Specification

The present disclosure of various embodiments generally relates to maintaining and servicing elevator installations. More particularly, the various embodiments described herein relate to a service tool for an elevator installation, a method of operating the service tool for enabling a technician to safely access an elevator shaft, and an elevator installation with a service tool. From time to time, a technician or other authorized person may have to access an elevator shaft (or hoistway) to perform maintenance, service or repair of an elevator installation or its components from within the elevator shaft. Shaft access typically occurs via a landing or shaft door that the technician can open using an unlocking key while standing on a floor (landing). At least for elevators installed in the USA, the unlocking key, also referred to as drop key, typically has an elongated body, e.g., a rod- shaped form, that is sized to be inserted into a keyhole at a discrete location of the shaft door. Once inserted, the technician manipulates the key to unlock a locking mechanism of the shaft door.

As the unlocking key may unlock a shaft door and allow the shaft door to be opened even if no elevator car is present on that floor, the safety of the person opening the shaft door, whether authorized or un-authorized, is of utmost concern. Various approaches for providing such safety are known: WO 2016/207683 Al, for example, discloses an unlocking key having an authorization device, and a detection device detecting the presence of the authorization device. If the detection device detects a key without an authorization device, the shaft door's lock cannot be unlocked. This is intended to allow only authorized access. Another approach is disclosed in JP2000072361 ; it uses a receiver on a sill of a landing to detect a beam emitted from a projector on a sill of an elevator car. When the beam is detected, the elevator is at the floor, and a shutter in a key hole is opened allowing insertion of an unlocking key. This is intended to ensure that the shaft door can only be opened when the car is behind the shaft door. JP2000072361A discloses a door device for an elevator. The device provides that, when an elevator car is at a landing on a floor, light emitted from a sensor light projecting section installed in the elevator car is transmitted to the landing sill and received by a sensor light receiving unit. This indicates that the car is at the landing, and a signal is output from the output device so as to open a shutter in a keyhole installed in the landing door. The signal opens the shutter in the keyhole allowing the unlocking key to be inserted to open the landing door. Even though these approaches generally improve the safety by allowing shaft access only with an authorized key or when a car is present behind the shaft door to be opened, these approaches may not be suitable for the various situations a technician may encounter when performing maintenance. For example, a technician's safety must also be provided once shaft access is obtained by means of an authorized key. Further, a technician may be required to open a shaft door even if no car is present at that floor. There is, therefore, a need for an alternative technology that further improves upon the safety of a technician while being more suitable for the various work situations. Accordingly, one aspect of such an improved technology involves a method of operating a service tool for an elevator installation subject to maintenance by a technician. The technician is required to open a shaft door at a first floor to access an elevator shaft from the first floor. Using a transducer of the service tool, it is detected if an elevator car movable within the elevator shaft is present at a level of the first floor, wherein the detecting takes place while the service tool in inserted into a receptacle of the shaft door at the first floor while the shaft door is closed. Using indication equipment of the service tool, a first indication signal is generated if the elevator car is not present, the first indication signal indicating a first warning level to the technician. Using a strain gauge of the service tool, it is detected if the technician applies force to the service tool when intending to unlock the shaft door using the service tool. Using the indication equipment, a second indication signal is generated if applied force is detected and the elevator car is not present at the first floor, wherein the second indication signal indicates a second warning level to the technician. Using the indication equipment, a third indication signal is generated if applied force is detected and the elevator car is present at the first floor, the third indication signal indicating a safe state to the technician. Another aspect involves an elevator service tool having a housing with an elongated part and a grip part. Within the housing, a processor unit, a battery, and an indicator equipment are arranged. A transducer is arranged at a distal end of the elongated part, and a strain gauge is arranged at one of the elongated part and the grip part. The transducer is configured to detect if an elevator car movable within an elevator shaft is present at a level of a first floor, wherein the detecting takes place while the service tool in inserted into a receptacle of a shaft door at the first floor while the shaft door is closed. The strain gauge is configured to detect if the technician applies force to the service tool when intending to unlock the shaft door using the service tool. The indication equipment is configured to generate a first indication signal indicating a first warning level to the technician if the elevator car is not present, a second indication signal indicating a second warning level to the technician if applied force is detected and the elevator car is not present at the first floor, and a third indication signal indicating a safe state to the technician if applied force is detected and the elevator car is present at the first floor.

A further aspect involves an elevator installation having such a service tool.

The technology described herein assists a technician when being required to access an elevator shaft. Using the service tool, the technology notifies the technician about a potentially hazardous situation existing when the elevator car is not at the floor where the technician intends to open a shaft door. This improves the overall safety at an elevator installation when being subject to maintenance.

The notification of the technician can occur using different warning levels. Depending on a set maintenance protocol, an additional notification can be implemented. For example, a fourth indication signal can indicate the elevator car's presence to the technician. In one embodiment, generation of at least one of the indication signals can be recorded in a storage device. This may allow the technician or the technician's supervisor to review events and when they took place at a later time, e.g., when evaluating whether the technician followed the set maintenance protocol. The recording may take place locally (e.g., within the service tool) or remotely (e.g., by means of the technician's mobile phone, or at a remote service center). For that purpose, a transceiver of the service tool transmits a notification signal to a remote receiver in response to generation of at least one of the indication signals.

The technology described herein can be used in connection with an existing elevator installation at relative low cost and requiring only minimal modifications, if any. The technician brings the service tool to the elevator installation to be serviced, and inserts it according to one embodiment into the receptacle that is used to unlock the shaft door. As such, the service tool serves to unlock the shaft door and to notify the technician about the elevator car's presence. In one embodiment, the service tool has a proximity detection system and performs the detection function on its own without requiring modifications of the elevator installation. The same applies if a radar detection system is used. In case detection of the elevator car's presence is based on interruption of a light path, a reflector or light source may be installed at an opposite shaft wall, or at the elevator car. In one embodiment, a modification of the shaft door is not necessary, in particular in elevator installations where the receptacle is arranged on a door panel of the shaft door. The novel features and characteristics of the technology are set out in the claims below. The various embodiments of the technology, however, as well as other features and advantages thereof, are best understood by reference to the detailed description, which follows, when read in conjunction with the accompanying drawings, wherein:

Fig. 1 shows a schematic illustration of an exemplary elevator installation subject to maintenance by a technician having a service tool, wherein the elevator installation is in a first state;

Fig. 2 shows a schematic illustration of the elevator installation of Fig. 1 being in a

second state;

Fig. 3 is a schematic illustration of one embodiment of a service tool;

Fig. 4 is a is a flow diagram of one embodiment of a method of operating the elevator installation during maintenance; and

Fig. 5 is a flow diagram of a further embodiment of a method of operating the elevator installation during maintenance. Fig. 1 is a schematic illustration of an exemplary elevator installation 1 subject to maintenance by a mechanic or technician 22, wherein the elevator installation 1 is in a first state. The elevator installation 1 is installed in a building which may be an apartment building, an office building, a commercial/shopping center, a hotel, a sports arena, an airport terminal, a ship, or any other structure suitable for a person to reside or stay for a longer period of time. The exemplary building shown in Fig. 1 is used herein to describe various embodiments of the technology; it has several floors L0, LI, L2, each one providing access to an elevator car 4 that is movable within an elevator shaft 2. The floor L0 may be a lobby or a basement of the building. Although the building shown in Fig. 1 has three floors L0, LI, L2, it is contemplated that the building may generally have a plurality of floors. It is further contemplated that the elevator installation 1 includes several elevator cars 4, which may be organized in one or more elevator groups.

On floor LI, the technician 22 is illustrated as being located next to a locked and closed shaft door 8, and equipped with a service tool 34. As described below in more detail, the service tool 34 has several functions: according to one function, it allows the technician 22 to unlock the shaft door 8 so that the technician 22 can manually open the shaft door 8, and, according to another function, it enables stopping the elevator car 4 responding to a call by the technician 22 so that the technician 22 can safely and conveniently step on top of a roof 4b of the elevator car 4 to perform maintenance from within the elevator shaft 2. In view of the first function, i.e., the unlocking function, the service tool 34 may be referred to as a key, e.g., an unlocking key. The receptacle 10 is located at a discrete or inconspicuous area of the shaft door 8, and shaped to receive a part of the service tool 34. The shaft door 8 includes at least one door panel and a door frame. In one embodiment, the receptacle 10 is a circular hole sized to receive an elongated part 38 of the service tool 25. In Fig. 1, the receptacle 10 is provided near an upper edge of the door panel. It is contemplated that in another embodiment the receptacle 10 may be provided at other locations of the shaft door 8. Within the shaft door 8 and actuatable via the receptacle 10, a locking mechanism is provided to lock the shaft door 8 when no elevator car 4 is present. Various locking mechanism are known to the skilled person, see, e.g., EP1845053B1 or WO200380495A1. To unlock the shaft door 8, the technician 22 inserts the service tool 34 and, for example, rotates it to act upon (unlock) the locking mechanism. In one embodiment, when the service tool 34 is inserted into the receptacle 10, a distal part 58 of the tool's elongated part 38 faces either an opposite shaft wall, or, when the elevator car 4 is at the floor LI, the elevator car 4. This allows a transducer 56 of the service tool 34 to interact with a detector 28 mounted on the elevator car 4.

In the first state of the elevator installation 1 illustrated in Fig. 1 the elevator car 4 is at about a level of the floor L2 moving downward towards the floor LI, as illustrated by an arrow 26. The car's downward movement may be in response to a floor call entered by the technician 22. A position indicator 24 above the shaft doors 8 on the floor LI may indicate the position and/or direction of travel of the elevator car 4. While car doors 4a are illustrated in Fig. 1, shaft doors on floor L2 are, for illustrative purposes, not shown. In the illustrated embodiment, the detector 28 is mounted on the roof 4b. It is contemplated that in another embodiment a detector may be mounted at another location of the elevator car 4, e.g., on a side wall (e.g., in proximity of the roof 4b or a bottom of the car 4). It is further contemplated that more than one detector 28 may be mounted to the elevator car 4, e.g., one on or in proximity of the roof 4b, and another one on or in proximity of the bottom. For illustrative purposes, Fig. 1 shows the detector 28 mounted on the roof 4b, and a further detector 30 at the bottom of the elevator car 4. The detector 30 may be optional and is, therefore, shown with dashed lines. Hereinafter, the technology is described with reference to the detector 28. In the illustration of Fig. 1, the elevator installation 1 is equipped to operate according to a conventional up/down control system employing floor terminals 6 having up/down buttons to call the elevator car 4 and to enter a passenger's desired direction of travel. Such floor terminals 6 may be installed, for example, in connection with low and mid-rise buildings and/or older elevator installations. Alternatively, the elevator installation 1 may be equipped to operate according to a destination call control system. A destination call control system may be installed, for example, in connection with high-rise buildings. Referring to additional elevator components shown in Fig. 1, an elevator controller (EC) 14 is coupled to a drive system 12, which is configured to move the elevator car 4 by means of one or more suspension members 18 up and down the shaft 2. The elevator controller 14 includes or is coupled to a call processing unit which processes calls received from the floor terminals 6, a car terminal (not shown), or both. The call processing depends on the kind of control system (up/down control or destination call control) used, and includes, for example, determining the floor LI, L2 where the elevator car 4 is currently positioned and where it is needed next (i.e., the floor LI, L2 a call is entered), determining the destination floor (LI, L2), allocating the call to the elevator car 4, and acknowledging the call. Based on that call processing, the elevator controller 14 controls the drive system 12 to move the elevator car 4 to a boarding floor (LI, L2) and subsequently to the destination floor (LI, L2). Although Fig. 1 shows a traction elevator system, wherein the drive system 12 moves the elevator car 4 by means of one or more suspension members 18, it is contemplated that the technology described herein is equally applicable to other elevator systems, such as hydraulic elevators, and not limit to traction elevator systems.

A communications line 16 couples the elevator controller 14 to the floor terminals 6. The

communications line 16 allows the elevator controller 14 to communicate with each one of the floor terminals 6. A communications line 20 couples the elevator controller 14 to the elevator car 4, wherein the communications line 20 allows the elevator controller 14 to communicate with components of the elevator car 4. The communications line 20 allows, e.g., communications between the elevator controller 14 and a car call terminal. The communications line 20 may be integrated into a so-called hanging or travelling cable that connects the elevator car 4 with the elevator controller 14. The communications line 20 is further coupled to a safety circuit 32 which is in Fig. 1 represented by a switch. As is known in the art, the safety circuit 32 must be closed to allow regular operation of the elevator installation 1, accordingly, interrupting/opening the safety circuit 32 disables regular operation. The communications lines 16, 20 may be embodiment as a wired communications bus. Communications over such a communications bus may follow a LON, BACnet or another serial bus protocol. Any other known technology for communications over a wired network may be used.

Briefly, in the exemplary situation illustrated in Fig. 1, the elevator installation 1 is subject to maintenance by the technician 22. In that situation, the technician 22 is required to get on top of the car's roof 4b to perform the maintenance while standing on the roof 4b. For safety reasons, the technician 22 is required to follow a defined maintenance protocol or procedure. According to one example of such a maintenance protocol, standing on the floor LI, the technician 22 enters a call at the floor terminal 6 to call the elevator car 4 to the floor LI . In response to that call, the elevator car 4 is moved to the floor LI , as indicated by the arrow 26 in Fig. 1. In case the elevator car 4 is already parked (e.g., in a stand-by mode) at the floor LI , no such movement takes place. Once the elevator doors 8 are open, the technician 22 steps into the elevator car 4, enters via a car terminal a car call to a (destination) floor LO below the floor LI , and exits the elevator car 4 before the elevator doors 8 close. Standing again on the floor LI , and while the elevator controller 14 initiates the trip to the

(destination) floor LO, the technician 22 inserts the service tool 34 into the receptacle 10. While the elevator car 4 moves from the floor LI downwards towards to floor LO, the tool's transducer 56 and the detector 28 interact, as described below. If that interaction indicates that a distance between the detector 28 and the transducer 56 is equal to a predetermined threshold distance, the drive system 12 is deactivated so that the elevator car 4 comes to a halt within a braking distance. The elevator installation 1 is then in a second state, as illustrated in Fig. 2. The timing of the deactivation is set so that the roof 4b of the stopped elevator car 4 is at a level that allows the technician 22 to step on top of the roof 4b from the floor LI . From there, the technician 22 may service components mounted on the roof 4b, or control the elevator car 4 to move up or down to service components located somewhere else from within the elevator shaft 2.

Fig. 3 is a schematic illustration of one embodiment of the service tool 34, wherein the illustration depicts a side view of the service tool 34. The service tool 34 has a housing 36 formed by the elongated part 38, and a part 40 the technician 22 can hold or grab when handling the service tool 34. The part 40 is herein referred to as grip part 40. It is contemplated that the shape of the service tool 34 is not limited to the shape shown in in Fig. 3, rather, the service tool 34 may have a different shape as long as the technician 22 can handle and insert a part of it into the receptacle 10. In particular the grip part 40 may be shaped depending on size and/or ergonomic requirements. For example, the size is selected to house electronic components, and the ergonomic form is selected to facilitate its handling by the technician 22, e.g., when wearing gloves.

In the embodiment of Fig. 3, the service tool 34 includes various electronic components, such as a processor unit (μΡ) 50, a battery 48, a transceiver (TX/RX) 44, an on/off switch (I/O) 64, and an indication equipment, such as a sound generator 42 (e.g., including a buzzer or loudspeaker) and/or an optical indicator 46 (e.g., including one or more LEDs). In one embodiment, the processor unit 50 is configured to perform processing tasks, as described herein, to store set operational values, and/or to record events, such as time and duration of tool activation, generation of warning signals, and/or processing results. For these functions, the processing unit 50 may include a storage device. The components may be arranged on a common carrier plate, e.g., a printed circuit board (PCB) 52 positioned within the grip part 40. The transducer 56 and a strain gauge 54 are arranged on or within the elongated part 38, whereas the transducer 56 is arranged at the distal end 58 of the elongated part 38. Conductors 60, 62 connect the strain gauge 54 and the transducer 56, respectively, to the PCB 52. As can be seen from the side view of the exemplary service tool 34 shown in Fig. 3, the distal end 58 has a crescent shape, whereas the elongated part 38 has a circular cross-section. It is contemplated that the service tool 34 may include less than these components, e.g., certain embodiments may not include the transceiver 44, a separate on/off switch 64, and/or the strain gauge 54.

The service tool 34 may be configured for different applications. For example, it may be used to facilitate access to the roof 4b of the elevator car, as described herein, e.g., with reference to Fig. 4. It may also be used to allow safe access to the shaft 2, as described herein, e.g., with reference to Fig. 5. In one embodiment, the service tool 34 may, therefore, have additional components, e.g., a selector switch that allows the technician 22 to set the service tool 34 for one of the applications, and/or an additional transducer optimized for one of the applications. For example, the additional transducer may include a proximity detector, a radar detection system, or an optical detection system. The additional transducer may be used for the safe shaft-access application of Fig. 5.

The transducer 56 converts an electrical signal into another physical signal. The transducer 56 may include an infrared (IR) light signal transmitter, a laser signal transmitter, an ultrasonic signal transmitter, or an RF signal transmitter. Depending on its configuration, the transducer 56 may in one embodiment include a proximity detection system, a radar detection system, or an optical detection system. The transducer 56 may be used for the roof-access application of Fig. 4. When activated by the technician 22 via the on/off switch 64, the transducer 56 transmits an IR signal, a laser signal, an ultrasonic signal or an RF signal. The intensity or power of such a transmitted signal is selected for communications over a short distance, e.g., a few meters, e.g., less than about 2 m. The transducer 56 may be arranged within the distal end 58 so that it transmits its signal in a defined direction. For example, the direction may be defined by an angle with respect to the longitudinal axis of the elongated part 38; the angle may be about 0° or between about 0° and about 90°. The angle may be set to transmit the signal "downwards" so that the detector 28, when positioned to detect in "upward" direction, detects the signal when passing by the detector 28 moving downwards. Depending on the technology selected for the transducer 56, the detector 28 on the elevator car 4 is compatible with the selected technology. That is, for example, the detector 28 is configured to detect IR light if the transducer 56 transmits IR light. Further, the detector 28 includes an electronic circuit that compares the detected signal (e.g., intensity of the IR light) with a stored threshold value. That functionality may be implemented by a processor and a storage device of the detector 28, wherein the processor generates an output signal depending on the result of the comparison; in one embodiment, the output signal is a YES (1) or NO (0) signal indicating that the threshold value is reached or not reached, respectively. The detector 28 is powered, for example, via the elevator installation's travelling cable.

The transducer 56 and the detector 28 may be viewed as a detection system. The detector 28 detects the transmitted signal when - and as long as - the detector 28 is sufficiently close to the transducer 56. For example, when the elevator car 4 moves from the floor LI to the lower floor L0, the detector 28 passes by the transducer 56 of the service tool 34 inserted into the receptacle 10. At that time, the detector 28 detects maximal signal intensity, which subsequently decreases with increasing distance between the transducer 56 and the detector 28. At a certain (threshold) distance, however, the detected signal intensity falls below a set threshold value. When that happens, the drive system 12 is deactivated so that the elevator car 4 comes to a halt within a braking distance.

The strain gauge 54 senses pressure or torque applied to the service tool 34, and generates a strain signal indicative of that pressure or torque. The strain signal is fed to the processor unit 50 for further processing. In one embodiment, pressure or torque is applied to the service tool 34 when the technician 22 applies force or pressure to the grip part 40 to rotate the inserted service tool 34 against the resistance of the shaft door's locking mechanism. The strain signal indicates the technician's intent to unlock the shaft door 8. The transceiver 44 is configured to operate in accordance with one of known technologies for radio communications. These technologies include the Bluetooth, RFID, WLAN/Wi-Fi or cellular mobile communications (e.g., GSM, UMTS, LTE) technologies. The transceiver 44, therefore, may be encompassed by a radio modem configured for one of these technologies. Depending on the implemented technology, the transceiver 44 communicates with a remote receiver that is in the vicinity of the service tool 34 (e.g., a Bluetooth and/or Wi-Fi enabled smartphone carried by the technician 22), or at a remote location (e.g., at an elevator service center). The service tool 34 may transmit one or more messages for various purposes, for example, to allow logging its device identifier and use, or - in case of a hazardous entry into the elevator shaft 2 - notifying a supervisor about such entry.

The indication equipment including the sound generator 42 and the indicator 46 provides for acoustic and/or visual notifications of the technician 22. These notifications may indicate various safe and critical situations to the technician 22, e.g., by means of warning signals, as described below with reference to Fig. 4 and Fig. 5. With the understanding of the general structure and function of the elevator installation 1 and certain features of the service tool 34 described with reference to Figs. 1-3, a description of how some embodiments of the service tool 34 are used by the technician 22 in conjunction with the elevator installation 1 , and how the elevator installation 1 operates during maintenance, follows with reference to Fig. 4 and Fig. 5. One object of the embodiment shown in Fig. 4 is to control the elevator installation 1 so that the car's roof 4b comes to a halt at about the level of the floor LI where the technician 22 is waiting. One object of the embodiment shown in Fig. 5 is to control the elevator installation 1 so that the technician 22 is warned when attempting a hazardous entry into the elevator shaft 2.

Fig. 4 shows a flow diagram of one embodiment of a method of operating the elevator installation 1 during maintenance by the technician 22 to allow the technician 22 to step on top of the roof 4b. It is contemplated that in another illustration of the flow diagram some of the shown steps may be merged into a single step, or split into several separate steps. Further, it is contemplated that the technician 22 on floor LI already initiated the maintenance procedure mentioned above, i.e., the elevator car 4 called by the technician 22 is at the floor LI , and the technician 22 stepped into the elevator car 4 to enter a car call and exited the elevator car 4 before the elevator doors 8 closed. To provide context, some of the illustrated steps are described as performed by the technician 22. It is contemplated, however, that the elevator installation 1 reacts to the technician's acts and executes corresponding tasks. The operational method is, therefore, performed by the elevator installation 1. The exemplary flow diagram starts at a step SI and ends at a step S7.

Proceeding to a step S2, the technician 22 inserts the service tool 34 into the receptacle 10 of the (closed) shaft door 8 while standing on the floor LI . The technician 22 may activate the service tool 34 prior to or after inserting it. Once activated, the tool's battery 48 provides electrical energy to the various components of the service tool 34. For example, the processor unit 50 may activate the transducer 56, determine if the strain gauge 54 senses pressure or torque, control the sound generator 42 and/or the indicator 46 to indicate activation, and cause the transceiver 44 to transmit a message indication the service tool's use.

Proceeding to a step S3, a transducer signal is detected. That is, the detector 28 detects the signal transmitted by the transducer 56 when - and as long as - the detector 28 is sufficiently close to the transducer 56 while the elevator car 4 moves downwards. Proceeding to a step S4, the detected signal (i.e., its value of intensity) is compared to a threshold value stored in the detector 28. As long as the threshold value is not reached, e.g., the detected signal's intensity value is higher than the threshold value, the comparing continues, as indicated by the NO branch of step S4. However, when the elevator car 4 is at a certain (threshold) distance from the service tool 34, the detected signal intensity reaches the threshold value and continues to fall below the threshold value. When that happens, the method proceeds along the YES branch to a step S5.

In step S5, the safety circuit 32 is interrupted. In response, the drive system 12 is deactivated and the elevator car 4 comes to a halt within a braking distance. The elevator car 4 may then be positioned as shown in Fig. 2. The braking distance can be determined, for example, for each elevator installation 1 individually. Depending on the braking distance, the timing of the deactivation of the drive system 12 can be determined keeping in mind that the roof 4b of the stopped elevator car 4 should be at a level that allows the technician 22 on the floor LI to step onto the roof 4b. The timing may be such that the interruption of the safety circuit 32 occurs at about the time the threshold value is reached.

Alternatively, the timing may be such that the interruption of the safety circuit 32 occurs with a delay after the time the threshold value is reached. Other parameters that may be considered when determining the timing include the locations of the detector 28 and the receptacle 10, the kind of transducer 56 used, and the intensity or range of the signal transmitted by the transducer 56.

Proceeding to a step S6, the shaft door 8 is open and the technician 22 can access to the shaft 2 and step onto the roof 4b. To open the shaft door 8, the technician 22 turns the service tool 34 to unlock the door's locking mechanism. According to the defined maintenance protocol, the technician 22 may initially open the shaft door 8 only a few centimeters (e.g., 15 cm) to verify and confirm the correct location of the roof 4b. Only after that, the technician 22 opens the shaft door 8, steps onto the roof 4b, and starts performing any intended maintenance. The flow diagram ends at step S7. Depending on the configuration of the service tool 34, one or more of the events, such as activation of the service tool 34, may be recorded either within the service tool 34 and/or transmitted to a remote receiver (e.g., carried by the technician 22 or located at a service center).

Fig. 5 shows a flow diagram of one embodiment of a method of operating the elevator installation 1 during maintenance by the technician 22 to provide for safe shaft access. It is contemplated that in another illustration of the flow diagram some of the shown steps may be merged into a single step, or split into several separate steps. To provide context, some of the illustrated steps are described as performed by the technician 22. It is contemplated, however, that the elevator installation 1 reacts to the technician's acts and executes corresponding tasks. The operational method is, therefore, performed by the elevator installation 1. The exemplary flow diagram starts at a step Al and ends at a step A13. Proceeding to a step A2, the technician 22 inserts the service tool 34 into the receptacle 10 of the shaft door 8 while standing at the floor LI . The technician 22 may activate the service tool 34 prior to or after inserting it. Once activated, the tool's battery 48 provides electrical energy to the various components of the service tool 34, as described with respect to step S2 of Fig. 4.

Proceeding to a step A3, detection of the elevator car 4 is activated. That is, the processor unit 50 activates the transducer 56 to determine if the elevator car 4 is at the floor LI (i.e., "behind" the closed shaft door 8). The transducer 56 may include a proximity detection system, a radar detection system, or an optical detection system. These kinds of detectors detect whether an object (i.e., the elevator car 4) is present, for example, by generating a signal when an object is close (e.g., when using a proximity or radar detector) or when an object interrupts a light path (e.g., when using an optical detector in combination with a light source). As used herein, the term "present" is to be understood that at least some part of the elevator car 4 is at a certain floor L0, LI, L2, for example, behind a closed shaft door 8. For example, the roof 4b may be somewhat level with the floor L0, LI, L2.

Proceeding to a step A4, it is determined if the elevator car 4 is positioned at the floor LI . If it is, the transducer 56 generates a signal that is fed to the processor unit 50. The processor unit 50 determines if the generated signal is indicative of the elevator car's presence. The method proceeds along the YES branch to a step A9. If it is determined that the elevator car 4 is not present, the method proceeds along the NO branch to a step A5. In step A5, a warning indication is activated. The warning indication is a first indication signal that indicates a first warning level to the technician 22. For example, the processor unit 50 activates the sound generator 42 and/or the indicator 46 to indicate to the technician 22 that the elevator car 4 is not present at the floor LI and that the technician 22 must, for example, wait. Proceeding to a step A6, it is determined if a lock operation is detected. A lock operation occurs when the technician 22, for example, rotates the service tool 34 to unlock the shaft door 8. In that case, the strain detector 54 is subject to strain (pressure or torque) that results in a change of an electrical characteristic (e.g., resistance) which the processor unit 50 detects. If no lock operation is detected, the method loops back along the NO branch to step A4. If, however, a changing electrical characteristic indicates a lock operation, the method proceeds along the YES branch to a step A7. In step A7, an alarm is activated. The alarm is a second indication signal indicating a second warning level to the technician 22. The processor unit 50 activates the sound generator42 and/or the indicator 46 to warn the technician 22 about a dangerous situation, i.e., the elevator car 4 is not present at the floor LI while the technician 22 attempts to access the shaft 2. To distinguish between the warning indication of step A5 and the alarm of step A7, the alarm may sound louder and/or have a different sound pattern, and/or the indicator 46 may emit light having a different color and/or pattern. As indicated in step A8, the technician 22 may be instructed to stop access to the shaft 2 when the alarm is activated. In one embodiment, the transceiver 44 may transmit a message for recording the attempted dangerous shaft access. The method proceeds to step A13 and ends.

Referring again to step A4, the method proceeds along the YES branch to step A9 if the elevator car 4 is positioned at the floor LI . In step A9, an OK indication is activated corresponding to a fourth indication signal. For that purpose, the processor unit 50 activates the indicator 46, for example, to emit a constant green light (or any other color that is usually not perceived as indicating danger or a warning (e.g., red)). Depending on the warning scheme defined for the maintenance procedure (e.g., warn only of critical or dangerous situations), step A9 may be optional.

Proceeding to a step A10, it is determined if a lock operation is detected. This determination is as described with respect to step A6. As long as there is no lock operation detected, the method loops back along the NO branch to step A10. If, however, a lock operation is detected, the method proceeds along the YES branch to a step All.

In step All, an OK indication is activated. As a third indication signal it indicates a safe state to the technician if applied force is detected and the elevator car 4 is present at the first floor LI. For that purpose, the processor unit 50 activates the indicator 46, as described with respect to step A9.

Proceeding to a step A12, the technician 22 may initially open the shaft door 8 only a few centimeters (e.g., 15 cm) to verify and confirm that the elevator car 4 is present. Only after that, the technician 22 opens the shaft door 8, and starts performing any intended maintenance. The flow diagram ends at step A13.

The generation of the indication signal may be recorded in a storage device. The storage device may be arranged within the service tool 34, or at a remote device. The remote device may be the technician's mobile phone, or provided at a service center. In case of a remote device, the transceiver 44 may send a notification signal to the remote device. The notification signal may include information about the event and the time the event occurred.