or pallet belt.Since the handrail or handrail belt is usually driven by a friction drive, the handrail must be sufficiently pretensioned against the friction wheel so that the friction force between the handrail and the friction wheel of the handrail drive is high enough to prevent slippage between these two friction partners.

[0005] For example, JP 2008-063056 A describes a handrail tensioning device with a tensioning element for tensioning handrails. Due to wear and tear, as well as constant bending changes during operation, the handrail becomes longer and therefore must be re-tensioned from time to time. To detect the time for re-tensioning, this handrail tensioning device has built-in detection means that scans the end position of the tensioning element and sends a signal to the passenger transport system's controller as soon as this end position is reached and the handrail needs to be re-tensioned. The problem with this device is that it only indicates the time for re-tensioning when necessary, but it does not allow for the prediction of possible maintenance times.

[0006] In addition, the handrail pretensioning force must not be too high, otherwise the handrail will be pressed too hard against the guide rollers and guide profiles along which it is continuously guided, and the energy required to move the handrail and the associated wear of these parts will be too high. Even this detection means cannot detect excessive handrail pretensioning. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-063056 Summary of the Invention [Problem to be solved by the invention]

[0008] It is therefore an object of the present invention to achieve an accurate and more meaningful determination of the pretensioning force of an existing handrail. [Means for solving the problem]

[0009] This object is achieved by a handrail tension monitoring device for a passenger transport system designed as a moving walkway or escalator. To this end, the handrail tension monitoring device comprises at least one distance sensor and a signal processing unit. Measurement signals detected by the distance sensor can be processed and evaluated in the signal processing unit, and the vibration frequency of the scanned handrail of the passenger transport system can be determined in the signal processing unit from the signal curve of the measurement signal. The determined vibration frequency can be compared with at least a lower threshold value, and an alarm signal is generated if the lower threshold value is not reached.

[0010] In other words, similar to a vibrating string, the handrail pretensioning force is evaluated based on the handrail's vibration behavior. Here, known parameters are the length of the handrail's freely suspended area, its structure, the dimensions and materials used, and the measured parameters of vibration frequency and, optionally, amplitude height. The determined parameter is the handrail pretensioning force. The higher the handrail pretensioning force, the higher the handrail vibration frequency, and vice versa. As soon as the determined vibration frequency falls below a lower threshold, the minimum handrail pretensioning force is not met, which may lead to slippage between the frictional partners mentioned above. Trends that can be extrapolated can also be identified from the vibration behavior or the changing vibration frequency. Using this extrapolation, predictions can be made as to when the lower threshold will be reached and when the handrail needs to be re-tensioned. This makes maintenance planning much easier.

[0011] The handrails are preferably stimulated to vibrate by movement during the conveying operation. Optionally, since the handrails have tension members, typically made of steel strands, a properly designed device, such as an alternating magnetic field switched on for a short period of time, can support the excitation to vibration.

[0012] The lower threshold is a comparative value that represents the minimum required handrail pretensioning force. The lower and upper thresholds, described further below, are preferably determined by on-board testing after assembly of the passenger transportation system and can then be used for all structurally identical and possibly similar passenger transportation systems. Naturally, the thresholds can also be determined specifically for each completed passenger transportation system and, for example, stored in and retrieved by a storage medium of the signal processing unit. Due to the lower threshold, a handrail failure (rupture) can also be immediately recognized depending on the operating state information (whether the passenger transportation system is stationary or in transport operation), and appropriate measures, such as an emergency shutdown of the passenger transportation system, can be initiated.

[0013] As already mentioned, the determined vibration frequency can also be compared with at least one upper threshold value, and if the upper threshold value is exceeded a warning signal is generated, the upper threshold value representing the maximum allowable handrail pretensioning force.

[0014] To enable installation in a passenger transport system, the handrail voltage monitoring device preferably includes a distance sensor holder, which can be attached to a stationary component of the passenger transport system. The holder can be designed so that, in the operating state of the handrail tension monitoring device, the distance sensor is directed toward the hand support surface or the rear side of the handrail in the freely hanging area of ​​the handrail. The hand support surface is the wide surface of the handrail where the user places their hands while grasping the two sides of the handrail with their thumbs and fingers. The rear side of the handrail is usually provided with a slidable fabric so that it can slide as far as possible on the surface of the guide profile. In this configuration, the hand support surface or the rear side of the handrail moves toward or away from the sensor. Continuously detecting measurements of the distance sensor results in a measurement curve that reflects the vibrations occurring in the handrail. Continuous detection of measurements can also be understood to mean detection in discrete steps, e.g., with a high frequency, resulting in a meaningful and assessable measurement curve.

[0015] For ease of installation, the holder can have adjustment means for aligning the distance sensor with respect to the hand support surface or the rear side of the handrail. During installation, the distance sensor can be aligned with the handrail so that, on the one hand, the distance can be continuously detected with sufficient accuracy, and, on the other hand, the handrail does not collide with the distance sensor when the minimum pretension and therefore the maximum amplitude is reached.

[0016] For example, a time-of-flight camera, an infrared distance sensor, a laser distance sensor, an ultrasonic sensor with time-of-flight detection, or a radar sensor can be used as a distance sensor. In principle, any sensor that can record vibrations as a distance signal curve can be used.

[0017] The signal processing unit of the handrail voltage monitoring device can be realized, for example, in the distance sensor, in the controller of the passenger transport system, or in the data cloud. In other words, the signal processing unit is not limited to a specific location and must be connected to the distance sensor via wired and / or wireless signal transmission, or at least be able to be connected periodically.

[0018] As soon as the signal processing unit detects that the lower threshold is not met or that the upper threshold is exceeded, it can output an alarm signal and / or a warning signal. This alarm signal and / or warning signal can be sent to a controller of the passenger transport system. This can affect the driving operation of the passenger transport system, and the passenger transport system can be stopped immediately, for example, by reducing the operating speed, or by waiting for a time until only a few users are registered by other sensors, and only then can the escalator be shut down for corresponding maintenance work.

[0019] Each passenger transportation system preferably has a handrail tension monitoring device for each of its handrails.

[0020] Furthermore, the handrail voltage monitoring device may have a signal transmitting device or may be connected to a signal transmitting device from which at least the detected signal curve of the measurement signal may be transmitted to the digital twin data record of the passenger transportation system.

[0021] In other words, a digital twin data record can exist in parallel with a physically existing passenger transportation system, virtually depicting this passenger transportation system. Here, measurement signals or signal curves generated by distance sensors can be transmitted to the digital twin data record via a signal transmitting device. By processing these measurement signals and signal curves in conjunction with the data of the digital twin data record, dynamic processes of the operational passenger transportation system can be simulated and displayed in real time on the digital twin data record.

[0022] The digital twin data record includes characterizing the characteristics of components of a physical passenger transportation system in a machine-processable manner, and is comprised of component model data records that include data determined by measuring characteristic properties of the physical passenger transportation system after assembly and installation into a structure.

[0023] A characteristic property of a physical component may be the geometric dimensions of the component, the weight of the component, and / or the surface quality of the component. The geometric dimensions of a component may be, for example, the length, width, height, cross-section, radius, fillets, etc. of the component. The surface quality of a component may include, for example, the roughness, texture, coating, color, reflectivity, etc. The characteristic property may also be dynamic information, for example, a motion vector of a component model data record indicating the direction and speed of movement relative to a static reference point of the surrounding component model data record or digital twin data record.

[0024] Characteristic properties may be associated with individual components or groups of components. For example, characteristic properties may be associated with individual components from which larger, more complex groups of components are assembled. Alternatively or additionally, properties may be associated with more complex equipment assembled from multiple components, such as drive motors, gear units, conveyor chains, etc.

[0025] Signals from the distance sensors are transmitted as measurement data to the digital twin data record, and a set of rules is used to redetermine characteristic properties of component model data records affected by the transmitted measurement data. The characteristic properties of the affected component model data records are then updated with the redetermined characteristic properties. Specifically, for example, the vibration frequency and amplitude measured by the distance sensors can be transferred to component model data records representing handrails and component model data records forming guide profiles and guide rails that guide the handrails. In this way, for example, when the digital twin data record is played back on a screen as a virtual representation, all dynamically movable component model data records can be displayed with the same movement as their physical components in the physical passenger transportation system at the time the signal was recorded. The interactions of the component model data records can be simulated from the movement of the component model data records, and the forces acting on the components can be determined using appropriate known computational programs from the fields of physics, mechanics, and strength theory.

[0026] After this, by monitoring, the changes and change trends of the continuously updated characteristic properties of the handrail and their influence on the handrail and the components interacting with said handrail can be tracked and evaluated by the digital twin data record by calculation and / or static and dynamic simulation. As a result, the timing of maintenance can be determined very accurately and, optionally, a list of components interacting with the handrail to be replaced due to wear can be created. Naturally, evaluations regarding dynamic processes that exceed limit values ​​are also possible on the digital twin data record, for example in the case of accumulating resonant vibrations.

[0027] The present invention also includes a method for processing and evaluating measurement signals from the handrail tension monitoring device described above. The vibration frequency of the scanned handrail is determined from the signal curve of the measurement signal in a signal processing unit, and the determined vibration frequency is compared with at least one lower threshold value. From the comparison (the change trend of the vibration frequency and the difference from the lower threshold value), for example, a maintenance time can be determined, during which the handrail must be re-tensioned. If the lower threshold value is not met, an alarm signal is generated and transmitted, for example, to a controller of the passenger transport system for further processing. Based on the alarm signal, the controller can, for example, stop the drive machine and send a message to a maintenance center.

[0028] The determined vibration frequency can also be compared in the signal processing unit with at least one upper threshold value, and if the upper threshold value is exceeded a warning signal is generated. The warning signal does not necessarily have to stop the drive, but in order to avoid excessive wear, the signal processing unit can send a message to a mobile phone belonging to a maintenance worker who has just over-tensioned the handrail.

[0029] To verify the vibration frequency, the number of consecutive amplitude heights of the vibrating handrail is determined from the signal curve of the measurement signal, and the amplitude heights are compared with a height limit value and a number limit value. If a certain amplitude number exceeds the height limit value, this determines that the vibration frequency is too low or the pretensioning force of the handrail is too low.

[0030] As already mentioned, the detected signal curves can be sent to the passenger transport system's digital twin data record, and the effect of the vibrating handrail on other components of the passenger transport system can be determined by static and dynamic simulations.

[0031] The vibration frequency of the handrail is typically direction-dependent, since the pulling forces in the handrail vary depending on the direction of rotation due to friction conditions and the position of the handrail driver relative to the position of the distance sensor, which allows thresholds to be established depending on the direction of travel.

[0032] It should be noted that some of the possible features and advantages of the present invention are described herein with reference to different embodiments, and those skilled in the art will recognize that features can be combined, adapted, or substituted as desired to arrive at further embodiments of the present invention.

[0033] Embodiments of the present invention are described below with reference to the accompanying drawings, the drawings and descriptions are not intended to be construed as limiting the invention. [Brief explanation of the drawings]

[0034] [Figure 1] 1 shows a schematic representation of the most important components or parts of an escalator, in particular its handrails and handrail tensioning devices, as well as components of a handrail tension monitoring device according to the invention with distance sensors. [Figure 2] 2 is an enlarged view of a handrail tensioning device and a distance sensor of the handrail tension monitoring device of the passenger transportation system shown in FIG. 1. [Figure 3A] 3 shows an aerial signal curve of the measurement signal of the distance sensor shown in FIGS. 1 and 2; [Figure 3B] 3B shows a possible evaluation of the measurement signal shown in FIG. 3A. DETAILED DESCRIPTION OF THE INVENTION

[0035] The drawings are only schematic and are not to scale. Like reference signs refer to like or equivalent features in the various drawings.

[0036] 1 shows diagrammatically the most important components or parts of a passenger transport system 1 designed as an escalator. The system has a support structure 3, indicated by a contour line, arranged between two support points 5, 7 of a structure 9. Here, the support structure 3 houses other components of the passenger transport system 1, such as a conveyor belt 11 continuously guided around the support structure 3, two balustrades 13 (only one balustrade 13 is shown) each having a continuously guided handrail 15, a drive unit 17 for driving the conveyor belt 11 and the handrails 15, and a controller 19 connected via a signal line 49 to the drive unit 17 for controlling them.

[0037] In this example, the return strand 21 of the handrail 15 is guided in the balustrade base 25 by guide rollers 27, and its leading strand 23 is guided on a guide profile 29 (see section AA in Figure 2). The part of the handrail 15 that is visible to the user, and therefore can be grasped, is the leading strand 23, while the return strand 21 is hidden in the balustrade base 25.

[0038] The drive unit 17 is operatively connected to the main drive shaft 31. The conveyor belt 11 is also guided around and driven by the main drive shaft 31. The handrails 15 are driven by friction wheels 35 of the handrail drivers 33, which are also operatively connected to the drive unit 17 via the main drive shaft 31. A handrail tensioning device 37 is provided to allow sufficient force to be transmitted between the friction wheels 35 and the handrails 15. The handrails 15 can be pretensioned by this tensioning device. The handrail tensioning device 37, the handrail drivers 33, and guide rollers 27 that guide the handrails 15 into place, as well as the return strand 21 of the handrails 15, are also arranged in the balustrade base 25.

[0039] Also located on the balustrade base 25 is a distance sensor 43 of the handrail tension monitoring device 41. The distance sensor 43 is connected to the controller 19 of the passenger transportation system 1 via a signal line 45, shown in dashed lines. As shown, the signal processing unit 47 of the handrail tension monitoring device 41 can be located within the controller 19 or realized within its electronics. However, it can also be realized within the distance sensor 43 itself or outside the physical realm of the passenger transportation system 1, for example in the data cloud 95.

[0040] To be able to detect vibrations of the handrail 15, the distance sensor 43 is placed in the freely hanging region 57 of the handrail 15, preferably between the two guide rollers 27. Depending on the existing handrail pretensioning force, the handrail will sag to different degrees in the freely hanging region 57. When properly tensioned, the handrail will sag slightly, as shown by the solid line 51. Too much tension will tend to result in the position shown by the dashed-dotted line 53, while insufficient tension will tend to result in the position shown by the dashed line 55.

[0041] FIG. 2 is an enlarged view of the handrail tensioning device 37 and distance sensor 43 of the handrail tension monitoring device 41 of the passenger transportation system 1 shown in FIG. 1 . The handrail tensioning device 37 includes a roller carrier 69 with a pressure roller 67, a spindle 63, an adjustment nut 65, and a support 61. The support 61 is attached to a fixed component 81 of the passenger transportation system 1, for example, by a screw, in the example shown on the upper chord of the support structure 3. The spindle 63, which is rigidly connected to the roller carrier 69, can be adjusted relative to the support 61 by the adjustment nut 65, so that a desired handrail pretensioning force can be applied to the handrail 15. Naturally, a handrail clamping device 37 with a different design, for example, one with a spring element, can also be used. However, such a handrail tensioning device 37 also needs to be re-tensioned from time to time.

[0042] The handrail tension monitoring device 41 comprises a holder 71, which is also attached to an upper chord or fixed component 81 of the passenger transport system 1. The holder 71 is designed in such a way that, in the operating state of the handrail tension monitoring device 41, its distance sensor 43, more precisely a sensor head 77 of the distance sensor 43, is directed towards the hand support surface 83 or the rear side 85 of the handrail 15, in the freely hanging area 51 of the handrail 15. Furthermore, the holder 71 comprises adjustment means 73, 75 for aligning the distance sensor 43 with respect to the hand support surface 83 or the rear side 85 of the handrail 15. In this embodiment, these adjustment means 73, 75 are an adjustment nut 75, which simultaneously serves to fix the distance sensor, and a slotted screw connection 73 for mounting and aligning the holder 71 to the fixed component 81.

[0043] The distance sensor 71 must be able to perform a rapid sequence of distance measurements, i.e. detect the changing distance caused by vibrations (deflection of the handrail in the freely hanging area 51 represented by double arrows 87 and shown by dashed lines) as a measurement signal and its signal curve. Various distance sensors 71 are suitable for this purpose, such as a TOF camera, an infrared distance sensor, a laser distance sensor, an ultrasonic sensor with time-of-flight detection, or a radar sensor.

[0044] As already mentioned, the measurement signal and its signal course are transmitted to the signal processing unit 47, for example via a signal line 45. Naturally, instead of the signal line 45, a wireless transmission can also take place, for example via a Bluetooth connection.

[0045] The signal processing unit 47 itself can be located in the distance sensor 71. However, it can also be integrated into the controller 19 of the passenger transport system 1, as shown in Figure 1. It is also possible for the signal processing unit 47 to be realized in a data cloud, where the necessary evaluations take place. Furthermore, the handrail voltage monitoring device 41 can have communication means 89 or be connected to communication means 89, by means of which at least the detected signal curve of the measurement signal can be transmitted to the digital twin data record 101 of the passenger transport system 1.

[0046] A possible evaluation of the measurement signal M and the signal profile MV is shown in Figures 3A and 3B: Figure 3A shows the fictitious signal curve MV of the measurement signal M of the distance sensor 43 shown in Figures 1 and 2 .

[0047] The illustrated signal curve MV starts on the left and shows a low amplitude A and a high vibration frequency f. Over an operating time t, there is a loss of pretensioning force on the handrail 15 as a result of settling and wear of the material of the handrail 15. This allows the handrail 15 to vibrate further, thereby decreasing the vibration frequency f and increasing the amplitude height H of the amplitude A. Naturally, the loss of pretensioning force does not occur within a few vibrations, but rather over a very long period of time.

[0048] FIG. 3B shows the frequency curve FK determined from the signal curve MV, as well as the upper and lower thresholds OS and US. Starting from the left, the measured vibration frequency f is so high that the frequency curve FK exceeds the upper threshold OS. Therefore, the handrail 15 is pulled too tight, and a warning signal W is generated in the signal processing unit 47 and sent to a maintenance technician, e.g., via a mobile phone. As a result, the maintenance technician can immediately see that the handrail pretensioning force is too high after re-tensioning the handrail 15. The maintenance technician can then reduce the handrail pretensioning force until the upper threshold OS is no longer met. Naturally, the warning signal W can also be sent to the controller 19 of the passenger transportation system 1 shown in FIG. 1, which can then stop the drive operation of the passenger transportation system 1 after a few seconds.

[0049] With the continued operation of the passenger transportation system 1, the handrail pretensioning force continuously decreases, resulting in a decrease in the vibration frequency f and an increase in the amplitude height H. If, at some point, the vibration frequency f falls below a lower threshold value US, an alarm signal Z is output by the signal processing unit 47. The lower threshold value US is sized so that, under normal load on the handrail 15, there is little slippage between the friction wheel 35 of the handrail actuator 33 and the handrail 15 (see FIG. 1). The lower threshold value US can be determined, for example, by testing, but can also be calculated from geometric data, the handrail actuator 33, the coefficients of friction between the handrail 15 and various friction partners along the entire handrail guide path, and the handrail pretensioning force.

[0050] The vibration frequency f of the handrail 15 depends on the direction of travel, since the tension in the handrail 15 varies depending on the direction of rotation due to friction conditions and the position of the handrail actuator 33 and handrail tensioning device 37 relative to the position of the distance sensor 71. This allows thresholds to be established depending on the direction of travel.

[0051] The alarm signal Z is sent to the controller 19 of the passenger transport system 1, which for safety reasons stops the drive operation of the passenger transport system 1, for example, until the handrail 15 is tensioned again by the handrail tensioning device 37.

[0052] As shown in FIG. 3A, to verify the vibration frequency f, the number of consecutive amplitude heights H of the vibrating handrail 15 can be determined from the signal curve MV of the measurement signal M, and the amplitude heights can be compared with the height limit value HG and the number limit value n. As a result, an unacceptably low handrail pretensioning force can also be determined when an external influence, such as a rapid pull on the handrail 15, stimulates the handrail 15 to vibrate at a higher frequency and therefore does not fall below the lower threshold value US. In this special case, the amplitude height H indicates that the handrail pretensioning force is too low. However, at the same time, because the number limit value n does not take into account a single exceedance of the height limit value HG, an alarm signal A is only generated if the height limit value HG is exceeded several times during the period of interest or during several consecutive amplitudes A.

[0053] FIG. 1 shows a further option for evaluating the measurement signal M and its signal curve MV from the handrail tension monitoring device 41 or its distance sensor 43. For this purpose, a digital twin data record 101 is used, which is stored, for example, on a data processing device 95 (cloud). This digital twin data record 101 virtually maps the passenger transportation system 1. This means that each individual component of the passenger transportation system 1 is also represented in the digital twin data record 101. The digital twin data record 101 is preferably structured into component model data records 113 linked to each other via interface information. In other words, the components of the passenger transportation system 1 are represented as component model data records 113. Each of these component model data records 113 (e.g., the component model data record 113 of the guide roller 27) has all the characteristic properties of the physical component to which it is mapped as completely as possible. Furthermore, the interface information present in the digital twin data record 101 is intended to represent the arrangement of the components in three-dimensional space, their interaction with each other during the action and transmission of forces, moments, etc., and possibly their degrees of freedom of movement relative to each other.

[0054] This digital twin data record 101 can be downloaded from a data processing device 95, which in the illustrated example is a personal computer, via an input / output interface 99, for further processing, and used in a simulation 105. Of course, the simulation 105 can also be run on the data processing device 95, in which case the input / output interface 99 can function solely as a computer terminal.

[0055] To be able to perform the simulation 105, there is the option of transmitting, for example, the signal curve of the distance sensor 43 and the measurement signal via the signal sending device 89 of the handrail voltage monitoring device 41 to the digital twin data record 101, as indicated by the double arrow 97. Supplemented in this way, this can be used to perform the simulation 105 by investigating how the measurement signal M of the handrail tension monitoring device 41 affects the individual virtual components of the digital twin data record 101, represented by the component model data record 113.

[0056] During the entire execution of the simulation 105, the input / output interface 99 is in communication with the data processing device 95, as indicated by the double arrow 115. Thus, the simulation 105 and the simulation results 107 can be displayed as a virtual representation 103 on the input / output interface 99. In this way, the processes occurring as the passenger transportation system 1 operates can be represented in real time on the input / output interface 99 in an evaluated form.

[0057] 1 and 2 show a passenger transport system 1 designed as an escalator, it is clear that the invention can also be used with passenger transport systems 1 designed as moving walkways.

[0058] Finally, it should be noted that terms such as "comprising" and "having" do not exclude other elements or steps, and terms such as "a" or "an" do not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above embodiments may be used in combination with other features or steps of other of the above embodiments. Reference signs in the claims should not be considered limiting.

Claims

1. 1. A handrail tension monitoring device (41) for a passenger transport system (1) designed as a moving walkway or escalator, the handrail tension monitoring device (41) comprising at least a distance sensor (34) and a signal processing unit (47), wherein a measurement signal (M) detected by the distance sensor (34) can be processed and evaluated in the signal processing unit (47), a vibration frequency (f) of a scanned handrail (15) of the passenger transport system (1) can be determined in the signal processing unit (47) from a signal curve (MV) of the measurement signal (M), the determined vibration frequency (f) can be compared with at least one lower threshold (US) and / or upper threshold (OS), and an alarm signal (Z) is generated if the lower threshold (US) is not reached, and a warning signal (W) is generated if the upper threshold (OS) is exceeded.

2. 2. The handrail tension monitoring device (41) of claim 1, wherein the device comprises a holder (37) that can be attached to a fixed component (81) of the passenger transport system (1), and the holder (37) is designed so that, in the operating state of the handrail tension monitoring device (41), its distance sensor (34) is directed towards the hand support surface (83) or the rear side (85) of the handrail (15) in the freely hanging area (51) of the handrail (15).

3. 3. The handrail tension monitoring device (41) of claim 2, wherein the holder (37) has adjustment means (73, 75) for aligning the distance sensor (34) with the hand support surface (83) or the rear side (85) of the handrail (15).

4. The handrail tension monitoring device (41) according to any one of claims 1 to 3, wherein the distance sensor (34) is a time-of-flight camera, an infrared distance sensor, a laser distance sensor, an ultrasonic sensor with time-of-flight detection, or a radar sensor.

5. The handrail tension monitoring device (41) according to any one of claims 1 to 4, wherein the signal processing unit (47) is implemented in the distance sensor (34), in the controller (19) of the passenger transport system (1), or in the data cloud (95).

6. A handrail tension monitoring device (41) as described in any one of claims 1 to 5, wherein an alarm signal (Z) and / or a warning signal (W) can be sent to a controller (19) of the passenger transport system (1), so that the drive operation of the passenger transport system (1) can be affected.

7. 7. The handrail voltage monitoring device (41) according to any one of claims 1 to 6, wherein the device has a communication means (89) or can be connected to a communication means (89) via which at least the detected signal curve (MV) of the measurement signal (M) can be transmitted to a digital twin data record (101) of the passenger transport system (1).

8. A passenger transport system (1) comprising at least one handrail tension monitoring device (41) according to any one of claims 1 to 7.

9. 8. A method for processing and evaluating a measurement signal (M) of a handrail tension monitoring device (41) according to any one of claims 1 to 7, characterized in that in a signal processing unit (47) the vibration frequency (f) of the scanned handrail (15) is determined from the signal curve (MV) of the measurement signal (M), the determined vibration frequency (f) is compared with at least one lower threshold value (US) and / or an upper threshold value (OS), and an alarm signal (Z) is generated if the lower threshold value (US) is not reached and a warning signal (W) is generated if the upper threshold value (OS) is exceeded.

10. 10. The method according to claim 9, wherein, to verify the vibration frequency (f), the number of successive amplitude heights (H) of the vibrating handrail (15) is determined from the signal curve (MV) of the measurement signal (M), and said amplitude heights are compared with a height limit value (HG) and a number limit value (n).

11. 11. The method according to claim 9 or 10, wherein the detected signal curve (MV) is transmitted to a digital twin data record (101) of the passenger transport system (1), and the effect of the vibrating handrail (15) on other components of the passenger transport system (1) is determined by static and dynamic simulations using the digital twin data record (101).

12. 12. The method according to any one of claims 9 to 11, wherein the thresholds (OS, US) are established as a function of the direction of travel.

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