WO2020245495A1

WO2020245495A1 - Control of an elevator system

Info

Publication number: WO2020245495A1
Application number: PCT/FI2019/050444
Authority: WO
Inventors: Tero Hakala; Ari Kattainen; Pasi Raassina; Seppo Suur-Askola
Original assignee: Kone Corporation
Priority date: 2019-06-07
Filing date: 2019-06-07
Publication date: 2020-12-10

Abstract

The present invention relates to a method for generating a trigger signal indicating an allowance to an elevator car (110) to initiate a travel in an elevator system, the method comprises: monitoring a position of an elevator door (120, 130) in its path of motion during a closing of the elevator door (120, 130), in response to a detection (310) that the elevator door (120, 130) resides at a first position (P1) generating (320) a first control signal causing a preparation of a travel of the elevator car (110); in response to a detection (330) that the elevator door (120, 130) resides at a second position (P2) generating (340) a second control signal indicating an allowance to an elevator car (110) to initiate a travel. Some aspects relate to a control unit, a computer program product and an elevator system.

Description

Control of an elevator system

TECHNICAL FIELD

The invention concerns in general the technical field of elevator systems. More particularly, the invention concerns controlling of an elevator system.

BACKGROUND

Safety is one of the most important aspects to consider in elevator systems. Due to this safety issues are addressed in requirements and specifications of eleva tor systems. One area under interest is a control of movement of an elevator car which refers to defined conditions under which the elevator car is allowed to start traveling from a landing. An aim by defining the conditions is that passengers, or their body parts, do not exist in door area when the travel is initiated.

A requirement EN 81 -20:2014 defines safety aspects in a situation the elevator car moves unintentionally. Specifically saying a paragraph relating to this in the requirement defines the following:

5.6.7.1 Lifts shall be provided with a means to prevent or stop unintended car movement away from the landing with the landing door not in the locked position and the car door not in the closed position, as a result of any single failure of the lift machine or drive control system upon which the safe move ment of the car depends.

The requirement, and the elevator systems complying with the requirement, has a drawback that it may cause delays in using the elevator system in question. This is because the existing elevator systems are configured to operate so that they detect when the elevator car door is open or closed, but nothing between these two extremities. The same applies to landing doors. As a result, the ele vator system waits until a signal is received that the door, or doors, is closed and locked and further operations may be initiated. The operation as described above is not optimal because, as said, it causes delays in an operation of existing elevator systems and especially in multicar elevator systems. Hence, there is need to develop solutions which mitigate at least in part the drawbacks of existing solutions. SUMMARY

The following presents a simplified summary in order to provide basic under standing of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying em bodiments of the invention.

An object of the invention is to present a method, a control unit, a computer program product and an elevator system controlling a travel of an elevator car. The objects of the invention are reached by a method, a control unit, a computer program product and an elevator system as defined by the respective independ ent claims.

According to a first aspect, a method for generating a trigger signal indicating an allowance to an elevator car to initiate a travel in an elevator system, the method comprises: monitoring a position of an elevator door in its path of motion during a closing of the elevator door; in response to a detection that the elevator door resides at a first position in its path of motion generating a first control signal causing a preparation of a travel of the elevator car; in response to a detection that that the elevator door resides at a second position in its path of motion gen- erating a second control signal indicating an allowance to an elevator car to ini tiate a travel.

The first control signal may be arranged to, for preparing the travel of the eleva tor car, cause at least one of the following: a generation of a force by an elevator motor to hold the elevator car stationary at a landing, a release of at least one brake of the elevator system.

Further, the second control signal may be arranged to cause the elevator car to start moving from a landing. The method may further comprise: controlling, in response to a movement of the elevator car, that the elevator car does not depart a door zone if at least one criterion is not fulfilled. The controlling may comprise at least one of the following: a limitation of a speed of the elevator car; a limitation of an acceleration of the elevator car; activation of an unintended car movement protection functionality. For example, the at least one criterion is at least one of the following: the elevator door is not fully closed; the elevator door is not locked.

The position of the elevator car door in its path of motion may be detected with at least one sensor.

Still further, at least one of the following: the first position of the elevator door, the second position of the elevator door may be determined by applying a motion profile of the elevator door in the determination of the position of the elevator door.

The at least one position of the elevator door may be determined by applying the motion profile of the elevator door with respect to a known position of the elevator door at an instant of time. The known position of the elevator door may e.g. be at least one of the following: fully open position of the door; a position of the door detected with at least one sensor.

A distance between the first position of the elevator door and the second position of the elevator door may be defined in accordance with a predetermined delay in the elevator system and the motion profile of the elevator door. The predeter- mined delay may be dependent on at least one of the following: an elevator motor; the at least one brake of the elevator system.

According to a second aspect, a control unit for generating a trigger signal indi cating an allowance to an elevator car (1 10) to initiate a travel in an elevator system is provided, the control unit comprising: at least one processor; at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the control unit to perform: monitor a position of an elevator door in its path of motion during a closing of the elevator door; in response to a detection that the elevator door resides at a first position in its path of motion generate a first con trol signal causing a preparation of a travel of the elevator car; in response to a detection that that the elevator door resides at a second position in its path of motion generate a second control signal indicating an allowance to an elevator car to initiate a travel.

The control unit may be arranged to generate the first control signal to, for pre paring the travel of the elevator car, cause at least one of the following: a gen eration of a force by an elevator motor to hold the elevator car stationary at a landing, a release of at least one brake of the elevator system. The control unit may be arranged to generate the second control signal arranged to cause the elevator car to start moving from a landing. Moreover, the control unit may further be caused to perform: control, in response to a movement of the elevator car, that the elevator car does not depart a door zone if at least one criterion is not fulfilled. For example, the control unit may be arranged to perform the controlling by at least one of the following: limiting a speed of the elevator car; limiting an acceleration of the elevator car; activation of an unintended car movement protection functionality.

The control unit may be arranged to apply, as the at least one criterion, at least one of the following: the elevator door is not fully closed; the elevator door is not locked.

Still further, the control unit may be arranged to detect the position of the elevator car door in its path of motion based on data received from at least one sensor. The control unit may also be arranged to determine at least one of the following: the first position of the elevator door, the second position of the elevator door by applying a motion profile of the elevator door in the determination of the position of the elevator door. The control unit may be arranged to determine the at least one position of the elevator door by applying the motion profile of the elevator door with respect to a known position of the elevator door at an instant of time. For example, the control unit may be arranged to determine the known position of the elevator door as at least one of the following: fully open position of the door; a position of the door detected with at least one sensor. According to a third aspect, a computer program product for generating a trigger signal indicating an allowance to an elevator car to initiate a travel in an elevator system is provided which computer program product, when executed by at least one processor, cause a control unit to perform the method as described above.

According to a fourth aspect, an elevator system is provided, the elevator system comprising: an elevator door; and a control unit as described above.

The elevator door may e.g. be at least one of the following: an elevator car door, a landing door.

Moreover, the elevator system may comprise at least one sensor for detecting a position of the elevator door. The expression "a number of” refers herein to any positive integer starting from one, e.g. to one, two, or three.

The expression "a plurality of” refers herein to any positive integer starting from two, e.g. to two, three, or four.

Various exemplifying and non-limiting embodiments of the invention both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying and non-limiting embodiments when read in connection with the accompanying drawings. The verbs“to comprise” and“to include” are used in this document as open limitations that neither exclude nor require the existence of unrecited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of“a” or“an”, i.e. a singular form, throughout this document does not exclude a plural ity.

BRIEF DESCRIPTION OF FIGURES

The embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. Figure 1 illustrates schematically an elevator system as a block diagram into which the invention may be implemented to.

Figure 2 illustrates schematically aspects relating to an implementation of an embodiment according to the invention in a context of an elevator car door.

Figure 3 illustrates schematically an example of a method according to the in- vention

Figure 4 illustrates schematically aspects relating to determining a position of an elevator door.

Figure 5 illustrates schematically an example of a control unit according to an embodiment of the invention. DESCRIPTION OF THE EXEMPLIFYING EMBODIMENTS

The specific examples provided in the description given below should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description given below are not exhaustive unless otherwise explicitly stated. Figure 1 schematically illustrates an elevator system as a block diagram into which the present invention may be implemented to. The elevator system as illustrated in Figure 1 is a non-limiting example and does not limit an implemen tation of the invention only to such an elevator system. The elevator system may comprise at least one elevator car 1 10 which may be arranged to travel in a shaft between a plurality of landings L1 , L2. The elevator car 1 10 may comprise an elevator car door 120. Alternatively or in addition, the elevator system may com prise a landing door 130 at every landing L1 , L2. The elevator car door 120 and the landing door 130 may be arranged to operate synchronously at least in part e.g. by means of so-called door coupler configured to couple the elevator doors 120, 130 mechanically together. The elevator system comprises an elevator mo- tor 140 for generating a force for moving the elevator car 1 10 in the shaft. The elevator motor 140 shall be understood in a broad manner herein as it may refer to an electric motor coupled with a drive sheave connecting the elevator car 1 10 and counterweight by elevator hoisting ropes or belts. The elevator motor 140 may also refer to a linear motor comprising a rotor and a stator arranged so that the rotor, also known as a mover, is arranged to move with respect to the stator beam along the motion of the elevator car. The electric linear motor implemented in the described manner enables a generation of the magnetic field and, thus, enables a levitation of the elevator car 1 10 in its pathway in embodiments with such an electric linear motor. The elevator motors 140 mentioned here are non- limiting examples of suitable elevator motors 140 in the context of the present invention. In addition to the above-mentioned elements the elevator system may comprise an elevator brake by means of which it is possible e.g. to hold the elevator car 1 10 at a certain position, such as at landing L1 , L2, in the shaft.

Furthermore, the elevator system may comprise a control unit 150 configured to control an operation of the elevator system at least in part. The control unit 150 may be implemented as a single entity or with a plurality of control entities ar ranged to operate in a distributed manner. The control unit 150 may be commu nicatively coupled to other entities, such as to the elevator motor 140 either di rectly or indirectly (e.g. through a drive), and to the elevator car 1 10, and any doors 125, 135, for example. The communication may be arranged in a wireless or in a wired manner. Depending on the applied communication type communicating entities may be equipped with necessary hardware and soft ware, such as a communication modem, for implementing a communication technology in use. In case of the wired communication the communicating enti ties may be connected with an applicable wiring or with a data bus. The control unit 150 may reside at a building of the elevator system, in an elevator car 1 10 or remotely e.g. in a data center, for example

Still further, the invention according to the present invention comprises at least one sensor 125, 135 arranged to measure a position of at least one elevator door 120, 130. The position of the at least one elevator door 120, 130 may be measured at its full path of motion, or only a portion of the path of motion, with the at least one sensor 125, 135. In other words, the at least one sensor 125, 135 may be configured to generate data in response to a detection of the at least one elevator door 120, 130 for indicating a position of the door. The data may indicate the position of the elevator door 120, 130 in question either directly or indirectly. Moreover, according to various embodiments of the invention the data obtainable from the sensor may be used for deriving information on the position of the door at plurality instants of time. This may e.g. be arranged by applying a known motion profile of the door in question with a position information at certain instant of time, and in that manner to derive the position of the door at least in one other instant of time.

In the following some aspects of the invention is described by referring to Figure 2 in which it is schematically illustrated some aspects relating to an implemen tation of the present invention in a context of an elevator car door 120. The ele vator car 1 10 is equipped, in the non-limiting example of Figure 2, with two sen- sors 125A, 125B suitable for obtaining data from an environment from which position data of the door 120 is derivable. The sensors 125A, 125B may e.g. be mounted in the door panel and/or in the door frame e.g. in the lintel, top track and/or sill profile. Generally speaking, the mounting position of the sensors 125A, 125B may vary according to the implementation of the present invention, but possible mounting positions may at least be the door frame either in the elevator car 1 10 but also in the door frame at the landing side. Moreover, the sensor implementation may be such in which the sensor 125A, 125B itself is mounted on the elevator door whereas the respective door frame is equipped with applicable markers detectable by the sensor 125A, 125B, and through the motion of the door, and thus the sensor 125A, 125B, the sensor scans the door frame, detects the markers and it is possible to derive information on the position of the door. The marker may e.g. be a separate part, such as a magnet, or mark ers machined to the door frame, or any other structure scannable by the sensor 125A, 125B. According to the invention an operation of the elevator system is controlled, at least in part, in accordance with a position of an elevator door. The controlling of the elevator system may refer to controlling of a motion of the ele vator car 110 as is described here. Moreover, even if Figure 2 illustrates the elevator car door 120 the same implementation, and mechanism, may be ap plied with other doors in the elevator system, such as with the landing door 130. Specifically, at least some aspects of the present invention relate to a monitoring of a closing of an elevator door 120, 130, such as elevator car door 120 as schematically illustrated in Figure 2, in question. The monitoring system com prising the at least one sensor 125, 125A, 125B, 135 may be active all the time the elevator system is operating, or it may be activated in response to an initia- tion of the closing of the door. The initiation of the closing of the door may e.g. be detected by identifying a trigger signal, e.g. to power generation device, such as a door motor, causing the closing of the door. Other trigger signals for acti vating the monitoring system may also be applied to, such as signals from an elevator controller to the door operator (i.e. a control unit of the door in question). Now, the elevator door 120, 130 starts closing (of. arrow in Figure 2) and in response the elevator door 120, 130 enters a detection area of a first sensor 125A of the implementation as schematically illustrated in Figure 2 the first sen sor 125A may generate data indicating that the door resides at certain first po sition of its path of motion. In other words, the control unit 150 may determine the first position of the door 120, 130 from the data obtained from the first sensor 125A. As the elevator door 120, 130 continues closing at some instant of time the elevator door 120, 130 enters a detection area of a second sensor 125B and, again, the second sensor 125B may generate data indicating that the door 120, 130 resides at certain second position of its path of motion. Again, the con trol unit 150 may determine the second position of the door 120, 130 from the data obtained from the second sensor 125B.

The sensor 125, 125A, 125B, 135 for generating data indicating the position of the elevator door 120, 130 may be any applicable sensor being suitable for measurement task as described. Especially, a reliability of the sensor 125, 125A, 125B, 135 plays an important role in its task in the safety solutions for elevators. For example, the sensor 125, 125A, 125B, 135 may be a switch arranged to change state in response to the elevator door 120, 130 enters the operational area of the switch. Alternatively or in addition, the sensor 125, 125A, 125B, 135 may be a proximity sensor, a light sensor, an ultrasound sensor or any similar which may generate an indication, such as a change in signal, in response to a detection of the elevator door 120, 130 in the operational area of the sensor 125, 125A, 125B, 135. As mentioned, in some embodiments of the invention the ele vator system may comprise only one sensor 125, 125A, 125B, 135. In response to a detection of the door in the operational area of the sensor 125, 125A, 125B, 135 any future positions of the door may be derived. The derivation of the door position may be implemented e.g. by utilizing a motion profile of the door within its path of motion known by the elevator system, e.g. by the control unit 150 arranged to perform the determination of the position of the elevator door 120, 130. The motion profile may e.g. comprise information on a speed of the door in the path of motion and/or information on an acceleration of the elevator door 120, 130 in the path of motion. Hence, in the implementations in which the door position is derivable from a detection of the position of the door with one sensor an entering of the door to another trigger position, i.e. reference position, may be defined mathematically.

Next at least some aspects according to the present invention relating to an operation of the elevator system in accordance with a position of the elevator door 120, 130 is described by referring to Figure 3 schematically illustrating an example of a method according to the present invention. It is hereby assumed that the monitoring system is set in active state. Now, at some instant of time a control unit 150 triggers the door under monitoring to close. The triggering may e.g. refer to a generation of a control signal to a door motor for generating a force for moving the elevator door 120, 130 in its path of motion. In response to a detection 310 that the elevator door 120, 130 enters, i.e. resides at, a first position in its path of motion the elevator system may be arranged to start pre paring a travel of the elevator car 1 10. More specifically, it may be arranged to that a control unit 150 may derive information that the elevator door 120, 130 resides at a first position and in response to such a detection the control unit 150 may generate a first control signal causing the preparation of the travel of the elevator car 1 10. The derivation of the information on that the elevator door 120, 130 resides at the first position may refer to a detection based on a signal from at least one sensor 125A, 125B indicating that the elevator door 120, 130 re sides at the first position. Alternatively or in addition, it may refer to a detection derived in any other manner, such as in response to a derivation of the position of the elevator door 120, 130 by applying the motion profile of the elevator door 120, 130 in a determination of the position of the elevator door 120, 130 in its motion path.

The generation of the first control signal 320 e.g. by the control unit 150 may cause a number of predetermined entities to initiate a preparation of a travel of the elevator car 1 10. According to an embodiment of the invention the control unit 150 may be configured to generate a control signal which causes an eleva- tor motor to generate a force for holding an elevator car stationary at a landing. In other words, the elevator motor is driven to an operational state that a moment of the force holds the elevator car 1 10 still at the landing even if an elevator brake is released. In case the elevator system is operated with a linear motor the control unit 150 may be arranged to generate a trigger signal for activating the linear motor to generate a magnetic field causing a rotor of the linear motor to levitate with respect to a stator of the linear motor. Alternatively or in addition, the generated control signal may cause a release of at least one elevator brake of the elevator system. The elevator brake may refer to at least one of the fol lowing: at least one elevator car brake, at least one machinery brake.

As the elevator door 120, 130 in question continues to close the control unit 150 may be arranged to detect 330, at a second instant of time, that the door 120, 130 enters, i.e. resides at, a second position in its path of motion. Again, it may be arranged to that a control unit 150 may derive information that the elevator door 120, 130 resides at the second position and in response to such a detection the control unit 150 may generate a second control signal causing a generation of an indication 340 that a travel of the elevator car 1 10 is allowed to be initiated. This may cause a travel of the elevator car 1 10 away from the landing i.e. the elevator motor is controlled accordingly.

The second detection i.e. the detection that the elevator door 120, 130 resides at the second position may be derived from information received from at least one sensor 125A, 125B, the information indicating either directly or indirectly that the door 120, 130 resides at the second position. Alternatively or in addition, it may refer to a detection derived in any other manner, such as in response to a derivation of the position of the elevator door 120, 130 by applying the motion profile of the elevator door 120, 130 in a determination of the position of the elevator door 120, 130 in its motion path.

In the description above it is mentioned that the position of the elevator door 120, 130 may be determined at two predetermined positions. Advantageously, the predetermined positions are determined so that they do not cause risk to passengers e.g. in a manner that they get caught by the elevator door 120, 130, or so that the risk is within acceptable limits. Some aspects in this regard are schematically illustrated in Figure 4. The elevator door 120, 130 is closing from left to right in Figure 4. According to exemplary embodiment of Figure 4 it may be determined that the first detection is performed when the elevator door 120, 130 is open a distance D1 , e.g. 100 mm. In other words, the elevator door 120, 130 is determined to reside at position P1 , and the preparation for the travel may then be initiated in the elevator system. The second detection, in turn, may be performed e.g. in response to a detection that the elevator door 120, 130 is open a distance D2, e.g. 20 mm. This corresponds to a situation that the elevator door 120, 130 resides at position P2, and the travel may be initiated. The values given above are non-limiting examples and may vary in various embodiments of the invention according to need. For example, in some implementation of the inven tion the first position P1 may be defined as the fully open position of the elevator door 120, 130 and the second position P2 may be defined as the closed position of the elevator door 120, 130. In some embodiments of the invention the closed position of the elevator door 120, 130 may refer to a situation that the elevator door 120, 130 is closed, but not yet locked.

In various example embodiments definitions of the first position P1 of the eleva tor door 120, 130 and the second position P2 of the elevator door 120, 130 may be dependent on one or more characteristics of the elevator system. For exam- pie, the distance between the first position P1 of the elevator door 120, 130 and the second position P2 of the elevator door 120, 130 may be defined in accord ance with a predetermined delay in the elevator system and the motion profile of the elevator door 120, 130. The predetermined delay may e.g. be dependent on at least one of the following: an elevator motor 140, the at least one brake of the elevator system. In other words, in the determination of the first position P1 and the second position P2 it may be advantageous to take into account any delay for taking the elevator system from one state to another. For example, the elevator motor 140 needs a predetermined time to generate a force for holding the elevator car still in its position. Additionally, it may be needed to use safety margin defined in time before the brakes are released. Moreover, the release of brakes takes also some time due e.g. sizes of the coils and mass of the brake parts, and so on. Flence, by taking these kinds of characteristics in the account by selecting the positions P1 and P2 optimally, the overall operation of the pre sent invention may be improved. In various embodiments of the invention the control unit 150 may be arranged to perform further safety related control operations. The further safety operations may at least refer to one or more rules set for departing from a door zone. For example, the door zone may be defined to extend a predetermined distance to at least one direction from the landing. For example, it may be defined that the door zone is ± 300 mm from the landing. Now, the control unit 150 may be ar ranged to monitor that the elevator car 1 10 is within the door zone. The control unit 150 may be arranged to operate so that in response to a detection that the door resides at the second position P2 and that the elevator car 1 10 is in motion the control unit 150 may be set to monitor that the elevator car 110 does not depart from the door zone before the elevator system is set to a mode complying at least one predetermined criterion, such as defining that the elevator car is not allowed to depart the door zone if the at least one door 120, 130 is open more than distance D2 of Figure 4. The predetermined criterion may e.g. be that at least one elevator door 120, 130, or a plurality of elevator doors 120, 130, such as an elevator car door 120 and/or a landing door 130 are fully closed. In some embodiment it may also be required that at least one of the elevator doors 120, 130, preferably the elevator car door 120 is locked prior to departing from the door zone. For example, the control unit 150 may be arranged to limit a speed and/or an acceleration of the elevator car 1 10 within the door zone so that the at least one predetermined criterion is met before departing from the door zone. According to various embodiments of the invention it may be arranged that the control unit 150 is configured to activate a functionality of an unintended car movement protection in response to a detection that the at least one criterion is not met and the elevator car 1 10 is departing from the door zone in which case the elevator car is stopped immediately. An accurate position of the elevator car 110 in the shaft, and thus in the door zone, may be determined with known mechanisms, such as with information derivable from reed switches mounted along the elevator shaft. As already mentioned, the position of the elevator door 120, 130 in its path of motion may be determined with sensor based solutions or by applying a known motion profile of the elevator door 120, 130. The sensor based solution may comprise one or more sensors 125A, 125B. On a basis of information, i.e. meas urement data, obtainable from the at least one sensor 125A, 125B at least one position of the elevator door 120, 130 may be determined in order to perform method as described. The motion profile based solution may be implemented without sensors 125A, 125B. For example, in response to a detection of a trigger signal instructing the elevator door 120, 130 to close it may be determined in stants of time, on the basis of the motion profile, when the elevator door 120, 130 resides at the first and at the second positions and based on the information the method may again be performed as described. The motion profile is appli cable with any known position of the elevator door 120, 130, such as a fully open position of the elevator door 120, 130 or a position of the elevator door 120, 130 detected with at least one sensor 125A, 125B. For sake of clarity the application of the motion profile may be performed so that the known position is determined from the motion profile and based on the motion profile it may be determined e.g. mathematically an instant of time when the door in question resides in an other position in the path of motion.

Figure 5 schematically illustrates a control unit 150 according to an embodiment of the invention. The control unit 150 may comprise a processing unit 510, a memory 520 and a communication interface 530 among other entities. The pro cessing unit 510, in turn, may comprise one or more processors arranged to implement one or more tasks for implementing at least part of the method steps as described. For example, the processing unit 510 may be arranged to perform the monitoring task with respect to the position of the elevator door 120, 130 as well as performing the detection according the one or more rules as well as gen erating control signal accordingly. The memory 520 may be arranged to store computer program code which, when executed by the processing unit 510, cause the control unit 150 to operate as described. Moreover, the memory 520 may be arranged to store, as described, the reference value, such as position information, and any other data. The communication interface 530 may be ar ranged to implement, e.g. under control of the processing unit 510, one or more communication protocols enabling the communication with external entities as described. The communication interface may comprise necessary hardware and software components for enabling e.g. wireless communication and/or commu nication in a wired manner. For sake of clarity it is hereby mentioned that the invention may be implemented in any elevator door 120, 130. As mentioned, the elevator door 120, 130 may e.g. be an elevator car door 120 or a landing door 130, for example.

The described solution according to the present invention enhances an effi ciency of an elevator system because a departure of the elevator car 1 10 from landing may accelerated, and, hence, passengers may be served in better way.

The specific examples provided in the description given above should not be construed as limiting the applicability and/or the interpretation of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.

Claims

WHAT IS CLAIMED IS:

1 . A method for generating a trigger signal indicating an allowance to an ele vator car (1 10) to initiate a travel in an elevator system, the method comprises: monitoring a position of an elevator door (120, 130) in its path of motion during a closing of the elevator door (120, 130), in response to a detection (310) that the elevator door (120, 130) resides at a first position (P1 ) in its path of motion generating (320) a first control signal caus ing a preparation of a travel of the elevator car (1 10), in response to a detection (330) that that the elevator door (120, 130) resides at a second position (P2) in its path of motion generating (340) a second control signal indicating an allowance to an elevator car (1 10) to initiate a travel.

2. The method of claim 1 , wherein the first control signal is arranged to, for preparing the travel of the elevator car (1 10), cause at least one of the following: a generation of a force by an elevator motor (140) to hold the elevator car (1 10) stationary at a landing, a release of at least one brake of the elevator system.

3. The method of any of claims 1 or 2, wherein the second control signal is arranged to cause the elevator car (1 10) to start moving from a landing (L1 , L2).

4. The method of claim 3, the method further comprising: controlling, in response to a movement of the elevator car (1 10), that the elevator car (1 10) does not depart a door zone if at least one criterion is not fulfilled.

5. The method of claim 4, wherein the controlling comprises at least one of the following: a limitation of a speed of the elevator car (1 10); a limitation of an acceleration of the elevator car (1 10); activation of an unintended car movement protection functionality.

6. The method of claim 4 or claim 5, wherein the at least one criterion is at least one of the following: the elevator door (120, 130) is not fully closed; the elevator door (120, 130) is not locked.

7. The method of any of preceding claims, wherein the position (P 1 , P2) of the elevator car door (120, 130) in its path of motion is detected with at least one sensor (125A, 125B).

8. The method of any of preceding claims, wherein at least one of the follow ing: the first position (P1 ) of the elevator door (120, 130), the second position (P2) of the elevator door (120, 130) is determined by applying a motion profile of the elevator door (120, 130) in the determination of the position (P1 , P2) of the elevator door (120, 130).

9. The method of claim 8, wherein the at least one position (P1 , P2) of the elevator door (120, 130) is determined by applying the motion profile of the ele vator door (120, 130) with respect to a known position of the elevator door (120, 130) at an instant of time.

10. The method of claim 9, wherein the known position of the elevator door (120, 130) is at least one of the following: fully open position of the door (120, 130), a position of the door (120, 130) detected with at least one sensor (125A, 125B).

1 1. The method of any of the preceding claims, wherein a distance between the first position (P1 ) of the elevator door (120, 130) and the second position (P2) of the elevator door (120, 130) is defined in accordance with a predeter mined delay in the elevator system and the motion profile of the elevator door (120, 130).

12. The method of claim 11 , wherein the predetermined delay is dependent on at least one of the following: an elevator motor (140), the at least one brake of the elevator system.

13. A control unit (150) for generating a trigger signal indicating an allowance to an elevator car (1 10) to initiate a travel in an elevator system, the control unit (150) comprising: at least one processor (510); at least one memory (520) including computer program code (525); the at least one memory (520) and the computer program code configured to, with the at least one processor (510), cause the control unit (150) to perform: monitor a position of an elevator door (120, 130) in its path of motion during a closing of the elevator door (120, 130), in response to a detection (310) that the elevator door (120, 130) resides at a first position (P1 ) in its path of motion generate (320) a first control signal causing a preparation of a travel of the elevator car (1 10), in response to a detection (330) that that the elevator door (120, 130) resides at a second position (P2) in its path of motion generate (340) a second control signal indicating an allowance to an elevator car (1 10) to initiate a travel.

14. The control unit (150) of claim 13, wherein the control unit (150) is arranged to generate the first control signal to, for preparing the travel of the elevator car (1 10), cause at least one of the following: a generation of a force by an elevator motor (140) to hold the elevator car (1 10) stationary at a landing, a release of at least one brake of the elevator system.

15. The control unit (150) of any of claims 13 or 14, wherein the control unit (150) is arranged to generate the second control signal arranged to cause the elevator car (1 10) to start moving from a landing (L1 , L2).

16. The control unit (150) of claim 15, the control unit (150) further caused to perform: control, in response to a movement of the elevator car (1 10), that the elevator car (1 10) does not depart a door zone if at least one criterion is not fulfilled.

17. The control unit (150) of claim 16, wherein the control unit (150) is arranged to perform the controlling by at least one of the following: limiting a speed of the elevator car (1 10); limiting an acceleration of the elevator car (1 10); activation of an unintended car movement protection functionality.

18. The control unit (150) of claim 16 or claim 17, wherein the control unit (150) is arranged to apply, as the at least one criterion, at least one of the following: the elevator door (120, 130) is not fully closed; the elevator door (120, 130) is not locked.

19. The control unit (150) of any of preceding claims 13-18, wherein the control unit (150) is arranged to detect the position (P1 , P2) of the elevator car door (120, 130) in its path of motion based on data received from at least one sensor (125A, 125B).

20. The control unit (150) of any of preceding claims 13-19, wherein the control unit (150) is arranged to determine at least one of the following: the first position (P1 ) of the elevator door (120, 130), the second position (P2) of the elevator door (120, 130) by applying a motion profile of the elevator door (120, 130) in the determination of the position (P1 , P2) of the elevator door (120, 130).

21. The control unit (150) of claim 20, wherein the control unit (150) is arranged to determine the at least one position (P1 , P2) of the elevator door (120, 130) by applying the motion profile of the elevator door (120, 130) with respect to a known position of the elevator door (120, 130) at an instant of time.

22. The control unit (150) of claim 21 , wherein the control unit (150) is arranged to determine the known position of the elevator door (120, 130) as at least one of the following: fully open position of the door (120, 130), a position of the door (120, 130) detected with at least one sensor (125A, 125B).

23. A computer program product for generating a trigger signal indicating an allowance to an elevator car (1 10) to initiate a travel in an elevator system which, when executed by at least one processor, cause a control unit (150) to perform the method according to any of claims 1 -12.

24. An elevator system, comprising: an elevator door (120, 130), and a control unit (150) of claim 13-22.

25. The elevator system of claim 24, wherein the elevator door (120, 130) is at least one of the following: an elevator car door (120), a landing door (130).

26. The elevator system of claim 24 or 25, wherein the elevator system com prises at least one sensor (125A, 125B) for detecting a position of the elevator door (120, 130).