METHOD FOR CENTERING AN ELEVATOR CABIN OF AN ELEVATOR SYSTEM

Description

[0001] There are methods for erecting an elevator system in an elevator shaft of a new building, in which method a construction phase elevator system with a self-propelled construction phase elevator car is installed for the duration of the construction phase of the building in the elevator shaft, which becomes higher with increasing building height, wherein the usable lifting height of the construction phase elevator car is gradually adapted to a currently existing elevator shaft height.

[0002] CN106006303 A discloses an indoor construction elevator that is installed in the elevator shaft of a building under construction. This elevator is installed synchronously with the construction of the building, meaning that the usable lifting height of the indoor construction elevator increases with the increasing height of the building or elevator shaft. Such an adjustment of the usable lifting height serves, on the one hand, to transport construction workers and building materials to the currently highest part of the building during construction progress. On the other hand, such an elevator can be used as a passenger and freight elevator for floors already used as residential or commercial premises during the building's construction phase.

[0003] To easily achieve an increasing usable lifting height of the elevator, its elevator car is designed as a self-propelled elevator car that moves up and down by a drive system comprising a rack and pinion attached to the elevator car and interacting with the rack and pinion. A guide system for the elevator car, whose length is adjustable to the current elevator shaft height, is installed along the elevator shaft. The rack and pinion, with a length that is also adjustable to the current elevator shaft height, is fixed to this guide system parallel to the guide system's guide direction. The pinion, which interacts with the rack and pinion to drive the elevator car, is attached to the output shaft of a drive unit arranged on the elevator car. The power supply to the drive unit is via an electrical conductor line.

[0004] The indoor construction elevator with backpack guide and rack drive described in CN106006303 A is not suitable as a high-speed elevator. However, high travel speeds of at least 3 m / s, for example, are required for final elevator systems in buildings whose height justifies the installation of a construction-phase elevator system whose usable lifting height can be adjusted to accommodate an increase in the elevator shaft height during the building's construction phase.

[0005] Elevators with friction wheels are known from EP1364904A1 and US5566784A.

[0006] According to a first aspect, the object is to create a method (not according to the invention) of the type described above, the use of which can avoid the disadvantages of the indoor construction elevator cited as prior art. In particular, the method is intended to solve the problem that the travel speed achievable by the indoor construction elevator is insufficient to serve as a normal passenger and goods elevator after the completion of a tall building.

[0007] The problem according to the first aspect is solved by a method of the type described above, in which, for the duration of the construction phase of the building, a construction phase elevator system is installed in the elevator shaft, which increases with increasing building height. The system comprises a self-propelled construction phase elevator car, the usable lifting height of which is adaptable to an increasing elevator shaft height. At least one guide rail track is installed to guide the construction phase elevator car along its travel path in the elevator shaft. A drive system is mounted to drive the construction phase elevator car, which drive system comprises a primary part attached to the construction phase elevator car and a secondary part attached along the travel path of the construction phase elevator car. The guide rail track and the secondary part of the drive system are gradually extended upwards during the construction phase in accordance with the increasing elevator shaft height.wherein the self-propelled construction-phase elevator car is used both for transporting persons and / or materials for the construction of the building and as a passenger and freight elevator for floors already used as residential or commercial premises during the construction phase of the building, and wherein, after the elevator shaft has reached its final height, a final elevator system modified from the construction-phase elevator system is installed in the elevator shaft instead of the construction-phase elevator system.

[0008] The advantages of the method not according to the invention are, in particular, that, on the one hand, an elevator optimal for this phase is available during the construction phase, with which the already constructed floors can be reached without repeatedly lifting a movable machine room in order to transport construction specialists, building materials and residents of already completed lower floors, and that, on the other hand, after the elevator shaft has reached its final height, a final elevator system suitable for the building, in particular with regard to travel speed, can be used.Possible modifications may include, for example, the use of a drive motor and / or an associated speed control device with higher power, the modification of gear ratios in drive components or the diameters of traction sheaves or friction wheels, the installation of elevator cars with reduced weight or different dimensions and equipment, or the integration of a counterweight into the final elevator system.

[0009] In one of the possible embodiments of the method not according to the invention according to the first aspect, instead of the construction phase elevator system, a final elevator system is installed in the elevator shaft, in which a drive system of an elevator car is modified compared to the drive system of the construction phase elevator car.

[0010] By modifying the elevator car drive system of the final elevator system, at least the required high travel speed of the elevator car of the final elevator system can be achieved. Examples of possible modifications to the elevator system include increasing the drive power of the drive motor and the associated speed control device, changing the gear ratios of drive components, using a different drive type, for example, one not suitable for a self-propelled elevator car, etc.

[0011] In a further possible embodiment of the method according to the first aspect, the drive system of the elevator car of the final elevator system is based on a different operating principle than the drive system of the construction-phase elevator car. Since the final elevator system, and thus the associated drive system, do not have to meet the requirement of being adaptable to increasing building heights, the use of a drive system based on a different operating principle enables optimal adaptation of the final elevator system to requirements regarding travel speed, transport capacity, and travel comfort. In the present context, the term "operating principle" refers to the method of generating a force for lifting an elevator car and transmitting this force to the elevator car.Preferred drive systems with a different operating principle than that used in the self-propelled construction-phase elevator car are drives with flexible support elements – such as wire ropes or belts – which, in various arrangements of the drive machine and support elements, support and drive the elevator car of a final elevator system. In general, however, all drive systems – including electric linear motor drives, hydraulic drives, recirculating ball screw drives, etc. – whose operating principle differs from that of the drive system of the self-propelled construction-phase elevator car, and which are suitable for relatively high lifting heights and can generate sufficiently high travel speeds of the elevator car, are applicable.

[0012] In a further possible embodiment of the method not according to the invention according to the first aspect, a final elevator car of the final elevator system is guided on the same at least one guide rail strand on which the construction phase elevator car was guided.

[0013] This avoids the large amount of work, the high costs and, in particular, the long interruption of elevator operation for replacing at least one guide rail strand.

[0014] In a further possible embodiment of the method according to the first aspect, the construction phase elevator car is used during the construction phase of the building both for the transport of people and / or materials for the construction of the building and as a passenger and freight elevator for floors already used as residential or commercial premises during the construction phase of the building. This ensures that, on the one hand, construction workers and construction materials can be transported with the construction phase elevator car during almost the entire construction period of the building. On the other hand, users of apartments or commercial premises already occupied before the building's completion can be transported in compliance with regulations between at least the floors assigned to these rooms, without requiring days of operational interruptions when adjusting the lifting height of the construction phase elevator car.

[0015] In a further possible embodiment of the method not according to the invention according to the first aspect, an assembly platform and / or a protective platform is / are temporarily installed above a current travel path upper limit of the construction phase elevator car, after which, when the usable lifting height of the construction phase elevator car is adapted to an increasing elevator shaft height, the assembly platform and / or the protective platform can be raised to a higher elevator shaft level by means of the self-propelled construction phase elevator car.

[0016] This ensures that the relatively heavy, absolutely necessary protective platform and, if necessary, also an assembly platform, which are required as protection against falling objects, can be lifted along the newly created elevator shaft and fixed in a new position with little expenditure of working time and lifting equipment.

[0017] In a further possible embodiment of the method not according to the invention according to the first aspect, the protective platform which can be raised by means of the self-propelled construction phase elevator car is designed as an assembly platform from which at least the said at least one guide rail strand is extended upwards.

[0018] The combination of the safety platform and the assembly platform not only saves costs for their production, but also allows the safety platform and the assembly platform to be moved and secured in a new position in the elevator shaft suitable for the assembly work in a single step and without the need for additional lifting equipment.

[0019] In a further possible embodiment of the method not according to the invention according to the first aspect, the primary part of the drive system mounted for driving the construction phase elevator car comprises a plurality of driven friction wheels, wherein the construction phase elevator car is driven by an interaction of the driven friction wheels with the secondary part of the drive system mounted along the travel path of the construction phase elevator car.

[0020] The use of friction wheels as the primary part of a drive of a construction-phase elevator car is advantageous because a corresponding secondary part extending along the entire travel path can be manufactured from simple and inexpensive elements, and because friction wheel drives enable relatively high speeds with low noise generation.

[0021] In a further possible embodiment of the method not according to the invention according to the first aspect, the at least one guide rail strand is used as the secondary part of the drive system of the self-propelled construction phase elevator car.

[0022] By using the guide rail track, which is required for both the construction phase elevator car and the final elevator car, as a secondary part of the drive system, very high costs for the production and, in particular, for the installation and adjustment of such a secondary part extending over the entire elevator shaft height can be saved.

[0023] In a further possible embodiment of the method not according to the invention according to the first aspect, at least two driven friction wheels are pressed against each of two opposing guide surfaces of the at least one guide rail track in order to drive the construction phase elevator car, wherein the friction wheels acting on the same guide surface are arranged at a distance from one another in the direction of the guide rail track.

[0024] By means of such an arrangement of at least four driven friction wheels acting on each guide rail strand, the high driving force required to lift at least the construction phase elevator car and the protective platform or the combination of protective platform and assembly platform can be achieved.

[0025] In a further possible embodiment of the method not according to the invention according to the first aspect, at least one of the friction wheels is rotatably mounted on one end of a pivot lever which is pivotally mounted at its other end on a pivot axis fixed to the construction phase elevator car, wherein the pivot axis of the pivot lever is arranged such that the center of the friction wheel lies below the center of the pivot axis when the friction wheel is placed or pressed against the guide surface of the guide rail track assigned to it.

[0026] Such an arrangement of the at least one friction wheel ensures that, when the construction-phase elevator car is driven upwards, a contact force is automatically established between the friction wheel and the guide surface that is approximately proportional to the drive force transmitted from the guide surface to the friction wheel. This avoids the friction wheels always having to be pressed so hard that the drive force required for the maximum total weight of the construction-phase elevator car can be transmitted.

[0027] In a further possible embodiment of the method not according to the invention, the at least one friction wheel is pressed against a guide surface of a guide rail track at any time with a minimum contact force by the action of a spring element - for example a helical compression spring.

[0028] In combination with the described arrangement of the friction wheels, the minimum contact pressure ensures that, as soon as the friction wheels begin to drive the construction phase elevator car in the upward direction, contact pressures are automatically established between the friction wheels and the guide surfaces of the guide rail track, which are approximately proportional to the current total weight of the construction phase elevator car.

[0029] In a further possible embodiment of the method not according to the invention according to the first aspect, the at least one friction wheel is driven by an electric motor exclusively assigned to this friction wheel or by a hydraulic motor exclusively assigned to this friction wheel.

[0030] Such a drive arrangement enables a very simple and compact drive configuration.

[0031] In a further possible embodiment of the method not according to the invention according to the first aspect, the at least one friction wheel and the electric motor associated therewith or the friction wheel and the associated hydraulic motor are arranged on the same axis.

[0032] With such an arrangement of friction wheel and drive motor, a further simplification of the entire drive configuration can be achieved.

[0033] In a further possible embodiment of the method not according to the invention according to the first aspect, in a drive system in which at least two driven friction wheels are pressed against each of two opposing guide surfaces of the at least one guide rail track and each friction wheel and its associated electric motor are arranged on the same axis, the electric motors of the friction wheels acting on one guide surface of a guide rail track are arranged offset in the axial direction of the friction wheels and electric motors by approximately one length of an electric motor relative to the electric motors of the friction wheels acting on the other guide surface.

[0034] By arranging the electric motors, whose diameters are significantly larger than the diameters of the friction wheels, offset from one another in their axial direction, the installation spaces of the electric motors of the friction wheels acting on one guide surface of the guide rail track do not overlap with the installation spaces of the electric motors of the friction wheels acting on the other guide surface of the guide rail track, even if the friction wheels arranged on either side of the guide rail track are positioned such that their mutual distances, measured in the direction of the guide rail track, are not significantly greater than the diameters of the electric motors. This arrangement of the drive system minimizes the required height of the installation space for the drive system - especially when using drive electric motors with a relatively large diameter.

[0035] In a further possible embodiment of the method not according to the invention according to the first aspect, at least one group of several friction wheels is driven by a single electric motor assigned to the group or by a single hydraulic motor assigned to the group, wherein a torque transmission to the friction wheels of the group is effected by means of a mechanical transmission.

[0036] With such a drive concept, a simplification of the electrical or hydraulic part of the drive can be achieved.

[0037] In a further possible embodiment of the method not according to the invention according to the first aspect, a chain wheel transmission, a belt transmission, a gear transmission or a combination of such transmissions is used as the mechanical transmission for transmitting torque to the friction wheels.

[0038] Such gears make it possible to drive the friction wheels of a group of several friction wheels from a single drive motor.

[0039] In a further possible embodiment of the method not according to the invention according to the first aspect, each of the electric motors driving at least one friction wheel and / or an electric motor driving a hydraulic pump which feeds at least one hydraulic motor driving at least one friction wheel is fed by at least one frequency converter controlled by a controller of the construction phase elevator system.

[0040] Such a drive concept enables perfect control of the travel speed of the construction phase elevator car.

[0041] In a further possible embodiment of the method not according to the invention according to the first aspect, a power supply device is installed to the construction phase elevator car, which power supply device comprises a conductor line installed along the elevator shaft, which is extended according to the elevator shaft height increasing during the construction phase.

[0042] This allows a power supply to the construction phase elevator car to be easily adapted to the current elevator shaft height, which can also transmit the electrical power required to lift the construction phase elevator car and the protective platform, or if necessary to lift the construction phase elevator car and the combination of protective platform and assembly platform.

[0043] In a further possible embodiment of the method not according to the invention according to the first aspect, during each standstill of the self-propelled construction phase elevator car of the construction phase elevator system, a holding brake acting between the construction phase elevator car and the at least one guide rail track is activated, and in at least one friction wheel, the torque transmitted from the associated drive motor to the at least one friction wheel to generate drive force is at least reduced.

[0044] Such a design has the advantage that the friction wheels do not have to exert the required vertical holding force when the elevator car is at a standstill during the construction phase. They therefore do not have to be pressed against the guide surfaces of the guide rail track with corresponding force. This largely mitigates the problem of flattening of the periphery of the friction linings when the elevator car is at a standstill. Since each friction wheel, due to the arrangement described above, is pressed against the guide surface approximately proportionally to the drive force transmitted between it and the guide surface, it is necessary to at least reduce this drive force, or the torque transmitted from the drive motor to the friction wheel.

[0045] In a further possible embodiment of the method not according to the invention according to the first aspect, a primary part of an electric linear drive is used as the primary part of the drive system for driving the construction phase elevator car and a secondary part of the said electric linear drive fixed along the elevator shaft is used as the secondary part of the said drive system.

[0046] Such a design of the method has the advantage that the drive of the construction phase elevator car is realized without contact and wear, and the traction capability of the drive cannot be impaired by contamination.

[0047] In a further possible embodiment of the method not according to the invention according to the first aspect, at least one electric motor or hydraulic motor driving a pinion and whose speed is controlled by a frequency converter is used as the primary part of the drive system for driving the construction phase elevator car, and at least one rack train fixed to the elevator shaft along the elevator shaft is used as the secondary part of the said drive system.

[0048] This type of method design has the advantage that, with a rack-and-pinion drive, the drive force is transmitted positively, eliminating the need for a holding brake on the elevator car during the construction phase. Furthermore, relatively few driven pinions are required to transmit the entire drive force. With speed control using a frequency converter, in which the frequency converter acts either on the electric motor driving at least one pinion or on an electric motor that controls the speed of a hydraulic pump feeding the hydraulic motor, the travel speed of the elevator car during the construction phase can be continuously controlled.

[0049] According to one aspect of the invention, the object is to provide a method for centering an elevator car, in particular a method for centering the construction phase elevator car in the method for erecting a final elevator system in an elevator shaft of a building as described above and below.

[0050] The object is achieved by a method for centering an elevator car of an elevator installation, wherein the elevator installation comprises a self-propelled elevator car, a first guide rail track and a second guide rail track for guiding the elevator car along its travel path in the elevator shaft, a drive system which has a primary part attached to the elevator car and a secondary part attached along the travel path, wherein the primary part of the drive system mounted for driving the elevator car comprises a plurality of driven friction wheels, wherein the elevator car is driven by an interaction of the driven friction wheels with the secondary part of the drive system attached along the travel path of the elevator car, wherein the first guide rail track and the second guide rail track are used as the secondary part of the drive system of the self-propelled elevator car,wherein, to drive the elevator car, at least two driven friction wheels are pressed against each of two opposing guide surfaces of the first guide rail strand and the second guide rail strand, wherein the first guide rail strand lies in a first plane, wherein the second guide rail strand lies in a second plane running substantially parallel to the first plane, wherein a center point of the elevator car is located in a centered state on a center plane running parallel to the first and second planes, wherein a first rotational speed of the friction wheels acting on the first guide rail strand and a second rotational speed of the friction wheels acting on the second guide rail strand are adjustable independently of one another, wherein upon detection of a deviation of the center point from the center plane, the first rotational speed and / or the second rotational speed is changed in such a way,that when the elevator car moves along the travel path, the center point moves towards the center planes.

[0051] In a further possible embodiment of the method according to the invention, the elevator car comprises at least two distance sensors, in particular in the form of an eddy current sensor and / or an optical triangulation sensor, wherein a first distance sensor measures a first distance of the elevator car to the first guide rail strand and wherein the second sensor measures a second distance of the car to the second guide rail strand, wherein the method regulates the first and / or second rotational speed as a function of the first and the second distance.

[0052] In a further possible embodiment of the method according to the invention, the elevator car comprises at least one inclination sensor from which an angle of inclination of the car to the center plane can be derived, wherein the first and / or second rotational speed are controlled such that the angle of inclination changes towards zero when the elevator car moves along the travel path.

[0053] In a further possible embodiment of the method according to the invention, if the center of the elevator car deviates from the center plane, the difference between the first rotational speed and the second rotational speed is gradually increased or decreased.

[0054] In a further possible embodiment of the method according to the invention, the difference between the first rotational speed and the second rotational speed is increased or decreased depending on a horizontal target speed which the elevator car should have in the direction of the travel path.

[0055] In a further possible embodiment of the method according to the invention, centering of the elevator car towards the center plane is supported by at least two passive guide rollers, which are mounted laterally to the car and each act on one of the two guide rail strands.

[0056] The method according to the aspect of the invention offers the advantage that the skew of the car can be actively controlled with a control system, thus reducing the load on the guide rails. This is particularly necessary with eccentric loads in the elevator car.

[0057] In the following, exemplary embodiments of the invention are explained with reference to the accompanying drawings. They show: Fig. 1 shows a vertical section through an elevator shaft with a self-propelled construction phase elevator car (not claimed as such) with a friction wheel drive as the drive system and with a first embodiment of auxiliary assembly devices (not claimed as such). Fig. 2 shows a vertical section through an elevator shaft with a self-propelled construction phase elevator car (not claimed as such) with a friction wheel drive as the drive system and with a second embodiment of auxiliary assembly devices (not claimed as such). Fig. 3A shows a side view of a self-propelled construction phase elevator car (not claimed as such) with a first embodiment of the friction wheel drive. Fig. 3B shows a front view of the construction phase elevator car according to Fig. 3A . Fig. 4A is a side view of a self-propelled construction phase elevator car with a second embodiment of the friction wheel drive. Fig. 4B is a front view of the construction phase elevator car according to Fig. 4A . Fig. 5A a side view of a self-propelled construction phase elevator car with a third embodiment of the friction wheel drive. Fig. 5B a front view of the construction phase elevator car according to Fig. 5A . Fig. 6 a detailed view of a fourth embodiment of the friction wheel drive of a self-propelled construction phase elevator car suitable for carrying out the method according to the invention, with a section through the area shown by the detailed view. Fig. 7 a side view of a self-propelled construction phase elevator car (not claimed as such) with a further embodiment of its drive system, as well as a section through the area of ​​the drive system. Fig. 8 a side view of a self-propelled construction phase elevator car (not claimed as such) with a further embodiment of its drive system, as well as a section through the area of ​​the drive system. Fig. 9 a vertical section through a final elevator system (not claimed as such) with an elevator car and a counterweight, wherein the elevator car and the counterweight are suspended from flexible support means and are driven by a drive machine via these support means.Fig. 10 schematically shows a front view of an elevator car equipped to be centered according to a claimed method. Fig. 11 schematically shows an implementation of a control system for carrying out the claimed method. Fig. 12 schematically shows an alternative embodiment of an implementation for carrying out the claimed inventive method.

[0058] Fig. 1 schematically shows a construction phase elevator system 3.1, which is installed in an elevator shaft 1 of a building 2 during its construction phase and comprises a construction phase elevator car 4, the usable lifting height of which is gradually adjusted to an increasing elevator shaft height. The construction phase elevator car 4 comprises a car frame 4.1 and a car body 4.2 mounted in the car frame. The car frame has car guide shoes 4.1.1, via which the construction phase elevator car 4 is guided on guide rail strands 5. These guide rail strands are extended upwards above the construction phase elevator car from time to time in accordance with the construction progress and, after reaching a final elevator shaft height, also serve to guide a final elevator car (not shown) of a final elevator system, replacing the construction phase elevator car 4.The construction-phase elevator car 4 is designed as a self-propelled elevator car and comprises a drive system 7, which is preferably installed within the car frame 4.1. The construction-phase elevator car 4 can be equipped with different drive systems, each of which comprises a primary part attached to the construction-phase elevator car 4 and a secondary part attached along the travel path of the construction-phase elevator car. In . Fig. 1 The primary part of the drive system 7 is schematically represented by a plurality of friction wheels 8 driven by drive motors (not shown), which interact with the at least one guide rail track 5 forming the secondary part to move the construction phase elevator car 4 up and down within its currently usable lifting height. The drive motors driving the friction wheels 8 can preferably be in the form of electric motors or hydraulic motors. Electric motors are preferably powered by at least one frequency converter system to enable regulation of the speed of the electric motors. This ensures that the travel speed of the construction phase elevator car 4 can be continuously controlled, so that any travel speed between a minimum speed and a maximum speed can be controlled.The minimum speed is used, for example, to control stop positions or for manually controlled movement to raise auxiliary assembly equipment using the construction-phase elevator car, and the maximum speed is used, for example, to operate an elevator for construction workers and for users or residents of the floors already constructed. The speed of hydraulic motors can be controlled accordingly either by feeding them via a hydraulic pump, preferably installed on the construction-phase elevator car 4, whose flow rate can be electrohydraulically controlled at a constant speed, or by feeding them via a hydraulic pump driven by an electric motor whose speed can be controlled by means of a frequency converter.

[0059] The control of the drive motors of the drive system 7 of the construction phase elevator car 4 can be carried out either by a conventional elevator control (not shown) or by means of a mobile hand control 10 - preferably with wireless signal transmission.

[0060] The electric motors of the drive system of the construction-phase elevator car 4 can be supplied via a conductor rail 11 running along the elevator shaft 1. A frequency converter 13 arranged on the construction-phase elevator car 4 can be supplied with alternating current via the conductor rail 11 and corresponding sliding contacts 12, with the frequency converter supplying the electric motors driving the friction wheels 8 or at least one electric motor driving a variable-speed hydraulic pump. Alternatively, a stationary AC-DC converter can feed direct current into such a conductor rail, which is tapped on the construction-phase elevator car via the sliding contacts and fed to the variable-speed electric motors of the drive system via at least one inverter with a controllable output frequency.If the friction wheels 8 are driven by hydraulic motors which are fed by a hydraulic pump with a flow rate that can be controlled at a constant speed, no frequency conversion is required.

[0061] In order to enable the above-mentioned elevator operation for construction workers and floor users, the construction phase elevator car 4 is equipped with a car door system 4.2.1 controlled by the elevator control system, which interacts with shaft doors 20, which are each installed along the additional travel area in the elevator shaft 1 before an adjustment of the usable lifting height of the construction phase elevator car 4.

[0062] In the Fig. 1 In the construction phase elevator system 3.1 shown, an assembly platform 22 is arranged above the currently usable lifting height of the construction phase elevator car 4, which assembly platform can be moved upwards and downwards along an upper section of the elevator shaft 1. From such an assembly platform 22, at least one guide rail strand 5 is extended above the currently usable lifting height of the construction phase elevator car 4, although other elevator components can also be mounted in the elevator shaft 1.

[0063] In the uppermost area of ​​the currently existing elevator shaft 1, a first protective platform 25 is temporarily fixed. This platform has the task, on the one hand, of protecting persons and equipment in the elevator shaft 1 - in particular in the aforementioned assembly platform 22 - from objects that may fall during the construction work taking place on the building 2. On the other hand, the first protective platform 25 can serve as a support element for a lifting device 24, with which the assembly platform 22 can be raised or lowered. Fig. 1 In the embodiment of the construction phase elevator system shown, the first protective platform 25 with the assembly platform 22 suspended therefrom must be raised from time to time by means of a construction crane to a higher level in the currently uppermost area of ​​the elevator shaft in accordance with the construction progress, where the first protective platform 25 is then temporarily fixed.

[0064] Below the assembly platform 22 is Fig. 1 a second protective platform 23 temporarily fixed in the elevator shaft 1 is shown, which protects persons and equipment in the elevator shaft 1 from objects falling from the aforementioned assembly platform 22.

[0065] In the Fig. 1 In the construction phase elevator system 3.1 shown, the self-propelled construction phase elevator car 4 and its drive system 7 are dimensioned such that at least the aforementioned second protective platform 23 can be raised in the elevator shaft 1 by means of the self-propelled construction phase elevator car 4 after the first protective platform 25, with the assembly platform 22 suspended from it, has been raised by the construction crane in order to increase the usable lifting height of the construction phase elevator car. For this purpose, the car frame 4.1 of the construction phase elevator car 4 is designed with support elements 4.1.2, which are preferably provided with damping elements 4.1.3.

[0066] In another possible embodiment of the construction phase elevator system 3.1, both the second protective platform 23 and the assembly platform 22 can be jointly raised by the construction phase elevator car 4 to a level desired for specific assembly work, temporarily fixed there in the elevator shaft 1, or temporarily held by the construction phase elevator car. Since in this case, no lifting device is present for raising the assembly platform 22, this embodiment requires that the construction phase elevator car, in addition to its function of ensuring the aforementioned elevator operation for construction workers and floor users, can be available sufficiently frequently and for a sufficiently long time for raising and, if necessary, for holding the assembly platform 22.

[0067] Fig. 2 shows a construction phase elevator system 3.2, which differs from the construction phase elevator system 3.1 according to Fig. 1 differs in that no construction crane is required to raise the first protective platform 25 and the assembly platform 22. Before each increase in the lifting height of the construction phase elevator car 4, the three components mentioned - first protective platform 25, assembly platform 22, and second protective platform 23 - are raised with the help of the self-propelled construction phase elevator car 4 equipped with a correspondingly powerful drive system, after which the first protective platform 25 is re-fixed in a higher position above the currently uppermost travel area of ​​the construction phase elevator car. At least one spacer element 26 is fixed between the assembly platform 22 and the first protective platform 25 such that a specified distance exists between the first protective platform 25 and the assembly platform 22 before the three components are raised.In the section of the elevator shaft 1 lying within this distance after each lifting of the three components mentioned, the assembly platform 22, which serves to extend the at least one guide rail section 5 and to mount additional elevator components, and the second protective platform 23 can be moved with the aid of the lifting device 24. Advantageously, the at least one spacer element 26 is fastened at its lower end to the assembly platform 22, and the at least one spacer element 26 can slide through at least one opening 27 in the first protective platform 25 associated with the at least one spacer element when the assembly platform is moved by means of the lifting device 24 against the first protective platform 25.Before the aforementioned three components are raised again to increase the lifting height of the construction phase elevator car, the assembly platform 22 and the at least one spacer element 26 are lowered by means of the lifting device 24 until the upper end of the spacer element is just within the aforementioned opening 27 in the first protective platform 25. Thereafter, the upward sliding of the at least one spacer element 26 through the first protective platform 25 is prevented by means of a blocking device—for example, by means of a locking pin 28—so that when the assembly platform 22 is raised again by the self-propelled construction phase elevator car 4, the first protective platform 25 is also raised at the intended distance from the assembly platform 22.

[0068] In Fig. 2 It is also shown that the second protective platform 23 and the assembly platform 22 can advantageously form a unit that can be lifted by means of the self-propelled construction phase elevator car 4, in that the Fig. 1 shown second protection platform 23 to the one in Fig. 2 The mounting platform 22 shown is formed from which at least one guide rail strand 5 can be extended upwards. However, such a combination of protective platform and mounting platform is not absolutely necessary.

[0069] Fig. 3A shows an unused construction phase elevator car 4 in a side view, and Fig. 3B shows this construction phase elevator car in a front view. The construction phase elevator car 4 comprises a car frame 4.1 with car guide shoes 4.1.1 and a car body 4.2 mounted in the car frame, which is intended to accommodate passengers and objects 4. The car frame 4.1 and thus also the car body 4.2 are guided via car guide shoes 4.1.1 on guide rail strands 5. These guide rail strands are preferably attached to the walls of the elevator shaft and - as explained above - form the secondary part of the drive system 7.1 of the construction phase elevator car 4 and later serve to guide the final elevator car of a final elevator system.

[0070] The Fig. 3A und 3B The illustrated drive system 7.1 comprises a plurality of driven friction wheels 8, which interact with the guide rail strands 5 to move the self-propelled construction-phase elevator car 4 along an elevator shaft of a building during its construction phase. The friction wheels are arranged within the car frame 4.1 of the construction-phase elevator car 4, above and below the car body 4.2, with at least one friction wheel acting on each of the opposing guide surfaces 5.1 of the guide rail strands 5. If sufficient space is available between the car body and the car frame for the drive motors, the friction wheels can also be mounted on the side of the car body.

[0071] In the embodiment of the drive system 7 shown here, each of the friction wheels 8 is driven by an associated electric motor 30.1, wherein the friction wheel and the associated electric motor are preferably arranged on the same axis (coaxially). Each of the friction wheels 8 is rotatably mounted coaxially with the rotor of the associated electric motor 30.1 at one end of a pivot lever 32. The pivot lever 32 associated with each of the friction wheels is pivotally mounted at its other end on a pivot axis 33 fixed to the car frame 4.1 of the construction phase elevator car 4 in such a way that the center of the friction wheel 8 lies below the axis line of the pivot axis 33 of the pivot lever 32 when the friction wheel 8 is pressed against the guide surface 5.1 of the at least one guide rail section associated with it. The arrangement of pivot lever 32 and friction wheel 8 is such that a line extending from the pivot axis 33 to the point of contact between friction wheel 8 and guide surface 5.1 is preferably inclined at an angle of 15° to 30° with respect to a normal to the guide surface 5.1. A pre-tensioned compression spring 34 loads the pivot lever 32 such that the friction wheel 8 mounted at the end of the pivot lever is pressed with a minimum contact force against its associated guide surface 5.1. The described arrangement of the friction wheels and the pivot lever ensures that, when the construction phase elevator car 4 is driven in the upward direction, contact forces are automatically generated between the friction wheels 8 and the associated guide surfaces 5.1 of the guide rail track, which contact forces are approximately proportional to the drive force transmitted from the guide surface to the friction wheel. This means that the friction wheels do not have to be constantly pressed as hard as would be necessary to lift the construction phase elevator car 4 loaded with its maximum load and the other components explained above.The risk of flattening of the periphery of the plastic-coated friction wheels as a result of prolonged contact pressure with the maximum required contact force is thus significantly reduced.

[0072] An additional measure to prevent flattening of the plastic friction linings of the friction wheels 8 consists in relieving the friction wheels 8 during each standstill of the construction-phase elevator car 4 by activating a holding brake 37 acting between the construction-phase elevator car and the elevator shaft—preferably between the construction-phase elevator car and the at least one guide rail section 5—and at least reducing the torque transmitted by the drive motors 30 to the friction wheels. A brake designed solely for this purpose or a controllable safety brake can be used as the holding brake.

[0073] To control the travel speed, the electric motors 30.1 are fed via a frequency converter 13, which is controlled by an elevator control system (not shown).

[0074] As can be seen from the Fig. 3A, 3B and the shown detail X, the diameters of the electric motors 30.1 are significantly larger than the diameters of the friction wheels 8 driven by the electric motors. This is necessary so that the electric motors can generate sufficiently high torques to drive the friction wheels. To ensure sufficient installation space for the electric motors 30.1 arranged on both sides of the guide rail track 5, relatively large vertical distances are required between the individual friction wheel arrangements. This means that the installation spaces for the drive system 7.1 and thus the entire cabin frame 4.1 are correspondingly high.

[0075] The Fig. 4A und 4B show a self-propelled construction phase elevator car 4, which is similar to the Fig. 3A und 3B The construction phase elevator car shown is very similar in function and appearance. Shown is a drive system 7.2 with driven friction wheels 8, which allows the use of electric motors whose diameters correspond, for example, to three to four times the friction wheel diameter, without their vertical distance from one another having to be greater than the motor diameter. The height of the installation spaces for the drive system 7.2 can thus be minimized. This is achieved by arranging the electric motors 30.2 of the friction wheels 8 acting on one guide surface 5.1 of a guide rail line 5 offset in the axial direction of the electric motors by approximately one motor length from the electric motors of the friction wheels acting on the other guide surface 5.1. Although the distance between two such electric motors is smaller than their diameters, this measure prevents the installation spaces of these electric motors from overlapping. This is particularly important for... Fig. 4B clearly visible, where it is also shown that the electric motors 30.2 are preferably relatively short and have relatively large diameters. With large motor diameters, the required drive torques for the friction wheels 8 are easier to generate.

[0076] In the Fig. 5A und 5B A self-propelled construction phase elevator car 4 is shown, which is used in the Fig. 3A, 3B and 4A, 4B shown in the construction phase elevator car is very similar in function and appearance. However, the height of the installation spaces for the drive system 7.3 and thus the overall height of the construction phase elevator car is reduced in this embodiment by using smaller drive motors for the friction wheels 8. The vertical distances between the individual friction wheel arrangements are no longer determined by the installation spaces for the drive motors. This is achieved by using hydraulic motors 30.3 instead of electric motors to drive the friction wheels 8. Relative to the total motor volume, hydraulic motors are capable of generating many times higher torques than electric motors. Hydraulic motors can therefore also drive friction wheels with larger diameters, which allow a higher contact force and can therefore transmit a higher traction force.

[0077] Hydraulic drives require at least one hydraulic unit 36, which preferably comprises an electrically driven hydraulic pump. For the supply of the hydraulic motors 30.3, which drive the friction wheels 8 at variable speeds, a hydraulic pump with an electro-hydraulically adjustable displacement driven by an electric motor with a constant speed or a hydraulic pump with a constant displacement driven by an electric motor with a speed controlled by a frequency converter can be used. The hydraulic motors are preferably operated in hydraulic parallel connection. Series connection is, however, also possible. The power supply to the hydraulic unit 36 ​​is preferably via a conductor line, as is the case for the supply of the electric motors in connection with the Fig. 1 und 2 was explained.

[0078] The construction phase elevator car 4 according to the Fig. 5A und 5B is locked in the elevator shaft by holding brakes 37 during a standstill, whereby the drive torques exerted by the hydraulic motors 30.3 on the friction wheels 8 are at least reduced.

[0079] Fig. 6 shows a part of a drive system 7.4 of a self-propelled construction-phase elevator car arranged below the car body 4.2 of this construction-phase elevator car. Shown is an arrangement of a group of several friction wheels 8.1-8.6 rotatably mounted on pivot levers 32.1-32.6 and pressed onto a guide rail line 5 by means of compression springs 34.1-34.6, which arrangement has already been described above in connection with the description of the Fig. 3A und 3B In contrast to the Fig. 3A, 3B , 4A, 4B and 5A, 5B However, in the drive system shown, not each of the friction wheels 8.1 - 8.6 is driven individually by a drive motor assigned to the friction wheel, but the friction wheels 8.1-8.6 are driven by a common motor assigned to the group of friction wheels.

[0080] The drive motor 30.4 is driven via a gear transmission 38 with two counter-rotating drive sprockets 38.1, 38.2 and via a mechanical transmission in the form of a chain transmission arrangement 40. A variable-speed electric motor or a variable-speed hydraulic motor, for example, can be used as the common drive motor. Instead of the chain transmission arrangement 40, other transmission types can also be used, for example, belt transmissions, preferably toothed belt transmissions, gear transmissions, bevel gear-shaft transmissions, or combinations of such transmissions.

[0081] The part of the chain drive assembly 40 shown on the left side of the drive system 7.4 comprises a first chain strand 40.1, which transmits the rotary motion from the drive sprocket 38.1 of the gear drive 38 to a triple sprocket 40.5 mounted on the fixed pivot axis of the uppermost pivot lever 32.1. From this triple sprocket 40.5, the rotary motion is transmitted, on the one hand, by means of a second chain strand 40.2 to a sprocket fixed on the rotation axis of the friction wheel 8.1 and thus to the friction wheel 8.1. On the other hand, the rotary motion is transmitted from the triple sprocket 40.5 by means of a third chain strand 40.3 to a triple sprocket 40.6 arranged below it and mounted on the fixed pivot axis of the middle pivot lever 32.2. From this triple sprocket 40.6, the rotational movement is transmitted by means of a fourth chain strand 40.4 to a chain on the rotational axis of the friction wheel 8.2 and thus to the friction wheel 8.2. On the other hand, the rotational movement is transmitted from the triple sprocket 40.6 by means of a fifth chain strand 40.5 to a triple sprocket 40.7 located below it and mounted on the fixed pivot axis of the lowest pivot lever 32.3. From this triple sprocket 40.7, the rotational movement is transmitted by means of a sixth chain strand 40.6 to a sprocket fixed on the rotation axis of the lowest friction wheel 8.2 and thus to the friction wheel 8.2.

[0082] The part of the chain transmission arrangement 40 shown on the right side of the drive system 7.4 is arranged substantially symmetrically to the above-described part of the chain transmission 40 shown on the left side of the drive system 7 and has the same functions and effects.

[0083] Fig. 7 shows another possible embodiment of a non-claimed, self-propelled construction phase elevator car. This construction phase elevator car 54 comprises a car frame 54.1 and a car body 54.2 mounted in the car frame with a car door system 54.2.1. The car frame 54.1 and thus also the car body 54.2 are guided via car guide shoes 54.1.1 on guide rail strands 5, which guide rail strands are preferably attached to the walls of an elevator shaft. At least one electric linear motor, preferably a reluctance linear motor, serves as the drive system 57 for the construction phase elevator car 54. This linear motor comprises at least one primary part 57.1 attached to the car frame 54.1 and at least one secondary part 57.2 extending along the travel path of the construction phase elevator car 54 and fixed to the elevator shaft. Fig. 8 In the embodiment shown, the construction phase elevator car 54 is equipped with a drive system 57, which comprises a reluctance linear motor on each of two sides of the construction phase elevator car 54, each with a primary part 57.1 and a secondary part 57.2. Each primary part 57.1 contains rows of electrically controllable electromagnets, not shown here, arranged on two sides of the associated secondary part. In the reluctance linear motor, the secondary part 57.2 is a rail made of soft magnetic material, which has projecting areas 57.2.1 at regular intervals on both sides facing the electromagnets of the primary part 57.1. With suitable electrical control of the electromagnets, which control is generally known, maximum magnetic fluxes result between any two adjacent, reversely polarized electromagnets when the existing magnetic resistance is at its lowest, ie when the projecting areas 57.2.1 of the secondary part are located approximately at the center of the magnetic flux between two electromagnets. The magnetic fluxes generate forces that attempt to minimize the magnetic resistance (reluctance) for the magnetic fluxes, resulting in the protruding regions 57.2.1 of the secondary part 57.2, which act like poles, being drawn to the center between two adjacent electromagnets currently carrying maximum current. Several pairs of electromagnets, whose maximum current or magnetic flux occurs at different times, thus generate the driving force required to drive the self-propelled construction-phase elevator car 54.

[0084] In principle, all known linear motor principles can be used as a drive system for a self-propelled elevator car during construction, including linear motors with a large number of permanent magnets arranged along the secondary section as counterpoles to electromagnets controlled by alternating currents in the primary section. However, for self-propelled elevator cars during construction with a large usable lifting height, reluctance linear motors can be implemented at the lowest cost.

[0085] To control such electric linear motors, frequency converters are advantageously used, the operation of which is generally known. Such a frequency converter 13 is shown in Fig. 7 mounted below the car body 54.2 on the car frame 54.1. A holding brake 37 acting between the construction-phase elevator car 54 and the guide rail track 5 also locks the construction-phase elevator car during its standstill in this embodiment 3 64, so that the linear motor of the drive system 17 does not have to be continuously activated and does not overheat.

[0086] Fig. 8 shows another possible embodiment of a non-stressed, self-propelled construction-phase elevator car. This construction-phase elevator car 64 comprises a car frame 64.1 and a car body 64.2 mounted in the car frame. This car body is also provided with a car door system 24.2.1, which interacts with shaft doors on the floors of the building during its construction phase. The car frame 64.1 and thus also the car body 64.2 are guided via car guide shoes 64.1.1 on guide rail strands 5, which guide rail strands are preferably attached to the walls of an elevator shaft. The drive system 67 for the construction phase elevator car 64 is a rack and pinion system, which has as primary part 67.1 at least one pinion 67.1.1 driven by an electric motor or electric gear motor 67.1.2 and as secondary part 67.2 comprises at least one rack 67.2.1 extending along the travel path of the construction phase elevator car 64 and temporarily fixed in the elevator shaft during the construction phase of the building. In the in . Fig. 8 In the illustrated embodiment, the construction phase elevator car 64 is equipped with a drive system 67, which comprises a rack 67.2.1 fixed in the elevator shaft on each of two sides of the construction phase elevator car 64, each of the racks having teeth on two opposite sides. A total of four pairs of driven pinions 67.1.1 interact with the two racks 67.2.1 to move the self-propelled construction phase elevator car 64 up and down in the elevator shaft. Preferably, each of the four pairs of pinions 67.1.1 is driven by an electric gear motor 67.1.2 installed in the car frame 64.1, which preferably has two output shafts 67.1.3 arranged side by side and driven via a distribution gear. Each of the two output shafts is connected via a torsionally flexible coupling 67.1.4 to a shaft of the associated pinion 67.1.1, which is mounted in the cabin frame 64.1.

[0087] This embodiment allows the use of standard motors with sufficient power even when the axes of a pair of pinions are located close to each other. In an alternative embodiment of the pinion-rack system, all pinions 67.1.1 can be driven by an electric motor or electric gear motor assigned to each of the pinions. In both of these embodiments, the use of asynchronous motors ensures that all pinions are driven with the same torque at all times.

[0088] It goes without saying that such a construction phase elevator car 64 can also be equipped with more than four pairs of pinions and associated drive devices. This may be necessary, in particular, if the construction phase elevator car has to lift auxiliary assembly equipment in addition to its own weight, as described above in the description of the Fig. 1 und 2 described.

[0089] Fig. 9 shows a vertical section through a final, unused elevator installation 70. This comprises an elevator car 70.1 and a counterweight 70.2, which are suspended from flexible support means 70.3 and driven via these support means by a stationary drive machine 70.4 with a traction sheave 70.5. The drive machine 70.4 is preferably installed in a machine room 70.8 arranged above the elevator shaft 1. After the elevator shaft 1 has reached its final height, the self-propelled construction phase elevator car (4; 54; 64, Fig. 1-7 ) were dismantled. Subsequently, the elevator car 70.1, the counterweight 70.2, the drive machine 70.4 and the suspension elements 70.3 of the final elevator system 70 were assembled, with the elevator car 70.1 being guided on the same guide rails 5 on which the construction phase elevator car was also guided. Reference numeral 70.6 designates compensating tension elements - for example, compensating ropes or compensating chains - with which a final elevator system 70 is preferably equipped. Such compensating tension elements 70.6 are preferably guided around a tension pulley (not visible here) arranged in the elevator shaft base. However, they can also hang freely in the elevator shaft 1 between the elevator car 70.1 and the counterweight 70.2.

[0090] Fig. 10 shows an elevator car 101, which is attached to a frame 102. In the illustrated embodiment, the elevator car 101 is a construction phase elevator car as described above and below. Figur 10 A horizontal Y-direction 103 and a vertical Z-direction 104 are defined. In the Z-direction, the center plane 105 of the elevator car is also indicated, which in the centered state shown falls on the Z-axis 104. Between the Y-direction 103 and the center plane 105 of the

[0091] Elevator car 101 spans a ϕ-skew angle 106 which, in the centered state of the car shown, is 90°. A first guide rail track 107 is shown, which is located on the left in the figure, and a second guide rail track 108 is shown, which is located on the right in the figure. In the Y direction 103, the car is guided by four passive guide rollers 109, which are attached to the end of the frame 102 on the two guide rail tracks 107, 108. The further the guide rollers 109 are from the car center point (not shown), the better their guiding effect. The elevator car is driven by friction wheels 110. In the exemplary embodiment, a total of twelve friction wheels 110 are shown, each with an electric motor 111.1, 111.2.If the friction wheels 110 are not precisely aligned or the drive force on the two guide rail strands 107, 108 is unequal, a misalignment, i.e., a transverse displacement of the elevator car 101, can occur despite the guide rollers 109. In such a case, the ϕ angle 106 deviates from the 90° shown in the figure. Depending on the type of misalignment, the ϕ angle is either greater or less than 90°. Such a misalignment can lead to large forces on the guide rollers 109.

[0092] To prevent this, four distance sensors S1, S2, S3, S4 are attached to the elevator car 101 in this embodiment. The four distance sensors S1, S2, S3, S4 measure the distance between the car frame 102 and the guide rail strands 107, 108 in the Y direction 103. They are mounted near the guide rollers 109. The distance sensors S1, S2, S3, S4 are designed as eddy current sensors. The signal from the distance sensors S1, S2, S3, S4 is fed to a controller 115, which, depending on the measured values, controls the motors 111.1 and 111.2 in such a way that the transverse displacement and the inclination of the elevator car 101 are compensated. For this purpose, all motors 111.1 which act on the first guide rail strand (left) are controlled with a first rotational speed 112 and all motors 111.2 which act on the second guide rail strand (right) are controlled with a second rotational speed 113.The ΔV speed difference results in a correction of the inclination during the movement of the elevator car 101 in the Z direction 104.

[0093] Fig. 11 shows a schematic description of an inventive control of the lateral position as it is used in an embodiment of the control 115 (see Figur 10 ) is implemented. From the sensor signals, a controller calculates the position deviation 116 in the Y direction of the car center from the center plane between the guide rails and from this the ϕ-slip angle 106.

[0094] The measured value ϕ is always related to the guide rails, i.e. the elevator follows the guide rails.

[0095] In an alternative embodiment (not shown), the ϕ slip angle 106 is measured directly as an absolute value using an inclination sensor.

[0096] The elevator car position is maintained centrally between the rails by the controller. If it is off-center, i.e., if the Z axis is not in the center plane 105 of the elevator car 101, the elevator car 101 is tilted so that it moves backwards depending on the direction of travel. The ϕ-skew angle 106 is a secondary controlled variable. The controller output is the speed or rpm deviations ΔV of the left motors 111.1 and the right motors 111.2 from the V set speed 122 in the vertical direction Z. This results in a first V1 set speed 123 for the left motors and a V2 set speed 124 for the right motors.

[0097] A deviation from the zero position is amplified with a proportional k1 factor 117, and the sign is selected depending on the direction of travel 118. The result is a desired ϕsoll slip angle 119. The deviation from ϕsoll is multiplied by a k2 gain factor 120, resulting in a speed deviation 121 between the left motors 111.1 and the right motors 111.2. This sets the slip angle to the desired value.

[0098] The controller can be refined and expanded as needed. For example, at zero speed, a smooth transition can be selected instead of a sudden change. And at higher speeds, the gain can be reduced to avoid noticeable vibrations. The simple proportional controller can be supplemented with integral and derivative gain.

[0099] Fig. 12shows a further implementation of a controller for implementing a method according to the second aspect of the invention. The ϕ - slip angle 106 is measured directly with an inclination sensor as an absolute value and is passed to the controller as an input value.

Claims

1. Method for centering an elevator car (101) of an elevator system (70), wherein the elevator system (70) comprises a self-propelled elevator car (101), a first guide rail portion (107) and a second guide rail portion (108) for guiding the elevator car (101) along its travel path in the elevator shaft (1), and a drive system (7) which has a primary part (57.1) attached to the elevator car (101) and a secondary part (57.2) attached along the travel path, wherein the primary part (57.1) of the drive system (7) which is mounted for driving the elevator car (101) comprises a plurality of driven friction wheels (8), wherein the elevator car (101) is driven by an interaction of the driven friction wheels (8) with the secondary part (57.2) of the drive system (7) attached along the travel path of the elevator car (101), wherein the first guide rail portion (107) and the second guide rail portion (108) are used as the secondary part (57.2) of the drive system (7) of the self-propelled elevator car (101), wherein at least two driven friction wheels (8) are pressed against each of two opposing guide surfaces (5.1) of the first guide rail portion (107) and the second guide rail portion (108) in order to drive the elevator car (101), characterized in that a first rotational speed of the friction wheels (8) which act on the first guide rail portion (107) and a second rotational speed of the friction wheels (8) which act on the second guide rail portion (108) can be adjusted independently of one another, wherein the first guide rail portion (107) lies in a first plane, wherein the second guide rail portion (108) lies in a second plane which extends substantially in parallel with the first plane, wherein, when in a centered state, a center point of the elevator car (101) is located on a center plane which extends in parallel with the first plane and second plane, wherein, if a deviation of the center point from the center plane is detected, the first rotational speed and / or the second rotational speed is changed such that, when the elevator car (101) moves along the travel path, the center point moves in the direction of the center planes.

2. Method according to the preceding claim, wherein the elevator car (101) comprises at least two distance sensors (S1-S4), in particular in the form of an eddy current sensor and / or an optical triangulation sensor, wherein a first distance sensor (S1) measures a first distance between the elevator car (101) and the first guide rail portion (107) and wherein the second sensor measures a second distance between the car (101) and the second guide rail portion (108), wherein the method controls the first and / or second rotational speed on the basis of the first and the second distance.

3. Method according to either one of the preceding claims, wherein the elevator car (101) comprises at least one inclination sensor, from which an inclination angle (106) of the car (101) with respect to the center plane can be derived, wherein the first and / or second rotational speed is controlled such that, when the elevator car (101) moves along the travel path, the inclination angle (106) changes toward zero.

4. Method according to any one of the preceding claims, wherein the difference between the first rotational speed and the second rotational speed gradually increases or decreases.

5. Method according to any one of the preceding claims, wherein the difference between the first rotational speed and the second rotational speed increases or decreases depending on a horizontal target speed which the elevator car (101) is intended to have in the direction of the travel path.

6. Method according to any one of the preceding claims, wherein the centering of the elevator car (101) toward the center plane is supported by at least two passive guide rollers (109) which are attached to the side of the car (101) and each act on one of the two guide rail portions (5).