Method for operating an elevator for maintenance

Abstract

A method for operating an elevator (1) for maintenance, wherein the elevator (1) comprises a car (2) and an elevator shaft (4), wherein the car is displaceable along the elevator shaft (4), a drive (6) for displacing the car (2), a plurality of shaft doors (8), at least one of the shaft doors (8) being arranged at each of a plurality of floors (10), the plurality of floors (10) comprising at least a lowest floor (10') and a highest floor (10"), and an elevator control unit (12). The elevator control unit (12) performs the following steps: the elevator control unit (12) checks whether a predetermined danger zone (18) is free of persons, wherein the predetermined danger zone (18) is preferably the elevator shaft (4), and the elevator control unit (12) switches from a maintenance mode back to a normal operation mode if the predetermined danger zone (18) is free of persons.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for operating an elevator for maintenance. Furthermore, the present invention relates to an elevator configured for carrying out such a method, a computer program product and a computer readable medium. BACKGROUND

[0002] An elevator comprises at least one car which can be displaced along an elevator shaft between a plurality of floors in a building using a drive engine. The car comprises at least one car door which can be opened and closed to allow and prevent access to the car, respectively. At each floor, at least one shaft door is provided which can be opened and closed to selectively allow or prevent access to the elevator shaft. The shaft door is sometimes referred to as a landing door. As long as the car door is not coupled with the shaft door, the shaft door is usually locked in its closed state.

[0003] During maintenance of the elevator, a technician needs to enter the elevator shaft in order to be able to, for example, check the integrity of components of the elevator comprised within the elevator shaft. To this end, in conventional elevators, the technician has to call the car to be close to one of the plurality of floors and set the elevator in a state in which calls from a landing operating panel or a car operating panel are ignored. Then, the technician has to unlock the shaft door. For this unlocking, the technician has to use a specific tool, for example a triangular key. Then, the technician has to manually open the shaft door and, for example, reach the top plate of the waiting car. On the top plate, usually a control unit is provided. By using the control unit, the technician is able to control the drive engine to displace the car to a desired position while being in a maintenance mode. Safety measures have to be taken to guarantee that the technician is not harmed during such displacement actions. For example, it has to be guaranteed that the car is not driven to a position during maintenance which endangers the technician on the top plate of the car or in a pit of the shaft. Finally, once the maintenance has been completed, the technician has to leave the elevator shaft and manually relock the associated shaft door.

[0004] Methods for opening a lock of a landing door of an elevator are presented in WO 2017 / 212105 A1 and WO 2017 / 212106 A1.

[0005] There can be a need for an alternative method for operating an elevator for maintenance. In particular, there can be a need for a method for operating an elevator for maintenance which can improve the level of safety of a technician. Furthermore, there can be a need for an elevator, a computer program product and / or a computer readable medium configured for carrying out such a method. SUMMARY

[0006] These needs can be met with the subject-matter of one of the independent claims. In the following description, advantageous embodiments are defined in the dependent claims.

[0007] According to a first aspect of the present application, a method for operating an elevator for maintenance is presented. The elevator comprises a car and an elevator shaft. The car is displaceable along the elevator shaft. The elevator further comprises a drive for displacing the car. It comprises a plurality of shaft doors, at least one of the shaft doors being arranged at each of a plurality of floors, the plurality of floors comprising at least a lowest floor and a highest floor. The elevator comprises an elevator control unit, wherein the elevator control unit performs the following steps:

[0008] - the elevator control unit receives a start maintenance request sent by a technician, wherein the start maintenance request is preferably sent via a mobile electronic device,

[0009] - the elevator control unit switches from a normal operation mode to a maintenance mode,

[0010] - the elevator control unit receives a stop maintenance request sent by the technician, wherein the stop maintenance request is preferably sent via a mobile electronic device,

[0011] - the elevator control unit checks whether there is a person within a predetermined dangerous area, wherein the predetermined dangerous area is preferably the elevator shaft,

[0012] - if there is no person within the predetermined dangerous area, the elevator control unit switches back from the maintenance mode to the normal operation mode.

[0013] The method steps are preferably performed in the order indicated.

[0014] With this method, it can be prevented that the technician is still within the dangerous area when the control unit switches back from the maintenance mode to the normal operation mode. It is ensured that the elevator resumes normal operation only when there is no person within the dangerous area and, thus, no risk of being harmed by the elevator in normal operation. Thus, the entire maintenance procedure can be safer for the technician and for other people compared to the state of the art procedures, in which the system can be switched back to the normal operation mode by one person outside the shaft while another person is still inside the shaft.

[0015] The start maintenance request can be merely an information requesting maintenance. In a preferred embodiment, the start maintenance request preferably contains information about where the maintenance is wanted to be performed and about which maintenance is planned to be performed, so that the elevator control unit learns where to displace the car to and from where the technician is expected to enter the shaft based on the nature of the start maintenance request.

[0016] In the above and below, a danger zone means a zone in which a person can be in danger during normal operation of the elevator. The danger zone can be the entire elevator shaft. The danger zone can also be a specific part of the elevator shaft, such as the top of the car, the top of the elevator shaft (also called the head), or the bottom of the elevator shaft (also called the pit).

[0017] Implementing the method step of checking whether a person is inside the predetermined danger zone with the elevator control unit has the advantage that the check is performed within the same device as the device in which all functions, in particular the displacement of the car, are performed. By bypassing the remote part of the safety system, in a way that the control unit does not recognize the presence of a person inside the shaft, the point at which the elevator is manually lured into an unsafe condition is minimized. In other words, the unit that judges whether to give a safe state and the unit that switches back to normal operation are implemented within the same unit, i.e. the elevator control unit.

[0018] The mobile electronic device can be a smartphone or any similar device. Using such a device to send the start maintenance request and / or the stop maintenance request allows to ensure that only an authorized technician, who owns such a device and is able to unlock the device with a password, via a fingerprint reader or any other unlocking feature, is able to send those requests.

[0019] In the above and below, the maintenance mode refers to a mode that differs from the normal operation mode at least in that calls entered by passengers at the landing floor operating panel and / or the car operating panel are ignored. Thus, during the maintenance mode, the elevator must not provide any transportation service to passengers. Thus, during the maintenance mode, there is no risk of a car being displaced in reaction to a call of a passenger.

[0020] During normal operation, when the elevator car is parked near a shaft door, the shaft door is exclusively opened. In this case, the car door and the corresponding shaft door are aligned. However, for the implementation of maintenance, an exception to this rule must be implemented within the maintenance mode. In particular, the technician should be able to enter the shaft through the shaft door without the car being parked directly adjacent.

[0021] For safety reasons, the method described above and below ensures that no person is inside the danger zone when the elevator switches back from the maintenance mode to the normal operation mode - a person can have entered the danger zone during the maintenance mode.

[0022] In a preferred embodiment of the method for operating an elevator for maintenance, the step of checking that no person is inside the predetermined danger zone comprises the steps of:

[0023] - capturing a pre-maintenance state of the elevator (1), preferably of the hazardous zone (18), after the elevator control unit (12) receives a start maintenance request and before the elevator control unit (12) switches from the normal operation mode to the maintenance mode; and / or

[0024] - capturing a post-maintenance state of the elevator (1) after the elevator control unit (12) receives a stop maintenance request and before the elevator control unit (12) switches back from the maintenance mode to the normal operation mode;

[0025] - evaluating a difference between at least two items of the group of: the pre-maintenance state of the elevator (1), the post-maintenance state of the elevator (1), a predetermined value for the pre-maintenance state, and a predetermined value for the post-maintenance state; and

[0026] - concluding that no person is inside the predetermined hazardous zone (18) if the evaluated difference and / or differences are below a predetermined threshold, preferably within ±5% of each other, particularly preferably within ±2% of each other.

[0027] In the above and below, capturing a pre-maintenance state means capturing the state of the elevator using one or a set of sensors of one or more types before entering the maintenance mode. Similarly, in the above and below, capturing a post-maintenance state of the elevator means evaluating the state of the elevator using one or a set of sensors of one or more types of the elevator. In this context, capturing means recording the state of the aforementioned sensors. Thus, capturing a pre-maintenance mode means recording the values of the one or more sensors before the control unit switches from the normal operation mode to the maintenance mode. Capturing a post-maintenance state means recording the values of the one or more sensors before the control unit switches from the normal operation mode to the maintenance mode.

[0028] In one embodiment, to conclude that no person is inside the predetermined hazardous zone, the pre-maintenance state of the elevator and the post-maintenance state of the elevator are evaluated, which means comparing, which means evaluating the difference between the two states. In another embodiment, the pre-maintenance state is compared to a predetermined value for that pre-maintenance state. In another embodiment, the post-maintenance state is compared to a predetermined post-maintenance state. In other embodiments, any combination of the mentioned embodiments is implemented.

[0029] If the evaluated difference and / or differences are below a predetermined threshold, preferably within ±5% of each other, particularly preferably within ±2% of each other, it is concluded that no person is inside the predetermined hazardous zone. The difference can be, for example, a difference in kilograms in case of measuring weight, or a difference in the state of the pixels of the captured snapshot or any representative part thereof, or a difference in the amount of objects identified within the snapshot.

[0030] By doing so, it can be concluded that the compared states are similar enough to each other to assume that nothing has changed in the dangerous area to such an extent that safe operation of the elevator is no longer possible. In particular, it is concluded that no one is in the dangerous area if the difference is below a predetermined threshold.

[0031] The embodiment of capturing and comparing the pre-maintenance state and the post-maintenance state is based on the assumption that the elevator is in a safe condition before it is switched from the normal operation mode to the maintenance mode. By capturing the relevant elements of this safe normal operation mode and then comparing them with the state of the same parts of the elevator captured before the mode was switched back to normal operation, the control unit is able to assess whether a change has occurred during the maintenance - a change for which safe normal operation is seemingly less likely. The comparison of the pre-maintenance state and the post-maintenance state of the predetermined dangerous area is an attempt to only check for spatial and temporal related changes and is thus an effective way of ensuring that no one is endangered when the elevator is operating normally again. Changes within the elevator, such as the ageing of sensors and the accumulation of dirt on the sensors and the resulting drift of the output values of the sensors, become irrelevant when assessing whether someone is in the dangerous area. The two states are captured within a very short time period compared to the service life of the elevator. During this time period, changes due to wear and tear should not occur. Thus, not only is the effort of detecting a person in the dangerous area reduced, but also its accuracy is improved. Minor changes within the elevator, such as an upgrade within or on the car but outside the dangerous area, do not need to be accommodated. Thus, the present embodiment allows for a more effective and safer method for operating the elevator for maintenance.

[0032] In a preferred embodiment of the method for operating the elevator for maintenance, capturing the pre-maintenance state and the post-maintenance state of the elevator comprises:

[0033] - measuring the pre-maintenance load and / or the post-maintenance load within the car or the pre-maintenance load and / or the post-maintenance load of the car and storing it in the elevator control unit.

[0034] For most maintenance work (all maintenance work not performed in the pit), the car is driven to a position where the elevator car door is not aligned with the shaft door, but access to the top of the car is possible from the shaft door. For example, the car can be moved and stopped such that the top of the car is adjacent to the lower end of the shaft door. Therefore, when a technician enters the elevator shaft, he can walk onto the top of the stopped car. During maintenance, the technician works on the top of the car. In this situation, the elevator's load measurement unit will measure the technician's weight based on the normal system weight. Therefore, measuring the car's load before maintenance mode and after receiving a request to switch back to normal operating mode can be used to see if any additional weight has been added to the car—indicating that someone is still on the top of the car. Furthermore, any tools that the technician may have carried onto the top of the car and left there will cause a change in the car's weight and can therefore also be detected.

[0035] Alternatively, the post-maintenance load and / or pre-maintenance load can be compared to predetermined values. Such predetermined values ​​can be loads measured immediately after car installation or nominal values ​​of the car. This method improves safety without requiring any additional sensors, as measuring the car load is necessary during elevator operation, for example, to determine pre-torque values. Therefore, load measurement sensors are available in the elevator anyway. Utilizing already available sensors to ensure technicians are not in predetermined danger zones is a simple and effective way to improve safety during methods used to operate the elevator for maintenance.

[0036] According to a preferred embodiment of the method for operating an elevator for maintenance, the step of capturing the elevator's pre-maintenance state and / or post-maintenance state includes:

[0037] - Capture snapshots of elevator shafts using classic cameras, ToF cameras, thermal cameras, and / or LiDAR systems.

[0038] In the preceding and following text, a snapshot refers to a record of one or more of the aforementioned cameras / LiDARs at a specific point in time.

[0039] A time-of-flight camera (ToF camera) is a range imaging camera system that uses time-of-flight technology to resolve distances by measuring the round-trip time of a pulsed laser or LED light signal. A thermal camera (also known as an infrared camera or thermal imaging camera) is a device that creates an image using infrared radiation, similar to how common cameras form images using visible light. Laser radar is a method for measuring distance (ranging) by illuminating a target with a laser light and measuring the reflected laser light with a sensor. The difference in time and wavelength of the returning laser can then be used to make a digital 3D representation of the target. All these devices are well known to the person skilled in the art.

[0040] In the above and below, comparing the pre-maintenance snapshot and the post-maintenance snapshot means comparing the snapshots as a whole, or alternatively means identifying certain objects (e.g. objects having certain dimensions or having certain color or reflection pattern) and then comparing the identified objects with objects identified in other snapshots.

[0041] The use of the snapshot before the maintenance and the snapshot after the maintenance helps to identify changes within the predetermined dangerous area that occurred during the maintenance. Thus, the use of such snapshots can be used to assess whether it is safe to switch back to normal operation, either alone or in combination with the measurement results of other sensors such as load measuring sensors.

[0042] The camera(s) / laser radar(s) can be located in a part of the shaft, for example in a pit and / or in the head of the shaft, or can be attached to the car, for example to the bottom and / or top of the car, so that areas that can endanger people can be monitored.

[0043] The advantage of using ToF cameras, thermal cameras and / or laser radar systems instead of classic cameras and / or in combination with classic cameras is that these cameras are less susceptible to contamination. Dust and dirt within the elevator shaft can over time affect the vision of classic cameras. None of these cameras are as susceptible to such contamination. Such cameras thus improve the safety of the system and also reduce the maintenance / cleaning effort required to keep the system in safe operation.

[0044] In a preferred embodiment of the method for operating an elevator for maintenance, the step of verifying that no person is within the predetermined dangerous area comprises the steps of:

[0045] - verifying that the technician is present within the car and / or on the landing after the elevator control unit has received a start maintenance request of the technician and before the elevator control unit switches from normal operation mode to maintenance mode; and / or

[0046] - verifying the presence of the technician inside the car and / or on the floor after the elevator control unit receives the technician's request to stop the maintenance and before the elevator control unit switches back from the maintenance mode to the normal operation mode.

[0047] In the above and in the following, verifying the presence of the above means inferring the technician to be in the vicinity of a certain component, i.e. inside the car or on the floor, to the extent that it can be inferred that the technician is outside the elevator shaft. If the technician is detected in the car, e.g. by a camera (such as described above) or by any other sensor such as a near field communication sensor allowing to infer that a person is inside the car, it is safely assumed that he cannot be present inside the dangerous area, i.e. inside the elevator shaft, as well. Similarly, if the technician is identified to be present on the floor, the above conclusion is valid as well. This can be done by a camera or any other sensor such as a near field communication sensor or the like. Such a sensor can be part of the landing operating panel or belong to any other part of the elevator on the floor level.

[0048] Detecting the presence of the technician inside the car or on the floor is a relatively easy, safe and reliable way to ensure that the technician is no longer in the shaft. In many elevators, such a sensor will be implemented in the car and / or on the floor anyway, as the presence of a person in the car or on the floor is information for other parts of the elevator controller.

[0049] Switching between the normal operation mode and the maintenance mode only after verifying the presence of the technician in the car or on the floor can be an additional safety element to ensure that the maintenance does not endanger personnel. Ensuring the presence of the technician inside the car or on the floor before entering the maintenance mode is a way to ensure that the elevator does not switch to the maintenance mode without an authorized person being in the vicinity of the elevator. Evaluating the presence of the technician inside the car or on the floor before switching the operation mode from the maintenance mode back to the normal mode is a safe way to ensure that the technician who initiated the maintenance mode is now already outside the shaft and inside one of the two mentioned areas before resuming the normal operation.

[0050] In a preferred embodiment of the method for operating an elevator for maintenance, verifying the presence of the technician in the car and / or on the floor is performed by identifying the technician by means of:

[0051] - displaying a code on a screen in the car and / or on the floor, which the technician has to scan with a mobile electronic device, and / or

[0052] - using a camera and / or a near field communication device in the car and / or on the floor to identify the technician.

[0053] In the above and below, the display code (which code is then scanned by the technician) can be implemented as a display changing code, wherein the pattern of the changing code is known to the App that the technician shall use to scan the code. The App can evaluate whether the code it scans is within the pattern it shall be. Using a dynamic code has the advantage that the code cannot be copied and then scanned from any other location (e.g. from another phone in the interior of the shaft that stores a picture of the static code). With a dynamic code, the App can infer that the person scanning the code was present in the vicinity of the displayed code at the moment of scanning.

[0054] The use of a camera in combination with face recognition or any other kind of recognition (e.g. iris detection and / or a near field communication device that is only coupled to a certain predetermined other device) alternatively or further helps to infer that an authorized person is in the vicinity of the camera and / or the near field communication device.

[0055] In a preferred embodiment of the method for operating an elevator for maintenance, the start maintenance request of the technician is a request to enter the elevator shaft at a certain shaft door. The method of this embodiment comprises the step of displacing the car to a predetermined position in the vicinity of the certain shaft door.

[0056] By requesting maintenance at a certain floor, the car can be displaced to a predetermined position in the vicinity of that floor. This allows in the method for operating an elevator for maintenance that only a predetermined number of positions will be used during maintenance. Such a method will for example comprise predetermined positions of the car for maintenance at each floor. This has the advantage that the car does not need to be displaced at all during maintenance. If the technician needs to perform more maintenance at another floor after he has finished maintenance at a certain floor, he will leave the shaft, exit the current maintenance mode by sending a stop maintenance request and then enter a new start maintenance request for the next maintenance work (e.g. at a different floor). Before the car is driven to the other floor, the maintenance mode will be exited and thus it will be checked whether the danger zone is occupied. This allows then to move the car to the other floor where the technician requested maintenance. This way a method for operating an elevator for maintenance is achieved, wherein the car does not need to be displaced manually within the shaft during maintenance mode. Thus, the safety of the method for operating an elevator for maintenance is improved because it is avoided that personnel within the shaft is endangered due to displacement of the car during maintenance mode.

[0057] The predetermined position near the particular shaft door can be any position at which the car facilitates maintenance on that particular floor. This can for example be a position at which the roof of the car is at the same height as the floor, so that a technician can conveniently walk on top of the roof of the car. For the lowest floor, the predetermined position near the particular shaft door can be a position at which the car does not block the entrance to the pit. In another similar maintenance request, for example to perform maintenance work on the bottom of the car, the car can be displaced to a position at which the car only partially blocks the entrance on the lowest floor and thus allows the technician to enter the pit, but still to comfortably reach the lowermost part of the car. In another exemplary start maintenance request, the technician can request to perform maintenance at the head of the elevator shaft. In this case, the car can be displaced to a position at which the roof of the car is at a certain height of the entrance of the highest floor, so that the technician can step onto the roof of the car and reach the components in the head of the elevator shaft.

[0058] In a preferred embodiment of the method for operating an elevator for maintenance, the method further comprises the steps of:

[0059] - if the maintenance mode is requested at the lowest floor, limiting the displacement of the car to only in upward direction; and / or

[0060] - if the maintenance mode is requested at the highest floor after the stop maintenance request has been received by the elevator control unit, limiting the displacement of the car to only in downward direction.

[0061] In this embodiment, the safety of the method for operating an elevator for maintenance is further improved. If maintenance is requested at the lowest floor, the technician will perform the maintenance work in the pit. By allowing only upward movement, the danger of collision with the technician due to movement of the elevator car is avoided. As a next step, the technician can need to identify himself inside the car at the next higher floor, i.e. at the first floor. In this case, the method for operating an elevator for maintenance can look as follows:

[0062] - sending a start maintenance request with the information that the technician wants to perform maintenance in the pit,

[0063] - the elevator control unit displacing the car to a position at which the entrance at the lowest floor is at least partially clear, so that the technician can comfortably enter the pit,

[0064] - the technician entering the pit and performing the required maintenance work,

[0065] - after performing the maintenance work, the technician leaving the pit in the same way as he entered the pit,

[0066] - outside the elevator shaft, the technician requests a stop maintenance, and sends a stop maintenance request to the elevator control unit,

[0067] - checking, by any of the above or below described means, whether there is a person inside the predetermined dangerous area, and / or

[0068] - enabling the technician to enter the car at the first floor by displacing the elevator car in upward direction to the first floor,

[0069] - the technician entering the car, the elevator control unit detecting the presence of the technician inside the car by any of the above described means,

[0070] - the elevator control unit concluding that the technician is no longer in the dangerous area (i.e. the pit), in case it knows that the technician who initially requested the maintenance is now inside the car one floor above the pit,

[0071] - the elevator control unit switching back from the maintenance mode to the normal operation mode,

[0072] A similar way of exiting the maintenance mode can be performed if the maintenance is requested at the topmost floor. In this case, the car is restricted to be able to move only downwards from the maintenance position. Then, the car can be stopped at a floor below the topmost floor. In this way, a technician who requested the maintenance mode and has left the head before sending the stop maintenance request can identify himself inside the car. After the elevator control unit has identified the presence of the technician inside the elevator car, the control unit can conclude that the technician is no longer in the head of the elevator shaft and thus can restore the safe normal operation mode.

[0073] In another embodiment of the method, the displacement of the car is restricted to be downwards for any start maintenance request except for the one requesting maintenance in the pit.

[0074] For any other maintenance work inside the elevator shaft than the one in the pit, it can be assumed that it is the safest to displace the car in downward direction, because for all these maintenance requests the technician will be working on top of the car roof.

[0075] In a preferred embodiment of the method for operating an elevator for maintenance as described above and below, at least one, preferably all, shaft door has an associated active door drive for opening and closing the shaft door, and / or an active door lock for locking and unlocking the shaft door. The method further comprises the steps of:

[0076] - unlocking and / or opening a certain shaft door by means of an active door lock and / or an active door drive, respectively, enabling a technician to enter the elevator shaft after inputting the maintenance mode, and / or

[0077] - closing and / or locking a certain shaft door by means of an active door drive and / or an active door lock, respectively, so that the technician can no longer enter the elevator shaft before exiting the maintenance mode.

[0078] The use of active door drives / active door locks allows to use the elevator shaft door as an additional safety element. Once the elevator control unit knows that the car has reached the predetermined position and thus it is safe to enter the elevator shaft at a certain floor, the shaft door can be opened by the elevator control unit, then the elevator control unit unlocks / opens this shaft door via the active door lock / active door drive. At the same time or in addition, the active door drive / active door lock also allows the elevator control unit to close a certain elevator shaft door as soon as a request to stop maintenance is received. This allows the elevator system to ensure that any state inside the elevator shaft existing at that point in time can no longer be changed from the outside of the elevator shaft. Then, the elevator control unit can perform a safety check and verify that no one is inside the predetermined danger zone. If no one is inside the predetermined danger zone, the elevator control unit switches back to the normal operation mode.

[0079] In a preferred embodiment, the car door is also equipped with an active door drive and / or lock.

[0080] In a preferred embodiment, the method as described above and below can also comprise the following step: ensuring that the car is empty after the elevator control unit receives a start maintenance request sent by a technician and before the elevator control unit switches from the normal operation mode to the maintenance mode.

[0081] This allows to ensure that no passengers are trapped inside the elevator car during the maintenance mode. Means to verify the personnel inside the car are known to the person skilled in the art.

[0082] In a preferred embodiment of the method for operating an elevator for maintenance, the elevator control unit prevents the car from being displaced; and / or engages the elevator brake, preferably the car brake, before the technician is admitted to enter the shaft.

[0083] In this embodiment, the method becomes even safer by deactivating the drive to be activated via the control unit and / or by preventing any movement of the car during the maintenance mode (by engaging the brake before the technician enters the shaft). With either of the above-mentioned solutions, it can be ensured that the elevator car cannot be displaced in any direction once the technician has entered the shaft for maintenance.

[0084] In a preferred embodiment of the method described above and below, the method further comprises the following steps:

[0085] - after exiting the maintenance mode and / or before entering the maintenance mode, the verification of the braking capability is initiated by performing a static brake test.

[0086] For both the safe normal operation mode and the safe maintenance mode, the normal functioning of the elevator brake is required. In the normal operation mode, the brake is required to stop the car at any floor. During the maintenance mode, the brake can be required to ensure that the car stays safely at a predetermined position. Therefore, the functioning of the brake should be checked whenever switching between the two modes.

[0087] In a preferred embodiment, the method for operating an elevator for maintenance at any floor except the lowest floor comprises the following steps:

[0088] - the technician arrives at the height at which he wants to perform maintenance (except the lowest floor);

[0089] - the technician sends a start maintenance request for a specific maintenance procedure at this floor to the elevator control unit via the mobile electronic device;

[0090] - the elevator control unit controls the car to move to this height;

[0091] - the elevator control unit opens the shaft door and the car door by controlling the active door drives of the shaft door and the car door;

[0092] - the technician enters the car to verify that the car is empty;

[0093] - the elevator control unit confirms his presence while the technician is in the car;

[0094] - the technician leaves the car and the elevator control unit closes the shaft door via the active door drive of the shaft door and the car door via the active door drive of the car door;

[0095] - the elevator control unit controls the car to move to a predetermined maintenance position near the height;

[0096] - the elevator control unit activates the brake, preferably the car brake;

[0097] - the elevator control unit measures, preferably by a car load measuring unit, and stores the pre-maintenance load;

[0098] - the control unit opens the landing door via the active door drive of the shaft door;

[0099] - the technician enters the shaft to perform the maintenance;

[0100] - once the maintenance is completed, the technician leaves the shaft, and as soon as the technician is located outside the shaft, he sends a stop maintenance request to the elevator control unit via the mobile electronic device;

[0101] - the elevator control unit closes the shaft door by controlling the active door drive of the shaft door;

[0102] - the elevator control unit measures the post-maintenance load and compares this value with the stored pre-maintenance load;

[0103] - if the value is within a predetermined range, the elevator control unit controls the car to be displaced to the next lower floor;

[0104] - the elevator control unit opens the shaft door and the car door by controlling the active door drive of the shaft door and the active door drive of the car door, respectively;

[0105] - the technician enters the car to confirm that he is present inside the car;

[0106] - the technician leaves the car, and the elevator control unit closes the shaft door via the active door drive of the shaft door and the car door via the active door drive of the car door;

[0107] - the elevator control unit performs a static brake test;

[0108] - if the brake test is passed, the elevator control unit switches from the maintenance mode back to the normal operation mode.

[0109] In a preferred embodiment, the shaft door and / or the car door additionally comprises an active door lock which unlocks the respective door before it is opened by the respective active door drive and which locks the respective door after it is closed by the respective door drive.

[0110] In a preferred embodiment, the method for operating an elevator for maintenance at a lowest floor comprises the following steps:

[0111] - the technician arrives at the lowest floor where he wants to perform maintenance;

[0112] - the technician sends a start maintenance request for a specific maintenance procedure at this floor to the elevator control unit via the mobile electronic device;

[0113] - the elevator control unit controls the car to be displaced to this height;

[0114] - the elevator control unit opens the shaft door and the car door by controlling the active door drive of the shaft door and the active door drive of the car door;

[0115] - the technician enters the car to verify that the car is empty;

[0116] - the elevator control unit confirms his presence while the technician is in the car;

[0117] - the technician leaves the car and the elevator control unit closes the shaft door via the active door drive of the shaft door and closes the car door via the active door drive of the car door;

[0118] - the elevator control unit controls the car to move to a predetermined maintenance position in the vicinity of the height;

[0119] - the elevator control unit activates the brake, preferably the car brake;

[0120] - the elevator control unit measures, preferably by a car load measuring unit, and stores the pre-maintenance load;

[0121] - the control unit opens the landing door via the active door drive of the shaft door;

[0122] - the technician enters the shaft to perform maintenance;

[0123] - once the maintenance is completed, the technician leaves the shaft and as soon as the technician is outside the shaft, a stop maintenance request is sent to the elevator control unit via the mobile electronic device;

[0124] - the elevator control unit closes the shaft door by controlling the active door drive of the shaft door;

[0125] - preferably, the elevator control unit measures the post-maintenance load and compares this value with the stored pre-maintenance load;

[0126] - if the value is within a predetermined range, the elevator control unit controls the car to move to the next higher floor, i.e. the first floor;

[0127] - the elevator control unit opens the shaft door and the car door by controlling the active door drive of the shaft door and the active door drive of the car door, respectively;

[0128] - the technician enters the car to confirm that he is inside the car;

[0129] - the technician leaves the car and the elevator control unit closes the shaft door via the active door drive of the shaft door and closes the car door via the active door drive of the car door;

[0130] - the elevator control unit performs a static brake test;

[0131] - if the brake test is passed, the elevator control unit switches back from the maintenance mode to the normal operation mode.

[0132] In a preferred embodiment, the shaft door and / or the car door additionally comprises an active door lock which unlocks the respective door before it is opened by the respective active door drive and locks the respective door after it has been closed by the respective door drive.

[0133] According to a second aspect of the present application, an elevator is presented which is configured to perform and control the method according to the embodiments of the first aspect of the present application.

[0134] In a preferred embodiment, the elevator comprises a car displaceable along an elevator shaft, a drive for displacing the car, an elevator control unit, a plurality of shaft doors, at least one shaft door being arranged at each of a plurality of floors, preferably each shaft door having an associated active door drive for opening and closing the shaft door and / or an active door lock activatable / deactivatable by the elevator control unit. The elevator is configured to perform the method as described above and below.

[0135] The active door lock is preferably a door lock with a lever and an actuator, preferably an electromagnetic actuator, to move the lever from a locked position to an unlocked position. In a preferred embodiment, the active door lock comprises a sensor for detecting the locked and unlocked position.

[0136] In a preferred embodiment, the elevator control unit of the elevator as described above and below or at least a part thereof is configured to meet the SIL3 requirements.

[0137] In an elevator, all components involved in controlling the displacement of the car and / or the opening of the shaft door can have to meet high safety requirements defined in the SIL3 (Safety Integrity Level 3) standard. It can thus be guaranteed that none of these components has a fault which could lead to a potentially dangerous situation, such as displacing the car while a technician is still inside the elevator shaft, or opening a shaft door without the car having been driven to a predetermined position close to the shaft door.

[0138] The elevator control unit or any part thereof can be programmable. They can have, for example, a processor for executing computer-readable instructions and / or processing data and a memory for storing instructions and / or data. Optionally, the door controller can be implemented within the elevator control unit or separately from the elevator control unit. In the latter case, both control units are connected with a data communication link.

[0139] According to a third aspect of the application, a computer program product comprises computer readable instructions which, when executed by a processor in an elevator according to an embodiment of the second aspect of the application, instruct the elevator to perform or control a method according to an embodiment of the first aspect of the application. Alternatively, the computer program product comprises computer readable instructions which, when executed by a processor in a mobile data communication device, instruct the mobile data communication device to send one of the request signal and the end signal to trigger the elevator according to an embodiment of the second aspect of the application to perform or control a method according to an embodiment of the first aspect of the application.

[0140] In a preferred embodiment, the computer program product comprises computer readable instructions which, when executed by a processor in an elevator as described above and below, instruct the elevator to perform or control a method as described above and below. Or alternatively, the computer program product comprises computer readable instructions which, when executed by a processor in a data communication device, instruct the data communication device to send a maintenance request to trigger the elevator as described above and below to perform a method as described above and below.

[0141] The computer program product can be in the form of an application (App) and can be used to instruct a mobile data communication device, such as a smartphone, to send one of the request signal and the end signal to trigger the elevator such that the elevator performs or controls a method as presented herein.

[0142] The computer program product comprising computer readable instructions can be in any computer readable language. When executing the computer readable instructions, the elevator control unit performs or controls the steps of a method as presented herein.

[0143] According to a fourth aspect of the application, a computer readable medium is presented. On the computer readable medium, a computer program product according to an embodiment of the third aspect of the application has been stored.

[0144] The computer readable medium comprising the computer program product stored thereon as described above can be any portable computer readable medium, such as a CD, a CVD, a flash memory, etc. for volatile or non-volatile data storage. Alternatively, the computer readable medium can be part of a computer or computer network, such as a cloud or the Internet, such that the computer program product can be downloaded therefrom.

[0145] It should be noted that possible features and advantages of embodiments of the application are described herein partly with reference to a method for operating an elevator for maintenance and partly with reference to an elevator configured for implementing such a method. The skilled person will realize that features can be transferred from one embodiment to another embodiment as appropriate and that features can be modified, adapted, combined and / or replaced etc. in order to obtain further embodiments of the application. BRIEF DESCRIPTION OF DRAWINGS

[0146] In the following, advantageous embodiments of the application will be described with reference to the accompanying drawings. The drawings and the description are not to be interpreted in a restrictive way.

[0147] Figure 1 An elevator configured to perform a method for operating an elevator for maintenance according to an embodiment of the application is shown.

[0148] The drawings are merely schematic and not drawn to scale. Identical reference signs refer to identical or similar features. DETAILED DESCRIPTION

[0149] Figure 1 An elevator 1 is shown. The elevator 1 is shown in a side view. Furthermore, a part of the elevator 1 is shown in a front view as shown in the partial view within the dashed line box.

[0150] The elevator 1 comprises a car 2 displaceable along an elevator shaft 4. The elevator car 2 is held and displaced by a suspension traction means, e.g. a rope or a belt. At opposite ends of the elevator car, the suspension traction means is coupled to counterweights. The suspension traction means is driven by a drive 6. The drive 6 is controlled by an elevator control unit 12.

[0151] The elevator car 2 comprises car doors 9 for opening and closing an entrance to the elevator car 2. The car doors 9 can be actively opened and closed by a car door drive 29. The car door drive 29 is controlled by the elevator control unit 12.

[0152] At each of the plurality of floors 10’, 10”, 10”’ at least one shaft door 8 is provided. The shaft doors 8 can be opened and closed to permit or prevent access to the elevator shaft 4. The elevator 1 presented herein comprises an active door drive 28 at each shaft door 8 for actively opening and closing the respective shaft door 8 by displacing the door leaf of the shaft door laterally. Each door drive 28 is controlled by the elevator control unit 12. Note that the term “door drive” 28 shall refer herein only to the shaft doors 8 and not to the car doors 9 which are equipped with a car door drive 29 for reasons of simpler construction.

[0153] In addition, at each of the multiple floors 10, a floor platform control panel is provided near the shaft door 8. For example, such a floor platform control panel may include one or more buttons that can be activated by passengers to call the car 2 to their floor 10.

[0154] During normal operation of elevator 1, in response to a passenger call provided via an actuation control panel on the floor platform, elevator control unit 12 controls drive 6 to move car 2 to a floor of floor 10. The drive is controlled such that car 2 stops at the floor platform position such that its bottom is substantially at the same height as the bottom of floor 10 where car 2 will collect and transport passengers.

[0155] For maintenance purposes, normal operation of elevator 1 must be temporarily suspended. To this end, according to the method proposed herein, a technician can approach elevator 1 at one of the 10 floors (e.g., the top floor). While near the shaft door 8 at that floor 10, the technician can send a maintenance request. This request is then received by elevator control unit 12.

[0156] When the elevator control unit 12 receives a maintenance request from the technician 14, the drive unit 6 will control the car 2 to move to a position such that the top of the car 2 is at the floor 10 where the maintenance work requested in the maintenance request must be performed (e.g., the top floor, such as...). Figure 1 (As shown) is adjacent to the shaft door 8. For this maintenance request, head 19 is equivalent to the predetermined danger zone 18. Subsequently, the elevator control unit 12 controls the door actuator 28 at the corresponding floor 10”’ to actively open the associated shaft door 8. The technician 14 can enter the elevator shaft 4 by walking to the top of the roof of the waiting car 2. From such a position, the technician 14 can inspect, modify, repair or replace various components of the elevator 1, such as the car guide shoe, components of the elevator control unit, front support fixing device, suspension traction device, load measuring system and connectors on the counterweight side and car side, counterweight guide shoe, shaft information, deflection pulley and / or other components.

[0157] After the maintenance has been completed, the technician 14 can leave the elevator shaft 4 via the opened shaft door 8. Then, the technician 14 can use his mobile electronic device 16 to send a stop maintenance request that can be received by the elevator control unit 12. Upon receiving the stop maintenance request, the elevator control unit 12 can control the door drive 28 of the opened shaft door 8 to close the shaft door 8. After the elevator control unit 12 has closed the shaft door 8, the elevator control unit 12 displaces the elevator car in a downward direction. As a next step, the technician 14, who is now considered to be outside of the shaft 4, has to identify himself as being inside the car that is positioned at a floor 10” below the highest floor 10”’. Thus, the elevator control unit 12 opens the respective shaft door and car door so that the technician 14 can enter the car 2 and identify himself, e.g. at the car operating panel 22, which can comprise a camera 24. After such an identification, the elevator control unit 12 knows that the technician 14 requesting the maintenance is no longer located inside the shaft and, thus, not in the predetermined danger zone (i.e. inside the head 19) and safely switches back to the normal operation mode.

[0158] In an exemplary embodiment, a load measuring unit implemented at the car brake 26 can be used to capture: a pre-maintenance state, i.e. a pre-maintenance load measurement before entering the maintenance mode; and a post-maintenance state, i.e. a post-maintenance load measurement before exiting the maintenance mode. Before displacing the car to the next lower floor 10”’ (see paragraph above), the elevator control unit 12 compares the two load measurements to conclude that they are within a predetermined range, e.g. within 5% of each other. Only if this is concluded, the car 2 is moved to the lower floor 10” at which the method continues as described above, i.e. identifying the technician 14 inside the car 2.

[0159] When the maintenance request is such that the maintenance is requested at the lowest floor 10 (not shown), the drive 6 will displace the car 2 to a position above the lowest floor 10 based on control by the elevator control unit 12, i.e. such that the car bottom is sufficiently above the pit 17 of the elevator shaft 4 to allow the technician 14 to enter such a pit 17. For this maintenance request, the pit 17 is equivalent to the predetermined danger zone 18. Subsequently, the elevator control unit 12 controls the door drive 28 of the lowest floor 10 to actively open the associated shaft door 8. Then, the technician 14 can enter the pit 17. In the pit 17, the technician can inspect, modify, repair or replace various components of the elevator 1.

[0160] Once a request for maintenance has been received (start maintenance request), the elevator control unit 12 switches to a maintenance mode. In such a maintenance mode, calls entered by passengers, for example at one of the floor landing operating panels at any of the other floors or at the car operating panel, are ignored. Furthermore, any displacement of the car 2 is prevented as long as the elevator control unit 12 is in the maintenance mode.

[0161] In an exemplary embodiment, the technician 14 can use a mobile electronic device 16, such as a smartphone, to generate and send data forming the maintenance request. For this purpose, a specific application can be programmed and uploaded to the mobile electronic device 16. The mobile electronic device 16 can send an electromagnetic wave that encrypts the maintenance request. This electromagnetic wave can be received by a suitable sensor that is part of or connected to the elevator control unit 12. Alternatively, a communication link between the mobile electronic device 16 and the elevator control unit 12 can also be established via a server, for example a cloud.

[0162] After the maintenance has been completed, the technician 14 can leave the elevator shaft 4 via the opened shaft door 8. Then, the technician 14 can use his mobile electronic device 16 to send a stop maintenance request that can be received by the elevator control unit 12. Upon receipt of the stop maintenance request, the elevator control unit 12 can control the door drive 28 of the opened shaft door 8 to close the shaft door 8. After the elevator control unit 12 has closed the shaft door 8, the elevator control unit 12 displaces the elevator car in upward direction. As a next step, the technician 14, who is now considered to be outside the shaft 4, has to identify himself as being located inside the car that is positioned at the first floor 10”. Thus, the elevator control unit 12 opens the respective shaft door and car door so that the technician 14 can enter the car 2 and identify himself, for example at the car operating panels 22, 24. After such an identification, the elevator control unit 12 knows that the technician 14 who requested the maintenance is no longer located inside the shaft and, thus, not inside the predefined danger zone (i.e., inside the pit 17) and safely switches back to the normal operation mode.

[0163] In an exemplary embodiment, the camera 20 can be implemented at the bottom of the car and can be used to capture: a pre-maintenance state, i.e., a pre-maintenance snapshot before entering the maintenance mode; and a post-maintenance state, i.e., a post-maintenance snapshot before exiting the maintenance mode. Before displacing the car to the next lower floor 10”’ (see paragraph above), the elevator control unit 12 compares the two snapshots to conclude that they are similar to each other to the extent that a person in the pit can be negated. Only if this is concluded, the car 2 is moved to the higher floor 10” at which the method continues as described above, i.e., identifying the technician 14 inside the car 2.

[0164] With the method and the elevator 1 presented herein, the maintenance of the elevator 1 can be substantially simplified and can become safer. After sending the start maintenance request, the shaft door 8 at the floor where the technician 14 has requested the maintenance can be opened actively and automatically. Furthermore, the car 2 has previously been driven to a suitable position. Since no further displacement of the car 2 is allowed during the maintenance mode, the risk of injury of the technician is minimized. Furthermore, no control unit on the car top or in the pit 17 is required. Usually, also no foot protection plate on the car top 41 and / or a skirt on the car sill is required. Thus, the costs for such equipment can be saved.

[0165] 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. Elements described in association with different embodiments can also be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

Claims

1. A method for operating an elevator (1) for maintenance, in, The elevator (1) includes: - A car (2) and an elevator shaft (4), wherein the car is movable along the elevator shaft (4); - A driver (6) for moving the car (2); - A plurality of shaft doors (8), at least one of which is arranged at each of a plurality of floors (10), the plurality of floors (10) including at least the lowest floor (10') and the highest floor (10''). - Elevator control unit (12), wherein the elevator control unit (12) performs the following steps: - The elevator control unit (12) receives a maintenance start request sent by the technician (14); - The elevator control unit (12) switches from normal operation mode to maintenance mode; - The elevator control unit (12) receives a stop maintenance request sent by the technician (14); - The elevator control unit (12) checks whether there is anyone in the predetermined danger zone (18); - When no one is in the predetermined danger zone (18), the elevator control unit (12) switches from the maintenance mode back to the normal operation mode; The step of verifying that no one is in the predetermined danger zone (18) includes the following steps: - After the elevator control unit (12) receives a maintenance start request from the technician (14) and before the elevator control unit (12) switches from normal operation mode to maintenance mode, verify that the technician (14) is present in the car (2) or on the floor (10); and / or - After the elevator control unit (12) receives the stop maintenance request from the technician (14) and before the elevator control unit (12) switches from the maintenance mode back to the normal operation mode, verify that the technician (14) is present in the car (2) and / or on the floor (10); and The presence of the technician (14) in the car (2) and / or on the floor (10) is verified by identifying the technician (14) through the following steps: - A code is displayed on a screen (20) in the car (2) and / or on the floor (10), and the technician (14) must scan the code using a mobile electronic device (16), and / or - Use another camera (24) in the car and / or on the floor (10) and / or a near-field communication device (24) to identify the technician (14).

2. The method according to claim 1, wherein, The procedure for checking that no one is in the designated danger zone (18) includes the following steps: - After the elevator control unit (12) receives the start maintenance request and before the elevator control unit (12) switches from the normal operation mode to the maintenance mode, capture the pre-maintenance state of the elevator (1); and / or - After the elevator control unit (12) receives the stop maintenance request and before the elevator control unit (12) switches from the maintenance mode back to the normal operation mode, the post-maintenance status of the elevator (1) is captured; - Evaluate the difference between at least two items from the following groups: the pre-maintenance state of the elevator (1), the post-maintenance state of the elevator (1), a predetermined value for the pre-maintenance state, and a predetermined value for the post-maintenance state; and - If one and / or more differences are assessed below a predetermined threshold, it is inferred that no one is in the predetermined danger zone (18).

3. The method according to claim 1, wherein, The start maintenance request is sent via a mobile electronic device (16).

4. The method according to claim 1, wherein, The stop maintenance request is sent via a mobile electronic device (16).

5. The method according to claim 1, wherein, The predetermined danger zone (18) is the elevator shaft (4).

6. The method according to claim 2, wherein, Capturing the pre-maintenance state of the elevator (1) is capturing the pre-maintenance state of the hazardous area (18).

7. The method according to claim 2, wherein, If one and / or more differences are within ±5% of each other, it is inferred that no one is in the predetermined danger zone (18).

8. The method according to claim 7, wherein, If one and / or more differences are within ±2% of each other, it is inferred that no one is in the predetermined danger zone (18).

9. The method according to claim 2, wherein, Capturing the pre-maintenance state and the post-maintenance state of the elevator (1) includes: - Measure the pre-maintenance load and / or post-maintenance load of the car (2) and store them in the elevator control unit (12).

10. The method according to claim 2 or 9, wherein, Capturing the pre-maintenance state and / or the post-maintenance state of the elevator (1) includes: - Snapshots of the elevator shaft (4) are captured using cameras, TOF cameras, thermal cameras and / or lidar systems.

11. The method according to claim 1, wherein, The request for technician (14) to begin maintenance is a request to enter the elevator shaft (4) at a specific shaft door (8), and the method includes the following steps: - Move the car (2) to a predetermined position near the specific shaft door (8).

12. The method according to claim 1, further comprising the following step: - If the maintenance mode is requested at the lowest floor, the displacement of the car (2) is restricted to the upward direction only; and / or - If the maintenance mode is requested at the top floor after the stop maintenance request is received by the elevator control unit (12), the displacement of the car (2) is restricted to the downward direction only.

13. The method according to claim 1, wherein, At least one of the shaft doors (8) has: Associated active door actuator (28), the active door actuator being used to open and close the shaft door (8); and / or An active door lock (30) is used to lock and unlock the shaft door, and the method further includes the following steps: - To unlock and / or open a specific shaft door (8) by means of the active door lock (30) and the active door actuator (28), respectively, so that the technician (14) can enter the elevator shaft (4) after entering the maintenance mode; and / or - The specific shaft door (8) is closed and / or locked by means of the active door actuator (28) and / or the active door lock (30) respectively, so that the technician (14) can no longer enter the elevator shaft before exiting the maintenance mode.

14. The method according to claim 13, wherein, All of the shaft doors (8) have: Associated active door actuator (28), the active door actuator being used to open and close the shaft door (8); and / or An active door lock (30) is used to lock and unlock the shaft door, and the method further includes the following steps: - To unlock and / or open a specific shaft door (8) by means of the active door lock (30) and the active door actuator (28), respectively, so that the technician (14) can enter the elevator shaft (4) after entering the maintenance mode; and / or - The specific shaft door (8) is closed and / or locked by means of the active door actuator (28) and / or the active door lock (30) respectively, so that the technician (14) can no longer enter the elevator shaft before exiting the maintenance mode.

15. The method according to claim 1, wherein, The method further includes the following steps: After the elevator control unit (12) receives the start maintenance request sent by the technician (14) and before the elevator control unit (12) switches from normal operation mode to maintenance mode, ensure that the car (2) is empty.

16. The method according to claim 1, in, In the maintenance mode, the elevator control unit (12) prevents the drive unit (6) from displacing the car (2), and / or The elevator brake (28) is engaged before the technician (14) is permitted to enter the shaft (4).

17. The method according to claim 16, wherein, Engage the car brake (28) before the technician (14) is permitted to enter the shaft (4).

18. The method according to claim 1, further comprising the following step: - After exiting the maintenance mode and / or before entering the mode, initiate the verification of braking capability by performing a static braking test.

19. An elevator (1), comprising: - Car (2), which is capable of moving along the elevator shaft (4); - A driver (6) for moving the car (2); - Elevator control unit (12); - Multiple shaft doors (8), at least one shaft door (8) is arranged at each of the multiple floors (10); The elevator (1) is configured to perform the method according to any one of claims 1 to 18.

20. The elevator according to claim 19, wherein, Each shaft door (8) has: Associated active door actuator (28), the active door actuator being used to open and close the shaft door (8); and / or Active door lock (30), which can be activated / deactivated by the elevator control unit (12).

21. The elevator according to claim 19, in, The elevator control unit (12) or at least a portion thereof is configured to meet the SIL3 requirement.

22. A computer program product comprising one of the following: - Computer-readable instructions, when executed by a processor in the elevator (1) according to any one of claims 19 to 21, instructing the elevator (1) to perform or control the method according to any one of claims 1 to 18, and - Computer-readable instructions, when executed by a processor in a data communication device (32), instruct the data communication device (32) to send a maintenance request to trigger the elevator (1) according to any one of claims 19 to 21 to perform the method according to any one of claims 1 to 18.

23. A computer-readable medium comprising a computer program product according to claim 22 stored on the computer-readable medium.

Images