Method for monitoring a car in an elevator system

Abstract

The following descriptions relate to a method (10) for monitoring a first car (3.1, 3.2) in an elevator system (1) with an elevator shaft (2) and at least one collision position of the first car (3.1, 3.2) in the elevator shaft (2), the method (10) comprising the steps of: moving (11) the first car (3.1, 3.2) according to a travel curve (14), wherein the travel curve (14) defines a position-dependent car speed, and monitoring (12) the first car (3.1, 3.2) according to a monitor curve (15.2), wherein the monitor curve (15.2) defines a position-dependent car speed for triggering at least one braking device acting on the first car (3.1, 3.2) in order to ensure compliance with a maximum collision speed (20) of the first car (3.1, 3.2) in the collision position. where the monitor curve (15.2) up to a limiting speed (21) is calculated using a first function and from the limiting speed (21) onwards using a second function.

Description

Technical field

[0001] The following descriptions relate to a method for monitoring a first car in an elevator system with an elevator shaft and at least one collision position of the first car in the elevator shaft, the method comprising the steps of: moving the first car according to a travel curve, wherein the travel curve defines a position-dependent car speed, and monitoring the first car according to a monitor curve, wherein the monitor curve defines a position-dependent car speed for triggering at least one braking device acting on the first car in order to ensure compliance with a maximum collision speed of the first car in the collision position.

[0002] Furthermore, the following descriptions relate to an elevator system designed to carry out such a procedure, comprising an elevator shaft and at least one first car arranged in the elevator shaft, wherein at least one collision position of the first car is formed in the elevator shaft. Technical background

[0003] Elevator systems for transporting people and / or goods are an integral part of modern residential and commercial buildings. A typical elevator system comprises one or more elevator shafts, in each of which one or more cars travel between landing positions by means of drive devices, such as suspension drives or linear drives.

[0004] In such elevator systems, it is known to move the cars using travel curves that define a position-dependent car speed, which is used to control the drive mechanism of each car. Should a fault or failure of a component of the elevator system occur, known monitor curves are used to initiate an emergency stop if the car speed reaches or exceeds the speed defined by the monitor curve at a specific position. The monitor curve defines a speed higher than the travel curve for each position.

[0005] Known monitor curves are typically determined using a mathematical function such that, in a position range near the collision position, they run relatively close to a maximum possible travel curve and deviate further from the maximum possible travel curve with increasing distance from the collision position. In this way, a high level of safety is achieved in the immediate vicinity of the collision position, while further away from the collision position, exceeding the speed defined in the maximum possible travel curve is tolerated relatively widely to avoid unnecessary activation of the braking device and the associated resetting of the elevator system.However, a disadvantage can arise in that, away from the collision position, the high trigger speed and a system-related delay ("reaction time") until the braking deceleration begins could result in an excessively high speed at the collision position.

[0006] Monitor curves are known, for example, in various versions from CN 106144852 A for an elevator system with multiple cars.

[0007] Based on this situation, the task at hand is to propose a monitor curve by means of which the elevator system can be operated safely and without unnecessary triggering of an emergency stop. Description - Technical Solution

[0008] The present problem is solved by the features of the independent claims. Advantageous embodiments are specified in the dependent claims, the description, and the drawings. Where technically feasible, the teachings of the dependent claims can be combined arbitrarily with those of the main and dependent claims.

[0009] In particular, the problem is solved by a method for monitoring a first car in an elevator system with an elevator shaft and at least one collision position of the first car in the elevator shaft, the method comprising the steps of: moving the first car according to a travel curve, wherein the travel curve defines a position-dependent car speed, and monitoring the first car according to a monitor curve, wherein the monitor curve defines a position-dependent car speed for triggering at least one braking device acting on the first car in order to ensure compliance with a maximum collision speed of the first car in the collision position, wherein the monitor curve is calculated up to a limit speed according to a first function and from the limit speed according to a second function.

[0010] The following sections explain advantageous aspects and subsequently describe preferred modified embodiments. Explanations, particularly regarding advantages and definitions of features, are essentially descriptive and preferred, but not limiting, examples. If an explanation is limiting, this will be explicitly stated.

[0011] Where ordinal numbers, such as "first," "second," etc., are used, for example to designate a component, an element, a process step, or a process action, these ordinal numbers are solely for differentiation in the designation and do not indicate any dependencies or sequences. This means, in particular, that a device does not need to have a "first component" to have a "second component." A device can also have a "first component" and a "third component" without necessarily having a "second component." Multiple units with the same ordinal number are also possible, for example, multiple "first components."

[0012] According to the present understanding, an elevator system is designed, for example, with at least one vertical and / or horizontal elevator shaft and at least one elevator car, but can also have several elevator shafts and / or several elevator cars, in particular several elevator cars per elevator shaft.

[0013] For example, a car is held and driven by a load-bearing element, with a drive device transmitting a drive torque to the load-bearing element via a drive shaft. The load-bearing element is preferably connected to a counterweight associated with the car. A drive device is, in particular, located in a machine room or in the head of a shaft. A load-bearing element is, in particular, designed as a rope, belt, strap, chain, or the like, and carries tensile loads in the direction of its longitudinal extension. A braking device acting on the car is then, for example, designed to act on the drive shaft of the drive device, either separately from the drive device or integrated into the drive device. In principle, a braking device can also act on another component in the car's drive train, for example, on the load-bearing element or the car itself.A braking device can be, for example, a service brake, an emergency brake and / or a safety device.

[0014] Alternatively, an elevator car can be held and driven by a linear actuator. A linear actuator consists, for example, of a primary part extending along the elevator shaft and a secondary part located on the elevator car. The primary part is formed by coils arranged in a line, each with its own converter. An energizer is applied to the coil to generate a magnetic field when the elevator car is within the area of ​​the respective coil, thus moving the car. The secondary part consists of a permanent or electromagnet that interacts with the magnetic fields of the coil. A braking device acting on the elevator car is then, in particular, arranged on the elevator car and interacts, for example, with a guide rail along which the elevator car is guided along the elevator shaft.A braking device can be, for example, a service brake, an emergency brake and / or a safety device.

[0015] A collision position can be configured depending on the design of the elevator shaft. For example, a buffer may be installed at one end of the shaft to catch the car without damaging the elevator system if the car strikes the buffer at a maximum impact speed. The collision position is then defined by the point at which the car makes contact with the buffer. The collision position can also be defined by a fixed obstacle, such as the shaft end itself, if no buffer is present. In particular, a collision position can also be created by a moving second car, in which case the collision position changes over time.The maximum collision speed is determined in particular in such a way that in the event of a collision at the collision speed, no or only minor damage and, in particular, no danger to a person located in the elevator car occurs.

[0016] A travel curve defines the speed profile of the elevator car over a distance within the elevator shaft. For example, if an elevator car is to be moved from a first landing position to a second landing position, a travel curve can be determined, which can be divided into an acceleration phase, a constant speed phase, and a deceleration phase. The boundary conditions for calculating the travel curve result, for example, from permissible and / or possible motion parameters of the elevator system, from a specific car call, and / or from other conditions defined for the elevator system. A maximum possible travel curve, which can only exist theoretically through calculation without ever being used in practice, or which can actually be used in the operation of the elevator system, is determined by applying the maximum possible / permissible parameters.Control commands for the car's drive mechanism are derived from the defined travel path and transmitted to the drive mechanism at specific times. A travel path can affect a collision position, particularly if the target landing position is located at the end of the shaft where the collision position is located, or in close proximity to this shaft end position relevant to a potential collision. A travel path can affect a collision position at any position along the elevator shaft, especially if there are multiple cars in the shaft. The car's movement is monitored by a monitor curve, particularly if the travel path affects at least one collision position.

[0017] A monitor curve, for example, is derived as an envelope for the maximum possible travel path and can be freely calculated from specific parameters or with reference to the maximum possible travel path. The monitor curve defines a threshold velocity profile across a specific position in the elevator shaft. Thus, if the elevator car moves at a specific speed in a certain position towards the collision position, the monitor curve is reached and the braking device is triggered. Insofar as monitoring via the monitor curve, or triggering the braking device, aims to ensure that the first elevator car in the collision position does not exceed a maximum collision speed, the maximum collision speed, or a lower speed, should be reached in every case before the collision position is reached.

[0018] The solution to the problem using the aforementioned method involves calculating the monitor curve in multiple stages. This is based on the understanding that a mathematical function which, near the collision position and at the low car speeds intended for that location, results in a favorable approximation of the monitor curve to the maximum possible travel curve, leads to an unnecessarily large gap between the monitor curve and the maximum possible travel curve at higher car speeds further away from the collision position. This unnecessarily large gap can be advantageously and significantly reduced by calculating the monitor curve differently in this area, without increasing the probability of a false triggering event, for example, due to a slight deviation in the travel curve control of the drive device.The monitor curve can therefore be positioned closer to the maximum possible travel curve even in the higher speed range. The two-part calculation of the monitor curve advantageously enables a sufficiently rapid activation of the braking device in the position range away from the collision position and the higher car speeds present there, thus preventing the maximum collision speed of the first car in the collision position from being exceeded.

[0019] This is based on the understanding that, due to the high car speeds in this area, the time delay with which the braking device engages, and the tolerable braking deceleration, even when an emergency stop is triggered away from the collision position, the maximum collision speed cannot always be safely maintained.

[0020] The overall advantage is that the monitor curve closely follows the maximum possible travel curve along its entire length. This ensures that, in the event of a fault or damage, a sufficiently rapid emergency stop is triggered at any point along the maximum possible travel curve, provided the car is moving along that curve, thus enabling safe operation of the elevator system. Simultaneously, a sufficient distance can be maintained between the monitor curve and the maximum possible travel curve along the entire length of the maximum possible travel curve to prevent unnecessary triggering due to the typical slight deviation of the car speed from the travel curve.

[0021] The limiting speed can be defined directly as such or, for example, derived from a limiting distance, from which the limiting speed is then determined via a one-to-one correspondence to a specific speed using the monitor curve. In any case, the limiting speed or the limiting distance is chosen, for example, based on simulations, such that exceeding the maximum collision speed of the first car in the collision position is reliably avoided at every point on the travel curve.

[0022] Alternatively or additionally, the monitor curve can be set to an offset at the collision position. An offset is understood as a displacement from a zero value. Thus, the monitor curve is shifted from zero velocity at the zero position defined by the collision position in order to represent a permissible (low) velocity that is tolerable. For example, in the case of a collision position defined by a buffer, the offset can be determined based on the maximum impact velocity that the buffer can absorb without damage, ensuring that the car can only impact the buffer at a velocity that can be absorbed. The offset thus ensures a maximum distance between the monitor curve and the maximum possible travel curve at all times, preventing unnecessary triggering due to a typical slight deviation of the car speed from the travel curve of the braking device.

[0023] Alternatively or additionally, the monitor curve can be calculated based on a car speed defined in a maximum possible travel curve. The monitor curve is then easily and safely derived from the travel curve for a journey with the maximum possible travel curve.

[0024] For example, the monitor curve for a first speed range can be calculated as follows: sM=vFK22∗z1−soff

[0025] This is M the position component of the monitor curve, which depends on the car speed v FK The maximum possible driving curve is obtained. The quantity z1 is also a first parameter with the dimension of acceleration or deceleration in m / s². 2 and s off is an offset value that defines the offset of the monitor curve at the collision position.

[0026] For a second speed range above a limiting speed v G The monitor curve can then be calculated as follows, for example: sM=vFK2−vG22∗z2+vG22∗z1−soff

[0027] The additional quantity z2 is a second parameter with the dimension of acceleration or deceleration m / s². 2 .

[0028] Alternatively or additionally, at least one collision position can be defined by a buffer located at one end of the elevator shaft. A buffer allows for a low remaining impact velocity at the collision position, which, by means of the resulting offset, advantageously ensures that the monitor curve remains sufficiently far from the maximum possible travel path, even in the immediate vicinity of the collision position, thus preventing unnecessary activation of the braking device. Furthermore, the buffer advantageously ensures that a car traveling into the collision position at a speed below the maximum collision velocity remains undamaged.

[0029] Alternatively or additionally, a monitor curve can be defined for each shaft end. This is readily achieved if the monitor curve is calculated from the maximum possible travel path and if two collision positions are defined. The monitor curve can therefore be advantageously calculated for the multiple collision positions or shaft ends, offering the aforementioned benefits.

[0030] Alternatively or additionally, the collision position can be defined by a second elevator car located in the elevator shaft. In this case, the collision position is not fixed to a specific position in the elevator shaft, but rather varies over time depending on the movement of the second elevator car. If the monitor curve is calculated differently than from the maximum possible travel path, the position of the second elevator car, and thus the collision position, can be known and taken into account when calculating the monitor curve.

[0031] The problem is further solved by an elevator system comprising an elevator shaft, at least one first car arranged in the elevator shaft, and at least one braking device acting on the first car, wherein at least one collision position for the first car is provided in the elevator shaft, and wherein the elevator system is configured to carry out a previously described method. The advantages described above regarding the method are achieved accordingly with the elevator system. In particular, the elevator system can be operated safely, thereby avoiding unnecessary activation of the braking device.

[0032] Alternatively or additionally, at least one collision position can be defined by a buffer located at one end of the elevator shaft. A buffer allows for a low remaining impact velocity at the collision position, which, by means of the resulting offset, advantageously ensures that the monitor curve is sufficiently distanced from the maximum possible travel curve, even in the immediate vicinity of the collision position. This prevents unnecessary activation of the braking device due to a typical slight deviation of the car speed from the travel curve. Furthermore, the buffer advantageously ensures that a car traveling into the collision position at a speed below the maximum collision velocity remains undamaged.

[0033] Alternatively or additionally, the elevator system may include a second car located in the elevator shaft. The second car then creates a changing collision position within the shaft for the first car. If the monitor curve is calculated differently than from the maximum possible travel curve, the position of the second car, and thus the collision position, can be known and taken into account when calculating the monitor curve. Brief description of the drawings

[0034] A preferred technical solution is explained in more detail below with reference to the accompanying drawings and preferred embodiments. The term "figure" is abbreviated as "Fig." in the drawings.

[0035] The drawings show Fig. 1 a highly schematic representation of an elevator system according to the present disclosure; Fig. 2 a flow diagram of a procedure for monitoring a first car in an elevator system according to Fig. 1; Fig. 3a a graphical representation of a travel curve and two monitor curves for a car in an elevator system according to Fig. 1; Fig. 3b a graphical representation of the two monitor curves from Fig. 3a with exemplary delay curves during an emergency stop according to the first monitor curve; and Fig. 3c a graphical representation of the two monitor curves from Fig. 3a with exemplary delay curves during an emergency stop according to the second monitor curve. Detailed description of the drawings

[0036] The described embodiments are merely examples that can be modified and / or supplemented in various ways within the scope of the claims. Each feature described for a particular embodiment can be used independently or in combination with other features in any other embodiment. Each feature described for an embodiment of a particular claim category can also be used accordingly in an embodiment of a different claim category.

[0037] Fig. Figure 1 shows an elevator system 1 with an elevator shaft 2 extending in the vertical direction V, a first car 3.1 and a second car 3.2 moving in the elevator shaft 2. Along the elevator shaft 2, landing positions 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, for example floors of a building in which the elevator system 1 is located, are arranged shaft doors 5.1, 5.2, 5.3, 5.4, 5.5, 5.6. Cars 3.1 and 3.2 can approach landing positions 4.1, 4.2, 4.3, 4.4, 4.5, and 4.6, so that the shaft doors 5.1, 5.2, 5.3, 5.4, 5.5, and 5.6 there align with the car doors 6.1 and 6.2 of cars 3.1 and 3.2 and, when open, provide access to cars 3.1 and 3.2. A buffer 7 is arranged at the lower shaft end 2.1, so that the second car 3.2, which enters the lower shaft end position 4.1 or generally moves towards the lower shaft end 2.1, passes over this shaft end position 4.The first car 3.1 is caught and slowed down. The buffer 7 for catching the second car 3.1 is only designed up to a certain impact speed. A corresponding buffer can be provided for the first car 3.1 or its counterweight for entering the shaft end position 4.6.

[0038] In order to move a car 3.1, 3.2 between two landing positions 4.1, 4.2, 4.3, 4.4, 4.5, 4.6 according to a corresponding car call, a travel curve 14 is created, for example by means of a data processing device not shown in detail, and the car 3.1, 3.2 is moved according to the travel curve 14 and monitored as described in more detail below with reference to the Fig. 2 and 3a to 3c are described. The driving curve 14 is shown in the diagram. Fig. 3a a maximum possible driving curve.

[0039] Fig. Figure 2 shows a method 10 for monitoring a first car 3.1, 3.2 in the elevator system 1. In a first step 11, the first car 3.1, 3.2 is moved according to a travel curve 14, whereby the travel curve 14 defines a position-dependent car speed. In a second step 12, the first car 3.1, 3.2 is monitored according to a monitor curve 15.2, whereby the monitor curve 15.2 defines a position-dependent car speed for triggering at least one braking device acting on the first car 3.1, 3.2 (not shown in detail in the figures) in order to ensure that a maximum collision speed 20 of the first car 3.1, 3.2 is maintained in the collision position.

[0040] The Fig. Figure 3a shows the maximum possible travel curve 14 for approaching the shaft end position 4.1 as a dashed line, as well as two monitor curves 15.1 and 15.2. The x-axis represents the position of a car 3.2 in the elevator shaft 2, and the shaft end position 4.1 corresponds to the intersection of the x- and y-axes. The y-axis represents a velocity, which corresponds to the car speed intended by travel curve 14 for travel curve 14 and to the tripping velocity for monitor curves 15.1 and 15.2. The maximum possible travel curve 14 leads to a standstill at the shaft end position 4.1, for example, corresponding to a quadratic y-function or a square root x-function. Thus, the car 3.2 should reach the car speed shown on the y-axis at the position shown on the x-axis.

[0041] The first monitor curve 15.1, which represents the state of the art, corresponds to a quadratic y-function or square root x-function, shifted upwards by an offset of 16 and calculated, for example, according to the first function F.1 above. It can be seen that the first monitor curve 15.1 closely follows the maximum possible travel curve 14 in the lower x-range. This results in the following for a situation in which the car 3.2 enters the first monitor curve 15.1 at a constant speed: at various speeds 18.1, 18.2, 18.3, the following results are obtained: Fig. 3b shows velocity profiles 17.1, 17.2, 17.3.

[0042] At a relatively high speed 18.1, after passing through the first monitor curve 15.1, a relatively long distance is initially covered due to the relatively high speed 18.1 before the braking process is initiated after a reaction time of the control system. Then, assuming a corresponding weight ratio between the car and the counterweight (worst-case scenario), the speed initially increases because the drive of the car 3.2 is switched to torque-free mode and the motor braking effect of the drive is eliminated, before the braking device then initiates braking with a specific deceleration intended or tolerated for the emergency stop. Due to the large distance between the maximum possible travel curve 14 and the first monitor curve 15.1 and the long distance that the car 3.2 travels after passing through the first monitor curve 15.1,The deceleration is insufficient to ensure that the distance traveled by the vehicle before the braking device engages is below the maximum collision speed 20 tolerated by buffers 7.1 and 7.2 when reaching the shaft end position 4.1, 4.6 on the y-axis. At a lower speed of 18.2, the resulting path is 17.2, which is essentially the same as 17.1, but due to the lower speed, it covers a shorter unbraked distance after passing through the first monitor curve 15.1 and before the braking device engages. Even at the lower speed of 17.2, the maximum collision speed of 20 is still exceeded at the shaft end position 4.1. At the low speed 18.3, the following path results, 17.3, which corresponds to paths 17.1 and 17.2, albeit with shorter distances, and in which the maximum collision speed 20 is now reached or undercut in the shaft end position 4.1.

[0043] The second monitor curve 15.2 according to the present disclosure corresponds up to a limiting speed 21 - which is purely exemplary as in Fig. 3a can result as a projection from the maximum possible driving curve 14 onto the second monitor curve 15.2, or alternatively as a freely definable value – the first monitor curve 15.1, which, as described above, is calculated as a quadratic y-function or square root x-function, for example, according to the first function F.1, and shifted upwards by an offset of 16. Furthermore, from the limiting speed 21 onwards, the second monitor curve 15.2 corresponds to another quadratic y-function or square root x-function, which is calculated in principle like the first monitor curve 15.1, but with differing parameters. The second monitor curve 15.2 is thus calculated from the limiting speed 21 onwards using a second function, for example, the second function F.2. It can be seen that the second monitor curve 15.2 behaves like the first monitor curve 15.1 in the lower x-range.Monitor curve 15.1 is positioned relatively close to the maximum possible travel curve 14 and, moreover, remains significantly closer to the maximum possible travel curve 14 in the upper x-range than the first monitor curve 15.1. At higher car speeds, a sufficient distance is then achieved between the maximum possible travel curve 14 and the second monitor curve 15.2 to avoid unnecessary activation of the braking device during typical deviations of the car speed from the maximum possible travel curve 14, when the car 3.2 is moving according to the maximum possible travel curve 14. Furthermore, for a situation in which the car 3.2 enters the second monitor curve 15.2 at a constant speed, the following results are obtained at various speeds 18.1, 18.2, 18.3. Fig.Figure 3c shows the velocity profiles 23.1, 23.2, and 23.3. Each velocity profile 23.1, 23.2, and 23.3 corresponds to the respective velocity profile 17.1, 17.2, and 17.3 from the first monitor curve 15.1, except that the starting point, i.e., the point at which the second monitor curve 15.2 is crossed and thus triggered, is shifted significantly to the right in each case. As a result, the maximum collision speed 20 can be reached or fallen below at the shaft end position 4.1 for each of the velocity profiles 23.1, 23.2, and 23.3. The relationships described above are to be applied accordingly to a situation in which the first car 3.1 enters the shaft end position 4.6 and is protected by a suitably positioned buffer (for example, at the lower shaft end 2.1 for the counterweight of the first car 3.1). Reference symbol list 1 elevator system 2 Elevator shaft of the elevator system 2.1 lower end of the elevator shaft 2.2 upper end of the elevator shaft 3.1 movable elevator car in the elevator shaft 3.2 movable elevator car in the elevator shaft 4.1 First landing position / shaft end position 4.2 Second landing position 4.3 Third landing position 4.4 fourth landing position 4.5 fifth landing position 4.6 sixth landing position / shaft end position 5.1 First shaft door 5.2 second shaft door 5.3 Third shaft door 5.4 fourth shaft door 5.5 fifth shaft door 5.6 sixth shaft door 6.1 Car door 6.2 Car door 7 buffers 10 methods for monitoring a first elevator car in an elevator system 11 First step - Moving the first car according to a travel curve 12. Second step - Monitoring the first car using a monitor curve 14 Driving curve 15.1 first monitor curve 15.2 second monitor curve 16 Offset 17.1 First velocity profile from the first monitor curve 17.2 Second velocity profile from the first monitor curve 17.3 Third velocity profile from the first monitor curve 18.1 first speed 18.2 second speed 18.3 third speed 20 maximum collision speed 21 Limit speed 23.1 First velocity profile from the second monitor curve 23.2 Second velocity profile from the second monitor curve 23.3 Third velocity profile from the second monitor curve V vertical direction QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] CN 106144852 A

[0006]

Claims

[1] Method (10) for monitoring a first car (3.1, 3.2) in an elevator installation (1) with an elevator shaft (2) and at least one collision position of the first car (3.1, 3.2) in the elevator shaft (2), the method (10) comprising the steps: Moving (11) the first car (3.1, 3.2) according to a travel curve (14), wherein the travel curve (14) defines a position-dependent car speed; and Monitoring (12) of the first car (3.1, 3.2) using a monitor curve (15.2), wherein the monitor curve (15.2) defines a position-dependent car speed to trigger at least one braking device acting on the first car (3.1, 3.2) to ensure compliance with a maximum collision speed (20) of the first car (3.1, 3.2) in the collision position; characterized by, that the monitor curve (15.2) is calculated up to a limiting speed (21) using a first function and from the limiting speed (21) using a second function. [2] Method (10) according to claim 1, wherein the monitor curve (15.2) corresponds to an offset (16) at the collision position. [3] Method (10) according to claim 1 or 2, wherein the monitor curve (15.2) is calculated as a function of a car speed defined in a maximum possible travel curve (14). [4] Method (10) according to one of the preceding claims, wherein the at least one collision position is defined by a buffer (7.1, 7.2) arranged at a shaft end (2.1, 2.2) of the elevator shaft (2). [5] Method (10) according to claim 4, wherein a monitor curve (15.2) is defined for each shaft end (2.1, 2.2). [6] Method (10) according to one of claims 1 to 3, wherein the collision position is defined by a second car (3.1, 3.2) located in the elevator shaft (2). [7] Lift installation (1) comprising an elevator shaft (2); at least one first elevator car (3.1, 3.2) arranged in the elevator shaft (2); and at least one braking device acting on the first elevator car (3.1, 3.2); wherein at least one collision position of the first car (3.1, 3.2) is formed in the elevator shaft (2); characterized by that the elevator system (1) is configured to perform a method (10) according to one of the preceding claims. [8] Lift system (1) according to claim 7, wherein the at least one collision position is defined by a buffer (7.1, 7.2) arranged at a shaft end (2.1, 2.2) of the lift shaft (2). [9] Lifting system (1) according to claim 7 or 8, further comprising a second car (3.1, 3.2) arranged in the lift shaft (2).

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