Method of monitoring braking capability of elevator brake, elevator controller, and elevator system

Abstract

A method of monitoring braking capability of an elevator brake (20). The method comprises engaging (410) at least one elevator brake unit (21A, 21B), applying (420) a torque by an elevator motor (18) of the elevator machine (10) against the braking torque of the engaged at least one elevator brake unit (21A, 21B), monitoring (430), at least during the applying of the torque, an amount of force caused due to the applied torque by a force sensor (24) arranged between the frame (12) and a brake body portion (22) of the elevator brake (20), monitoring (440), at least during the applying of the torque, a position or movement of the drive shaft (14), and determining (450) the braking capability based on the monitoring of the amount of force and the monitoring of the position or movement of the drive shaft (14).

Description

[0001] METHOD OF MONITORING BRAKING CAPABILITY OF ELEVATOR BRAKE, ELEVATOR CONTROLLER, AND ELEVATOR SYSTEM

[0002] FIELD OF THE INVENTION

[0003] The present invention relates in general to elevator brakes. In particular, however not exclusively, the present invention concerns methods and controllers for monitoring braking capability, such as whether braking force produced by the brake is at a sufficient level.

[0004] BACKGROUND

[0005] In elevators, the elevator brakes serve an important purpose of stopping and / or maintaining the elevator car in its place. When designing the brakes, one must ensure that the brakes are able to stop the elevator car in all imaginable cases, regardless of the loading. However, even if the brakes are designed in such a way, during the use of the elevator, the brakes are prone to tear and wear, and, even if they don’t break entirely, their braking capabilities may indeed become lower. For example, it may be that the brakes were originally designed to cope with an elevator car with full loading and by taking into account the most non-optimal weight distribution of the hoisting rope or belt and the counterweight of the elevator. During the use of the elevator, one or more of the brakes may have lost some of its braking capability such that they are not anymore capable of braking with sufficient force. Thus, there is still a need to develop solutions for monitoring the braking capability of the elevator brake.

[0006] SUMMARY

[0007] An objective of the present invention is to provide a method of monitoring braking capability of an elevator brake, an elevator controller, and an elevator system. Another objective of the present invention is that the method, the elevator controller, and the elevator system enable to monitor the braking capability in a convenient manner essentially without requiring manual labor and / or long disruptions to the operation of the elevator.

[0008] The objectives of the invention are reached by a method of monitoring braking capability of an elevator brake, an elevator controller, and an elevator system as defined by the respective independent claims.According to a first aspect, a method of monitoring braking capability of an elevator brake is provided. The method comprises engaging at least one elevator brake unit of the elevator brake to produce a braking torque for at least resisting, preferably preventing, a rotation of a traction sheave mechanically coupled to a drive shaft of an elevator machine. The method also comprises applying a torque by an elevator motor of the elevator machine against the braking torque of the engaged at least one elevator brake unit, the elevator motor being arranged to rotate the drive shaft relative to a frame of the elevator machine. Furthermore, the method comprises monitoring, at least during the applying of the torque, an amount of force caused due to the applied torque by a force sensor arranged between the frame and a brake body portion of the elevator brake, and monitoring, at least during the applying of the torque, a position or movement of the drive shaft. Still further, the method comprises determining the braking capability based on the monitoring of the amount of force and the monitoring of the position or movement of the drive shaft.

[0009] The force sensor may be any kind of known force sensor. For example, the force sensor may be an S-shaped force sensor, the operation of which is based on compression and elongation of the force sensor due to an external force to be determined.

[0010] The braking capability may refer herein to amount of braking force or torque produced by the elevator brake during braking in comparison to a reference braking force or torque.

[0011] The method may comprise, prior to the applying of the torque, determining that an elevator car to be moved by the elevator machine is empty of persons.

[0012] The applying of the torque may comprises applying a magnitude of torque causing the amount of force to be in a pre-defined range.

[0013] The determining of the braking capability may comprise comparing the amount of force to a threshold value.

[0014] The determining of the braking capability may comprise determining that the braking capability is at an acceptable level if no change of position or movement of the drive shaft is detected for values of the amount of force lower than or in the pre-defined threshold range.

[0015] The determining of the braking capability may comprise detecting a change of position of or detecting the movement of the drive shaft during the applying of the torque.Optionally, the determining of the braking capability may comprises determining the amount of force at which the detecting of the change of position of the movement occurs.

[0016] The change of position of or the detecting of the movement of the drive shaft position may be performed by a position or speed sensor, such as a motor encoder (incremental or absolute). The position or speed sensor may, thus, be arranged to measure shaft position or speed.

[0017] The method may comprise arranging the brake body portion of the elevator brake to be able to move relative to the frame of the elevator machine up to a limit when the at least one elevator brake unit is being engaged, wherein the limit is at most one centimeter in a movement direction.

[0018] The method may comprise, prior to the engaging, moving an elevator car movable by the elevator machine to a pre-defined position in an elevator shaft, such as to the top or the bottom.

[0019] The force sensor may be configured to determine the amount of force based on a compression or an elongation of the force sensor due to the applied torque.

[0020] The elevator brake may comprise at least two elevator brake units, and the engaging may then comprise engaging a fewer number of elevator brake units than a total number of the at least two elevator brake units. For example, only one elevator brake unit of the two units may be engaged.

[0021] The brake body portion may be attached to the frame via the force sensor. Furthermore, optionally, the brake body portion may comprise a frame flange arranged adjacent to the frame.

[0022] The method may comprise, when the elevator brake is braking, determining an elevator car loading at a position in an elevator shaft by the force sensor and by information about an elevator balance state in the position.

[0023] According to a second aspect, an elevator controller is provided. The elevator controller is configured to perform the method in accordance with the first aspect or any embodiment thereof.

[0024] According to a third aspect, an elevator system is provided. The elevator system comprises an elevator machine comprising a frame, a drive shaft, a traction sheave mechanically coupled to the drive shaft, an elevator motor arranged to rotate the driveshaft relative to the frame, an elevator brake comprising a brake body portion and at least one elevator brake unit for producing a braking torque for at least resisting, preferably preventing, a rotation of the traction sheave, and a force sensor arranged between the frame and the brake body portion. The elevator system also comprises the elevator controller in accordance with the second aspect or any embodiment thereof.

[0025] The present invention provides a method of monitoring braking capability of an elevator brake, an elevator controller, and an elevator system. The present invention provides advantages over known solutions in that the force sensor can be utilized to directly and in an online manner measure the braking torque produced by the elevator brake. Another advantage is accuracy and reliability compared to counting on torque estimation by an electric drive unit of the electric motor. The invention provides a cost-effective solution that can substitute the use of an elevator weight scale and has a simple structure. The braking torque monitoring can be used also for predictive maintenance.

[0026] Various other advantages will become clear to a skilled person based on the following detailed description.

[0027] The terms “first” and “second” are herein used to distinguish one element from another element, and not to specially prioritize or order them, if not otherwise explicitly stated.

[0028] The exemplary embodiments of the present invention presented herein are not to be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used herein as an open limitation that does not exclude the existence of also unrecited features. The features recited in the appended patent claims are mutually freely combinable unless otherwise explicitly stated.

[0029] The novel features which are considered as characteristic of the present invention are set forth in particular in the appended claims. The present invention itself, however, both as to its construction and its method of operation, together with additional objectives and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

[0030] BRIEF DESCRIPTION OF FIGURES

[0031] Some embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings.

[0032] Figure 1 illustrates schematically an elevator system.Figure 2 illustrates schematically an elevator brake of an elevator system as a cross-sectional side view.

[0033] Figure 3 illustrates schematically an elevator brake of an elevator system from a perspective.

[0034] Figure 4 shows a flow diagram of a method.

[0035] Figure 5 illustrates schematically an elevator system.

[0036] DETAILED DESCRIPTION OF SOME EMBODIMENTS

[0037] Figure 1 illustrates schematically an elevator system 100. The elevator system 100 comprises an elevator machine 10. The elevator system 100 also comprises an elevator controller 1000. The elevator controller 1000 is, preferably, configured to perform at least some, if not all, of the method steps shown and / or described in connecting with Figure 4.

[0038] The elevator machine 10 comprises a frame 12, such as including a base plate and other portions which can be fixed relative to surroundings of the machine 10. The elevator machine 10 also comprises a drive shaft, a traction sheave 16 mechanically coupled to the drive shaft, an elevator motor 18 arranged to rotate the drive shaft relative to the frame 12, and an elevator brake 20.

[0039] The elevator brake 20 comprises a brake body portion 22, and at least one elevator brake unit (not visible in Fig. 1) for producing a braking torque for at least resisting, preferably preventing, a rotation of the traction sheave 16. The elevator brake 20 comprises a force sensor 24 arranged between the frame 12 and the brake body portion 22.

[0040] As illustrated highly schematically in Fig. 1, the elevator system 100 may comprise hoisting means 35, such as a hoisting rope or belt, arranged in connection with the traction sheave 16, such as wound around it, to move an elevator car 30 in an elevator shaft. There may also be a counterweight 40 coupled to the hoisting means 35. The hoisting means 35 may, as is familiar to a skilled person in the art, run via one or various sheaves or pulleys. Ends of the hoisting means 35 may be connected to hoisting means terminals instead of the elevator car 30 and the counterweight 40. Various kinds of different hoisting means arrangements are possible.

[0041] Figure 2 illustrates schematically an elevator brake 20 of an elevator system 100 as a cross-sectional side view. The elevator brake 20 may be identical or similar to the oneillustrated in Fig. 1. Fig. 2 also illustrates armature plate 15 which rotates together with the drive shaft 14. Fig. 2 further illustrates bearings marked with circles. As can be seen, the shaft 14 and the traction sheave 16 are rotatable relative to the frame 12 and the brake 20, when the brake 20 is open, that is when the brake 20 is not braking.

[0042] The at least one elevator brake unit 21 A, 21B, such as one, two or more brake units 21 A, 21B, may be electromechanical brake units. The brake units 21A, 21B are, preferably, independently controllable so that one brake unit 21 A can be opened and closed independently of another brake unit 21B. There may be one or several brake units 21 A, 2 IB arranged on or into a housing of the elevator brake 20.

[0043] Operation of the brake unit or units 21A, 21B may be performed by the elevator controller 1000 which may include a motor controller (not shown) and / or a brake controller (not shown). The elevator controller 1000 may be a single processing unit, such as with a processor and a memory, or may comprise several, even physically separated, however, in connection with each other, processing units.

[0044] An electromechanical brake unit 21A, 21B may comprise a brake coil 25 and a brake pad 23 so that, when the brake coil 25 is not excited by electric current, the brake 20 or said brake unit 21A, 21B remains closed or activated as the brake pad 23 is pressed against a braking surface by the force generated by a mechanical force applying means, for example, by a spring 29. The braking surface or surfaces may be arranged onto the armature plate 15.

[0045] When the brake 20 is closed, that is one or more of the brake units 21 A, 2 IB thereof are braking, the brake pad 23 or pads 23 push(es) against the armature plate 15 to keep the shaft 14 in its position. If the motor 18 is not producing any torque, the force sensor 24 detects torque that depends on the load of the elevator car or imbalance in the system of elevator car 30 and counterweight 40 (taking into account the distribution of the hoisting means 35).

[0046] In some embodiments, the armature plate 15 may become further in contact with the brake body portion 22 so that the armature plate 15 gets squeezed between the brake pad 23 and the brake body portion 22.

[0047] On the other hand, when the brake coil 25 is excited by electric current, the brake pad 23 is pulled away from the braking surface by electromagnetic force produced by the braking coil 25 against spring force of the spring 29, thereby opening or deactivating thebrake 20 or at least said brake unit 21A, 21B. Then the armature plate 15 can rotate freely relative to the brake body portion 22 and the brake pad 23.

[0048] The force sensor 24 may be configured to determine the amount of force based on a compression or an elongation of the force sensor 24 due to the applied torque.

[0049] The brake body portion 22 may be attached to the frame 12 via the force sensor 24 as illustrated in Fig. 2. The brake body portion 22 may comprise a frame flange arranged adjacent to the frame 12. Thus, any torque between the brake body portion 22 and the frame 12 may be measured by the force sensor 24.

[0050] Furthermore, the elevator machine 10 may comprise a position or speed sensor 31, such as an encoder. The position or speed sensor 31 may be arranged to determine position and / or speed of the shaft 14. The position or speed sensor 31 may be connected to the elevator controller 1000.

[0051] Figure 3 illustrates schematically an elevator brake 20 of an elevator system 100. The elevator brake 20 is shown from a perspective view. The force sensor 24 in Fig. 3 is an S-shaped force sensor or load sensor. Operation of the force sensor 24 is based on compression and elongation of the force sensor 24 due to external forces. Thus, a torque between the brake body portion 22 and the frame 12 causes the force sensor 24 of Fig.

[0052] 3 to either compress or elongate. This can be detected and the amount of force measured by the sensor 24.

[0053] As can be seen, the brake body portion 22 may be attached to the frame 12 via the force sensor 24. An example of this is clearly illustrated in Fig. 3 in which the lower end of the force sensor 24 in the figure is attached to the brake body portion 22 and the upper end of the force sensor 24 in the figure is attached to the frame 12.

[0054] Furthermore, as can be seen in Fig. 3, for instance, the brake body portion 22 may comprise a frame flange 26 arranged adjacent to the frame 12.

[0055] In the frame flange 9 there may be a plurality of holes for coupling means 27, such as bolts, connecting the frame flange 9 and the rest of the brake body portion 22. Correspondingly, there may be holes in the corresponding points in the armature plate 15 and / or the brake pad 23.

[0056] The coupling means 27 may be arranged so that the armature plate 15 is able to slide guided by the coupling means 27 when the brake opens and closes. Furthermore, thecoupling means 27 may be arranged so that the distance between the frame flange 9 and the rest of the brake body portion 22 remains essentially unchanged.

[0057] As can be seen, there may be a further flange 17 for attaching an end of the force sensor 24 to the frame 12. The further flange 17 is fixed relative to the frame 12 via two attaching points. The other end of the force sensor 24 may also be attached to the frame flange via a support element (e.g., by an L-shaped support element as illustrated in Fig.

[0058] 3).

[0059] Figure 4 shows a flow diagram of a method. The method is, preferably, for monitoring braking capability of an elevator brake 20. The elevator machine 10 and the elevator brake 20 utilized in the method may be, for example, as described in connection with and / or illustrated in Figs. 1-3. Alternatively, they may be different.

[0060] Item or method step 410 refers to engaging at least one elevator brake unit 21 A, 21B of the elevator brake 20 to produce a braking torque for at least resisting, preferably preventing, a rotation of a traction sheave 16 mechanically coupled to a drive shaft 14 of an elevator machine 10. The engaging may be performed by removing excitation electric current from the coil(s) of the brake unit(s) 21 A, 21B.

[0061] Item or method step 420 refers to applying a torque by an elevator motor 18 of the elevator machine 10 against the braking torque of the engaged at least one elevator brake unit 21A, 21B, the elevator motor 18 being arranged to rotate the drive shaft 14 relative to a frame 12 of the elevator machine 10. The torque may be applied by injecting current to the motor 18 by the elevator controller 1000 (that may be in connection or comprise the motor controller).

[0062] Item or method step 430 refers to monitoring, at least during the applying of the torque, an amount of force caused due to the applied torque by a force sensor 24 arranged between the frame 12 and a brake body portion 22 of the elevator brake 20. The amount of force may be monitored based by elevator controller 1000 in connection with the force sensor 24, for instance.

[0063] Item or method step 440 refers to monitoring, at least during the applying of the torque, a position or movement of the drive shaft 14. This may be done, for example, by the speed or position sensor 31. On the other hand, it may be performed based on signals (current and / or voltage) from the elevator motor 18.Item or method step 450 refers to determining the braking capability based on the monitoring 430 of the amount of force and the monitoring 440 of the position or movement of the drive shaft 14. The determining 450 of the braking capability may comprise comparing the amount of force to a threshold value. Thus, if no movement occur at lower torques than the threshold value, the braking capability is at an acceptable level. Otherwise, it may be at a non-acceptable level.

[0064] The determining 450 of the braking capability may comprise determining that the braking capability is at an acceptable level if no change of position or movement of the drive shaft 14 is detected for values of the amount of force lower than or in the predefined threshold range. The pre-defined threshold range may be defined relative to a nominal braking torque of the brake 20, for instance, such as being 90 percent of the nominal braking torque.

[0065] On the other hand, the determining 450 of the braking capability may comprise detecting a change of position of or detecting the movement of the drive shaft 14 during the applying of the torque. Optionally, the determining of the braking capability may comprises determining the amount of force at which the detecting of the change of position of the movement occurs. Thus, if the movement occurs at higher torques than the nominal braking torque or the pre-defined threshold range, the braking capability is at an acceptable level. Otherwise, it is at a non-acceptable level.

[0066] The method may be ended at 499.

[0067] The method may comprise, prior to the applying of the torque 420, determining that an elevator car 30 to be moved by the elevator machine 10 is empty of persons. This may be done based on a weighing device in the elevator car 30 or by an optical sensor, such as a camera.

[0068] The applying of the torque 240 may comprises applying a magnitude of torque causing the amount of force to be in a pre-defined range.

[0069] The method may comprise arranging the brake body portion 22 of the elevator brake 20 to be able to move relative to the frame 12 of the elevator machine 10 up to a limit when the at least one elevator brake unit 21A, 21B is being engaged, wherein the limit is at most one centimeter in a movement direction. Thus, the sensor 24 may detected the torque at within the limits. However, if the brake body portion 22 moves more than the limit, it will run to a mechanical limit.The method may comprise, prior to the engaging 410, moving an elevator car 30 movable by the elevator machine 10 to a pre-defined position in an elevator shaft, such as to the top or the bottom of the shaft.

[0070] In some embodiments, where the elevator brake 20 comprises at least two elevator brake units 21A, 21B, and the engaging 410 comprises engaging a fewer number of elevator brake units 21A, 21B than a total number of the at least two elevator brake units 21A, 21B, such as one out of two units 21 A, 21B.

[0071] The method may comprise, when the elevator brake 20 is braking, determining an elevator car loading at a position in an elevator shaft by the force sensor 24 and by information about an elevator balance state in the position. The elevator balance state may be pre-defined for each position of the elevator shaft.

[0072] Figure 5 illustrates schematically an elevator system 100. The elevator system 100 comprises an elevator machine 10. The elevator machine 10 comprises the frame 12, the drive shaft 14, the traction sheave 16 mechanically coupled to the drive shaft 14, the elevator motor 18 arranged to rotate the drive shaft 14 relative to the frame 12, and the elevator brake 20 as described hereinabove, such as in connection to Figs. 1-3.

[0073] The elevator brake 20 comprises the brake body portion 22 and the at least one elevator brake unit 21A, 21B for producing a braking torque for at least resisting, preferably preventing, a rotation of the traction sheave 16, and a force sensor 24 arranged between the frame 12 and the brake body portion 22, such as to measure torque therebetween.

[0074] The elevator system 100 may comprise the elevator controller 1000 configured to perform some or even all of the method steps described above in connection to Fig. 4.

[0075] The elevator system 100 may comprise a motor controller 220, such as including an electric converter (a frequency converter and / or an inverter), in connection with an elevator motor 18 of the elevator machine 10.

[0076] The motor 18 may be arranged to rotate a traction sheave 16. The elevator car 30 may be mechanically coupled to the electric motor 18, preferably, by hoisting means 35, preferably, extending via the traction sheave 16.

[0077] The hoisting means 35 may comprise, for example, steel or carbon fibers. The term ‘hoisting rope’ does not limit the form of the rope anyhow. For example, the hoisting rope 35 may be implemented as a rope or a belt. The elevator system 100 may alsocomprise a counterweight 40 in connection with the elevator car 30, such as via the hoisting means 35.

[0078] The elevator car 30 may be moved in and / or along an elevator shaft 242. The elevator car 30 may be moved in a normal operation mode to serve landings 240 or landing floors 240 in accordance with elevator calls. Also shown are the elevator doors 280 and the landing floor doors.

[0079] The elevator controller 1000 may be a separate device or may be comprised in the other components of the elevator system 100 such as in or as a part of the motor controller 1000. In various embodiments, the elevator controller 1000 may comprise the motor controller 220. The elevator controller 1000 may be in connection with a brake controller 300, if any, to control the operation thereof.

[0080] In some embodiments, the elevator controller 1000 may comprise the motor controller 220, however, in other embodiments, they may be separate entities, in which case the elevator controller 1000 may be in communication connection with the motor controller 220, such as providing input signal / data thereto and / or therefrom.

[0081] There may be also a main electrical power supply 225 such as a three-phase or singlephase electrical power grid, an electrical connection 230 between the power supply 225 and the motor controller 220, another electrical connection 235 between the motor controller 220 and the motor 18 of the elevator hoisting machine 10.

[0082] It is also noted herein that while the above describes example embodiments, these should not be viewed in a limiting sense. Rather, there are several variations and modifications, which may be made without departing from the scope of the present disclosure as defined in the appended claims.

[0083] The previously presented considerations concerning the various embodiments of the device may be flexibly applied to the embodiments of the method, and vice versa, as being appreciated by a skilled person.

[0084] Some advantageous embodiments according to the invention have been described above. The invention is not limited to the embodiments described above, but the inventive idea can be applied in numerous ways within the scope of the claims. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated.

Claims

CLAIMS1. A method of monitoring braking capability of an elevator brake (20), comprising:engaging (410) at least one elevator brake unit (21A, 21B) of the elevator brake (20) to produce a braking torque for at least resisting, preferably preventing, a rotation of a traction sheave (16) mechanically coupled to a drive shaft (14) of an elevator machine (10);applying (420) a torque by an elevator motor (18) of the elevator machine (10) against the braking torque of the engaged at least one elevator brake unit (21A, 21B), the elevator motor (18) being arranged to rotate the drive shaft (14) relative to a frame (12) of the elevator machine (10);monitoring (430), at least during the applying of the torque, an amount of force caused due to the applied torque by a force sensor (24) arranged between the frame (12) and a brake body portion (22) of the elevator brake (20);monitoring (440), at least during the applying of the torque, a position or movement of the drive shaft (14);anddetermining (450) the braking capability based on the monitoring of the amount of force and the monitoring of the position or movement of the drive shaft (14).

2. The method of claim 1, comprising, prior to the applying of the torque, determining that an elevator car (30) to be moved by the elevator machine (10) is empty of persons.

3. The method of claim 1 or 2, wherein the applying of the torque comprises applying a magnitude of torque causing the amount of force to be in a pre-defined range.

4. The method of any one of claims 1-3, wherein the determining of the braking capability comprises comparing the amount of force to a threshold value.

5. The method of any one of claims 1-4, wherein the determining of the braking capability comprises determining that the braking capability is at an acceptable level if no change of position or movement of the drive shaft (14) is detected for values of the amount of force lower than or in the pre-defined threshold range.

6. The method of any one of claims 1-5, wherein the determining of the braking capability comprises detecting a change of position of or detecting the movement of the drive shaft (14) during the applying of the torque.

7. The method of claim 6, wherein the determining of the braking capability comprises determining the amount of force at which the detecting of the change of position of the movement occurs.

8. The method of any one of claims 1-7, comprising arranging the brake body portion (22) of the elevator brake (20) to be able to move relative to the frame (12) of the elevator machine (10) up to a limit when the at least one elevator brake unit (21 A, 21B) is being engaged, wherein the limit is at most one centimeter in a movement direction.

9. The method of any one of claims 1-8, comprising, prior to the engaging, moving an elevator car (30) movable by the elevator machine (10) to a pre-defined position in an elevator shaft (242), such as to the top or the bottom.

10. The method of any one of claims 1-9, wherein the force sensor (24) is configured to determine the amount of force based on a compression or an elongation of the force sensor (24) due to the applied torque.

11. The method of any one of claims 1-10, wherein the elevator brake (20) comprises at least two elevator brake units (21 A, 21B), and the engaging (410) comprises engaging a fewer number of elevator brake units (21A, 21B) than a total number of the at least two elevator brake units (21 A, 21B).

12. The method of any one of claims 1-11, wherein the brake body portion (22) is attached to the frame via the force sensor (24).

13. The method of claim 12, wherein the brake body portion (22) comprises a frame flange (26) arranged adjacent to the frame (12).

14. The method of any one of claims 1-13, comprising, when the elevator brake (20) is braking, determining an elevator car loading at a position in an elevator shaft (242), by the force sensor (24) and by information about an elevator balance state in the position.

15. An elevator controller (1000) configured to perform the method of any one of claims 1-14.1416. An elevator system (100), comprising:an elevator machine (10), comprisinga frame (12),a drive shaft (14),a traction sheave (16) mechanically coupled to the drive shaft (14),an elevator motor (18) arranged to rotate the drive shaft (14) relative to the frame (12),an elevator brake (20) comprising a brake body portion (22) and at least one elevator brake unit (21 A, 21B) for producing a braking torque for at least resisting, preferably preventing, a rotation of the traction sheave (16), anda force sensor (24) arranged between the frame (12) and the brake body portion (22);andthe elevator controller (1000) of claim 15.

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