OVERSPEED CONTROL DEVICE, LIFT SAFETY GEARBOX AND METHOD FOR MONITORING THE OPERATION OF AN OVERSPEED CONTROLLER

Description

FIELD OF THE INVENTION

[0001] The present invention relates in general to elevator systems and safety gears thereof. In particular, however, not exclusively, the present invention concerns overspeed governor (OSG) devices utilized in or in connection with a safety gear of an elevator system.BACKGROUND

[0002] Elevators have safety gears to stop elevator car movement in case of an emergency, such as in an overspeed situation of the elevator car moving in the elevator shaft or hoistway. Traditionally, a safety gear is activated by a mechanical overspeed governor, which has a governor rope coupled to the safety gear and running via a governor sheave or pulley, which is disposed in elevator shaft or in a separate machine room, if any. In an overspeed situation, the safety gear is activated by means of the overspeed governor so that a gripping mechanism of the safety gear moves into a gripping position against a guide rail, thereby providing braking.

[0003] Known solutions are not very space-efficient, because said governor sheave or pulley, governor ropes and a separate rope tensioning pulley require a lot of space. Furthermore, due to the disposal of different components in many different places within the elevator system, the maintenance and / or inspection may become difficult and laborious as the maintenance person needs to go to several, typically narrow, places to perform the maintenance or inspection work. This holds true especially for machine roomless elevator systems with reduced pit and / or overhead. Consequently, there is a need for space-saving solutions that facilitate and improve maintenance and inspection processes.

[0004] Document JP 2008239260 A discloses an overspeed governor device according to the preamble of claim 1. Document JP 2008239260 A presents in particular a rotating body that moves in a hoistway in conjunction with an elevator car, and a means for converting rotational motion of the rotating body into an electrical pulse. The document presents first magnetism generating means installed on a rail at a predetermined interval and second magnetism generating means arranged at a predetermined interval on an outer periphery of the rotating body, and also means for converting the rotational motion of the rotating body into an electrical pulse. For example, the outer peripheral portion has the second magnetism generating means in the rotating body opposed to the first magnetism generating means of the rail while maintaining a spatial distance.

[0005] Document WO 2016 / 030570 A1 presents an overspeed governor and an elevator comprising the same. The overspeed governor comprises a governor sheave, a permanent magnet rotor coupled to the governor sheave, a stator arranged to interact with the permanent magnet rotor, a safety gear for braking movement of an elevator car and a safety rope fixed to the safety gear and arranged to run via the governor sheave. Said stator includes a winding adapted to exert, when energized, to the permanent magnet rotor a braking force that brakes movement of the permanent magnet rotor and, consequently, movement of the governor sheave and the safety rope, thereby activating the safety gear.SUMMARY

[0006] An objective of the present invention is to provide an overspeed governor (OSG) device for an elevator safety gear, an elevator safety gear for an elevator car or for a counterweight of an elevator car, and a method for monitoring operation of an overspeed governor. Another objective of the present invention is that the overspeed governor device, the elevator safety gear, and the method provides a simple mechanical system, which can work bi-directionally, and in non-contact manner relative to a guide rail, and can be used to trigger safety gears either mechanically or electronically.

[0007] The objectives of the invention are reached by an overspeed governor device for an elevator safety gear, an elevator safety gear for an elevator car or for a counterweight of an elevator car, and a method for monitoring operation of an overspeed governor as defined by the respective independent claims.

[0008] According to a first aspect, an overspeed governor device for an elevator safety gear is provided. The overspeed governor device comprises a driving unit comprising at least one driving member, the driving member comprising a body and a plurality of magnets arranged to the body in a pole-wise alternating manner around a rotation axis of the driving unit. Preferably, the plurality of magnets causes rotation of the overspeed governor device via a non-contact coupling or interaction with, for example, a guide rail when the overspeed governor device moves relative to the guide rail.

[0009] The overspeed governor device also comprises an actuation arrangement. The actuation arrangement comprises a first member arranged in mechanical coupling with the driving unit, and arranged to rotate together with the driving unit, and a second member. The actuation arrangement is configured so that the second member is stationary, when the first member rotates slower than a threshold speed value, and engages with the first member, when the first member reaches the threshold speed value, so that the second member starts to move.

[0010] The actuation arrangement may comprise a spring-loaded mechanism to provide the engaging between the first member and the second member. In addition, the spring-loaded mechanism may be adapted so that a force, such as a centrifugal force, related to rotation of the spring-loaded mechanism overcomes a spring force of the spring-loaded mechanism in response to the first member reaching the threshold speed value. Alternatively or in addition, the spring-loaded mechanism may include a spring-loaded rocker arm to provide the engaging.

[0011] In various embodiments, the at least one driving member may be arranged to rotate based a magnetic interaction between the plurality of magnets and a magnetic field generated by eddy currents which are produced by the driving member being moved relative to an electrically conductive surface, preferably of ferromagnetic material, in proximity and non-contact with the driving member.

[0012] The overspeed governor device may comprise a motion sensor, such as an encoder, arranged to sense rotation of the driving member and / or the first member, and to produce a sensing signal.

[0013] In some embodiments, the driving unit may comprise a plurality of driving member, for example, to improve the magnetic engagement. Furthermore, optionally, adjacent driving members of the plurality of driving members are spaced apart in a direction of the rotation axis so that a guide rail can be arranged between the adjacent driving members. Thus, there may be driving members on opposite sides of the guide rail providing good and balanced magnetic engagement.

[0014] The overspeed governor device may further comprise a rotational shaft between the driving unit and the actuation mechanism, thereby providing a compact device. In some embodiments, the rotational shaft may even extend between the plurality of driving members.

[0015] According to a second aspect, an elevator safety gear for an elevator car or for a counterweight of an elevator car is provided. The elevator safety gear comprises a gripping mechanism having a gripping position and an inactive position, wherein the gripping mechanism is configured in the gripping position for gripping a rail for providing braking. The elevator safety gear further comprises a linkage system for changing the position of the gripping mechanism from the inactive position to the gripping position. Still further, the elevator safety gear comprises an overspeed governor device according to the first aspect, configured to operate the linkage system.

[0016] Furthermore, the linkage system may comprise a mechanical coupling between the second member of the overspeed governor device and the gripping mechanism. Optionally, the linkage system comprises rope or wires, such as steel ropes or wires, between the second member and the gripping mechanism.

[0017] In various embodiments, the linkage system may comprise an electric actuator for changing the position of the gripping mechanism from the inactive position to the gripping position. In addition, the linkage system may comprise a safety switch operable based on the movement of the second member to electrically operate the electric actuator.

[0018] Furthermore, the rail may be of or may at least comprise a longitudinal portion of an electrically conductive material, preferably of ferromagnetic material, and the elevator safety gear is adapted for arranging to an elevator car or to a counterweight of an elevator car so that the overspeed governor device is arranged in proximity and non-contact with the rail.

[0019] According to a third aspect, a method for monitoring operation of an overspeed governor according to the first aspect is provided. The method comprises comparing a sensing signal produced by a motion sensor of the overspeed governor with a second sensing signal produced by another motion or positioning sensor, wherein said another motion or positioning sensor is arranged to determine motion or position with respect to the same elevator car relative to which the overspeed governor is arranged to operate. Thus, in order to verify that the driving member is rotating normally and / or is not stuck, for example due to bearing or other mechanical failure when elevator is moving, or that there is no failed or detached magnet in the driving member, the sensing signal can be compared with another sensing signal, such as of a motor encoder or an absolute positioning system encoder signal. If there is a too large of a difference in the motion information included in the sensing signals, it can be concluded that one of them might be from a faulty sensor or device. If the second sensing signal is already verified by other means, it may be concluded that the overspeed governor may be faulty.

[0020] The motion sensor of the overspeed governor may, preferably, be supplied with electric power to operate from an elevator control unit or the like.

[0021] The present invention provides an overspeed governor device for an elevator safety gear, an elevator safety gear for an elevator car or for a counterweight of an elevator car, and a method for monitoring operation of an overspeed. The present invention provides advantages over known solutions by providing a simpler and more compact system which doesn't require external energy units in operation.

[0022] Furthermore, there is no need for overspeed governor rope and its tensioning devices. Also, bi-directional operation is possible. There are practically no wearing parts needed to create force to lift the safety gears compared to traditional mechanical OSG clutch mechanisms or rope slip in the OSG rope groove. Furthermore, there are practically no wearing parts needed to rotate the OSG compared to the rope and rope groove wear in traditional OSG systems.

[0023] Various other advantages will become clear to a skilled person based on the following detailed description.

[0024] The expression "a plurality of" may refer to any positive integer starting from two (2), that is, being two, at least two, three, at least three, or the like.

[0025] The terms "first", "second", etc. are herein used to distinguish one element from another element, and not to specially prioritize or order them, if not otherwise explicitly stated.

[0026] 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 claims are mutually freely combinable unless otherwise explicitly stated.

[0027] 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.BRIEF DESCRIPTION OF FIGURES

[0028] Some embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. Figure 1 illustrates schematically an overspeed governor device. Figure 2 illustrates schematically an overspeed governor device. Figure 3 illustrates schematically an overspeed governor device. Figure 4 illustrates schematically an elevator car comprising an overspeed governor device. Figure 5 illustrates schematically an overspeed governor device arranged to a support structure. Figure 6 illustrates schematically a safety gear. Figure 7 illustrates schematically a safety gear. Figure 8 illustrates schematically an elevator system. Figure 9 shows a flow diagram of a method for monitoring operation of an overspeed governor device. DETAILED DESCRIPTION OF SOME EMBODIMENTS

[0029] Figure 1 illustrates schematically an overspeed governor device 20, such as to be operated in connection with an elevator safety gear, and gripping mechanism 40 thereof. The overspeed governor device 20 comprises a driving unit 21 comprising at least one driving member 22. The driving member 22 comprises a body 23 and a plurality of magnets 24 arranged to the body 23 in a pole-wise alternating manner around a rotation axis 29 of the driving unit 21.

[0030] The overspeed governor device 20 further comprises an actuation arrangement 25. The actuation arrangement 25 comprises a first member 26A arranged in mechanical coupling with the driving unit 21, and arranged to rotate together with the driving unit 21. The actuation arrangement 25 also comprises and a second member 26B. The actuation arrangement 25 is configured so that the second member 26B is stationary or idle, when the first member 26A rotates slower than a threshold speed value, and so that the second member 26B engages with the first member 26A, when the first member 26A reaches the threshold speed value, so that the second member 26B starts to move, for example, to rotate.

[0031] Permanent magnets 24 may be in electromagnetic interaction with a rail, causing eddy currents in the rail when the overspeed governor device 20 is moving relative to the rail. Eddy currents cause rotation of the driving member 22 in a manner that speed of the rotation of the driving member 22 is proportional to the speed of the elevator car, for instance.

[0032] Figure 1 also illustrates that there may be only one driving member 22 or a plurality of driving members 22, such as two. The other driving member 22 is drawn with dashed lines to indicate optionality. However, there could be even more, such as three, four, or five, or more driving members 22. Furthermore, adjacent driving members 22 of the plurality of driving members 22 are spaced apart in a direction of the rotation axis 29 so that a guide rail 18 can be arranged between the adjacent driving members 22. This is clearly shown in Fig. 1, wherein the guide rail 18, especially the nose of the guide rail 18, extends into the space between the adjacent driving members 22. The overspeed governor device 20 is, preferably, adapted and to be arranged so that the guide rail 18 extends at least to the portion of the space in which the plurality of magnets 24, that is their magnetic fields, reach the guide rail 18.

[0033] In various embodiments, the at least one driving member 22 may be arranged to rotate based a magnetic interaction between the plurality of magnets 24 and a magnetic field generated by eddy currents which are produced by the driving member 22 being moved relative to an electrically conductive surface, preferably of ferromagnetic material, in proximity and non-contact with the driving member 22. In many embodiments, the electrically conductive surface may be comprised in the guide rail 18, however, may alternatively be arranged to some other beam, rail, or structure of the system.

[0034] In Fig. 1, there is also shown a rotational shaft 31 between the driving unit 21 and the actuation mechanism 25. In case of multiple driving members 22, the rotational shaft 31 may, preferably, extend between the plurality of driving members 22, thus providing a compact overspeed governor device 20 with good magnetic interaction with the guide rail 18, for instance.

[0035] Therefore, in some embodiments, the driving members 22 may be interconnected to each other with a shaft 31, and there can be, for example, on the surfaces of the driving member(s) 22 permanent magnets in N-S-N-S etc order. Magnetic field produced by the magnets 24 reach the guide rail 18 arranged next to one or two or between two driving members 22. Otherwise the field may be on the air, although there may be encapsulation to control the field. Once the overspeed governor device 20, such as on an elevator car, starts to move, the driving members 22 start to rotate. There may be a small slip depending on the air gap, which can be taken into account in the determination of the threshold speed value (for example, by pre-tension of the flyweight system or rocker arm system). As, in some advantageous cases, the driving members 22 are on both sides of the guide rail 18, the magnetic force generated by the driving members 22 remains relatively stable even with lateral movements of the device 20, because when the air gap on one side of the guide rail 18 gets larger, it gets smaller on the opposite side. This will reduce the total effect of said movement on the operation of the device 20.

[0036] Furthermore, alternatively or in addition, the overspeed governor device 20 may comprise a motion sensor 27, such as an encoder, arranged to sense rotation of the driving member 22 and / or the first member 26A, and to produce a sensing signal. The sensing signal may, thus, carry information about the speed and direction of the rotation of the driving member 22 and / or the first member 26A. For example, the motion sensor 27 may be attached to the opposite side of the overspeed governor device 20 relative to the first member 26A. On the other hand, the motion sensor 27 may be attached on the same side of the device 20 than the first member 26A. In some embodiments, the motion sensor 27 may be attached to the rotational shaft 31, directly or via attachment or gear arrangement. There may also be an electrical power supply device (not shown) for supplying the motion sensor 27. The electrical power supply device may be arranged fixed relative to the sensor 27 and the overspeed governor device 20, or merely provided an electrical connection therebetween in cases the electrical power supply device is not arranged fixed relative to the overspeed governor device 20. Also batteries may be used.

[0037] Regarding the actuation arrangement 25, there are various ways of providing it. For example, the actuation arrangement 25 may comprise a spring-loaded mechanism to provide the engaging between the first member 26A and the second member 26B. In some embodiments, the spring-loaded mechanism may be adapted so that a force, such as a centrifugal force, related to rotation of the spring-loaded mechanism overcomes a spring force of the spring-loaded mechanism in response to the first member reaching the threshold speed value. Thus, when the first member 26A rotates fast enough, that is at or faster than the threshold speed value, the spring force is being overcome, and the second member 26B becomes engaged, such as mechanically and / or magnetically, with the first member 26A. For example, the spring-loaded mechanism may include a spring-loaded rocker arm to provide the engaging.

[0038] In some embodiments, the activation arrangement 25 may have, as the first member 26A and the second member 26B, two parallel plates. The first plate is fixed to the rotating axis 31 of the driving member 22, which may be a magnetic wheel, such that it rotates when the driving member 22 rotates. The second plate may normally be idle and does not rotate, but in an overspeed situation the actuation arrangement 25, such as by centrifugal activation mechanism, causes coupling between the first and the second plates such that also the second plate, and any pulley or the like component, starts to rotate. This rotation drives the mechanical linkage (such as a wire or a rod, or the like) such that the gripping mechanism 40, such as including a safety brake or brakes (wedges or rollers, for instance), of the safety gear move into a gripping position against, for example, the guide rail 18. Instead of said two parallel plates, any suitable, rotatable and compatible parts could be used for the coupling and, consequently, activation of the safety gear.

[0039] As rotating direction of the driving member 22 and the first and second members 26A, 26B depend on the movement direction of the overspeed governor device 20 relative to the portion, such as the guide rail 18, comprising the electrically conductive material, preferably of ferromagnetic material, activation of the safety brake is possible in both movement directions; in other words the overspeed governor device 20 can be used in bidirectional safety gear as well.

[0040] Thus, in various embodiments, the safety gear may, preferably, be a bidirectional safety gear, optionally with an electrically controllable activation. Bi-directional safety gear means that it has a gripping mechanism that acts in both movement directions, such as, in up and down directions of an elevator car.

[0041] The actuation arrangement 25 may, alternatively, be based on other than spring-loaded mechanism. For example, on the pendulum principle, flyweight arrangement, and / or acting against the gravitational force. The threshold speed value may thus be determined based on the structure, such as masses, of the mechanism having the gravity affecting it components, thereby requiring certain speed to overcome the counterforce, and then providing the engagement.

[0042] In Fig.1, the second member 26B is shown as more or less directly connected to the schematical gripping mechanism of the safety gear. This connection may be, for example, a mechanical linkage, such as by wires, rods, or other mechanical force transmitting elements.

[0043] Thus, in various embodiments, while the driving members 22 and / or the first member 26A rotates below the threshold speed value, there is no force being generated to the activation mechanism of the safety gear other than the bearing friction (neglible), or the safety switch 30 is not actuated from its normal state.

[0044] Figure 2 illustrates schematically an overspeed governor device 20, such as to be operated in connection with an elevator safety gear. The overspeed governor device 20 in Fig. 2 may be in most parts similar or even identical to the one shown in Fig. 1. However, the second member 26B of the actuation arrangement 25 may be coupled to a safety switch 30 controlling electric actuation of safety gear, and finally the gripping mechanism 40. Thus, the overspeed governor device 20 may be arranged to operate the switch 30 when the threshold speed value is reached. The switch 30 then controls the actuation of the safety gear electrically. Thus, there is no need for a mechanical linkage or connection to be arranged between the overspeed governor device 20 and other components of the safety gear.

[0045] Electrically controlled activation may mean that, for example, the safety gear is activated (such as braking initiated) in response to a receiving an electrical activation signal. An electric actuator may be activated and may change the position of the gripping mechanism 40 of the safety gear to provide braking, such as by a coupling mechanism therebetween for transmitting the force generated by the electric actuator to change the position of the gripping mechanism or mechanisms. Thus, safety gear wedge or roller movement is implemented based on an electrical activation, wherein the overspeed detection device, or the overspeed governor, is utilized to supply power to electric actuator generating the force to change the position to the gripping position. This is in contrast to traditional safety gears where the activation of the safety gear occurs in response to a tripping of an overspeed governor by centrifugal force during overspeed condition thereof, and then causes, via a mechanical coupling, the safety gear to activate.

[0046] Figure 3 illustrates schematically an overspeed governor device 20 as a perspective view. There is shown two driving members 22, however, other one is drawn with dashed lines indicating optionality. The overspeed governor device 20 may, in general, be similar to ones shown schematically in Figs. 1 and 2, however, there are also further details visible.

[0047] In Fig. 3, the driving members 22 comprise the plurality of permanent magnets 24 which are arranged in a pole-wise alternating manner around a rotation axis 29 of the driving unit 21. As can be seen, the permanent magnets are marked reference signs 24A and 24B to indicate that adjacent magnets are arranged in different way regarding their polarity and / or direction of their magnetic field. In some embodiments, the permanent magnets 24, 24A, 24B may be arranged to holes at the peripheral portion of the body 23 of the driving member(s) 22. For example, the permanent magnets 24A may have their south pole S pointing towards the other driving member 22, whereas permanent magnets 24B may have their north pole N towards the other driving member 22, or vice versa. As understood by the skilled person, the magnets 24 may be arranged in various alternative arrangement to obtain similar effect. For example, a pair of magnets 24 may be arranged in the same way and another pair of magnets 24 into the opposite way. Alternatively, more complex magnet arrangements, such as Halbach arrays or the like, may be used as long as the same or similar effect is obtained, according to which the overspeed governor device 20 starts to rotate when being moved relative to the electrically conductive surface, such as of the guide rail 18.

[0048] Figure 3 also illustrates support or fixing members 34 for attaching the overspeed governor device 20 to an elevator car and a counterweight of the elevator car, for instance. In various embodiments, the support members 34 may be coupled to the axis 29 via bearings so as to enable rotation of the axis 29 relative to the support members 34. In some embodiments, the support member 34 is used to fix or attach the overspeed governor device 20 to a support frame (not shown, however, could be adjacent to the support member(s) 34), which the support frame may be further in connection with the elevator car.

[0049] As illustrated in Fig. 3, the overspeed governor device 20 is, preferably, at least functionally connected to the gripping mechanism 40 of a safety gear, either by mechanically or electrically via a safety switch 30, for instance. Even though shown in Fig. 3 that the overspeed governor device 20 and the gripping mechanism 40 are arranged close to the same guide rail 18, in various embodiments, this may not be the case. The overspeed governor device 20 may indeed be arranged to be close to a guide rail 18 while the gripping mechanism 40 is arranged close to another braking rail which is different and spaced apart from the guide rail 18.

[0050] Figure 4 illustrates schematically an elevator car 60 comprising an overspeed governor device 20. Fig. 4 shows an example of the support frame 32 to which an overspeed governor device 20 may be attached to. In Fig. 4, the overspeed governor device 20 and the gripping mechanism 40 of the safety gear 100 are shown highly schematically. The guide rail 18 may extend, for example, along the whole elevator shaft or at least along most of it. The guide rail 18 may be fixed to the elevator shaft so that it maintains its position.

[0051] Furthermore, regarding Fig. 4, there can be only one safety gear 100 and guide rail 18, or several safety gears 100 and rails 18 arranged coupled to the elevator car 60. In case of having a plurality of safety gears, they may be connected to each other by an interconnection 39, such electrically and / or mechanically. Thus, in some embodiments, one overspeed governor device 20 can be utilized to operate several activation and / or gripping mechanisms 40 of safety gears 100. As can be understood, there may alternatively be one overspeed governor 20 and one activation and / or gripping mechanisms 40, or several such pairs.

[0052] Figure 5 illustrates schematically an overspeed governor device 20 arranged to a support frame or structure 32. As can be seen, the support frame or structure 32, which is attached to the elevator car 60 or the counterweight of the elevator car 60, may extend parallel relative to the guide rail 18. In Fig. 5, the guide rail 18 is shown partly behind the support frame or structure 32. Portion of the guide rail 18 extends between the driving members 22 of the overspeed governor device 20, although not clearly visible in Fig. 5. Figs. 1 and 2 show examples of the position of the overspeed governor device 20 with respect to the guide rail 18 more clearly.

[0053] Figure 6 illustrates schematically a safety gear 100 comprising an overspeed governor 20. The elevator safety gear 100 for an elevator car 60 or for a counterweight of an elevator car 60 is shown schematically. The elevator safety gear 100 comprises a gripping mechanism 40 having a gripping position and an inactive position, wherein the gripping mechanism 40 is configured in the gripping position for gripping a rail (such as the guide rail 18 or some other rail) for providing braking. In Fig. 6, the brake pads 41, 42 are shown. First brake pad 41 (or pads, for instance) is stationary and second brake pads 42 on the opposite side of the braking surfaces (not shown) are movable by the operation of the gripping mechanism 40.

[0054] Furthermore, the safety gear 100 comprises a linkage system 45 for changing the position of the gripping mechanism 40 from the inactive position to the gripping position. In Fig. 6, this is implemented by ropes, wires 44, or rods, and sheave(s), trolley(s), roller(s) or the like. As visible, there may be two wires 44 or the like for enabling bi-directional operation.

[0055] Finally, the safety gear 100 comprises an overspeed governor device 20 configured to operate the linkage system 45, either mechanically or electrically as is described hereinabove.

[0056] As shown in Fig. 6, the linkage system 45 may comprise a mechanical coupling between the second member 26B of the overspeed governor device 20 and the gripping mechanism 40. Furthermore, the linkage system 45 may comprises rope or wires, such as steel ropes or wires, between the second member 26B and the gripping mechanism 40.

[0057] Alternatively, the linkage system 45 may comprise an electric actuator (not shown) for changing the position of the gripping mechanism 40 from the inactive position to the gripping position, and a safety switch 30 operable based on the movement of the second member 26B to electrically operate the electric actuator 40.

[0058] Furthermore, the rail is of or at least comprises a longitudinal portion of an electrically conductive material, preferably of ferromagnetic material, and the elevator safety gear 100 is adapted for arranging to an elevator car 60 or to a counterweight of an elevator car 60 so that the overspeed governor device 20 is arranged in proximity and non-contact with the rail.

[0059] In view of the above, in various embodiments, the required safety gear components are located in connection to the car 60. Therefore, maintenance may be carried out from one single location. In some embodiments, a maintenance person inside an elevator car 60 may reach the safety gear 100 via a hatch or an openable car wall or car roof.

[0060] Figure 7 illustrates schematically a safety gear 100.The safety gear 100 comprises a gripping mechanism 40 having a gripping position and an inactive position, wherein the gripping mechanism 10 is configured in the gripping position for gripping a guide rail 18 for providing braking. In Fig. 7, the gripping mechanism 40 is shown in the inactive position. In the gripping position portion of the gripping mechanism 40 becomes in contact with the guide rail 18.

[0061] In some embodiments, the safety gear 100 may further comprise an electric actuator 35 and a linkage system 45 between the electric actuator 35, such as an electric motor, and the gripping mechanism 40, wherein the linkage system 45 is adapted to arrange the gripping mechanism 40 into the gripping position by the operation of the electric actuator 35. In various embodiments, the linkage system 45 may mechanically transmit force generated by the electric actuator 35 to change the position of the gripping mechanism 40. For example, the electric actuator 35 may be directly operating the linkage system 45 or via a sheave 48 or the like. The safety gear 100 also comprises an overspeed governor device 20. The gripping mechanism 40 is arranged to the gripping position in response to determining, based on the operation of the overspeed governor 20, such as a measurement thereof, that there is the overspeed situation.

[0062] Figure 7 further illustrates an optional position or proximity sensor 50 for determining position of a safety gear wedge 52 of the safety gear 100. The gripping mechanism 40 preferably also comprises a safety gear block 54 for guiding the wedge 52. The safety gear wedge 52 may thus provide braking when it gets wedged between the safety gear block 54 and the rail, such as the guide rail 18. The gripping mechanism 40 may be arranged to provide instantaneous or progressive braking. In some embodiments, the safety gear 100 may comprise a roller instead of a wedge 52. The wedge 52 or the roller may be arranged to move on a dedicated track between the gripping and inactive positions.

[0063] In various embodiments, and as is visible in Fig. 7 to a skilled person in the art, the safety gear 100 may comprise a bidirectional gripping mechanism 40, that is, it may be configured to provide braking selectively in either one of directions with respect to the longitudinal direction of the guide rail 18 with respect to movement of the elevator car 60 in said direction.

[0064] Regarding the position or proximity sensor 50, it can be used to identify the central position of the wedge 52, for instance. Furthermore, in some embodiments, it can alternatively or in addition, be used in the process of resetting the safety gear 100.

[0065] The sensor 50 may also be utilized to check, such as periodically, the operation of safety gear 100 and components thereof. For example, the elevator car 60 may be moved up and down. During said moving, the sensor 50 would change its state, such as on-off-on, if operating correctly. Thus, the correct operation may be determined and verified with the safety gear 100.

[0066] For example, the surface, or at least a region close to the surface, of the driving member 22 may have permanent magnets 24A, 24B arranged in a pole-wise alternating manner, that is, having their poles in north-south-north-south order or the like, as stated hereinbefore. The magnetic field of the driving member 22 thus preferably reaches the rail, such as the guide rail 18, which may preferably be of ferromagnetic material. The permanent magnets 24A, 24B thereby produce an alternating magnetic field when the driving member 22 moves relative to the rail which generates eddy currents 104 in the rail. This causes the rotation of the driving member 22 due to the interaction 102 of the permanent magnets 24A, 24B and the magnetic field generated by the eddy currents 104. The driving member 22 thus rotates due to a touchless or contactless manner or interaction 102 with the rail.

[0067] Still further, the linkage system 45 may comprise a rope, a wire 44, or a belt for transmitting force generated by the second member 26B or the electric actuator 35 to the gripping mechanism 40. The linkage system 45 may comprise a counterweight 46 for balancing mass of a safety gear wedge 52 of the gear 100. Thus, the safety gear wedge 52 maintains its position more easily. As can be seen, the rope, wire 44, or belt may be arranged to extend around a safety gear sheave 48 in order to be able to move the wedge 52 selectively in different directions for, e.g., providing the bidirectional braking and / or moving the wedge 52 back to neutral position when being displaced therefrom for any reason, such as due to braking. Alternatively or in addition, a small magnet could be added keep the wedge(s) 52 and / or counterweight 46, if any, in place.

[0068] The safety gear 100 may, thus, comprise wedges 52 or wedge brake pads, wedge guiding mechanism comprising safety gear block(s) 54, rope(s), wire(s) 44, belt(s), the electric actuator 35, counterweight 46, and the position or proximity sensor 50.

[0069] In various embodiments, such as shown in Fig. 7, the wedges 52 may be arranged on both sides of the rail, and they may be connected to each other. The connection may be such that the wedges 52 on both sides operate substantially simultaneously. This is marked in Fig. 7 by the arc with a dashed line between the wedges 52.

[0070] In addition, in various embodiments, the safety gear 100 may comprise at least two gripping mechanisms, each of which are configured to be operated based on determining the overspeed situation by the overspeed governor device 20. A mechanical synchronization axis may be needed, however, not necessarily if the gripping mechanism 40 is activated electrically.

[0071] Figure 8 illustrates schematically an elevator system 200. The elevator system 200 may comprise an electric motor 155 for moving an elevator car 60 in an elevator shaft 150 comprised in the elevator system 200. The elevator car 60 may be mechanically coupled to the electric motor 155, for example, by a hoisting rope 140, hydraulic means or in more direct manner in case of a linear motor. The operation of the electric motor 155 may, optionally, be controlled by an electrical drive 105 such as a frequency converter or an inverter. The motor 155 may be arranged to rotate an elevator sheave.

[0072] The elevator system 200 also comprises a motion or position sensor 61, such as a motor encoder or an absolute positioning system encoder. The motor encoder may be arranged in connection with the elevator motor 155. On the other hand, there may be a motion or position sensor 61 arranged to extend along the elevator shaft 150 for providing information about the position of the elevator car 60 in the shaft 150.

[0073] As can be seen, the elevator system 200 comprises the safety gear 100 as described hereinbefore. The safety gear 100 is coupled to the elevator car 60 and arranged to operate in connection with the guide rail 18 extending in the elevator shaft 150.

[0074] The hoisting rope 140 may comprise, for example, steel or carbon fibers. The hoisting rope 140 may in various embodiments be coupled to the elevator sheave, and may therefore be operated by the motor 155. The term 'hoisting rope' does not limit the form of the element anyhow. For example, the hoisting rope 140 may be implemented as a rope, a belt, or a track in ropeless or rope-free elevators.

[0075] The elevator system 200 may comprise an elevator control unit 1100 for controlling the operation of the elevator system 200. The elevator control unit 1100 may be a separate device or may be comprised in the other components of the elevator system 200 such as in or as a part of the electrical drive 105. The elevator control unit 1100 may also be implemented in a distributed manner so that, e.g., one portion of the elevator control unit 1100 may be comprised in the electrical drive 105 and another portion in the elevator car 60. The elevator control unit 1100 may also be arranged in distributed manner at more than two locations or in more than two devices.

[0076] The elevator system 200 may comprise a further elevator brake arrangement 145 comprising an elevator brake, preferably, an electromechanical elevator brake, such as in connection with the motor 155 and / or the elevator sheave.

[0077] Other elements shown in Fig. 8, which may or may not be utilized in embodiments of the present invention, are a main electrical power supply 125 such as a three- or single-phase electrical power grid, an electrical connection 120 to the electrical drive 105, if any, and / or the electric motor 155. The elevator car 60 may operate in the shaft or hoistway 150 serving landing floors 160. There may or may not be a counterweight 135 utilized in embodiments of the present invention. In such embodiments, the overspeed governor device 20 may be arranged in connection with the counterweight 135.

[0078] Figure 9 shows a flow diagram of a method for monitoring operation of an overspeed governor device 20.

[0079] Item or method step 900 refers to a start-up phase of the method. Suitable equipment and components are obtained and systems assembled and configured for operation. This may mean arranging an overspeed governor device 20 and / or a safety gear 100 as described hereinbefore in connection with an elevator car 60 and a rail, such as a guide rail 18.

[0080] Item or method step 910 refers to comparing a sensing signal produced by a motion sensor 27 of the overspeed governor device 20 with a second sensing signal produced by another motion or positioning sensor 61, wherein said another motion or positioning sensor 61 is arranged to determine motion or position with respect to the same elevator car 60 relative to which the overspeed governor device 20 is arranged to operate.

[0081] Method execution may be stopped at step 999.

[0082] Thus, the method may comprise checking continuously, periodically, intermittently, or randomly operation of safety components of the safety gear 100. To verify that the driving member(s) 22 are rotating normally and not stuck due to bearing or other mechanical failure when the elevator car 60 is moving.

[0083] The method and the system can be also programmed for remote monitoring purposes, as the increase of signal difference can detect for example slowly failing bearings or reducing magnetic force. Additionally electrical tripping device to trip the OSG 20 remotely from elevator control panel can be used.

Claims

1. An overspeed governor device (20) for an elevator safety gear (100), the overspeed governor device (20) comprising: a driving unit (21) comprising at least one driving member (22), the driving member (22) comprising a body (23) and a plurality of magnets (24) arranged to the body (23) in a pole-wise alternating manner around a rotation axis (29) of the driving unit (21); and an actuation arrangement (25) comprising: a first member (26A) arranged in mechanical coupling with the driving unit (21), and arranged to rotate together with the driving unit (21), and a second member (26B), characterized in that the actuation arrangement (25) is configured so that the second member (26B) is stationary, when the first member (26A) rotates slower than a threshold speed value, and engages with the first member (26A), when the first member (26A) reaches the threshold speed value, so that the second member (26B) starts to move.

2. The overspeed governor device (20) of claim 1, wherein the actuation arrangement (25) comprises a spring-loaded mechanism to provide the engaging between the first member (26A) and the second member (26B).

3. The overspeed governor device (20) of claim 2, wherein the spring-loaded mechanism is adapted so that a force, such as a centrifugal force, related to rotation of the spring-loaded mechanism overcomes a spring force of the spring-loaded mechanism in response to the first member (26A) reaching the threshold speed value.

4. The overspeed governor device (20) of claim 2 or 3, wherein the spring-loaded mechanism includes a spring-loaded rocker arm to provide the engaging.

5. The overspeed governor device (20) of any of claims 1-4, wherein the at least one driving member (22) is arranged to rotate based on a magnetic interaction between the plurality of magnets (24) and a magnetic field generated by eddy currents which are produced by the driving member (22) being moved relative to an electrically conductive surface, preferably of ferromagnetic material, in proximity and non-contact with the driving member (22).

6. The overspeed governor device (20) of any of claims 1-5, comprising a motion sensor (27), such as an encoder, arranged to sense rotation of the driving member (22) and / or the first member (26A), and to produce a sensing signal.

7. The overspeed governor device (20) of any of claims 1-6, wherein the driving unit (21) comprises a plurality of driving members (22).

8. The overspeed governor device (20) of claim 7, wherein adjacent driving members (22) of the plurality of driving members (22) are spaced apart in a direction of the rotation axis (29) so that a guide rail (18) can be arranged between the adjacent driving members (22).

9. The overspeed governor device (20) of any of claims 1-8, comprising a rotational shaft (31) between the driving unit (21) and the actuation mechanism (25).

10. The overspeed governor device (20) of claims 7 and 9, wherein the rotational shaft (31) extends between the plurality of driving members (22).

11. An elevator safety gear (100) for an elevator car (60) or for a counterweight (135) of an elevator car (60), the elevator safety gear (100) comprising: a gripping mechanism (40) having a gripping position and an inactive position, wherein the gripping mechanism (40) is configured in the gripping position for gripping a rail (18) for providing braking, a linkage system (45) for changing the position of the gripping mechanism (40) from the inactive position to the gripping position, characterized by an overspeed governor device (20) of any of claims 1-10 configured to operate the linkage system (45).

12. The elevator safety gear (100) of claim 11, wherein the linkage system (45) comprises a mechanical coupling between the second member (26B) of the overspeed governor device (20) and the gripping mechanism (40), wherein, optionally, the linkage system (45) comprises rope or wires (44), such as steel ropes or wires, between the second member (26B) and the gripping mechanism (40).

13. The elevator safety gear (100) of claim 11, wherein the linkage system (45) comprises an electric actuator (35) for changing the position of the gripping mechanism (40) from the inactive position to the gripping position, and a safety switch (30) operable based on the movement of the second member (26B) to electrically operate the electric actuator (35).

14. The elevator safety gear (100) of any of claims 11-13, wherein the rail is of or at least comprises a longitudinal portion of an electrically conductive material, preferably of ferromagnetic material, and the elevator safety gear (100) is adapted for arranging to an elevator car (60) or to a counterweight (135) of an elevator car (60) so that the overspeed governor device (20) is arranged in proximity and non-contact with the rail.

15. A method for monitoring operation of an overspeed governor device (20) of any one of claims 1-10, the method comprising comparing a sensing signal produced by a motion sensor (27) of the overspeed governor device (20) with a second sensing signal produced by another motion or positioning sensor (61), wherein said another motion or positioning sensor (61) is arranged to determine motion or position with respect to the same elevator car (60) relative to which the overspeed governor device (20) is arranged to operate.