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 (2) is displaceable along the elevator shaft (4), a drive (6) for displacing the car (2), a brake for temporarily braking the displacement of the elevator car within the elevator shaft; the elevator comprises a plurality of floors (10), a plurality of shaft doors (8), at least one of the shaft doors (8) being arranged at each of the plurality of floors (10), and an elevator control unit (12) comprising a car control unit (16) and at least one door control unit (18) for opening / unlocking one of the shaft doors (8), wherein the elevator control unit (12) is configured to switch between a normal operating mode, a normal maintenance mode and a repair maintenance mode.

Description

Technical Field

[0001] The invention relates to a method for operating an elevator for maintenance. Furthermore, the invention relates to an elevator, a computer program product and a computer readable medium configured for performing such a method. Background Art

[0002] The elevator comprises at least one car which can be displaced between a plurality of floors in a building along an elevator shaft using a drive engine. The car comprises at least one car door which can be opened and closed, respectively, for providing and blocking access to the car. At each floor, at least one shaft door is provided which can be opened and closed to selectively provide or block 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 to the shaft door, the shaft door is usually locked in its closed state.

[0003] During elevator maintenance, a technician needs to enter the elevator shaft in order to, for example, be able to check the integrity of the elevator components included in the elevator shaft. For this purpose, in conventional elevators, the technician must call the car to approach a floor and set the elevator to a state in which calls from the landing operating panel or the car operating panel are ignored. Then, the technician must unlock the shaft door. For this unlocking, for example, the technician must use a specific tool, such as a triangular key. Then, the technician must manually open the shaft door and, for example, climb onto the roof of the waiting car. The control unit is usually arranged on the roof. Using the control unit, the technician can control the drive motor in maintenance mode to shift the car to the desired position. Safety measures must be taken to ensure that the technician will not be injured during this displacement action. For example, during maintenance, it must be ensured that the car will not be driven to a place that puts the technician on the top of the car roof or in the pit of the shaft in danger. Finally, after completing the maintenance, the technician must leave the elevator shaft and manually lock the relevant shaft door again.

[0004] Methods for opening the lock of elevator landing doors are proposed in WO 2017 / 212105 A1, WO 2017 / 212106 A1 and WO 2021 / 121905 A1. Summary of the invention

[0005] An alternative method for operating an elevator for maintenance may be desired. In particular, a method for operating an elevator for maintenance that can increase the safety level of a technician may be desired. Furthermore, an elevator, a computer program product, and / or a computer-readable medium configured to implement such a method may be desired.

[0006] These needs can be met by the subject matter of one of the independent claims. Advantageous embodiments are defined in the dependent claims in the following description.

[0007] According to a first aspect of the present invention, a method for operating an elevator for maintenance is proposed. The elevator comprises a car and an elevator shaft. The car can be displaced along the elevator shaft. The elevator also comprises a drive, a brake and a plurality of shaft doors, wherein the drive is used to displace the car, and the brake is used to temporarily brake the displacement of the elevator car in the elevator shaft. At least one of the shaft doors is arranged at each of a plurality of floors. The elevator comprises an elevator control unit, which comprises a car control unit and at least one door control unit, wherein the at least one door control unit is used to open / unlock one of the shaft doors. The elevator control unit is configured to switch between a normal operating mode, a normal maintenance mode and a repair and maintenance mode. The elevator control unit performs the following steps in the normal operating mode:

[0008] - receiving a start maintenance request, preferably sent by an external entity, wherein the external entity is preferably a mobile electronic device, preferably a mobile electronic device assigned to a technician; and

[0009] -Switch from normal operation mode to normal maintenance mode. The elevator control unit performs the following steps in normal maintenance mode:

[0010] - In response to the car reaching a predefined position, unlocking / opening of the shaft door is permitted by the car control unit via at least one door control unit.

[0011] The elevator control unit performs the following steps continuously in normal maintenance mode:

[0012] - detecting that the car cannot be moved; and / or

[0013] - Failure of the car control unit is detected. In response to detecting an inability to move the car and / or a failure of the car control unit, the elevator control unit performs the following steps:

[0014] -Switch from normal operation mode to service and maintenance mode.

[0015] Preferably, the method steps are performed in the order indicated. "Continuously" above and below means that the step (detection) is run until the condition is met, ie in parallel with any other steps that the elevator may perform.

[0016] By this method, safe access to the shaft for maintenance (normal maintenance mode) can be achieved. In contrast to the existing methods, the door cannot be opened with a triangular key, but the opening / unlocking of the door is performed in the normal maintenance mode, i.e., the procedure run by the elevator control unit in the normal maintenance mode. This ensures safer shaft access compared to the prior art method in which the shaft can be entered in any elevator state by using a key. This normal maintenance method / maintenance entry method is described in detail in the international patent application PCT / EP2021 / 081136 and the European patent application 21218431.1, which are incorporated herein by reference. In addition, in the normal operating mode, in which access to the shaft is authorized by the elevator control unit, it must be ensured that a repair maintenance mode is implemented, with which access to the shaft is possible even if the procedure cannot be executed / completed in the normal operating mode due to the emergency state of the elevator (also known as forced registration). In the maintenance entry concept described herein, the position of the car is a prerequisite for unlocking / opening the shaft door under normal operation. Therefore, if the car can no longer be displaced, or if the car control unit (main control unit) responsible for displacing the car is no longer functional (due to an emergency), access to the shaft must be authorized in a different way, i.e. using a modified procedure, i.e. a procedure run by the elevator control unit in service maintenance mode. It is important that this procedure for authorizing access also meets safety requirements, thereby ensuring that the elevator is safe.

[0017] In this context (but not extensively discussed in this application), it is also important to ensure a mode / method for so-called forced-checkout, i.e. ensuring that a shaft entry is concluded in a safe manner in the event that the entity requesting the entry (e.g. a technician) is not able to safely check out of maintenance mode itself. This is discussed in European patent application 21218430.3, which is incorporated herein by reference.

[0018] The start maintenance request may be only the information of the requested maintenance. In a preferred embodiment, the start maintenance request preferably includes information about where the maintenance is expected to be performed and what kind of maintenance is planned, so that according to the nature of the start maintenance request, the elevator control unit knows where to move the car and where the technician is expected to enter the shaft.

[0019] In some cases, the first entity may be synonymous with the first person, in particular with the first technician. For communication with the elevator, the technician may be represented by a personal mobile electronic device that is only accessible to the technician due to a password or fingerprint or any other equivalent security measure.

[0020] The mobile electronic device may be a smartphone or any similar device. Using such a device to send a start maintenance request and / or a stop maintenance request allows ensuring that only authorized technicians who have such a device and are able to unlock the device by a password, via a fingerprint reader or any other unlocking feature are able to send these requests.

[0021] Normal maintenance mode in the above and below refers to a mode that differs from the normal operating mode, at least in that calls entered by passengers at the landing operating panel and / or the car operating panel are ignored. Thus, during the maintenance mode, the elevator may not provide any transportation service for passengers. Therefore, during the maintenance mode, there is no risk that the car will be displaced in response to a passenger's call.

[0022] During normal operating mode, the shaft doors should be opened exclusively when the elevator car is parked near the shaft doors. In this case, the car door and the corresponding shaft door are aligned. However, in order to be able to carry out maintenance, in maintenance mode, an exception to this rule must be implemented. In particular, a technician should be able to enter the shaft through the shaft door while the car is not parked directly near the shaft.

[0023] During normal maintenance mode, the method should ensure that a technician can enter the elevator shaft only if the elevator shaft is safe. To this end, in addition to other method steps (e.g. verifying the presence of a technician at the respective floor or ensuring that there are no hazards in a predefined danger zone), the elevator control unit can shift the car to a safe position and engage a brake (preferably a car brake) to secure the car in this safe position so that the shaft door can be unlocked / opened to start maintenance.

[0024] Now, if moving the car to a predefined safe position in order to access the shaft is a prerequisite, then in the event that the car cannot be moved due to an emergency, access to the shaft is not possible at all in such an emergency, since manual opening of the shaft via a triangular key or any similar device is deliberately not foreseen. The service maintenance mode described above and below is a mode to which the method switches, in which the authorization of the shaft door via the door control unit can be done independently of the position of the car. This therefore allows access to the shaft for maintenance work in emergency situations when the normal maintenance mode (access) fails.

[0025] In the above and below, permission to open the shaft door by the door control unit via the car control unit means that the car control unit (which acts in the position of the master control unit) enables / allows / permits the door control unit (which acts in the position of the slave control unit) to unlock / open the shaft door. It is thus preferred that the door control unit itself has all the intelligence and components (e.g. door locks and / or door drive units) required for opening / unlocking the shaft door, but only does so in response to receiving permission from the car control unit.

[0026] The predefined position may be a single fixed position, such as a position in the shaft head or pit, or a position forming part of the initiation maintenance request (ie a variable position), depending on the type of maintenance requested by the external entity.

[0027] In a preferred embodiment of the method for operating an elevator for maintenance, the elevator comprises a plurality of door control units, wherein if switching to a service maintenance mode occurs due to the inability to move the car, the car control unit further performs the following steps:

[0028] - Opening / unlocking of the shaft door is authorized via at least one door control unit based on the state of the other door control unit / control units.

[0029] In other words, in the case where the switch to the service and maintenance mode is triggered by the inability to move the car, the car control unit then performs the step of granting permission for opening / unlocking the shaft door via at least one door control unit based on the door status of one or more other shaft doors / door control units. For this purpose, preferably, the door status of all shaft doors is sent by the respective door control units to the car control unit.

[0030] Based on the state of the other door control unit / control units (i.e. the locked or open state of the shaft door), the car control unit decides to authorize the opening of the shaft door via at least one door control unit. The car control unit can be configured so that the opening is only authorized if no other shaft door is open. This can provide a safe method for operating the elevator for maintenance, since it avoids that personnel can enter the shaft at multiple locations.

[0031] In a preferred embodiment, the elevator further comprises a car door, a load measurement system, a slack detection system, a communication system (which at least enables the car control unit to communicate with at least one door control unit), a positioning system and / or a power supply. The method steps of detecting that the car cannot be moved include:

[0032] - At least one fault from the group consisting of a drive fault, a brake fault, a shaft door fault, a load measurement system fault, a slack detection system fault, a communication system fault, a positioning system fault, a car door fault and a power supply fault is detected.

[0033] The above components are individually or collectively related to displacing the car. Therefore, a failure in any of these systems will affect the ability to safely displace the car. When the elevator is operating in the normal maintenance mode, a failure in one or more of these components may affect the ability of the car to reach a predefined position. Therefore, a failure in one or more of these components is used as a basis for switching to a repair maintenance mode.

[0034] All or most of these components can be connected to the car control unit, which monitors the function of these components. Therefore, the car control unit will record the failure of any of these components at any point in time. Based on this, the control unit can then trigger the switch from normal maintenance mode to repair maintenance mode.

[0035] In a preferred embodiment of the method, if switching to the maintenance mode occurs due to a malfunction of the car control unit, at least one door control unit performs the following steps:

[0036] - Receiving a door opening request; preferably the door opening request is sent by an external entity, wherein the external entity is preferably a mobile electronic device, preferably a mobile electronic device assigned to a technician.

[0037] - Opening / unlocking the corresponding shaft door by means of at least one door control unit.

[0038] In normal operating mode, the method foresees that the car control unit is used to receive a start maintenance request, in a repair maintenance mode to which the method switches due to a failure of the car control unit, this task (receiving the request) is transferred to the door control unit.

[0039] In this way, despite a malfunction of the car control unit, a request can still be received and the shaft door can be opened.

[0040] In a preferred embodiment, the elevator comprises a plurality of door control units. At least one door control unit performs the following steps:

[0041] - Unlocking / opening of the shaft door is authorized via the corresponding door control unit.

[0042] If there are multiple door control units, one of the door control units can take over the master role from the failed car control unit and allow the opening / unlocking of other shaft doors via the corresponding door control unit. In other words, after a car control unit fails, the door control unit is selected as the new master control unit.

[0043] In a preferred embodiment, the method further comprises the following steps:

[0044] - continuously sending messages from the car control unit to the door control unit at time intervals of a predefined first period of time; and

[0045] If more than a predefined time interval has elapsed without the door control unit receiving a message, the door control unit concludes that the car control unit has failed.

[0046] In other words, an auditory beat between the car control unit and at least one door control unit is implemented. Once the door control unit does not receive the auditory beat for a period of time, it can be inferred that the car control unit (and / or the communication between them) must have failed. For example, the first period of time can be 10 seconds, 30 seconds or 1 minute.

[0047] This allows the door control unit to determine in a simple manner whether the car control unit is functioning and can therefore act as a master. In the absence of functioning, the door control unit can take over parts of the functions of the car control unit which are essential for maintenance access.

[0048] In a preferred embodiment, the door control unit is connected to the landing operating panel of the elevator, which is used as a passenger input panel in normal operating mode. In the maintenance mode, the door control unit also performs the following steps:

[0049] -Detect input to the landing operation panel;

[0050] - Opening / unlocking the shaft door via the door control unit if the door control unit detects / receives an input to the landing operating panel and a door opening request. Preferably, the input and the request are detected / received within a predefined second time period from each other.

[0051] This allows additional safety in the event of a car control unit failure by verifying the presence of an external entity (i.e. a technician) close to the elevator. In this way, it is ensured that the shaft door is opened only when a request has been sent and the presence of an entity has been verified. For example, the second time period may be 10 seconds, 20 seconds or 30 seconds.

[0052] In a preferred embodiment of the method, at least in the case of switching to the maintenance mode due to a malfunction of the car control unit, the door control unit performs the following steps:

[0053] -Persistently stores any door unlock / open actions performed.

[0054] Persistently above and below means storing information / data persistently.

[0055] In this embodiment, the door control unit stores data about any unlocking / opening actions controlled by a specific door control unit. As in other operating modes, this is done by the car control unit as the master, and importantly, in the maintenance mode triggered by a failure of the car control unit, this task is the responsibility of the door control unit. Based on the stored information, it can be ensured that any action related to the door is recorded, which can therefore be used to ensure that other shaft doors are only opened after the already opened door has been closed again.

[0056] In a preferred embodiment, the door control unit further performs the following steps:

[0057] - continuously re-evaluating the state of the car control unit by at least one door control unit, preferably by continuously checking whether messages are received; and

[0058] - wherein in response to inferring that the car control unit is operational again, the door control unit sends the stored data of the unlocking / opening action to the car control unit.

[0059] After the car control unit is operational again, it is important that the car control unit knows the current state of the elevator so that it can once again assume the main task of coordinating the opening of the shaft doors in a safe manner. Therefore, as soon as the door control unit becomes aware that the car control unit is operational again (i.e. after receiving another acoustic beat), the door control unit sends the stored information to the car control unit.

[0060] According to a second aspect of the invention, an elevator is proposed, the elevator being configured to perform one of executing the method according to an embodiment of the first aspect of the invention and controlling the method according to an embodiment of the first aspect of the invention.

[0061] In a preferred embodiment, the elevator comprises a car that can be displaced along the elevator shaft, a drive for displacing the car, a brake for temporarily braking the displacement of the car in the elevator shaft, a plurality of shaft doors, at least one shaft door being arranged at each of a plurality of floors, an elevator control unit. The elevator control unit comprises a car control unit and at least one door control unit for opening / unlocking one of the shaft doors. The elevator is configured to perform the method as described above and below.

[0062] In a preferred embodiment, an elevator control unit (or at least a part of an elevator control unit) of an elevator as described above and below is configured to meet SIL3 requirements.

[0063] In an elevator, all components involved in controlling the displacement of the car and / or opening the shaft door may have to meet high safety requirements as specified in the SIL3 (Safety Integrity Level 3) standard. Thus, it can be ensured that the failure of none of the components can lead to the creation of a potentially dangerous situation, such as displacing the car while a technician is in the elevator shaft, or opening the shaft door without the car being driven to a predefined position close to the shaft door.

[0064] The elevator control unit or any part thereof may be programmable. For example, they may have a processor for executing computer-readable instructions and / or processing data and a memory for storing instructions and / or data. Optionally, the door controller may be implemented within the elevator control unit, or may be implemented separately from the elevator control unit. In the latter case, the two control units are connected via a data communication link.

[0065] In a preferred embodiment, each shaft door of the elevator comprises a door control unit for opening / unlocking the respective shaft door, wherein the door control unit is preferably wirelessly connected to the car control unit.

[0066] Preferably, each shaft door comprises an associated active door drive for opening and closing the shaft door and / or an active door lock which can be activated / deactivated by a door control unit.

[0067] Preferably, the active door lock is a door lock having a rod and an actuator, preferably an electromagnetic actuator, to move the rod from a locked position to an unlocked position. In a preferred embodiment, the active door lock comprises a sensor to detect the locked position and the unlocked position.

[0068] In a preferred embodiment, the brake is realized as a car brake and / or the drive is realized as a double drive consisting of two separate drives.

[0069] The method for operating an elevator described above and below is particularly useful if the brake is implemented as a car brake. Since the safety of the elevator with simultaneous maintenance access / shaft access is granted by the described method, it depends on the ability to fix the position of the car. Furthermore, the method is particularly useful if the drive is implemented as a dual drive, since with such a system the probability that the drive needs maintenance may be higher, thus requiring a method to operate / access the shaft during maintenance when the car cannot be moved.

[0070] According to a third aspect of the present invention, 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 present invention, instruct the elevator to perform one of the method according to the first aspect of the present invention and the method of controlling the first aspect of the present invention. Alternatively, the computer program product comprises computer readable instructions, which, when executed by a processor in a mobile data communication device, instructs the mobile data communication device to transmit one of a request signal and a final signal for triggering the elevator according to an embodiment of the second aspect of the present invention, to perform one of the method according to the first aspect of the present invention and the method of controlling the first aspect of the present invention.

[0071] 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 one of the methods described above and below and control the methods described above and below. 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 transmit a maintenance request for triggering the elevator as described above and below, so as to perform the methods described above and below.

[0072] The computer program product may be in the form of an application program ("App") and may be used to instruct a mobile data communication device (such as a smartphone) to transmit one of a request signal and a final signal to trigger an elevator so that the elevator performs or controls the method proposed herein.

[0073] The computer program product comprising computer readable instructions may be in any computer readable language. When executing the computer readable instructions, the elevator control unit performs or controls the steps of the method proposed herein.

[0074] According to a fourth aspect of the present invention, a computer readable medium is provided, on which a computer program product according to an embodiment of the third aspect of the present invention is stored.

[0075] The computer-readable medium including the computer program product described above stored thereon may be any portable computer-readable medium for transient or non-transient data storage, such as a CD, CVD, flash memory, etc. Alternatively, the computer-readable medium may be part of a computer or a computer network (such as the cloud or the Internet), such that the computer program product can be downloaded therefrom.

[0076] It should be noted that possible features and advantages of embodiments of the present invention are described in part with respect to a method for operating an elevator for maintenance, and in part with respect to an elevator configured for implementing such a method. Those skilled in the art will recognize that features may be appropriately transferred from one embodiment to another, and features may be modified, adapted, combined and / or replaced, etc., to form other embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In the following, advantageous embodiments of the present invention will be described with reference to the accompanying drawings. However, neither the drawings nor the description should be interpreted as limiting the present invention.

[0078] Figure 1 An elevator configured for performing a method for operating an elevator for maintenance according to an embodiment of the invention is shown.

[0079] The accompanying drawings are schematic and not drawn to scale. Like reference numerals refer to like or similar features. DETAILED DESCRIPTION

[0080] Figure 1 An elevator 1 is shown. The elevator 1 is shown in a side view. In addition, a part of the elevator 1 is shown in a front view, as shown in the partial view within the dashed box.

[0081] The elevator 1 comprises a car 2 which can be displaced along an elevator shaft 4. The elevator car 2 is held and displaced by a suspension traction device such as a rope or a belt. At its other end, the suspension traction device is coupled to a counterweight. The suspension traction device is driven by a drive 6. The drive 6 is controlled by an elevator control unit 12.

[0082] The elevator 1 comprises a car 2 which is displaceable along an elevator shaft 4. The elevator car 2 is held and displaced by a suspension traction device such as a rope or a belt. At its opposite ends, the suspension traction device is coupled to a counterweight. The suspension traction device is driven by a drive 6. The drive 6 is controlled by an elevator control unit 12. The elevator control unit 12 comprises a car control unit 16 and several door control units 18.

[0083] A brake system 5 in the form of a car brake is attached to the car 2. Furthermore, a load measuring system 22 can be found at the car 2. Other sensors which are essential for determining the state of the elevator 1 are attached to the car 2 or are arranged in the shaft (not shown in the figure).

[0084] The elevator car 2 comprises a car door 20 for opening and closing the passage to the elevator car 2. The car door 20 can be actively opened and closed by a car door drive 29. The car door drive 29 is controlled by the car control unit 16.

[0085] At each of the plurality of floors 10', 10", 10'", at least one shaft door 8 is provided. The shaft door 8 can be opened and closed to authorize or prevent access to the elevator shaft 4. The elevator 1 presented herein comprises an active door drive 30, which is located at each shaft door 8 for actively opening and closing the respective shaft door 8 by laterally displacing a shaft door blade. Each door drive 30 is controlled by a respective door control unit 18. It should be noted that, for reasons of simplifying terminology, the term door drive 30 refers herein only to the shaft door 8, and not to the car door 9 (the car door 9 is equipped with a car door drive).

[0086] Furthermore, at each of the plurality of floors 10, a landing operating panel 26 is provided near the shaft door 8. For example, such a landing operating panel 26 may comprise one or more buttons which can be actuated by a passenger to call the car 2 to the corresponding floor 10.

[0087] During normal operation of the elevator 1, the elevator control unit 12 controls the drive 6 to shift the car 2 to one of the floors 10 in response to a passenger's call provided by actuating one of the landing operating panels 26. Therein, the drive is controlled so that the car 2 stops at the landing position so that the car bottom of the car 2 is substantially at the same height as the bottom at the floor 10 where the car 2 should pick up or transport passengers.

[0088] For maintenance purposes, the normal operation of the elevator 1 must be temporarily interrupted. For this purpose, according to the method proposed herein, a technician (first entity) can approach the elevator 1 at one of the floors 10, such as, for example, the top floor. When approaching the shaft door 8 at this floor 10, the technician can send a request for maintenance. This request is then received by the elevator control unit 12.

[0089] When the elevator control unit 12 receives a maintenance request sent by the technician 14, the drive 6 will try to move the car 2 to a predetermined position so that, for example, the roof of the car 2 is located at the floor 10 (for example, the highest floor, such as the upper floor) where the maintenance work requested in the maintenance request must be performed. Figure 1 Near the shaft door 8 at (as shown).

[0090] As another example, when the maintenance request is such that maintenance is requested at the lowest floor 10, the drive 6 will attempt to displace the car 2 to a position above the lowest floor 10 based on the control of the elevator control unit 12, i.e., so that the bottom of the car is sufficiently higher than the pit 12 of the elevator shaft 4 to allow the technician 14 to enter such a pit 12. Subsequently, the elevator control unit 12 will control the door drive 30 of the lowest floor 10 to actively open the associated shaft door 8. The technician 14 can then enter the pit 12. In the pit 12, the technician can inspect, modify, repair or replace various components of the elevator 1.

[0091] When receiving the request for maintenance (start maintenance request), the elevator control unit 12 switches to the normal maintenance mode. In this normal maintenance mode, the call input by the passenger, for example, on one of the respective landing operating panels 26 at any other floor 10 or on the car operating panel is ignored.

[0092] In one example, the technician 14 can use a mobile electronic device 16 (such as a smartphone) to generate and transmit data forming a 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. The electromagnetic wave can be received by a suitable sensor that is part of the elevator control unit 12 or connected to the elevator control unit 12. Alternatively, the communication link between the mobile electronic device 16 and the elevator control unit 12 can also be established via a server (e.g., the cloud).

[0093] When in the normal maintenance mode, the elevator control unit 12 (in particular the car control unit 16) monitors the functionality of different (safety-related) systems that are relevant for performing the above-mentioned maintenance "registration", such as the brake system 5 and / or the load measurement system 22, etc. If it is determined that the previously described displacement of the car 2 to a predetermined position (which is necessary for entering the maintenance mode) cannot be carried out due to a malfunction in any of these systems, the elevator control unit 12 switches to the repair maintenance mode. This repair maintenance mode is necessary for the elevator 1, which relies on the functionality of at least some of its components to enter the normal maintenance mode. Therefore, as long as the normal maintenance mode for normal operation cannot be reached / performed, it is necessary to switch to the repair maintenance mode.

[0094] Two types of faults requiring switching to the maintenance mode can be distinguished: The first type is the case where it is detected that the car 2 cannot be moved. The second type is the case where the car control unit 16 fails.

[0095] In the first case, if the car 2 cannot be moved to the predetermined position, the registration procedure will not be completed and the shaft door will not be opened. Therefore, the technician cannot enter the shaft. However, in this case, in order to open the shaft door, the elevator can rely on the information and help of the car control unit 16 (main controller). The car control unit 16 updates the opening / unlocking of each of the multiple shaft doors 8 (i.e., the status of each door control unit 18) in any operating mode (normal operation, normal maintenance mode, and preferably also during the repair and maintenance mode). Therefore, in the repair and maintenance mode, the car control unit (16) can help ensure that only one of the door control units 18 is opened / unlocked at any given time, thereby helping to increase the safety of the elevator 1 (i.e., maintenance of the elevator). To this end, the car control unit 16 can allow the opening of one of the shaft doors by allowing the opening process of the corresponding door control unit 18 (e.g., the door control unit 18 on the highest floor 10). Then, the door control unit 18 can, for example, be able to communicate directly with the mobile device 32 of the technician 14. The technician 14 can request to open the shaft door 8 via the mobile device, and then the authorized door control unit 18 can open / unlock the corresponding shaft door 8 independently of any other requirements. Thus, the technician 14 is authorized to enter the shaft 4 and can start to carry out maintenance. The door control unit 18 can make the actions performed safe.

[0096] In the second case, the car control unit 16 fails and is therefore not able to act as a master controller to additionally ensure the opening of the shaft door 8. In this case, the elevator 1 can be preconfigured to allow one or more door control units 18 to communicate directly with the mobile device 32 of the technician 14 and to perform the opening of the shaft door 8 independently of any other control unit. In an embodiment in which the car control unit 16 fails, one of the door control units 18 (e.g. the door control unit 18 on the highest floor 8) can inherently have a master function and is therefore the one door control unit 18 to which the mobile device 32 can be connected (i.e. a predefined master selection can be made).

[0097] Finally, it should be noted that the term "comprising" does not exclude other elements or steps, and "a" or "an" does not exclude a plurality. Furthermore, elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

Claims

1. A method for operating an elevator (1) for maintenance, wherein the elevator (1) include: - a car (2) and an elevator shaft (4), wherein the car (2) is displaceable along the elevator shaft (4), - a drive (6) for displacing the car (2), - a brake for temporarily braking the displacement of the elevator car in the elevator shaft (4); - a plurality of shaft doors (8), at least one of the shaft doors (8) being arranged at each of a plurality of floors (10); - an elevator control unit (12), the elevator control unit comprising a car control unit (16) and at least one door control unit (18) for opening / unlocking one of the shaft doors (8), wherein the elevator control unit (12) is configured to switch between a normal operating mode, a normal maintenance mode and a repair maintenance mode, wherein the elevator control unit (12) performs the following steps in the normal operating mode: - receiving a start maintenance request, preferably sent by an external entity (14), wherein the external entity (14) is preferably a mobile electronic device, preferably a mobile electronic device assigned to a technician; and -Switch from normal operation mode to normal maintenance mode; The elevator control unit (12) performs the following steps in the normal maintenance mode: - in response to the car (2) reaching a predefined position, enabling unlocking / opening of the shaft door (8) by the car control unit (16) via the at least one door control unit (18); The elevator control unit (12) continuously performs the following steps in the normal maintenance mode: - detecting that it is impossible to move the car (2); and / or - a failure of the car control unit (16) is detected; and In response to detecting an inability to move the car (2) and / or a fault in the car control unit (16), the elevator control unit (12) performs the following steps: -Switch from normal operation mode to service and maintenance mode.

2. The method according to claim 1, in, The elevator (1) comprises a plurality of door control units (18), wherein in the case of switching to the repair and maintenance mode due to the inability to move the car (2), the car control unit (16) further performs the following steps: - based on the state of another door control unit (18) / a plurality of door control units (18), the opening / unlocking of the shaft door (8) is permitted via the at least one door control unit (18).

3. The method according to any one of the preceding claims, in, The elevator further comprises a car door (34), a load measurement system (22), a slack detection system (38), a communication system (40), a positioning system (42) and / or a power supply (44), the communication system at least enabling the car control unit (16) to communicate with the at least one door control unit (18), wherein the step of detecting an inability to move the car (2) comprises: - at least one fault from the group consisting of a drive (6) fault, a brake (5) fault, a shaft door (8) fault, a load measurement system (22) fault, a slack detection system (38) fault, a communication system (40) fault, a positioning system (22) fault, a car door (34) fault and a power supply (24) fault is detected.

4. The method according to any one of the preceding claims, in, In case of switching to the maintenance mode due to a failure of the car control unit (16), the at least one door control unit (18) performs the following steps: - receiving a door opening request; preferably the door opening request is sent by an external entity (14), wherein the external entity (14) is preferably a mobile electronic device, preferably a mobile electronic device assigned to a technician; - opening / unlocking the corresponding shaft door (8) by means of the at least one door control unit (18).

5. The method according to claim 4, in, The elevator (1) comprises a plurality of door control units (18); wherein at least one of the door control units (18) performs the following steps: - Unlocking / opening of the shaft door (8) is authorized via the corresponding door control unit (18).

6. The method according to any one of the preceding claims, further comprising: The following steps are involved: - continuously sending messages from the car control unit (16) to the door control unit (18) at time intervals of a predefined first time period; and If more than a predefined time interval has elapsed without the door control unit (18) receiving the message, the door control unit (18) concludes that the car control unit (16) has failed.

7. The method according to any one of claims 4 to 6, in, The door control unit (18) is connected to a landing operating panel (26) of the elevator (1), the landing operating panel (26) being used as a passenger input panel in a normal operating mode, wherein in the maintenance mode, the door control unit (18) further performs the following steps: - Detecting input to the landing operation panel (26); - opening / unlocking the shaft door (8) via the door control unit (18) when the door control unit (18) detects / receives an input to the landing operating panel (26) and the door opening request, wherein the input and the request are preferably detected / received within a predefined second time period from each other.

8. The method according to any one of the preceding claims, in, At least in the case of switching to the maintenance mode due to the failure of the car control unit (16), the door control unit (18) performs the following steps: -Persistently stores any door unlock / open actions performed.

9. The method according to claim 8, wherein the door control unit (18) further performs the following steps: - continuously re-evaluating the state of the car control unit (16) by the at least one door control unit (18), preferably by continuously checking whether messages are received; and - wherein in response to inferring that the car control unit (16) is operating again, the door control unit (18) sends the stored data of the unlocking / opening action to the car control unit (16).

10. An elevator, wherein the elevator (1) include: - 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 brake for temporarily braking the displacement of the car (2) in the elevator shaft (4); - a plurality of shaft doors (8), at least one of the shaft doors (8) being arranged at each of a plurality of floors (10); - an elevator control unit (12) comprising a car control unit (16) and at least one door control unit (18) for opening / unlocking one of the shaft doors (8), wherein the elevator control unit (12) is configured to perform the method according to any of the preceding claims.

11. The elevator according to claim 10, in, Each shaft door (8) comprises a door control unit (18) to open / unlock the corresponding shaft door (8), wherein the door control unit (18) is preferably wirelessly connected to the car control unit (16).

12. The elevator according to claim 10 or 11, in, The brake (5) is implemented as a car brake and / or the drive (6) is implemented as a dual drive consisting of two separate drives (6).

13. The elevator according to claim 10 to 12, in, Each of the shaft doors (8) comprises a door control unit (18), a door locking unit (28) and / or a door drive unit (30).

14. A computer program product, the computer program product comprising one of the following: - computer readable instructions which, when executed by a processor in an elevator (1) according to one of claims 10 to 13, instruct the elevator (1) to perform a method according to one of claims 1 to 9 and to control one of the methods according to one of claims 1 to 9, and - computer readable instructions for instructing the data communication device (32) to transmit, when executed by a processor in the data communication device (32), for triggering a maintenance request for the elevator (1) according to one of claims 10 or 13, to perform the method according to one of claims 1 to 9.

15. A computer-readable medium comprising the computer program product according to claim 14 stored thereon.

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