EP2840054B1 - Surveillance device for a lift cabin - Google Patents

Description

The invention relates to a monitoring device for an elevator car, an elevator installation with a monitoring device and a method for monitoring an elevator cage. The elevator car can serve for the transport of persons and / or other loads.

From the WO 2012/080103 A1 is a monitoring device for detecting an unintentional driving away of an elevator car from a standstill known. Here, a normal position and a ready position are given. A spring pushes a rocker together with a follower of the monitoring device in the standby position and a solenoid pulls the rocker against the spring force back to the normal position. At a standstill of the elevator car, the monitoring device is switched from the normal position to the standby position. In the standby position, the follower wheel is then pressed against a raceway. When the elevator car moves away from rest, the idler wheel rotates, causing the cam to rotate upwardly and actuate an electromechanical switch. Then, the electromechanical monitoring device is in a release position, whereby a braking device is actuated. Thus, the usual small movements of the elevator car can be collected at a standstill, which arise for example by stretching the suspension means during loading and unloading operations.

From the US 2011/186385 For example, a monitoring device is known in which a rotation disk can be coupled to a first rotation element if required. This allows two different speeds to be monitored for up and down travel.

The from the WO 2012/080103 A1 known monitoring device has the disadvantage that the functionality of the monitoring device depends essentially on the static friction between the idler and the raceway. Contamination by grease, oil, dust and the like may lead to slippage of the follower wheel relative to the track, whereby the predetermined response delay is exceeded. The problem here is that accumulate such contamination over the service life of the Mitlaufrad. Thus, a regular maintenance and cleaning of the known monitoring device is required.

From the EP 0 366 526 B1 a safety brake device is known. Here, a hub is provided which is rotationally driven about a horizontal axis. The hub includes radial guides in which cylindrical flyweights are slidably mounted. The centrifugal weights dip into an oil bath, wherein the radial movement of the centrifugal weights causes the lubrication for the sliding movement in the guides. Depending on the speed of the hub results in a height to get to the flyweights. A rupturable approach of the device is placed close to the transition trajectory according to the limit speed at which it is desired to initiate the safety brake. One of the centrifugal weights then serves as a striking element, which breaks the approach, whereby the braking device is actuated. Restore is accomplished by replacing the broken neck and building pressure with a hand pump.

The from the EP 0 366 526 B1 known safety brake device has the disadvantage that the structure is complex and a reset requires considerable effort. Also, a regular check and possibly a timely oil change is required.

The object of the invention is to provide a monitoring device for an elevator car and an elevator installation with a monitoring device, which are designed improved. Specifically, it is an object of the invention to provide a monitoring device and an elevator installation with a monitoring device, in which an activation and deactivation of the monitoring in a reliable and low maintenance possible manner and wherein over the operating time preferably as constant as possible triggering behavior is ensured.

In the following, solutions and proposals for a corresponding monitoring device and an elevator system are presented, which solve at least parts of the task. In addition, advantageous additional or alternative developments and refinements are given.

The proposed monitoring device for an elevator car includes a sensor device and a switching device. The switching device is of the Sensor device actuated. Further, a drive wheel is provided which rotates upon movement of the elevator car. The sensor device can be coupled at least indirectly to the drive wheel by means of a coupling device. Thus, if necessary, the sensor device can be simply coupled to the drive wheel. The coupling point is permanently definable and thus largely protected from influences such as contamination or oiling.

The elevator car is not part of the monitoring device of the invention. However, parts of the elevator car, in particular a carrier or a mounting plate, may also be components of the monitoring device. This is particularly advantageous when the monitoring device is retrofitted. For example, when the monitoring device is mounted, an operating cable serving as the actuating means drives the driving wheel of the monitoring device, and it can run in a groove of the driving wheel to give a reliable driving of the driving wheel. As an actuating means, for example, a speed limiter cable of the elevator system is suitable. At best, this can be a speed limiter cable of a speed limiter which is already present in the system. Thus, the monitoring device is ideal for retrofitting in a lift system.

The sensor device serves to actuate the switching device. The actuation of the switching device can be effected in a mechanical manner, in particular by a switching disk of the sensor device. However, an operation is possible in other ways, such as electrical or optoelectronic. This is advantageous because with the possibility of a simple mechanical operation, an energy-independent system can be provided.

The sensor device can be coupled via the coupling device at least indirectly with the drive wheel. The coupling is advantageously carried out in the axial direction. The sensor device is thus arranged on a common axis with the drive wheel, whereby a simple and compact design is possible. In this case, the sensor device can be coupled directly to the drive wheel via the coupling device. However, the sensor device can also be indirectly coupled to the drive wheel via the coupling device, in particular via a transmission. In the coupled state can thereby the switching disc in a certain translation with the Rotate the drive wheel. The translation can be done in a ratio of 1: 1, which can be realized by a direct connection. If a gear is provided, then other translations can be realized. Thus, a behavior and a sensitivity of the monitoring device can be influenced.

It is advantageous that the sensor device is designed as a displacement sensor, wherein the sensor device actuates the switching device after a predetermined travel path of the elevator car when the sensor device is at least indirectly coupled to the drive wheel by means of the coupling device. As a result, a travel limit can be realized when the elevator car is at a standstill. In normal operation, for example, when the elevator car is traveling from a floor to a destination floor, the coupling between the sensor device and the drive wheel can be opened. This deactivates the path limitation. The drive wheel still rotates during the movement of the elevator car. Thus, the contact of the drive wheel with an actuating means, in particular an operating cable, always maintained. Thus, a reliable drive of the drive wheel can be realized, which is independent of the activation or deactivation of the sensor device. The coupling device can be protected in a suitable manner against the environment and thus against possible contamination. Furthermore, the coupling device can thereby be designed robust and independent of a cooperation with the actuating means.

It is also advantageous that the sensor device has a rotatable indexing disk, that the switching device is at least indirectly operable by the indexing disk when the indexing disk is rotated, and that the indexing disk rotates in a specific ratio with the traction wheel, if the sensor device at least indirectly engages by means of the coupling device coupled to the drive wheel. The switching disk can actuate the switching device at least indirectly in the coupled state. In this case, the switching disk preferably actuates a switch of the switching device with a switching curve or an approach provided on the switching disk approach. However, in this case also an indirect operation is possible, which is possible via a pin, optoelectronic or the like.

In a modified embodiment, it is also advantageous that the sensor device is designed as a speed sensor, wherein the Sensor device actuates the switching device when a speed of the elevator car exceeds a predetermined limit speed and the sensor device is coupled by means of the coupling device at least indirectly with the drive wheel. Specifically, the speed sensor can be deactivated during a normal drive of the elevator car. At a standstill of the elevator car or a special drive, the speed sensor can be activated by the clutch between the sensor device and the drive wheel is closed. One possible application is the speed monitoring during a positioning run of the elevator car. For example, the elevator car can be used to carry loads and be driven to a certain level with the door open. Such a level may be determined by a cargo bed of a truck. While the elevator car is moved to the level of the loading area, the sensor device designed as a speed sensor is active by closing the clutch. Misbehavior can now occur, for example, in that a heavy item to be transported from the truck is driven by means of a lift truck into the elevator car, whereby the elevator car is overloaded. This leads to an acceleration of the elevator car. By specifying a suitable limit speed early emergency braking can be initiated. Such a limit speed may be, for example, in a range of about 0.1 m / s to about 0.3 m / s. Thus, a high level of security can be ensured even in such applications. In particular, this makes possible a regulation in which a travel path of the elevator car to a suitable level is comparatively large, in particular greater than 50 cm.

In this case, it is also advantageous that the sensor device has a rotatable indexing disk, that the indexing device can be actuated at least indirectly by the indexing disk when the indexing disk is rotated. Furthermore, it is also advantageous that a speed wheel is provided which rotates in a specific ratio with the drive wheel due to the at least indirect coupling with the drive wheel when the sensor device is coupled to the drive wheel by means of the coupling device and that the speed wheel at least indirectly entrains the shift wheel, if a speed of the elevator car exceeds a predetermined limit speed. In this case, driving body, in particular rolling bodies, may be provided, which are arranged in associated driving body receptacles, in particular rolling body receptacles, the speed wheel. Such Carrying body are preferably arranged on a certain radius of the speed wheel and evenly distributed over the circumference. One of the driving body then passes due to its centrifugal force against gravity partly from the driving body receiving and thereby rotates the switching disc when the speed of the elevator car exceeds the predetermined limit speed. Specifically, due to its centrifugal force, a rolling element may partly roll out of the rolling element receptacle against the force of gravity and take the switching disk to rotate the switching disk when the speed of the elevator car exceeds the predetermined limit speed.

In this case, it is also advantageous that the predetermined limit speed by the specific ratio in which the speed wheel rotates with the drive wheel, a radius of the drive wheel on which the drive wheel is driven, and the radius of the speed wheel on which the driving body in the driving body shots the speed wheel are arranged, is given. As a result, a geometric specification of the limit speed is possible.

Furthermore, it is advantageous that the coupling device closes the coupling between the sensor device and the drive wheel by the spring force of a spring. The opening of the clutch can be effected via an electromagnet, which opens in the energized state, the coupling between the sensor device and the drive wheel against the spring force. Since the travel times of the elevator car generally have a comparatively small proportion of the total operating time, the mode of operation of the monitoring device is thereby optimized with regard to energy consumption and heat generation. Furthermore, at the same time the reliability is increased, since in case of failure of the electromagnet or the energization of the electromagnet, the clutch is automatically closed, whereby the sensor device is active.

Specifically, a control device may be provided which energizes the electromagnet during normal driving. The predetermined limit speed can be predetermined smaller than the travel speed during normal driving. Thus, when the elevator car is at a standstill and / or during a positioning run, the electromagnet can not be energized in order to activate the sensor device.

Further, it is advantageous that the monitoring device is mounted on the elevator car, wherein the drive wheel of the monitoring device so cooperates with the actuating means or the speed governor rope, that the drive wheel rests on the radius at which the actuating means and the Begrenzsbegrenzerseil on the drive wheel with the double speed of the elevator car is driven in rotation. Thus, already a higher rotational speed of the drive wheel can be achieved. This allows a more compact design and optionally a simplified design of the transmission. This is preferably achieved in that the monitoring device is arranged on the elevator car on a continuous part of the speed governor cable. The speed limiter cable is connected at the elevator car to an operating lever of a catching device. It runs from the actuating lever to a speed limiter usually arranged in an upper region of the elevator, extends therefrom - in the continuous part - along the elevator car to a tensioning roller arranged in the lower region of the elevator and from there back to the actuating lever. This speed limiter ensures, for example, the elevator car against excessive speed in the downward direction. The part of the overspeed governor which passes through from the governor to the idler pulley accordingly runs past the elevator car at twice the relative speed. Accordingly, the drive wheel arranged on this continuous part of the speed governor cable already rotates at twice the speed of the elevator car.

The elevator installation can also have several monitoring devices. Specifically, a monitoring device may comprise a sensor device which is designed as a displacement sensor. Another monitoring device may comprise a sensor device, which is designed as a speed sensor. In a variant, which is particularly provided for retrofitting in an existing elevator installation, the monitoring device includes on the one hand a speed sensor which is permanently coupled or connected to the drive wheel and on the other hand, a sensor device in the form of a displacement sensor is temporarily coupled to the drive wheel, as before described. The speed sensor is designed here to a driving limit speed at an upward travel of the To detect elevator car and to operate when exceeding the same the switching device. The couplable displacement sensor is designed to be coupled with the drive wheel at a stop of the elevator car and then monitor any uncontrolled driving away the elevator car from the floor and, if necessary, preferably to operate the same switching device. This embodiment is useful in the retrofitting of old equipment, since such systems often have only one acting in the downward direction speed limiter. With the proposed embodiment, the monitoring device can be arranged on the elevator car on the continuous part of the existing speed governor rope. Thus, the safety of the elevator system can be increased.

If the switching device is actuated by the sensor device, then a braking, in particular an emergency braking, usually triggered as a safety measure. Depending on the application and design, however, other or additional security measures are conceivable.

• Fig. 1 eine Aufzugsanlage mit einer Überwachungsvorrichtung entsprechend einem ersten Ausführungsbeispiel der Erfindung in einer auszugsweisen, schematischen Schnittdarstellung;
• Fig. 2 einen schematischen Schnitt durch die in Fig. 1 dargestellte Überwachungsvorrichtung des ersten Ausführungsbeispiels der Erfindung;
• Fig. 3 eine Überwachungsvorrichtung in einer schematischen Darstellung zur Erläuterung der Funktionsweise möglicher Ausgestaltung der Erfindung;
• Fig. 4 ein Diagramm zur Erläuterung der Funktionsweise möglicher Ausgestaltungen der Erfindung;
• Fig. 5 einen schematischen Schnitt durch die in Fig. 1 dargestellte Überwachungsvorrichtung entsprechend einem zweiten Ausführungsbeispiel der Erfindung und
• Fig. 6 einen schematischen Schnitt durch die in Fig. 1 dargestellte Überwachungsvorrichtung entsprechend einem dritten Ausführungsbeispiel der Erfindung.

Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings, in which corresponding elements are provided with corresponding reference numerals, and the accompanying formulas. Show it:

• Fig. 1 an elevator installation with a monitoring device according to a first embodiment of the invention in an excerpt, schematic sectional view;
• Fig. 2 a schematic section through the in Fig. 1 illustrated monitoring device of the first embodiment of the invention;
• Fig. 3 a monitoring device in a schematic representation for explaining the operation of possible embodiment of the invention;
• Fig. 4 a diagram for explaining the operation of possible embodiments of the invention;
• Fig. 5 a schematic section through the in Fig. 1 shown monitoring device according to a second embodiment of the Invention and
• Fig. 6 a schematic section through the in Fig. 1 illustrated monitoring device according to a third embodiment of the invention.

Fig. 1 shows an elevator system 1 with a monitoring device 2 in a partial, schematic sectional view. The elevator installation 1 of the exemplary embodiment has an elevator shaft 3, which is accommodated, for example, in a building 4. In the building 4 access 5, 6, 7 are provided, via which a person 8 in an elevator car 9 of the elevator system 1 board and later can get off again. At the entrances 5 to 7 shaft doors can be provided. Furthermore, the elevator car 9 may have a suitable door. The elevator car 9 can also serve to transport other loads. Embodiments of the elevator installation 1 are also conceivable which serve exclusively for transporting loads in the form of goods or things.

A suspension of the elevator car 9 with traction and suspension means, a prime mover, suitable brake and guide rails and the like are not shown for ease of illustration.

In a specific application, the elevator installation 1 can also be provided on a ramp or the like in order to simplify loading and unloading of loads, in particular pallets loaded with goods, into or out of a lorry. In such a case, positioning of the elevator car 9 can also take place at a level of the loading area of the truck. Thus, the loading and unloading is considerably facilitated with respect to different loading areas of the truck. A corresponding application is the loading and unloading of a freight wagon.

The monitoring device 2 can be designed as a retrofittable monitoring device 2. In this embodiment, the monitoring device 2 is mounted on a support 10 which is fixedly connected to the elevator car 9. During a travel of the elevator car 9 through the elevator shaft 3 thus the monitoring device 2, which is attached to the carrier 10, moves together with the Elevator car 9 through the elevator shaft 3.

The monitoring device 2 cooperates with an actuating means 11, an upper guide roller 12 and a lower guide roller 13. The actuating means 11 is formed in this embodiment as an operating cable 11. However, the actuating means 11 can also be configured in other ways, in particular in the form of an actuating belt.

In addition, the actuating means 11 may also be formed of a plurality of operating cables and / or operating belt or the like, which run parallel to each other. Alternatively, the actuating means 11 may also be a Geschwindigkeitsbegrenzerseil which is guided via a speed limiter as the upper guide roller 12 and a tension roller as the lower guide roller 13, and which is moved by the elevator car.

The actuating means 11 is guided around the upper guide roller 12 and around the lower guide roller 13. Here, the upper guide roller 12 is disposed in an upper portion of the elevator shaft 3 in the vicinity of a ceiling 14. The lower guide roller 13 is disposed in a lower portion of the elevator shaft 3 near a bottom 15.

The actuating means 11 is divided by the guide rollers 12, 13 in a carrier-fixed part 17 and a running part 18. The carrier-fixed part 17 of the actuating means 11 is connected via a connecting element 19 with the carrier 10. When using the Geschwindigkeitsbegrenzerseils as actuating means 11 this is connected via the connecting element 19 to an actuating lever of a catching device. Normally, the carrier-fixed part 17 of the actuating means 11 moves with the elevator car 9. When the elevator car 9 moves through the elevator shaft 3, then there is a relative movement between the running part 18 of the actuating means 11 and the carrier 10.

angegeben ist. Wenn die Geschwindigkeit vK der Aufzugskabine 9 verschwindet, dann verschwindet auch die Sensorgeschwindigkeit vS.The elevator car 9 moves, for example, through the elevator shaft 3 at a speed vK. Depending on the speed vK of the elevator car 9, a relative speed vS results between the running part 18 of the elevator car The speed vS serves as a sensor speed vS for the monitoring device 2. The sensor speed vS is in this case twice as large as the speed vK of the elevator car 9, as determined by the $$\mathrm{vS}=2*\mathrm{v\; K}$$

is specified. When the speed vK of the elevator car 9 disappears, the sensor speed vS.

In a modified embodiment of the carrier-solid part 17, the upper guide roller 12 and the lower guide roller 13 may also be omitted. Then only the part 18 of the actuating means 11 is provided, which is fixed on the one hand in the area of the ceiling 14 and on the other hand in the region of the bottom 15. In this modified embodiment, the sensor speed vs is then equal in magnitude to the speed vK of the elevator car 9.

In the following, the case of the first exemplary embodiment will be considered, in which the relationship between the sensor speed vS and the speed vK of the elevator car 9 given in formula (1) exists.

Fig. 2 shows a schematic section through the in Fig. 1 illustrated monitoring device 2 of the first embodiment of the invention. The monitoring device 2 has a housing 20 which is connected to the carrier 10. In the housing 20, an axle 21 is rotatably mounted. As a result, a rotation of the axis 21 about a rotation axis 22 is made possible. The monitoring device 2 also has a drive wheel 23 with a groove 24. In the groove 24, the actuating means 11 is guided. Depending on the speed vS thereby rotates the drive wheel 23. Between the drive wheel 23 and the axis 21, a bearing 25 is provided. Further, a gear 26 is provided between the drive wheel 23 and the axis 21, via which the drive wheel 23 drives the axis 21. Thus, the drive wheel 23 rotates upon movement of the elevator car 9, whereby the axis 21 rotates.

On the axis 21, a sliding bush 27 is arranged, which is displaceable along the axis of rotation 22. The sliding bush 27 is acted upon by the spring force of a spring element 28 in a direction 29. Furthermore, a speed wheel 30 is provided. The Speed wheel 30 is mounted on the sliding bushing 27 via a bearing 31. In this case, the spring force of the spring element 28 is transmitted from the sliding bush 27 via the bearing 31 on a shoulder 32 of the speed wheel 30 to the speed wheel 30. Thus, the speed wheel 30 is urged in the direction 29 by the spring element 28.

The axle 21 has a shoulder 33. At the shoulder 33, a friction surface 34 is configured. On a friction surface 34 facing side 35 of the speed wheel 30, a friction surface 36 of the speed wheel 30 is further configured. The friction surface 34 of the axis 21 and the friction surface 36 of the speed wheel 30 are in this case components of a coupling 40 of a coupling device 41 of the monitoring device 2.

In the in the Fig. 2 illustrated initial position, the friction surfaces 34, 36 cooperate so that a frictional connection or frictional engagement between the speed wheel 30 and the axis 21 exists. Thus, the clutch 40 is closed. The pressure force required for this purpose can be adjusted by the choice of the spring element 28. When the clutch 40 is closed, the speed wheel 30 thus rotates together with the axle 21.

Furthermore, a sliding bearing 42 is provided between the speed wheel 30 and the housing 20. As a result, the speed wheel 30 is guided along the axis of rotation 22 or in and against the direction 29 and aligned reliably with respect to the axis of rotation 22. The speed wheel 30 can be so in the axial direction to the drive wheel or put away.

The coupling device 41 also has an electromagnet 43 with a magnetic coil 44. Between the electromagnet 43 and the speed wheel 30, an air gap 45 is provided in the initial position shown. When the solenoid coil 44 is energized, then the electromagnet 43 attracts the speed wheel 30 counter to the direction 29. The electromagnet 43 thus acts against the spring force of the spring element 28. The electromagnet 43 is designed so that the spring force of the spring element 28 is overcome, whereby the coupling 40 between the friction surface 36 of the speed wheel 30 and the friction surface 34 of the axis 21 is opened.

Depending on the application and the design of the monitoring device 2, when the magnetic coil 44 is energized, a releasable connection, which is non-positive and / or positive, between an end face 46 of the speed wheel 30 and a side surface 47 of the electromagnet 43 can come about. By such a connection, a standstill of the speed wheel 30 is enforced relative to the housing 20. For example, 47 can be made possible by locking a positive connection between the end face 46 and the side surface, which is made possible for example by a small toothing.

A possible application is that the clutch 40 is closed at a standstill and possibly also during a slow ride, in particular a positioning drive, the elevator car 9, while in a normal drive, the clutch 40 is open. At a standstill, the clutch 40 can then be opened, so that the relative speed between the speed wheel 30 and the electromagnet 43, which is connected to the housing 20, disappears or is only very small. In this case, the relative speed between the speed wheel 30 and the housing 20 is understood to be an angular speed. Thus, in this application, the positive connection can be made. In order to reduce the component stress, which is useful especially at relatively high relative speeds, a pure frictional connection via friction surfaces or the like can be realized between the end face 46 and the side surface 47. Thus, for example, can be switched directly from a positioning drive in a normal drive.

When the solenoid 43 is active, the clutch 40 is opened and the speed wheel 30 is stationary relative to the housing 20. As a result, the monitoring device 2 is deactivated. In this case, however, the axis 21 rotates in a fixed ratio i to the drive wheel 23. The ratio i is predetermined by the gear 26. By means of a suitable sensor, in particular a rotation angle sensor, the speed of the elevator car 9 can then be detected with correspondingly high accuracy even during normal driving.

angegebene Zusammenhang. Da die Sensorgeschwindigkeit vS in diesem Ausführungsbeispiel dem in Formel (1) angegebenen Zusammenhang genügt, ergibt sich für die Winkelgeschwindigkeit ω₁ des Treibrads 23 der in $$\mathrm{w}1=\frac{2\ast \mathrm{vK}}{\mathrm{R}}$$

angegebene Zusammenhang.When the clutch 40 is closed, the speed wheel 30 rotates with the axis 21. Die Angular velocity ω _{1 of} the drive wheel 23 results from the sensor speed v S and the radius R of the drive wheel 23, on which the drive wheel 23 is driven by the actuating means 11. The radius R results in this embodiment with respect to the running surface in the groove 24. For the angular velocity ω _{1 of} the drive wheel 23 thus results in in $$\mathrm{<figure-callout\; id="1"\; label="w"\; filenames="imgf0001.png"\; state="\{\{state\}\}">w</figure-callout>}1=\frac{\mathrm{vS}}{\mathrm{R}}$$

specified context. Since the sensor speed vS in this embodiment satisfies the relationship given in formula (1), the angular velocity ω _{1 of} the drive wheel 23 is given by the in $$\mathrm{<figure-callout\; id="1"\; label="w"\; filenames="imgf0001.png"\; state="\{\{state\}\}">w</figure-callout>}1=\frac{2*\mathrm{v\; K}}{\mathrm{R}}$$

specified context.

angegebene Zusammenhang. Hierbei ist in der Formel (4) auch der Zusammenhang der Winkelgeschwindigkeit ω2 des Geschwindigkeitsrades 30 mit der Geschwindigkeit vK der Aufzugskabine 9 angegeben, was sich aus dem in Formel (3) angegebenen Zusammenhang ergibt.When the clutch 40 is closed results between the angular velocity ω _{2 of} the speed wheel 30 and the angular velocity ω _{1 of} the drive wheel 23 of in $$\mathrm{<figure-callout\; id="2"\; label="w"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">w</figure-callout>}2=\mathrm{i}*\mathrm{<figure-callout\; id="1"\; label="w"\; filenames="imgf0001.png"\; state="\{\{state\}\}">w</figure-callout>}1=\mathrm{i}*\frac{2*\mathrm{v\; K}}{\mathrm{R}}$$

specified context. In this case, the relationship of the angular velocity ω2 of the speed wheel 30 with the speed vK of the elevator car 9 is indicated in the formula (4), which results from the relationship indicated in formula (3).

Fig. 3 shows the monitoring device 2 in a schematic representation for explaining the operation of possible embodiments of the invention. The speed wheel 30 has as a rolling body receptacles 48, 49, 50, 51 designed driving body receptacles 48 to 51. In the Rollkörperaufnahmen 48 to 51 of the speed wheel 30 as a rolling body 52,53, 54, 55 designed driving body 52 to 55 are arranged. The rolling bodies 52 to 55 are in this case arranged on a radius r of the speed wheel 30 in the rolling body receptacles 48 to 51. In the reference frame of the monitoring device 2, the rolling bodies 52 to 55 move along a movement path 56 during operation. In this case, the rolling bodies 52 to 55 move at angular velocity ω2 of the speed wheel 30 along the movement path 56. The angular velocity ω2 is represented by the formula (4). with respect to the angular velocity ω1 of the driving wheel 23 and the speed vK of the elevator car 9, respectively, when the clutch 40 of FIG Coupling device 41 is closed.

The monitoring device 2 also has a switching disk 60. On the switching disk 60, a switching cam 61 is provided on a switching cam part 62. Furthermore, the monitoring device 2 has a switching device 63 with a switch 64.

To explain the mode of operation, the roller body 52 with the mass m is considered below by way of example when the speed wheel 30 rotates at the angular speed ω2. Over time, this consideration also applies to the other rolling elements 53, 54, 55.

angegeben ist. Somit beschreibt die Formel (5) die Auslösebedingung für die Überwachungsvorrichtung 2, wenn diese als Geschwindigkeitssensor 2 arbeitet.As long as the rolling body 52 is on the movement path 56, it acts on the one hand, the centrifugal force FZ and on the other hand, the weight FG. The speed limit by the monitoring device 2 becomes active when the rolling body 52 enters an open recess 65 of the indexing disk 60 and abuts in the sequence on a driving stop 66. The open recess 65 is open in the illustrated starting situation down. The condition for the speed limit is, therefore, that the centrifugal force FZ becomes greater than the weight force FG as determined by the $$\mathrm{FZ}>\mathrm{FG}$$

is specified. Thus, the formula (5) describes the trigger condition for the monitoring device 2 when operating as the speed sensor 2.

angegeben ist.The centrifugal force FZ depends on the angular velocity ω2 of the speed wheel 30, the radius r of the speed wheel 30 and the mass m of the rolling body 52, as indicated by the $$\mathrm{FZ}=\mathrm{<figure-callout\; id="2"\; label="w"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">w</figure-callout>}{2}^2*\mathrm{r}*\mathrm{m}$$

is specified.

angegeben ist.The weight force FG depends on the mass m of the rolling body 52 and the gravitational acceleration g, as determined by the $$\mathrm{FG}=\mathrm{m}*\mathrm{G}$$

is specified.

angegebene Ungleichung. Die auf der rechten Seite der in Formel (8) angegebene Ungleichung bestimmte Größe kann als Grenzgeschwindigkeit vG definiert werden. Überschreitet die Geschwindigkeit vK der Aufzugskabine 9 diese Grenzgeschwindigkeit vG, dann ist die Bedingung gemäß Formel (5) erfüllt, so dass der Rollkörper 52 in die nach unten offene Ausnehmung 65 rollt. Dann verlässt der Rollkörper 52 die Bewegungsbahn 56, die den Radius r hat.By inserting the centrifugal force FZ according to formula (6) and the weight force FG according to formula (7) into the inequality according to formula (5), it follows that the triggering condition for the speed limit is independent of the mass m of the rolling body 52. Taking into account the relationship given in formula (4), the triggering condition with respect to the speed vK of the elevator car 9 is the in $$\mathit{v\; K}>\frac{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">R</figure-callout>}}{2*i}*\sqrt{\frac{G}{r}}=\mathit{vG}$$

given inequality. The quantity determined on the right side of the inequality given in formula (8) can be defined as limit speed vG. If the speed vK of the elevator car 9 exceeds this limit speed vG, then the condition according to formula (5) is fulfilled so that the rolling body 52 rolls in the downwardly open recess 65. Then, the rolling body 52 leaves the movement path 56 having the radius r.

When the rolling body 52 enters the recess 65, then the rolling body 52 abuts against the driving stop 66. As a result, the speed wheel 30 takes the switching disk 60 with it. Thus, the indexing disk 60 rotates in the direction of the angular velocity ω1. After passing through a predetermined angle of rotation 67, the switching cam 61 or the switching cam portion 62 actuates the switch 64 of the switching device 63. By the operation of the switch 64, a predetermined measure, in particular a braking initiated.

Thus, the limit speed vG for the elevator car 9 according to formula (8) can be specified. The predetermined limit speed vG can be arranged by the ratio i of the transmission 26, the radius R of the drive wheel 23 on which the drive wheel 23 is driven, and the radius r of the speed wheel 30 on which the rolling bodies 52 to 55 in the rolling body receptacles 58 to 51 are, be given. The specification of the limit speed vG is thus given geometrically. Thus, a robust detection is feasible, which does not require a secure electronics, which is expensive.

The indexing disk 60 is mounted in a suitable manner on the housing 20 in this embodiment.

Thus, a sensor device 70 can be realized. In this case, the sensor device 70 can be designed as a speed sensor 70b. Then, the sensor device 70 has the speed wheel 30, the rolling bodies 52 to 55 and the indexing disk 60. The sensor device 70 actuates the switching device 63 when the speed vK of the elevator car 9 exceeds the predetermined limit speed vG and the sensor device 70 is coupled by means of the coupling device 41 via the gear 26 to the drive wheel 23. For this purpose, the sensor device 70 may have the rotatable switching disk 60, wherein the switching device 63 can be actuated when the switching disk 60 is rotated by the switching cam 61 of the switching disk 60. However, the actuation of the switching device 63 can also be done in other ways in a modified embodiment. Furthermore, the speed wheel 30 rotates in the specific ratio i with the drive wheel 23 when the sensor device 70 is coupled to the drive wheel 23 by means of the coupling device 41. The speed wheel 30 then takes the switching disk 60 by means of one of the rolling bodies 52 to 55, when the speed vK of the elevator car 9 exceeds the predetermined limit speed vG and the speed wheel 30 rotates due to the coupling with the drive wheel 23 in the specific ratio i with the drive wheel 23 ,

In a modified embodiment, the sensor device 70 can be coupled by the coupling device 41 with a ratio of 1: 1 with the drive wheel 23.

Fig. 4 shows a diagram for explaining the operation of a possible embodiment of the invention. The speed vK of the elevator car 9 is plotted on the abscissa of the diagram. On the ordinate, the centrifugal force FZ and the weight FG, which act on the roller body 52 with the mass m, are shown. Furthermore, a sensor signal S is plotted on the ordinate, which describes a stroke of the rolling body 52 from its rolling body seat 58 into the recess 65 of the indexing disk 60 as a result of the centrifugal force FZ. The in the diagram of Fig. 4 Values entered here are in each case snapshots, when the rolling body 52 is in its movement at the highest point of the movement path 56, as in the Fig. 3 is shown.

At speeds vK of the elevator car 9, which are significantly below the limit speed vG defined according to formula (8), the rolling element 52 is located on the radius r of the movement path 56, wherein no stroke of the rolling element 52 occurs. Thus, the sensor signal S disappears. This is because the centrifugal force FZ for such speeds is less than the constant weight force FG.

In the area of the limit speed vG, a triggering occurs in which the rolling body 52 rolls in the downwardly open recess 65. In this case, the centrifugal force FZ outweighs the weight force FG when the speed vK of the elevator car 9 exceeds the limit speed vG. Thus, the sensor signal S in the range of the limit speed vG acts as a trigger signal for triggering the switching device 63. At least theoretically, the diagram can also be continued to the right for speeds vK, which are significantly greater than the limit speed vG. In practice, however, a further increase is prevented by the triggering of the switching device 63. In particular, by increasing the number of the rolling bodies 52 to 55, which are arranged uniformly distributed over the circumference in the rolling body receptacles 48 to 51 of the speed wheel 30, the triggering time can be reduced. This also limits the possible increase in the speed vK of the elevator car 9 in practice.

Specifically, in a distinction between a normal drive and a positioning drive, in which the speed limit is to be active, the limit speed vG can be selected smaller than the normal driving speed. In a normal drive, the sensor device 70 is deactivated by opening the clutch 40, so that higher speeds vK of the elevator car 9 than the limit speed vG are possible without any limitation. For a positioning drive or at standstill, the sensor device 70 is activated by closing the clutch 40. Then, the monitoring device 2 monitors whether the speed vK of the elevator car 9 is smaller than the limit speed vG.

Fig. 5 shows a schematic section through the in Fig. 1 illustrated monitoring device 2 according to a second embodiment of the invention. In this embodiment, the monitoring device 2 acts alone as a way limitation. The axle 21 may be mounted firmly in the housing 20 in this embodiment. The spring element 28 acts on the indexing disk 60 via an element 75 with the spring force. Further, a guide bushing 76 is provided between the switching disc 60 and the electromagnet 43 with the solenoid coil 44. In the in the Fig. 5 illustrated starting position between the solenoid 43 to the solenoid 44 and the switching disk 60 air gaps 77, 78 are provided which allow movement of the switching disk 60 against the direction 29. When the magnetic coil 44 of the electromagnet 43 is energized, then close the air gaps 77, 78 at least partially, the switching disc 60 is adjusted against the spring force of the spring element 28.

The indexing disk 60 has a friction surface 80 on its end face 79. Further, the rotatably mounted on the axis 21 of the drive wheel 23 has a friction surface 81 which faces the end face 79 of the switching disk 60 and cooperates with the friction surface 80 of the switching disk 60. The friction surface 80 of the indexing disk 60 and the friction surface 81 of the drive wheel 23 are components of the coupling 40 of the coupling device 41st

In the in the Fig. 5 illustrated initial position are the friction surfaces 80, 81 to each other, so that the clutch 40 is closed. In this case, the coupling 40 is acted upon by the spring force of the spring element 28. A rotation of the drive wheel 23 thus acts directly in an equal rotation of the indexing disk 60. Thus, in a corresponding modification, for example, a rotation angle 67 can be predetermined, as it is based on the Fig. 3 is illustrated. The predetermined rotation angle 67 then represents the limit for a rotation of the drive wheel 23. In this case, the same rotation angle 67 can be predetermined in each case in relation to the two possible directions of rotation.

This sensor device 70 then serves as a displacement sensor 70a, which delimits a movement of the elevator car 9 wegmäßig. The travel limit can be specified here by the radius R of the drive wheel 23 and the rotation angle 67.

When the solenoid 44 of the solenoid 43 is energized, then the clutch 40 is opened. In this case, between a front side 82 of the indexing disk 60 and the side surface 47 of the electromagnet 43, a positive and / or positive connection can be predetermined with the coupling 40 open. This can, for example, by friction surfaces the end face 82 and on the side surface 47 can be realized. In the open state of the clutch 40 thus the switching disc 60 is still with rotating drive wheel 23 still. Alternatively, the indexing disk 60 is designed such that a weight or a spring puts the indexing disk 60 in a neutral position. Thus, the switching disk 60 is always in a predetermined neutral position with the clutch 40 open. As a result, a normal drive can be performed. In the case of a subsequent standstill or a positioning movement of the elevator car 9, the travel limitation by the sensor device 70 is then active when the energization of the magnet coil 44 ends and thus the clutch 40 is closed.

Thus, in this exemplary embodiment, the sensor device 70 is designed solely as a displacement sensor 70a, wherein the sensor device 70 actuates the switching device 63 after a predetermined travel path of the elevator car 9 when the sensor device 70 is coupled to the drive wheel 23 by means of the coupling device 41. Here, the sensor device 70, the rotatable switch disk 60, wherein the switching device 63 is actuated upon rotation of the indexing disk 60 thereof and wherein the indexing disk 60 rotates in this embodiment in a specific ratio of 1: 1 with the drive wheel 23 when the sensor device 70 is coupled by means of the coupling device 41 with the drive wheel 23.

Fig. 6 shows a schematic section through the in Fig. 1 illustrated monitoring device 2 according to a third preferred embodiment of the invention. In this embodiment, the speed wheel 30 is rotatably connected to the axis 21. Here, a one- or multi-part design is possible. In this case, a speed limit can be realized via the rolling bodies 52 to 55 arranged in the rolling body receptacles 48 to 51, as can be seen in a corresponding manner with reference to FIG Fig. 3 is described. However, this speed limit is provided due to the fixed connection of the speed wheel 30 to the drive wheel 23 in this embodiment for limiting the speed vK of the elevator car 9 in all operating conditions, in particular also in a normal drive. If the limit speed vG is exceeded by the speed vK of the elevator car 9, then the speed wheel 30 by means of one of the rolling bodies 52 to 55, the switching disk 60 with, whereby the switch 64 of the switching unit 63 is actuated.

At a standstill of the elevator car 9, the coupling between the friction surface 80 of the switching disk 60 and the friction surface 81 of the drive wheel 23 is closed, so that the switching disk 60 is now coupled to the drive wheel 23. Then there is a corresponding operation of the sensor device 70, as they are based on the Fig. 5 is described. The sensor device 70 is used in the basis of the Fig. 6 described embodiment as a displacement sensor.

Thus, essential components which serve to monitor the speed vK of the elevator car 9 in normal operation can be used for the sensor device 70 configured as a travel sensor 70. For normal driving, the sensor device 70 is deactivated in this case by the clutch 40 is opened. This is done by energizing the solenoid coil 44. This design is particularly suitable for retrofitting in an existing elevator installation. The continuous monitoring of the limit speed vG can be used for monitoring an upward speed and by means of the switchable displacement sensor 70a can be monitored and prevented uncontrolled driving away the elevator car from a floor.

In a modified embodiment, it is also possible for a sensor device 70 configured as a displacement sensor 70a to be coupled to the drive wheel 23 via a suitable gear 26 when the clutch 40 is closed. Then, via the ratio i of the transmission 26, a factor i for travel limitation can be taken into account.

definiert werden. Hierbei wird der Winkel α in Radiant eingesetzt. Wenn der Winkel α in Grad eingesetzt wird, dann ist zu berücksichtigen, dass definitionsgemäß 1° gleich 2π/360 ist. Der Divisor 2 in Formel (9) berücksichtigt, dass entsprechend der Formel (1) der laufende Teil 18 des Betätigungsmittels 11 die doppelte Wegstrecke wie die Aufzugskabine 9 zurücklegt. Der Divisor i berücksichtigt die Übersetzung i eines möglichen Getriebes 26.If the predetermined rotation angle 67 is equal to α, then the limit distance sG corresponding to $$\mathit{sK}>\frac{\mathrm{R}*\mathrm{<figure-callout\; id="2"\; label="\alpha "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}{2*i}=\mathit{sG}$$

To be defined. Here, the angle α is used in radians. When the angle α is set in degrees, it is to be considered that by definition 1 ° is equal to 2π / 360. The divisor 2 in formula (9) takes into account that according to the formula (1) the running part 18 of the actuating means 11 covers twice the distance as the elevator car 9. The divisor i takes into account the ratio i of a possible transmission 26.

The trigger condition for the switching device 63 is given by the inequality given in the formula (9). If the travel distance sK of the elevator car 9 exceeds the limit distance sG, then the switch 64 is actuated. As a result, a corresponding measure, in particular braking, is initiated.

Thus, a travel path sK for the elevator car 9 can be predetermined by the limit distance sG, wherein the sensor device 70 actuates the switching device 63 after the predetermined travel path sK of the elevator car 9 when the sensor device 70 is coupled to the drive wheel 23 by means of the coupling device 41.

The monitoring device 2 can advantageously have a control device 90, which energizes the electromagnet 43 or the magnet coil 44 of the electromagnet 43 during a normal travel of the elevator car 9. As a result, the sensor device 70 can be deactivated during normal driving. If the sensor device 70 is configured as a speed sensor 70b, then the limit speed vG is smaller than the travel speed vK of the elevator car 9 during normal travel. By disconnecting the sensor device 70 from the drive wheel 23, a triggering is then prevented. If, on the other hand, the sensor device 70 is designed as a travel sensor 70a, the travel limit can be canceled in a corresponding manner for the normal travel of the elevator car 9.

An advantageous application is that the sensor device 70 is designed as a speed sensor 70b. At a standstill of the elevator car 9 and / or a special positioning travel of the elevator car 9, the clutch 40 is closed. Thus, starting from a standstill of the elevator car 9 in a possible movement, a speed limit can be realized. This can be done additionally or alternatively to a travel limit. In contrast to a pure travel limit, there is the advantage here that suitable measures can be taken early on, especially with large accelerations of the elevator car 9, as can occur, for example, in the event of overloading of the elevator car 9. As a result, the speed vK of the elevator car 9 can be more limited during a planned standstill or during a particular positioning travel than is possible with a pure travel limit in practice.

In this case, a low speed vK of the elevator car 9 during a crawl drive can be made possible, especially during a special positioning journey. A pure path limitation may be impractical or insufficient for such purposes. For example, the positioning of the elevator car 9 can be on the order of one meter. A pure travel limit would allow for the occurrence of a fault already very high speeds vK the elevator car 9 at the moment of triggering by the travel limit. Due to the speed limit, the speed vK of the elevator car 9 can be continuously monitored during such a crawl. Here, the limit speed vG according to the formula (8) can be set, for example, to a value between 0.1 m / s to about 0.3 m / s. The elevator car 9 can then be driven over a travel of, for example, 50 cm to a level of a loading area of a truck. If an error occurs in this case, then a suitable measure, in particular braking, can be initiated at an early stage. For example, a pallet with a load can be driven into the positioned elevator car 9 with the aid of a lift truck. If thereby the elevator car 9 is overloaded, then a high acceleration of the elevator car 9 can occur. This means that already after a short distance the predetermined limit speed vG is exceeded. Thus, in such an overload of the elevator car 9 early braking can be initiated.

It should be noted that, in particular, measures for detecting an error during an upward movement of the elevator car 9 are described on the basis of the exemplary embodiments. In a corresponding manner, the monitoring device 2 can also be designed for speed monitoring and / or path limitation with respect to a downward movement of the elevator car 9. Furthermore, an embodiment for direction-independent travel and / or speed limitation can also be realized. For example, multiple speed wheels 30 can be coupled with different geometry so that different speeds of travel can be selectively monitored. Furthermore, the in Fig. 3 shown switching disk 60 in both directions an operation of the switch 64 of the switching device 63rd

The invention is not limited to the described embodiments.

Claims (14)

1. A monitoring device (2) for a lift cabin (9) having a sensor unit (70) and a switching unit (63), wherein the switching unit (63) can be actuated by the sensor unit (70), wherein a driving wheel (23) that rotates when the lift cabin (9) is in motion and a coupling unit (41) are provided, wherein the sensor unit (70) can be at least indirectly coupled with the driving wheel (23) by means of the coupling unit (41), wherein the sensor unit (70) is designed as a position sensor (70a) and wherein the sensor unit (70), after a specified distance of travel (sD) of the lift cabin (9), actuates the switching unit (63) when the sensor unit (70) is at least indirectly coupled with the driving wheel (23) by means of the coupling unit (41), characterised in that the sensor unit (70) can be axially moved towards and away from the driving wheel by means of the coupling unit (41) and can at least indirectly be coupled with the driving wheel (23) by means of the axial advance movement.
2. The monitoring device as claimed in claim 1, characterised in that

   - the sensor unit (70) has a rotatable switching disk (60),

   - the switching unit (63) can, during a rotation of the switching disk (60), at least indirectly be actuated by the switching disk (60), and

   - the switching disk (60) rotates together with the driving wheel (23) at a predefined transmission ratio (i), when the sensor unit (70) is at least indirectly coupled with the driving wheel (23) by means of the coupling unit (41).
3. The monitoring device as claimed in claim 1 or 2, characterised in that

   - a transmission (26) with a predefined transmission ratio (i) is provided and that the sensor unit (70) can be coupled with the driving unit (23) through the coupling unit (41) by means of the transmission (26), or

   - the sensor unit (70) can be coupled with the driving wheel (23) through the coupling unit (41) with a transmission ratio of 1:1.
4. The monitoring device as claimed in any one of claims 1 to 3, characterised in that

   - a spring force of the coupling unit (41) closes the coupling (40) between the sensor unit (70) and the driving wheel (23), and

   - an electric magnet (43) of the coupling unit (41) opens, in the energised condition, the coupling (40) between the sensor unit (70) and the driving wheel (23) against the spring force.
5. The monitoring device as claimed in claim 4, characterised in that

   - a control unit (90) is provided, and

   - the control unit (90) energises the electric magnet (43) during normal operation.
6. The monitoring device (2) for a lift cabin (9) having a sensor unit (70) and a switching unit (63), wherein the switching unit (63) can be actuated by the sensor unit (70), wherein a driving wheel (23) that rotates whilst the lift cabin (9) is in motion and a coupling unit (41) are provided, and wherein the sensor unit (70) can be at least indirectly coupled with the driving wheel (23) by means of the coupling unit (41), and
   wherein the sensor unit (70) is designed as a speed sensor (70b), wherein the sensor unit (70) actuates the switching unit (63) when a speed (vK) of the lift cabin (9) exceeds a specified speed limit (vG) and the sensor unit (70) is at least indirectly coupled with the driving wheel (23) by means of the coupling unit (41), characterised in that

   - the sensor unit (70) has a rotatable switching disk (60),
   the switching unit (63) can be at least indirectly actuated by the switching disk (60) during a rotation of the switching disk (60),

   - a speed wheel (30) is provided that rotates at a predefined transmission ratio (i) with the driving wheel (23) when the sensor unit (70) is at least indirectly coupled with the driving wheel (23) by means of the coupling unit (41), and

   - the speed wheel (30) at least indirectly entrains the switching disk (60) when a speed (vK) of the lift cabin (9) exceeds a predefined speed limit (vG) and the speed wheel (30) rotates, due to the at least indirect coupling with the driving wheel (23), with the driving wheel (23) at a certain transmission ratio (i).
7. The monitoring device as claimed in claim 6, characterised in that the specified speed limit (vG) is specified by

   - the certain transmission ratio (i) at which the speed wheel (30) rotates with the driving wheel (23),

   - a radius (R) of the driving wheel (23) on which the driving wheel (23) is driven, and

   - a radius (r) of the speed wheel (30), on which is disposed at least one follower body (52) in a follower body receptacle (48) of the speed wheel (30), by means of which the speed wheel (30) entrains the switching disk (60) when the speed (vK) of the lift cabin (9) exceeds the specified speed limit (vG) and the speed wheel (30) rotates with the driving wheel (23) due to the at least indirect coupling with the driving wheel (23) with the predefined transmission ratio (1).
8. The monitoring device as claimed in claim 6 or 7, characterised in that

   - the driving wheel (23) is connected to the speed sensor (70b) and the speed sensor (70b) actuates the switching unit (63) when a speed (vK) of the lift cabin (9) exceeds a predefined speed limit (vG), and

   - the sensor unit (70) that can be at least indirectly coupled with the driving wheel (23) by means of the coupling unit (41) actuates the same switching unit (63) if necessary.
9. The monitoring device as claimed in any one of claims 6 to 8, characterised in that

   - a transmission (26) with a predetermined transmission ratio (i) is provided and that the sensor unit (70) can be coupled with the driving unit (23) through the coupling unit (41) by means of the transmission (26), or

   - the sensor unit (70) can be coupled with the driving wheel (23) through the coupling unit (41) with a transmission ratio of 1:1.
10. The monitoring device as claimed in any one of claims 6 to 9, characterised in that

    - a spring force of the coupling unit (41) closes the coupling (40) between the sensor unit (70) and the driving wheel (23), and

    - an electric magnet (43) of the coupling unit (41) opens, in the energised condition, the coupling (40) between the sensor unit (70) and the driving wheel (23) against the spring force.
11. The monitoring device as claimed in claim 10, characterised in that

    - a control unit (90) is provided, and

    - the control unit (90) energises the electric magnet (43) during normal operation.
12. A lift system (1) having a lift cabin (9), an actuation means (11) and a monitoring device (2) as claimed in any one of claims 1 to 11, wherein the driving wheel (23) of the monitoring device (2) is rotationally driven by the actuating means (11) by the movement of the lift cabin (9).
13. The lift system as claimed in claim 12, characterised in that

    - the monitoring device (2) is provided on the lift cabin (9), and

    - the driving wheel (23) of the monitoring device (2) interacts with the actuation means (11) in such a way that the driving wheel (23) is rotationally driven on the radius (R) thereof, on which the actuation means (11) rests against the driving wheel (23), at twice the speed (vK) of the lift cabin (9).
14. A method for monitoring a lift cabin (9) by means of a sensor unit (70) and a switching unit (63), wherein the switching unit (63) is actuated by the sensor unit (70), wherein a driving wheel (23) is driven by the lift cabin (9) whilst the lift cabin (9) is in motion, and wherein the sensor unit (70) is axially moved towards and away from the driving wheel and the sensor unit (70) is at least indirectly coupled as needed with the driving wheel (23) by means of the axial advance movement, characterised in that

    - the sensor unit (70) is designed as a position sensor (70a),

    - the position sensor (70a) is, if needed, at least indirectly coupled with the driving wheel (23) by means of the coupling unit (41), and

    - the switching unit (63) is actuated, once the position sensor (70a) has been coupled with the driving wheel (23), after a predetermined distance of travel (sG) of the lift cabin (9) (63) by the position sensor (70a).

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