Device and method for measuring the rotational speed of components of elevators, escalators, moving walkways or moving ramps

Abstract

A measuring device (20a, 20b, 20c) for measuring the rotational speed of a component (6, 7a, 7b, 8, 9) of an elevator, escalator, moving walkway or moving ramp, the measuring device comprising an inductive sensor (11), the inductive sensor (11) being arranged stationary relative to the rotational axis (10) of the component (6, 7a, 7b, 8, 9) and adjacent to the component (6, 7a, 7b, 8, 9) or adjacent to a measuring part (16) attached to the component (6, 7a, 7b, 8, 9) in a rotationally fixed manner, and the component (6, 7a, 7b, 8, 9) or the measuring part (16) being configured to be rotationally asymmetric around the rotational axis (10), so that different angular positions of the component (6, 7a, 7b, 8, 9) around the rotational axis (10) generate different output signals in the inductive sensor (11).

Description

Technical Field

[0001] The invention relates to a measuring device for measuring the rotation speed of an elevator, escalator, moving walkway or moving ramp component according to claim 1. The invention also relates to a rotation speed monitoring method of an elevator, escalator, moving walkway or moving ramp component as defined in the other independent claims. Background Art

[0002] For various reasons, it is crucial to know the speed and / or position of the elevator car and / or counterweight of the elevator in an elevator. The position of the elevator car in the shaft can be determined, for example, with the help of a linear encoder. One problem associated with the use of a linear encoder is that the linear encoder requires a scale that must extend over the entire length of the shaft, which makes the linear encoder clumsy and fragile. For example, dirt can affect the reliability of the linear encoder. Another solution for determining the speed and / or position of the elevator car is an encoder with a friction wheel that engages with the guide rails of the elevator car. A problem with this solution is that there may be roller slippage, making such an encoder unreliable. Similarly, a reliable and cost-effective way to determine the speed and / or position of different components is also needed in escalators, moving walkways and moving ramps. Summary of the invention

[0003] One object of the invention is to provide an improved measuring device for measuring the rotation speed of components of elevators, escalators, moving walkways or moving ramps. The distinctive features of the device according to the invention are given in claim 1. Another object of the invention is to provide an improved monitoring method for the rotation speed of components of elevators, escalators, moving walkways or moving ramps. The distinctive features of the method according to the invention are given in the other independent claims.

[0004] In a device according to the invention, the component is rotatable about a rotation axis, the device comprises an inductive sensor, the inductive sensor is arranged stationary relative to the rotation axis of the component and adjacent to the component or adjacent to a measuring part attached to the component in a rotationally fixed manner, and the component or the measuring part is configured to be asymmetric about the rotation axis, so that different angular positions of the component about the rotation axis generate different output signals in the inductive sensor.

[0005] In the method according to the invention, the rotational speed of a component of an elevator, escalator, moving walkway or moving ramp is monitored by means of a measuring device as defined above.

[0006] With the measuring device and the method according to the invention, the rotational speed of, for example, a rotating part in an elevator can be reliably determined in an inexpensive manner. The measuring device is insensitive to dirt and does not require mechanical contact between the rotating part and the sensor. Based on the speed measurement, the position of the elevator car, the counterweight, etc. can also be determined.

[0007] According to an embodiment of the invention, the component or the measuring portion is provided with a surface, the surface being shaped and / or positioned such that the distance from the surface to the inductive sensor changes as the component rotates about the axis of rotation, and the inductive sensor is arranged to detect the changing distance between the surface and the inductive sensor.

[0008] The surface may be, for example, a plane arranged at an angle different from 90 degrees relative to the axis of rotation of the component. Alternatively, the surface may be a non-circular periphery of the component or the measuring portion. The surface may also be the surface of a circular groove or cutout.

[0009] According to one embodiment of the invention, the component is a sheave, a pulley or a sprocket, or an axle or a shaft supporting a sheave, a pulley or a sprocket.

[0010] According to one embodiment of the present invention, the component or the measuring portion is provided with a material removal or addition area for compensating for the influence of the asymmetric shape of the component or the measuring portion on the inertia force of the component or the measuring portion.

[0011] According to one embodiment of the invention, the component or the measuring portion comprises a bore for compensating for the influence of the asymmetric shape of the component or the measuring portion on the inertial forces of the component or the measuring portion.

[0012] According to one embodiment of the invention, the component is attached to the elevator car or the counterweight of the elevator.

[0013] According to one embodiment of the invention, the component or the measuring portion is configured such that each angular position of the component about the axis of rotation generates a unique output signal in the inductive sensor. This allows the absolute angular position of the component to be determined using a single inductive sensor.

[0014] The monitoring system according to the invention comprises a measuring device as defined above, which is arranged to monitor the rotation speed of an elevator, escalator, moving walkway or moving ramp component.

[0015] The elevator according to the invention comprises a measuring device as defined above.

[0016] According to one embodiment of the invention, the elevator comprises a first measuring device arranged to monitor the rotation speed of a pulley of the elevator car and a second monitoring device arranged to monitor the rotation speed of a pulley of the elevator counterweight. This allows, for example, to detect a stall of the elevator car or the counterweight. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings, in which:

[0018] Figure 1 A simplified view of an elevator is shown schematically,

[0019] Figure 2 Schematically showing a simplified view of a measuring device according to a first embodiment of the invention,

[0020] Figure 3 Schematically showing a simplified view of a measuring device according to a second embodiment of the invention,

[0021] Figure 4 A simplified view schematically shows a measuring device according to a third embodiment of the invention,

[0022] Figure 5 Show Figure 4 Another view of the device,

[0023] Figure 6 Schematically showing a simplified view of a measuring device according to a fourth embodiment of the invention,

[0024] Figure 7 Show Figure 6 Another view of the device,

[0025] Figure 8 A simplified view of a measuring device according to a fifth embodiment of the invention is schematically shown, and

[0026] Fig. 9 A monitoring system according to an embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0027] Figure 1 A simplified view of an elevator is schematically shown. The elevator comprises an elevator car 1 and a counterweight 2 configured to move in a vertical direction in a shaft 3. For the sake of clarity, Figure 1 Many parts of the elevator are omitted, such as the guide rails of the elevator car 1 and the counterweight 2. The elevator car 1 is connected to the counterweight 2 via traction members 4. The traction members 4 can be, for example, steel wires, belts such as toothed belts or flat belts, carbon fiber ropes or coated ropes. The elevator can include several traction members 4. The elevator car 1 and the counterweight 2 are connected to each other in such a way that they move in opposite directions relative to each other. The elevator is also provided with a motor 5. The motor 5 is preferably an electric motor. The motor 5 drives a sheave 6. The sheave 6 can be connected to the motor 5 directly or via gears. When the sheave 6 rotates, the traction members 4 move, thereby moving the elevator car 1 and the counterweight 2. In Figure 1 In the example of , each end of the traction member 4 is fixed to the upper end of the shaft 3. The elevator car 1 is provided with a first pulley 7a and a second pulley 7b. Figure 1In the example of , the pulleys 7a, 7b are arranged below the elevator car 1. The traction member 4 engages with the first pulley 7a and the second pulley 7b. The pulleys 7a, 7b of the elevator car 1 are configured to rotate freely around the axis of rotation. The counterweight 2 is provided with a pulley 8 engaged with the traction member 4. Likewise, the pulley 8 of the counterweight 2 is configured to rotate freely around the axis of rotation. The sheave 6, the pulleys 7a, 7b, 8 and the traction member 4 form the rope system of the elevator.

[0028] It should be noted that Figure 1 Only one example of an elevator rope system is shown, the traction member 4 can be arranged in many alternative ways. For example, the elevator car 1 can be provided with a single pulley. The counterweight 2 can be provided with more than one pulley. The first end of the traction member 4 can be attached to the elevator car 1 and the second end of the traction member 4 can be attached to the counterweight 2. The traction member 4 can be guided twice around the sheave 6 of the motor 5.

[0029] exist Figure 1 In the example of , the motor 5 is arranged in a machine room 21 located above the shaft 3. However, the elevator may also be a machine room-less elevator. Therefore, the motor 5 may be arranged in the shaft 3. The motor 5 may be arranged at the upper end or the lower end of the shaft 3. The lower end of the shaft 3 is provided with at least one end buffer 22 for the elevator car 1 and at least one end buffer 23 for the counterweight 2. The purpose of the end buffers 22, 23 is to stop the elevator car 1 or the counterweight 2 in case the elevator car 1 or the counterweight 2 descends beyond its normal range of movement. The buffers 22, 23 are configured to accumulate or consume the kinetic energy of the elevator car 1 or the counterweight 2 in case the elevator car 1 or the counterweight 2 hits the buffers 22, 23, thereby limiting the deceleration of the elevator car 1 or the counterweight 2 in this case. Figure 1 Also shown is the door 25 of the shaft 3 at the lowest landing.

[0030] In an elevator, it is crucial to know the speed and position of the elevator car 1 precisely. The speed information can be used, for example, to detect elevator overspeed, to perform a controlled deceleration when the elevator car 2 approaches the end of the shaft 3, or to detect a stall of the elevator car 1 or the counterweight 2. Position information is needed, for example, when the elevator car 1 approaches the end of the shaft 3. In order to monitor the speed and position of various parts of the elevator, different sensors and measuring devices can be provided in the elevator. Figure 1 A first measuring device 20a is shown which is arranged to measure the rotation speed of the first pulley 7a of the elevator car 1. A second measuring device 20b is arranged to measure the rotation speed of the pulley 8 of the counterweight 2. A third measuring device 20c is arranged to measure the rotation speed of the second pulley 7b of the elevator car 1. Figure 1 Also shown is a sensor 26 configured to detect that the elevator car 1 is at the lowest landing, and another sensor 27 configured to detect that the elevator car 1 is at the highest landing.

[0031] The rotational speed of the pulleys 7a, 7b, 8 of the elevator car 1 or the counterweight 2 can be measured by means of a measuring device according to the invention. The measuring device according to the invention allows the measurement of the rotational speed of the rotatable component of the elevator. The component can rotate around the axis of rotation. In addition to elevators, the measuring device can also be applied to escalators, moving walkways or moving ramps. In an elevator, the rotatable component can be, for example, a sheave, a pulley or an axle or shaft supporting such a sheave or pulley. The measuring device includes an inductive sensor, which is arranged to be fixed relative to the axis of rotation of the component and adjacent to the component or adjacent to a measuring portion attached to the component in a rotationally fixed manner. The component or the measuring portion is configured to be asymmetric about the axis of rotation so that different angular positions of the component about the axis of rotation generate different output signals in the inductive sensor.

[0032] By "inductive sensor" is meant a sensor which uses the principle of electromagnetic induction to detect the presence of a metal object. The operation of a typical inductive sensor is based on the generation of an oscillating electromagnetic field by supplying an alternating current to a coil. The presence of a metal object causes a change in frequency or current in the coil. These changes can be monitored directly from the coil or using a second coil. The inductive sensor used in the device according to the invention is configured to detect the amplitude of changes in the electromagnetic field and to generate an output signal representative of the changes in the electromagnetic field. Thus, the sensor can, for example, be used to determine the distance to a metal object, rather than being used as an on / off type sensor. The inductive sensor may be a digital sensor.

[0033] The measuring device according to the invention is reliable and inexpensive. By determining the rotation speed of the pulleys 7a, 7b of the elevator car 1, the speed of the elevator car 1 can be determined. By determining the rotation speed of the pulley 8 of the counterweight 2, the speed of the counterweight 2 can be determined. Likewise, the position of the elevator car 1 and / or the counterweight 2 can be determined based on the speed data obtained. Likewise, the acceleration or deceleration of the elevator car 1 or the counterweight 2 can be determined.

[0034] Figure 2 A measuring device 20b according to a first embodiment of the present invention is shown. Figure 2 In the embodiment of the invention, the rotatable component is a weighted pulley 8. The pulley 8 is arranged around an axle 9. The pulley 8 is configured to be rotatable around an axis of rotation 10. The axle 9 may be supported by at least one bearing, and the pulley 8 may rotate with the axle 9. Alternatively, the axle 9 may be stationary, and the pulley 8 may rotate around the axle 9. Therefore, the pulley 8 may be supported by a bearing arranged on the axle 9.

[0035] The measuring device is provided with an inductive sensor 11. Figure 2In an embodiment of the invention, the inductive sensor 11 is arranged adjacent to the pulley 8. One side surface 12 of the pulley 8 is configured such that the distance from the surface 12 to the inductive sensor 11 depends on the angular position of the pulley 8. The side surface 12 is arranged at an angle α different from 90 degrees relative to the rotation axis 10 of the pulley 8. The angle α between the rotation axis 10 and the surface 12 can be, for example, 80-89 degrees. The inductive sensor 11 is configured to generate an output signal that depends on the distance between the sensor 11 and the surface 12. By determining the distance from the side surface 12 to the sensor 11, the angular position of the pulley 8 can be determined. By monitoring the angular position of the pulley 8, the rotation speed of the pulley 8 can also be determined.

[0036] because Figure 2 The pulley 8 in the illustrated embodiment is not rotationally symmetrical, and the thickness of the pulley 8 varies along the axial direction of the pulley 8, so the rotation of the pulley 8 generates an inertial force. In order to compensate for the inertial force caused by the varying thickness of the pulley 8, the pulley 8 may be provided with a bore 13, such as Figure 2 As shown. Figure 2 In the embodiment of the present invention, the boreholes 13 extend inwardly from the side surface 12 of the pulley 8 in the axial direction of the pulley 8. However, the boreholes 13 may also be arranged on the opposite side surface of the pulley 8. Instead of or in addition to the boreholes 13, the pulley 8 may also be provided with some other type of material removal or addition area for balancing the pulley 8. For example, the thicker side of the pulley 8 may be provided with grooves or cutouts, and / or the thinner side of the pulley 8 may be provided with protrusions or counterweights.

[0037] Figure 3 A measuring device 20b according to a second embodiment of the present invention is shown. Figure 3 In the embodiment of the invention, the pulley 8 is supported by a rotatable axle 9. Therefore, the axle 9 is supported by at least one bearing (not shown). The pulley 8 is attached to the axle 9 in a rotationally fixed manner. Therefore, the rotation speed of the pulley 8 is equal to the rotation speed of the axle 9. Figure 3 The device further comprises an inductive sensor 11. The inductive sensor 11 is arranged to monitor the distance to the end face 14 of the axle 9. Figure 2 Similar to the embodiment of the present invention, the end surface 14 of the axle 9 is arranged at an angle α different from 90 degrees relative to the rotation axis 10 of the pulley 8. The angle α between the rotation axis 10 and the surface 14 can be, for example, 80-89 degrees. Figure 3 In the embodiment of the present invention, the axle 9 is provided with a bore 15 for balancing the axle 9. Figure 3 In the embodiment of the present invention, the bores extend inwardly from the end face 14 of the axle 9 in the axial direction of the axle 9. However, the bores may also extend radially inwardly from the outer circumference of the axle 9. Instead of or in addition to the bores, the axle 9 may be provided with some other type of material removal or addition area, such as a cutout or a groove or a counterweight. Figure 3 The working principle of the device shown is similar to Figure 2 The working principle of the device shown is similar. The angular position and rotation speed of the pulley 8 correspond to the angular position and rotation speed of the axle 9. By determining the rotation speed of the axle 9, the rotation speed of the pulley 8 can be determined.

[0038] Figure 4 A measuring device 20b according to a third embodiment of the present invention is shown. Figure 5 Show Figure 4 An end view of the device (sensing sensor not shown). Figure 4 and Figure 5 In the device of , the assembly comprising the pulley 8 and the axle 9 is provided with a separate measuring section 16 for determining the rotation speed of the pulley 8. Figure 4 and Figure 5 In an embodiment of the invention, the pulley 8 is attached to the axle 9 in a rotationally fixed manner. The measuring portion 16 is attached to the axle 9 in a rotationally fixed manner. If the pulley 8 rotates relative to the axle 9, the measuring portion 16 will be attached to the pulley 8 in a rotationally fixed manner. The device is provided with an inductive sensor 11, which is arranged to monitor the distance to the periphery 19 of the measuring portion 16. The measuring portion 16 is arranged around the axle 9 and has a non-circular shape. Therefore, the thickness of the measuring portion 16 is variable. As the axle 9 and the measuring portion 16 rotate, the distance from the periphery 19 of the measuring portion 16 to the inductive sensor 11 changes. By monitoring the distance between the measuring portion 16 and the sensor 11, the rotation speed of the measuring portion 16 and the pulley 8 can be determined. Figure 4 and Figure 5 In the embodiment of the invention, each distance from the periphery 19 of the measuring section 16 to the inductive sensor 11 corresponds to two angular positions of the pulley 8. Therefore, the absolute angular position of the pulley 8 cannot be determined only by the inductive sensor 11. However, even in this embodiment, the rotation speed of the pulley 8 can be determined. The absolute position of the pulley 8 can be determined, for example, by providing two measuring sections on the axle 9, measuring the distance from each measuring section to the inductive sensor, and combining the obtained information.

[0039] Figure 6 A measuring device 20b according to a fourth embodiment of the present invention is shown. Figure 7 Show Figure 6 An end view of the device (sensing sensor not shown). Figure 6 and Figure 7In the embodiment of the invention, the end face 14 of the axle 9 is provided with a groove 17. The groove 17 is circular and extends a full circle. The groove 17 has a varying depth. The inductive sensor 11 is arranged to measure the distance to the bottom of the groove 17. The groove 17 is configured so that each point along the groove 17 has a separate depth value. Therefore, each measured depth corresponds to a single point along the groove 17. The groove 17 has a discontinuity 17a. On a first side of the discontinuity 17a, the groove 17 has a maximum value. Away from the discontinuity along the groove 17, the depth of the groove 17 decreases, and the depth of the groove 17 has a minimum value on a second side of the discontinuity 17a. Therefore, each measured distance from the inductive sensor 11 to the bottom of the groove 17 corresponds to a single angular position of the axle 9 and the pulley 8. Instead of arranging the groove 17 in the axle 9, the groove can also be arranged in the pulley 8. The groove is not necessarily located on the end face of the axle 9 or in the pulley 8, but can also be located, for example, on the outer circumference of the axle 9. Instead of having a varying depth, the groove 17 may have a varying width, and the inductive sensor 11 may be arranged to measure the distance to one side wall of the groove. Figure 6 and Figure 7 One benefit of the arrangement is that each angular position of the pulley 8 corresponds to a unique distance from the bottom of the groove 17 to the inductive sensor 11. Figure 2 The arrangement allows the absolute angular position of the pulley 8 to be determined using a single inductive sensor 11 .

[0040] Figure 8 The fifth embodiment of the measuring device according to the present invention is shown. The arrangement is similar to the previous embodiment, in particular Figure 3 and Figure 4 The embodiment of is similar. Figure 4 In an embodiment, the assembly comprising the pulley 8 and the axle 9 is provided with a separate measuring section 16 for determining the rotation speed of the pulley 8. Figure 8 In the embodiment of the invention, the pulley 8 is attached in a rotationally fixed manner to the axle 9. The measuring part 16 is attached in a rotationally fixed manner to the axle 9. If the pulley 8 rotates relative to the axle 9, the measuring part 16 will be attached in a rotationally fixed manner to the pulley 8. The device is provided with an inductive sensor 11, which is arranged to monitor the distance to the side surface 24 of the measuring part 16.

[0041] The side surface 24 is arranged at an angle different from 90 degrees relative to the rotation axis 10 of the pulley 8. The angle between the rotation axis 10 and the surface 24 may be, for example, 80-89 degrees. The inductive sensor 11 is configured to generate an output signal that depends on the distance between the sensor 11 and the surface 24. By determining the distance from the side surface 24 to the sensor 11, the angular position of the pulley 8 can be determined. Figure 8The measuring portion 16 of the illustrated embodiment may be provided with a bore, cutout or counterweight for balancing the inertial forces in a manner similar to the previous embodiment. One benefit of using a separate measuring portion 16 is that the pulley 8 and the axle 9 do not have to be modified. Thus, by adding the measuring portion 16 and the inductive sensor 11, the measuring device can be applied to an existing pulley axle assembly.

[0042] The measuring device can also be configured in many alternative ways. For example, the outer circumference of the axle 9 or the pulley 8 can be made non-circular, or the side surface of the pulley 8 can be provided with grooves. Although the embodiment of the present invention has been described in conjunction with the pulley 8 of the counterweight 2, the rotation speed of the pulley or the motor 5 of the elevator car 1 can also be measured in a similar manner. In an escalator or a moving walkway, a similar measuring device can be used to monitor the rotation speed of the sprocket.

[0043] exist Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 8 In the embodiment of the present invention, each distance from the inductive sensor 11 to the monitored surface 12, 14, 19, 24 corresponds to two angular positions of the pulley 8 or the axle 9. The measurement data from the inductive sensor 11 can be combined with other data to determine the absolute angular position of the pulley 8 or the axle 9. For example, according to different embodiments of the present invention, two inductive sensors 11 can be used to measure the distance to two different surfaces, and by combining the data from the sensors 11, the absolute angular position of the pulley 8 can be determined. Alternatively or in addition, data from some other sensors (such as sensors that detect that the elevator car 1 is at a specific landing) can be used to supplement the data provided by the inductive sensor 11.

[0044] The measuring device according to the invention can be used in many different ways. Figure 1 An elevator comprising a first measuring device 20a, a second measuring device 20b and a third measuring device 20c is schematically shown. Fig. 9 A monitoring system is shown comprising first, second and third measuring devices 20a, 20b, 20c.

[0045] The first measuring device 20a is arranged to measure the rotation speed of the pulley 7a of the elevator car 1. Based on the measurement data from the first measuring device 20a, the speed and / or position of the elevator car 1 can be determined. The second measuring device 20b is arranged to measure the rotation speed of the pulley 8 of the counterweight 2. Based on the measurement data from the second measuring device 20b, the speed and / or position of the counterweight 2 can be determined. The measurement data from the second measuring device 20b can be compared with the measurement data from the first measuring device 20a. Alternatively, the speed of the counterweight 2 determined based on the measurement data can be compared with the speed of the elevator car 1. The speed difference can be an indication of a stall condition, in which the elevator car 1 or the counterweight 2 is ascending at the desired speed, while the descending part is stopped by reaching the bottom of the shaft 3 or by getting stuck. This causes the traction member 4 to slack. The elevator car 1 or the counterweight 2 can continue to move until the upper end of the shaft 3 is reached or until the friction of the traction member 4 against the sheave 6 of the motor 5 is insufficient to maintain the movement of the ascending part. Both situations are dangerous, since a hit against the upper end of the shaft 3 may result in significant damage, whereas a loss of friction between the sheave 6 and the traction member 4 may result in a free fall of the elevator car 1 or the counterweight 2.

[0046] The third measuring device 20c is arranged to measure the rotation speed of the other pulley 7b of the elevator car 1. The third measuring device 20c can be used as a backup for the first measuring device. The measurement data from the first measuring device 20a can also be compared with the measurement data from the third measuring device 20c. In case the comparison result indicates that there is a speed difference between the first pulley 7a and the second pulley 7b, the traction member 4 may slip on one of the pulleys 7a, 7b. This may be an indication of a bearing fault and a warning signal may be generated.

[0047] Fig. 9 An inductive sensor 11 is shown connected to the measuring devices 20a, 20b, 20c of the control unit 18. Sensors 26, 27 which detect whether the elevator car 1 is at a specific landing are also connected to the control unit 18. The signals from the sensors 26, 27 which detect the presence of the elevator car 1 at a specific landing can be used as reference points and by using the measurement data from the first or third measuring devices 20a, 20c the vertical position of the elevator car 1 can be determined even between landings. This allows, for example, to calculate the distance of the elevator car 1 to the end buffer 27 or to the upper end of the shaft 3. The determined distance and the speed of the elevator car 1 can be used as input for the speed control of the elevator car 1 when the elevator car 1 approaches one end of the shaft 3. This helps to ensure that the deceleration of the elevator car 1 does not exceed a predetermined limit value.

[0048] The measuring device according to the invention can also be used to measure the rotation speed of the sheave 6 driven by the motor 5. The measurement data can be compared with the rotation speed of the pulleys 7a, 7b of the elevator car 1 and / or the pulley 8 of the counterweight 2. In addition, the speed of the traction member 4 can be determined based on the measurement data and compared with the speed of the elevator car 1 and / or the counterweight 2. The speed difference can be an indication about the slip of the traction member 4 on the sheave 6 driven by the motor 5, or the bearings of the pulleys 7a, 7b, 8 of the elevator car 1 or the counterweight 2 are stuck. By comparing the rotation speed of the sheave 6 driven by the motor 5 with the rotation speed of the pulleys 7a, 7b, 8 of the elevator car 1 and / or the counterweight 2, certain overspeed situations can also be detected. It is not necessary to determine all rotation speeds using the measuring device according to the invention, but data from different sources can be combined. For example, the rotation speed of the pulleys 7a, 7b, 8 of the elevator car 1 or the counterweight 2 can be determined by means of the measuring device according to the invention, but the rotation speed of the sheave 6 driven by the motor 5 can be determined based on the rotation speed of the motor 5.

[0049] It will be appreciated by a person skilled in the art that the invention is not limited to the embodiments described above, but may be varied within the scope of the appended claims.

Claims

1. A measuring device (20a, 20b, 20c) for measuring the rotational speed of a component (6, 7a, 7b, 8, 9) attached to an elevator car (1) and / or a counterweight (2) of an elevator, wherein: The components (6, 7a, 7b, 8, 9) are rotatable about a rotation axis (10), the device comprises an inductive sensor (11), the inductive sensor (11) is arranged to be fixed relative to the rotation axis (10) of the components (6, 7a, 7b, 8, 9) and adjacent to the components (6, 7a, 7b, 8, 9), and the components (6, 7a, 7b, 8, 9) are configured to be asymmetric about the rotation axis (10), so that different angular positions of the components (6, 7a, 7b, 8, 9) about the rotation axis (10) generate different output signals in the inductive sensor (11), wherein the component (6, 7a, 7b, 8, 9) is provided with a surface (12, 14), the surface (12, 14) being shaped and / or positioned such that the distance from the surface (12, 14) to the inductive sensor (11) changes as the component (6, 7a, 7b, 8, 9) rotates about the rotation axis (10), and the inductive sensor (11) is arranged to detect the changing distance between the surface (12, 14) and the inductive sensor (11), Therein, the surface (12, 14) is a plane (12, 14) arranged at an angle (α) different from 90 degrees relative to the rotation axis (10) of the component (6, 7a, 7b, 8, 9).

2. The measuring device (20a, 20b, 20c) according to claim 1, wherein: The component (6, 7a, 7b, 8, 9) is a pulley (7a, 7b, 8), or an axle (9) or shaft supporting the pulley (7a, 7b, 8).

3. The measuring device (20a, 20b, 20c) according to claim 1 or 2, wherein: The components (6, 7a, 7b, 8, 9) are provided with material removal or addition areas for compensating for the influence of the asymmetric shape of the components (6, 7a, 7b, 8, 9) on the inertia force of the components (6, 7a, 7b, 8, 9).

4. The measuring device (20a, 20b, 20c) according to claim 1 or 2, wherein: The components (6, 7a, 7b, 8, 9) comprise bores (13, 15) for compensating the influence of the asymmetric shape of the components (6, 7a, 7b, 8, 9) on the inertial forces of the components (6, 7a, 7b, 8, 9).

5. The measuring device (20a, 20b, 20c) according to claim 1 or 2, wherein: The components (6, 7a, 7b, 8, 9) are configured such that each angular position of the components (6, 7a, 7b, 8, 9) about the axis of rotation (10) generates a unique output signal in the inductive sensor (11).

6. A monitoring system comprising a measuring device (20a, 20b, 20c) according to any one of claims 1 to 5, the measuring device (20a, 20b, 20c) being arranged to monitor the rotation speed of a component (6, 7a, 7b, 8, 9) of an elevator.

7. An elevator comprising a measuring device (20a, 20b, 20c) according to any one of the preceding claims 1-5.

8. The elevator according to claim 7, wherein: The elevator comprises: a first measuring device (20a) arranged to monitor the rotation speed of pulleys (7a, 7b) of an elevator car (1); and a second measuring device (20b) arranged to monitor the rotation speed of a pulley (8) of a counterweight (2) of the elevator.

9. A method for monitoring the rotational speed of a component (6, 7a, 7b, 8, 9) of an elevator, wherein: The rotational speed is monitored by means of a measuring device according to any one of claims 1 -5.

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