Rotary Encoder and Method for Judging Fault of Rotary Encoder

Abstract

The present invention relates to a rotary encoder and a method for determining a fault of a rotary encoder. The rotary encoder (200) includes means (250, 260; 201; 202; 500) for detecting a fault of the rotary encoder. The rotary encoder includes a rotor (250), a stator (260), and a shaft (210) having a bearing arrangement (220). An axial bushing (230) is internally connected to the bearing arrangement (220) and rotatably arranged in a housing (280) of the rotary encoder. Spring means (270) are arranged to prestress the bushing and the bearing arrangement. Spacing means are arranged to change an axial distance between the rotor and the stator by means of rotation of the bushing due to a fault of the bearing arrangement and by means of an increased distance generated between the rotor and the stator. The increased distance is sufficient to reduce the detectability of the angular position of the shaft as detected by the rotary encoder to a level below a predetermined threshold.

Description

Technical Field

[0001] The present invention relates to a method for determining a fault of a rotary encoder, which includes a rotor, a stator, and a shaft having a bearing configuration. The present invention also relates to a computer program product including program code for a computer to implement the method according to the present invention. The present invention also relates to a rotary encoder and a component equipped with the rotary encoder. Background Art

[0002] Rotary encoders are used in industry for position and speed monitoring and are typically mounted on the shaft of a motor or the gearbox of a component. A rotary encoder may be equipped with a rotor unit and a stator unit for detecting operating parameters of a component shaft.

[0003] The rotary encoder is mounted on a rotary encoder shaft and can operate properly using various bearings. If the bearing of the rotary encoder gets stuck or slows down, the drive torque on the rotary encoder shaft increases and may eventually cause the connection between the rotary encoder shaft and the shaft of the component to break. Summary of the Invention

[0004] The object of the present disclosure is to provide a rotary encoder that attempts to alleviate, mitigate, or eliminate, individually or in any combination, one or more of the above-identified deficiencies and drawbacks in the art.

[0005] The object of the present invention is to propose a novel and advantageous method for determining a fault of a rotary encoder.

[0006] Another object of the present invention is to propose a novel and advantageous rotary encoder and a novel and advantageous computer program for determining a fault of a rotary encoder.

[0007] Another object of the present invention is to propose a novel and advantageous method that provides a more reliable and safe operation of a rotary encoder.

[0008] Another object of the present invention is to propose a method, a rotary encoder, and a computer program that achieve an automatic and user-friendly detection of a faulty bearing of a rotary encoder.

[0009] Another object of the present invention is to propose an alternative method, an alternative rotary encoder, and an alternative computer program for determining a fault of a rotary encoder.

[0010] Some of these objects are achieved by the method according to claim 1. Other objects are achieved by the rotary encoder as depicted herein. Advantageous embodiments are described in the dependent claims. Substantially the same advantages of the method steps of the proposed method hold for the corresponding means of the proposed rotary encoder.

[0011] According to an example, a method for determining a failure of a rotary encoder is provided. The rotary encoder includes a rotor, a stator, and a shaft having a bearing configuration. The method includes the following steps:

[0012] - Provide an axial bushing that is internally connected to the bearing configuration and rotatably disposed in the housing of the rotary encoder. The rotary encoder includes a spacer device arranged to change the axial distance between the rotor and the stator;

[0013] - Apply a prestress to the bushing and the bearing configuration in a first axial direction by means of a spring member;

[0014] - Displace the bushing, the bearing configuration, and the rotor together in a second axial direction opposite to the first axial direction by means of the rotation of the bushing caused by a bearing configuration failure and by means of an increased distance generated between the rotor and the stator due to the spacer device. The increased distance is sufficient to reduce the detectability of the angular position of the shaft detected by the rotary encoder to a level below a predetermined threshold.

[0015] According to the example, the spacer device may include a plurality of elongated members, such as pins, which are arranged in respective recesses during normal fault-free operation of the rotary encoder. Accordingly, according to an example, the bushing includes at least one recess, and each recess is arranged to receive a pin. The spacer arrangement may be any suitable device arranged to increase the distance between the rotor and the stator in a fault state of the operation of the rotary encoder.

[0016] Here, the angular position of the shaft corresponds to the angular position of the rotor.

[0017] The reduction in the detectability of the angular position of the rotor / shaft detected by the rotary encoder may be related to the amplitude value of the measurement of the angular position of the rotor / shaft. According to an example, if the measurement amplitude values of at least a plurality of angular positions are below a predetermined threshold level during a predetermined time interval, it is determined that a reduction in detectability related to the angular position of the rotor / shaft is imminent.

[0018] The reduction in the detectability of the angular position of the rotor / shaft detected by the rotary encoder may be related to the detection frequency of the angular position of the rotor / shaft. According to an example, if the detection frequency of the angular position is below a predetermined threshold level during a predetermined time interval, it is determined that a reduction in detectability related to the angular position of the rotor / shaft is imminent. In such cases, the detection of the angular position of the rotor / shaft is not completely interrupted, but multiple measurements during the predetermined time interval are not accurately detected / recorded.

[0019] Advantageously, a safe and reliable operation of the rotary encoder is provided. Thus, the operation of the associated component can be interrupted before severe damage or wear occurs to the component and / or the parts of the rotary encoder. Thus, a high operating standard involving few unexpected interferences can be maintained.

[0020] The method may include the steps of: displacing a bushing and bearing arrangement together with a rotor in a second axial direction by a distance suitable for a detection method of a rotary encoder. Examples of such detection methods may involve capacitive, optical, inductive, and magnetic detection techniques. Thereby, a general method is provided. Based on the detection method of the rotary encoder, by displacing the bushing and bearing arrangement together with the rotor in the second axial direction, a robust signal interruption manner is achieved. In addition, the gap between the rotor and the stator thereby need not be greater than necessary, which advantageously enables a compact design of the rotary encoder.

[0021] The method may include the steps of: generating an alarm signal when the detectability of the angular position of the shaft as detected by a rotary encoder is about to decrease to a level below a predetermined threshold. Thereby, an automatic and user-friendly method is provided.

[0022] The method may include the steps of: automatically interrupting the operation of a component connected to a rotary encoder when the detectability of the angular position of the shaft as detected by the rotary encoder is about to decrease to a level below a predetermined threshold. Thereby, an automatic and user-friendly method is provided.

[0023] The method may include the steps of: generating an alarm signal when an interruption in the detection of the angular position of the shaft / rotor as detected by a rotary encoder is about to occur. Thereby, the operator of the rotary encoder can be notified of the detection interruption and appropriate measures can be taken, such as interrupting the operation of a component arranged together with the rotary encoder.

[0024] The method may include the steps of: automatically interrupting the operation of a component connected to a rotary encoder when an interruption in the detection of the angular position of the shaft / rotor as detected by the rotary encoder is about to occur. Thereby, a user-friendly method is provided.

[0025] Advantageously, thereby, a controlled shutdown of the component can be achieved.

[0026] The method may include the steps of: providing more than one recess in the bushing, each of the recesses being arranged to receive a respective pin. Thereby, a more balanced operation of the rotary encoder is achieved. By providing a plurality of recesses that symmetrically hold the respective pins at the bushing, a reduced noise emission level is achieved. By providing a plurality of recesses that symmetrically hold the respective pins at the bushing, a reduced level of vibration is achieved during the operation of the encoder.

[0027] According to one aspect of the present disclosure, there is provided a rotary encoder including means for detecting a failure of the rotary encoder, the rotary encoder including a rotor, a stator, and a shaft having a bearing arrangement, the rotary encoder further including:

[0028] - An axial bushing, internally connected to a bearing arrangement and rotatably arranged in the housing of a rotary encoder;

[0029] - A spring device, arranged to prestress the bushing and the bearing arrangement in a first axial direction.

[0030] - A spacing device, arranged to change the axial distance between a rotor and a stator, wherein the bushing and the bearing arrangement together with the rotor are arranged to be displaced in a second axial direction opposite to the first axial direction by means of rotation of the bushing due to a failure of the bearing arrangement and by means of an increased distance generated between the rotor and the stator, the increased distance being sufficient to reduce the detectability of the angular position of the shaft, as detected by the rotary encoder, to a level below a predetermined threshold.

[0031] The rotary encoder may include a tool arranged to displace the bushing and the bearing arrangement together with the rotor in the second axial direction by a distance adapted to the detection method of the rotary encoder. The spacing device may include at least one recess and a corresponding pin, wherein when the bearing arrangement fails, the pin may move out of position from the recess.

[0032] The rotary encoder may include:

[0033] - A device arranged to generate an alarm signal when the detectability of the angular position of the shaft, as detected by the rotary encoder, is about to be reduced to a level below a predetermined threshold; and / or

[0034] - A device arranged to automatically interrupt the operation of a component connected to the rotary encoder when the detectability of the angular position of the shaft, as detected by the rotary encoder, is about to be reduced to a level below a predetermined threshold.

[0035] The rotary encoder may include:

[0036] - A device arranged to generate an alarm signal when the detection of the angular position of the shaft / rotor, as detected by the rotary encoder, is about to be interrupted; and / or

[0037] - A device arranged to automatically interrupt the operation of a component connected to the rotary encoder when the detection of the angular position of the shaft / rotor, as detected by the rotary encoder, is about to be interrupted.

[0038] The device arranged to generate an alarm signal may include an electronic control unit (ECU). The tool arranged to automatically interrupt the operation of the component may include an electronic control unit.

[0039] According to one example, a rotary encoder may include more than one recess in a bushing, each of the recesses being arranged to receive a respective pin. For example, 3, 4 or 5 recesses may be provided, each recess being associated with a pin. The pin may be an elongate member suitable for any purpose. The pin may be composed of any metal or metal alloy. The pin may be at least partially composed of a plastic material or any other suitable material.

[0040] According to one aspect of the present invention, there is provided an assembly including a rotary encoder according to the present disclosure. The assembly may be any device, system, installation, machine, platform, structure to which the rotary encoder can be applied. The assembly may include any one of an electric motor, an internal combustion engine, and a drive shaft structure.

[0041] According to one aspect of the present invention, there is provided a computer program product including instructions which, when executed by a computer, cause the computer to perform any one of the steps of the methods described herein.

[0042] According to one aspect of the present invention, there is provided a computer-readable storage medium including instructions which, when executed by a computer, cause the computer to perform any one of the steps of the methods described herein.

[0043] According to one aspect of the present invention, there is provided a computer program product including instructions which, when executed by an electronic control device, cause the electronic control device to perform any one of the steps of the methods described herein.

[0044] According to one aspect of the present invention, there is provided a computer-readable storage medium including instructions which, when executed by an electronic control device, cause the electronic control device to perform any one of the steps of the methods described herein.

[0045] According to one aspect of the present invention, there is provided a computer program for determining a rotary encoder fault, wherein the computer program includes program code for causing an electronic control device or a computer connected to the electronic control device to perform any one of the method steps described herein when run on the electronic control device or the computer.

[0046] According to one aspect of the present invention, there is provided a computer program for determining a rotary encoder fault, wherein the computer program includes program code stored on a computer-readable medium for causing an electronic control device or a computer connected to the electronic control device to perform any one of the method steps described herein.

[0047] According to one aspect of the present invention, there is provided a computer program for determining a failure of a rotary encoder, wherein the computer program includes program code stored on a computer-readable medium, and when running on an electronic control device or a computer connected to the electronic control device, causes the electronic control device or the computer to execute any one of the method steps described herein.

[0048] According to one aspect of the present invention, there is provided a computer program product, which includes program code stored on a computer-readable medium, and is used to execute any one of the method steps described herein when the computer program runs on an electronic control device or a computer connected to the electronic control device.

[0049] According to one aspect of the present invention, there is provided a computer program product including program code non-volatilely stored on a computer-readable medium, and is used to execute any one of the method steps described herein when the computer program runs on an electronic control device or a computer connected to the electronic control device.

[0050] Further objects, advantages and novel features of the present invention will become apparent to those skilled in the art from the following details and by putting the present invention into practice. Although the present invention is described below, it should be noted that the present invention is not limited to the specific details described. Those skilled in the art who can obtain the teachings herein will recognize further applications, modifications and combinations in other fields within the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] To more fully understand the embodiments of the present invention and its further objects and advantages, the following detailed description should be read in conjunction with the accompanying drawings, in which the same reference numerals represent similar items in each figure, and in the drawings:

[0052] Figure 1 Schematically shows components according to an embodiment of the present invention;

[0053] Figure 2 Schematically shows a rotary encoder according to an embodiment of the present invention;

[0054] Figure 3a Schematically shows two different states of a rotary encoder according to an embodiment of the present invention;

[0055] Figure 3b Schematically shows two different states of a rotary encoder according to an embodiment of the present invention;

[0056] Figure 4a Is a schematic flowchart of a method according to an embodiment of the present invention;

[0057] Figure 4bis a schematic flowchart of a method according to an embodiment of the present invention; and

[0058] Figure 5 schematically shows a computer according to an embodiment of the present invention. Detailed Description

[0059] Figure 1 shows a side view of the component 100. The exemplary component 100 is a crane for moving various goods. The component 100 includes a motor unit 120 which is arranged to control the operation of a cylinder unit 130 for holding a lifting line 180. The cylinder unit 130 may alternatively be referred to as a "drum". The lifting line 180 is adapted to removably hold a load 170 at one of its ends. The crane may be provided with a plurality of support members 160. A first electronic control device 201 is arranged to communicate with a second electronic control device 202 via a link L202. Alternatively, the first control device 201 is arranged to communicate directly with the motor unit 120. The second control device 202 is arranged to communicate with the motor unit 120 via a link L120. The first and / or second control device may be arranged to control the operation of the component 100, for example, by controlling the motor unit 120. Thus, the rotational / transverse movement of the cylinder unit 130 can be controlled according to an operator's command signal, and thereby the load 170 can be transported / located / moved in the vertical and transverse directions. Alternatively, the operation of the cylinder unit 130 can be performed automatically / autonomously by means of the second control device 202.

[0060] The shaft 210 of the rotary encoder 200 may be mechanically arranged to the shaft of the cylinder unit 130 via a clutch 140. The second control device 202 may be arranged to control the operation of the clutch 140. According to an example, the shaft 210 of the rotary encoder 200 is mechanically arranged to the shaft of the cylinder unit 130 via a coupling tool. Refer Figure 2 shows in more detail a coupling tool for connecting the shaft 210 of the rotary encoder 200 to an external shaft such as the shaft of the cylinder unit 130. The first control device 201 is arranged to communicate with the rotary encoder via a link L201. The rotary encoder 200 is arranged to determine the operating parameters of the component 100. The operating parameters may be, for example, the rotational speed of the cylinder unit shaft and / or the relative rotational position of the cylinder unit shaft.

[0061] The methods and rotary encoders disclosed herein are applicable to paper mill systems and rolling mill systems. The methods and rotary encoders disclosed herein may be applicable to elevator systems, oil rig systems, and various machine tools. Thus, the rotary encoder may be applicable to a variety of components.

[0062] The proposed method and the proposed rotary encoder can be applied to various components including an engine / motor for rotating a shaft. The component can be a vehicle, such as a mining machine, a tractor, a dump truck, a wheel loader, forestry machinery, a bulldozer, a road construction vehicle, a road planning vehicle, an emergency vehicle or a tracked vehicle. According to one aspect of the present disclosure, the proposed method and the proposed rotary encoder are well suited for other applications including a rotating shaft other than a vehicle, for example, a watercraft. The watercraft can be of any kind, such as a speedboat, a steamship, a ferry, a ship or a submarine.

[0063] The method and the rotary encoder disclosed herein can be applied to various fixed components / platforms including a rotating shaft, such as a windmill for power generation.

[0064] According to one example, a plurality of rotary encoders 200 are provided to a component 100 for detecting operating parameters of various parts / units / devices of the component 100. The number of the rotary encoders 200 can be two, three, four or more.

[0065] The term "link" as used herein refers to a communication link, which can be a physical connection such as a multi-core cable, an optoelectronic communication line, or a non-physical connection such as a wireless connection (e.g., a radio link or a microwave link).

[0066] According to one embodiment herein, the term "electronic control device" is defined as a device including only one electronic control device or a plurality of connected electronic control devices. The one electronic control device or the plurality of connected electronic control devices can be arranged to perform the steps of the method according to this disclosure.

[0067] The terms used herein are for the purpose of describing particular aspects of the present disclosure only and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly indicates otherwise.

[0068] In some embodiments, and according to some aspects of the present disclosure, the functions or steps indicated in the blocks may not occur in the order indicated in the operation diagram. For example, depending on the functions / actions involved, two consecutively shown blocks can actually be executed substantially simultaneously, or sometimes these blocks can be executed in the reverse order. In addition, according to some aspects of the present disclosure, the functions or steps indicated in the blocks can be continuously executed cyclically.

[0069] It should be emphasized that when the term "comprising / including" is used in this specification, it is used to specify the presence of the described features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0070] It should be further noted that any reference signs do not limit the scope of the claims, that example embodiments may be implemented at least in part by both hardware and software, and that several "means", "tools", "units" or "devices" may be represented by the same item of hardware.

[0071] Figure 2 The rotary encoder 200 according to an embodiment of the present invention is schematically shown. The rotary encoder 200 includes a shaft 210. The shaft 210 is configured to be attached to a reference Figure 1 The rotary device of the assembly 100 of the assembly is depicted in more detail. The rotary encoder is arranged to determine the value of a set of operating parameters of the shaft 210. The operating parameters may be operating characteristics of the assembly 100. According to an example, the set of operating parameters may include a parameter "predominant angular position of the shaft 210". According to an example, the set of operating parameters may include any of the following parameters: the predominant angular position of the shaft 210 and the rotational speed of the shaft 210.

[0072] According to one example, the shaft 210 can be connected to the rotating device of the assembly by means of the recess 290. This allows connection in a rotatable fixed manner. Alternatively, the shaft 210 can be connected to the rotating device of the assembly by means of any suitable fastening tool. According to one example, the connection between the shaft 210 and the rotating device of the assembly is performed via a shaft coupling device. According to one example, the connection between the shaft 210 and the rotating device of the assembly is performed via a clutch. This allows a releasable connection. The connection between the shaft 210 and the rotating device of the assembly allows movement of the package including the bearing arrangement 220, the bushing 230, the shaft 210 and the rotor 250.

[0073] The bearing arrangement 220 is securely arranged to the shaft 210. The bearing arrangement 220 may include any suitable bearing. According to this embodiment, the bearing arrangement 220 includes a set of two rolling element bearings. Advantageously, at least two rolling element bearings are provided to achieve a balanced and low-vibration operation of the rotary encoder 200.

[0074] The axial bushing 230 is internally connected to the bearing arrangement 220. The bearing arrangement 220 is securely arranged inside the bushing 230. The bushing 230 is rotatably arranged in the housing 280 of the rotary encoder 200. Thus, the outer surface of the bushing 230 is not securely fixed to the housing 280. The axial bushing 230 can provide a cylindrical shape. The bushing 230 can be composed of any suitable material, such as a metal or alloy, for example copper or stainless steel. The housing 280 can be composed of any suitable material, such as a metal, alloy or plastic material.

[0075] The spring member 270 is arranged to prestress a package including the bushing 230, the bearing arrangement 220, the shaft 210, and the rotor 250 in a direction towards the stator 260. This direction is referred to as the first axial direction. The spring member 270 can be any suitable spring element. According to one embodiment, the spring member is a wave spring. The wave spring can include a helical flat wire with a waveform. The wave spring can be a single-turn wave spring. The wave spring can be a multi-turn wave spring. According to one example, the spring member 270 can be a helical spring. According to one embodiment, the spring member 270 includes a plurality of spring elements arranged to prestress a package including the bearing arrangement 220 and the bushing 230 in the first axial direction of the shaft 210.

[0076] The bushing 230 includes at least one recess. According to one example embodiment, the bushing 230 includes a first recess 245a and a second recess 245b. According to one example, the first recess 245a and the second recess 245b are arranged diametrically opposite to each other. Advantageously, this provides a more balanced operation of the rotary encoder 200. Any suitable number of recesses can be provided in the bushing 230. Preferably, the recesses are evenly distributed at the bushing 230. Each recess of the bushing 230 is provided at the first end of the bushing 230 facing the rotor 250. The bushing 230 has a second end facing the spring member 270. Each recess provides a profile having an extension in the axial direction of the bushing 230. Each recess provides a profile having an extension in the circumferential direction of the bushing 230.

[0077] Each of the provided recesses of the bushing 230 is arranged to receive a respective pin. Alternatively, any suitable structure, such as a screw, an elongate member, a protrusion, can be arranged to force the bushing 230 when the bushing rotates towards the spring member 270. According to this example, the first recess 245a is arranged to receive the first pin 240a, and the second recess 245a is arranged to receive the second pin 240b. The first pin 240a and the second pin 240b are arranged such that when the bushing 230 is forced to rotate due to a failure of the bearing arrangement 220, when they leave their respective recesses, they cause an axial movement of the bushing 230 and the bearing arrangement 220. Thereby, the first pin 240a and the second pin 240b contact respective parts of the housing 280. Thereby, the pins are arranged to push / move the package including the bearing arrangement 220 and the bushing in the axial direction towards the spring member 270. Thereby, a displacement between the rotor 250 and the stator 260 is achieved, which, according to one example, is sufficient to interrupt the detection of the angular position of the shaft 210 / rotor 250 provided by the rotary encoder 200. Thus, a displacement between the rotor 250 and the stator 260 is achieved, which, according to one example, is sufficient to reduce the detectability of the angular position of the shaft 210 / rotor 250 provided by the rotary encoder 200 to a level below a predetermined threshold.

[0078] The contour of the recess and the corresponding pin are designed according to the detection method (e.g., optical detection method or inductive detection method) of the rotary encoder 200. Thus, the displacement of the bushing 230 and the bearing arrangement 220 together with the rotor 250 and the shaft 210 is pre-determined and adapted to the detection method of the rotary encoder. The displacement required for signal interruption between the rotor 250 and the stator 260 of the rotary encoder 200 can be determined empirically.

[0079] The rotary encoder 200 operates by being configured to detect the relative rotation of the rotor 250 and the stator 260. Any technique capable of detecting such changes can be used to detect the rotation of the rotor 250 relative to the stator 260. Examples of such techniques include capacitive, optical, inductive, and magnetic detection. The rotary encoder 200 can be constructed as an incremental and / or absolute rotary encoder. The terms rotor and stator can refer to a single component as well as an assembly that serves the common function of a rotor or a stator.

[0080] The rotor 250 further includes a first disk that has a scale for detecting the relative rotation between the rotor 250 and the stator 260. The first disk is mounted at the shaft 210. When the shaft 210 rotates relative to the stator 260, the rotation measurement circuit at the stator 260 can detect a proportional change relative to the rotation measurement circuit. For example, the scale can include inductive, capacitive, and / or magnetic elements that are configured to cause corresponding inductive, capacitive, or magnetic signals when the first disk rotates relative to the stator 260. The scale can be part of an optical rotary encoder, where the rotary encoder is configured to shine light through slits in the first disk onto a photodiode. Alternatively, a reflective version of the optical rotation measurement technique for an optical rotary encoder can be used. Alternatively, any suitable component arranged for detecting the operating parameters can be used in the rotary encoder 200. The component is selected based on the operating parameter detection method of the rotary encoder 200.

[0081] The stator 260 includes a second disk. The second disk includes a measurement device that is configured to detect the relative movement between the first disk and the second disk, for example, by detecting the inductive, capacitive, or magnetic signal. The second disk can be a printed circuit board. According to one example, the stator 260 is not disk-shaped and can be represented as a "scanner" or a "scanning unit".

[0082] The first control device 201 is arranged to communicate with the rotary encoder 200 via the link L201. According to one embodiment, the first control device 201 is arranged to communicate with the rotation measurement circuit at the stator 260 via the link L201. Thus, the stator 260 is arranged to send a signal including information about the operating parameter to the first control device 201 via the link L201. The first control device 201 is arranged to determine the value of the operating parameter. The first control device 201 is arranged to present the determined value of the operating parameter to the operator of the assembly 100 and / or the rotary encoder 200 via any suitable presentation means (not shown). The first control device 201 is arranged to determine whether the detection of the operating parameter is interrupted. According to one example, the control device 201 is arranged to determine whether the displacement between the rotor 250 and the stator 260 due to a fault in the bearing arrangement 220 has interrupted the detection of the operating parameter.

[0083] According to an embodiment, the first control device 201 is arranged to generate an alarm signal when an interruption in the detection of the angular position of the shaft 210 / rotor 250 detected by the rotary encoder 200 is imminent. Thus, the first control device 201 is arranged to provide the alarm signal to any means (such as a presentation means) which is arranged to indicate to the operator a fault in the bearing arrangement 220.

[0084] According to an embodiment, the first control device 201 is arranged to automatically interrupt the operation of the assembly 100 connected to the rotary encoder 200 when an interruption in the detection of the angular position of the shaft 210 / rotor 250 detected by the rotary encoder 200 is imminent.

[0085] The operator of the assembly 100 and / or the rotary encoder 200 can manually restart the operation of the assembly 100 when applicable. This can be carried out via a suitable user interface by means of the first control device 201 and / or the second control device 202.

[0086] According to one example, when applicable, the restart operation of the assembly 100 can be carried out automatically. Thus, a holding circuit can be provided to the rotation measurement circuit at the stator 260 for example.

[0087] According to one example, when applicable, the detection of the operating parameter is automatically resumed after a signal interruption.

[0088] The second control device 202 is arranged to communicate with the first control device 201 via the link L202. It can be releasably connected to the first control device 201. It can be a control device external to the assembly 100. It can be adapted to perform the steps according to the embodiments disclosed herein. It can be used to cross-load software onto the first control device 201, in particular for applying the software according to the methods disclosed herein. It can alternatively be arranged to communicate with the first control device 201 via the internal network of the assembly 100. It can be adapted to perform functions corresponding to those of the first control device 201, such as generating an alarm signal when an interruption in the detection of the angular position of the shaft 210 / rotor 250 as detected by the rotary encoder 200 is impending, and / or when the detectability of the angular position of the shaft 210 / rotor 250 as detected by the rotary encoder 100 drops below a predetermined threshold level. The second control device 202 can be arranged to operate the assembly 100. For example, the second control device 202 can be arranged to control the operation of the motor 120 and the clutch 140 of the assembly 100.

[0089] According to one example, the rotary encoder 200 is arranged to be connected to the assembly 100 for detecting its operating parameters. According to one example, a set including the rotary encoder 200 and the first control device 201 is arranged to be connected to an assembly including the second control device 202, where the second control device 202 is a control device external to the rotary encoder 200. Thus, according to one example, a set including the rotary encoder 200 and the first control device 201 can be arranged to be "plugged into" the assembly 100 in which the operating parameters are to be detected for various purposes.

[0090] According to one embodiment, the rotational measurement circuit at the stator 260 can be arranged to perform the same functions as the first control device 201 and the second control arrangement 202. Thus, the method steps disclosed herein can be performed by any one of the rotational measurement circuit at the stator 260, the first control device 201, and the second control device 202.

[0091] The connecting member 290 is arranged at the shaft 210. The connecting member 290 can be integrally formed with the shaft 210. According to one embodiment, the connecting member 290 is one or more recesses. This is schematically shown in Figure 2 which. According to another example, the connecting member is formed as one or more protrusions. The connecting member 290 is arranged to fix the shaft 210 to the shaft of the assembly 100. In other words, the connecting member 290 is configured to firmly fix the shaft 210 to the shaft external to the rotary encoder 200.

[0092] According to one version, a holding tool for the shaft external to the rotary encoder 200 can be arranged to interact with at least one recess of the shaft 210 in order to achieve a firmly fixed connection between the two shafts. According to another version, a holding tool for the shaft external to the rotary encoder 200 can be arranged to interact with at least one protrusion of the shaft 210 in order to achieve a firmly fixed connection between the two shafts. The tool for connecting the outer shaft and the shaft 210 can be referred to as a coupling tool.

[0093] It should be noted that the package including the bearing arrangement 220, the bushing 230, the shaft 210, and the rotor 250 is arranged to be displaced in the second axial direction. The package is arranged to move such that the distance between the rotor 250 and the stator 260 increases from a first distance d1 to a second distance d2 (see Figure 3b ). Thus, the connecting member 290 and / or the outer shaft are arranged to allow such movement of the package.

[0094] According to one example, a smooth shaft 210 is used and the shaft is connected by means of a clamp. According to one example, the shaft 210 is a hollow shaft for allowing the reception of the outer shaft.

[0095] According to one example, any suitable locking device can be provided to firmly fix the shaft 210 to the shaft external to the rotary encoder 200.

[0096] The connecting member 290 can be configured to releasably fix the shaft 210 to the shaft external to the rotary encoder 200.

[0097] The rotary encoder 200 can further be configured for electromagnetic compatibility scenarios. The housing 280 of the rotary encoder 200 can be arranged to fix and protect the fragile EMC components from vibrations. According to some aspects, the rotary encoder 200 further includes an electrostatic discharge ESD shield which is arranged to shield the rotary encoder 200 from electrostatic charging and / or discharging. According to some aspects, the rotary encoder 200 further includes an electromagnetic shield which is arranged to prevent electromagnetic radiation going to and / or from the rotary encoder 200 from exceeding a predetermined threshold. According to some aspects, the rotary encoder 200 is configured to function without degrading in the presence of a predetermined electromagnetic interference. In other words, according to some aspects, the rotary encoder 200 is configured to be electromagnetically unaffected by a predetermined radio frequency interference.

[0098] According to some aspects, the rotary encoder 200 can further include a set of sealing components arranged at the rotary encoder 200. The set of sealing components is arranged to seal the rotary encoder 200 from the environment.

[0099] According to some aspects, the rotary encoder 200 includes a set of sealing components. The set of sealing components is arranged to seal the rotary encoder 200 from the environment.

[0100] According to some aspects, the rotary encoder 200 includes a set of spacers. The set of spacers is configured to fix the relative positions between two or more components of the rotary encoder 200.

[0101] It should be noted that many different versions of the spacing device can be implemented. Compared with what is depicted above, according to one example, the spacing device can provide an inverted structure, where, with reference Figure 2 and Figure 3a the depicted recesses are replaced by protrusions, and the pins are replaced by mates having recesses. According to this example, the bushing 230 is provided with a plurality of protrusions, and the housing is provided with corresponding recesses, each of the plurality of recesses being arranged to receive a corresponding protrusion. The function of such a design is similar to the function of the design depicted with reference Figure 2 and Figure 3a that is, the bushing 230 and the bearing arrangement 220, together with the rotor 250, are displaced in the second axial direction by virtue of the rotation of the bushing 230 caused by a failure of the bearing arrangement 220, and by virtue of the increase in the distance between the rotor 250 and the stator 260 caused by the spacing device. The increased distance between the rotor 250 and the stator 260 is sufficient to reduce the detectability of the angular position of the shaft 210 / rotor 250, as detected by the rotary encoder 200, to a level below a predetermined threshold.

[0102] According to one example, the spacing device can include a plurality of recesses provided on the outer surface of the bearing arrangement 220, each recess being arranged to receive a protrusion of the housing 280. According to another example, the spacing device can include a plurality of protrusions provided on the outer surface of the bearing arrangement 220, each protrusion being arranged in a corresponding recess of the housing 280.

[0103] Figure 3a Two different states of the rotary encoder 200 are schematically shown. The rotary encoder 200 is shown in cross-section. According to this embodiment, two recesses (245a, 245b) are provided in the bushing 230. However, only one recess 245a is shown. The recess 245b and the corresponding pin 240b are not shown. The first state A of the rotary encoder is shown on the left. The second state B of the rotary encoder is shown on the right.

[0104] The first state A refers to the normal operating state of the rotary encoder 200. Here, the distance between the rotor 250 and the stator 260 is sufficient to detect the operating parameters of the shaft 210 normally / desirably / accurately. Examples of such operating parameters can be the relative rotational position of the shaft 210 and the angular velocity of the shaft 210. The distance between the rotor 250 and the stator 260 can be the optimal distance for accurately and reliably detecting the operating parameters of the shaft 210.

[0105] As shown with reference to the rotary encoder in the first state A, the spring member 270 is arranged to prestress the bushing 230 and the bearing arrangement 220 in the first axial direction of the shaft 210, i.e., towards the stator 260. The pin 240a is disposed in the recess 245a. The pin 240b is disposed in the recess 245b.

[0106] The second state B refers to the operating state of the rotary encoder 200 in which a failure of the bearing arrangement 220 is imminent. Thus, the driving torque of the bearing arrangement 220 has increased to a certain level due to the bearing arrangement 220 being blocked or slowed down. Here, compared to the distance according to the first operating state A, the distance between the rotor 250 and the stator 260 has increased to the extent of interrupting the detection of the operating parameters of the shaft 210. Thus, the displacement between the rotor 250 and the stator 260 is not small enough to accurately and reliably detect the operating parameters of the shaft 210.

[0107] As shown with reference to the rotary encoder 200 in the second state B, the spring member 270 is in a compressed state, which is caused by the movement of the bushing 230 and the bearing arrangement 220 in the second axial direction of the shaft 210 (i.e., away from the stator 260). The pins 240a and 240b are not respectively disposed in the recesses 245a and 245b, but affect the movement of the bushing 230, the bearing arrangement 220, and the rotor 250 in the second axial direction, thereby achieving the second operating state B. Thus, the force generated by the misalignment of the pins exceeds the force of the winning spring member 270. As the pins leave the respective recesses, an increase in the distance between the rotor 250 and the stator 260 is achieved. Thus, due to the failure of the bearing arrangement 220, the rotation of the bushing 230 forces the pins to leave the respective recesses. This newly increased distance between the rotor 250 and the stator 260 is sufficient to interrupt the detection of the operating parameters of the rotor 250 and the stator 260.

[0108] The form / profile of at least one recess of the bushing 230 can be any suitable form / profile. The size of at least one recess of the bushing 230 can be any suitable size. According to one example, the recess of the bushing 230 presents a V - shape. According to one example, the recess of the bushing presents a U - shape. According to one example, the recess of the bushing 230 presents a concave shape.

[0109] The form / profile of the pins of the rotary encoder 200 can be any suitable form / profile. The size of the pins of the rotary encoder 200 can be any suitable size. According to one example, the pins of the rotary encoder 200 present a circular cross-sectional area. According to one example, the pins of the rotary encoder 200 present an oval cross-sectional area.

[0110] It should be noted that the form / profile and size of the recess of the bushing 230 and the form / profile and size of the corresponding pins are selected such that when the bearing arrangement 220 fails, the detection of the operating parameters is interrupted by means of the rotor 250 and the stator 260. The failure of the bearing arrangement 220 can be related to bearing jamming or the bearing arrangement 220 slows down for any reason.

[0111] Figure 3b Schematically shows the distance between the rotor 250 and the stator 260 in the first operating state A and the second operating state B.

[0112] In the first operating state A, the rotor 250 and the stator 260 are separated by a distance d1. The distance d1 is a predetermined distance that allows the proper detection of the operating parameters of the shaft 210.

[0113] In the second operating state B, the rotor 250 and the stator 260 are separated by a distance d2. The distance d2 is a predetermined distance that does not allow the correct detection of the operating parameters of the shaft 210. In the second operating state B, the detectability of the angular position of the shaft 210 / rotor 250 is about to drop below a predetermined threshold level. In the second operating state B, a complete interruption of the detection of the angular position of the shaft 210 / rotor 250 can be imminent.

[0114] The distance d2 is greater than the distance d1.

[0115] Figure 4a Schematically shows a flowchart of a method for determining a fault of a rotary encoder 200 according to an example of the present invention, the rotary encoder 200 including a rotor 250, a stator 260, and a shaft 210 having a bearing arrangement 220. The method step s401 includes the step of providing an axial bushing 230 that is internally connected to the bearing arrangement 220 and rotatably arranged in the housing 280 of the rotary encoder, the rotary encoder including a spacer device arranged to change the axial distance between the rotor 250 and the stator 260.

[0116] The method step s402 includes the following steps: prestressing the bushing 230 and the bearing arrangement 220 axially by means of a spring member 270.

[0117] Method step s403 includes the following steps: Displace the bushing 230 and the bearing arrangement 220 together with the rotor 250 in a second axial direction opposite to the first axial direction by means of the rotation of the bushing 230 caused by a failure of the bearing arrangement 220 and by means of an increased distance generated between the rotor 250 and the stator 260 by a spacer device, the increased distance being sufficient to reduce the detectability of the angular position of the shaft 210, as detected by the rotary encoder 100, to a level below a predetermined threshold.

[0118] The detectability can be related to the amplitude of the measured angular position signal. The predetermined threshold can be any suitable threshold, for example, 90%, 80%, or 50% of the average amplitude of the measured angular position signal over a certain predetermined time interval. The predetermined time interval can be any suitable time interval, such as 1 second or 5 seconds. The predetermined time interval can be less than 1 second. The predetermined time interval can be greater than 5 seconds.

[0119] The detectability can be related to the frequency of the angular positions actually detected during a predetermined time interval. The predetermined threshold can be any suitable threshold, for example, 90%, 80%, or 50% of the detection frequency of the normal / correct detection frequency during a predetermined time interval. The predetermined time interval can be any suitable time interval, such as 1 second or 5 seconds. The predetermined time interval can be less than 1 second. The predetermined time interval can be greater than 5 seconds.

[0120] After method step s403, the method ends / returns.

[0121] Figure 4b A flowchart schematically showing a method for determining a failure of a rotary encoder 200, the rotary encoder 200 including a rotor 250, a stator 260, and a shaft 210 having a bearing arrangement 220.

[0122] The method includes method step s410. Method step s410 includes the step of providing an axial bushing 230 that is internally connected to the bearing arrangement 220 and rotatably arranged in the housing 280 of the rotary encoder 200. The bushing 230 includes at least one recess, each recess being arranged to receive a corresponding pin. The at least one recess is formed to have a certain depth in the axial direction of the bushing 230. Thus, the at least one recess is arranged to receive the corresponding pin in a direction orthogonal to the axial direction of the bushing 230. Step s410 can include the step of providing more than one recess in the bushing 230, each recess being arranged to receive a corresponding pin. After method step s410, subsequent method step s420 can be performed.

[0123] Method step S420 may include the following steps: applying prestress to the bushing 230 and the bearing arrangement 220 in a first axial direction by means of a spring member 270. The force of the spring member 270 may be selected based on the characteristics of the rotary encoder 200, such as the design parameters of the recesses and the corresponding pins.

[0124] After method step S420, subsequent method step S430 may be performed.

[0125] Method step S430 may include the following steps: due to a bearing failure, by means of the rotation of the bushing 230, displacing the bushing 230 and the bearing arrangement 220 together with the rotor 250 in a second axial direction opposite to the first axial direction, such that the pins move out of the corresponding recesses, and thereby creating a displacement between the rotor 250 and the stator 260 sufficient to interrupt the angular position detection of the shaft 210 provided by the rotary encoder 200. Thereby, the detection provided by the rotary encoder 200 is reliably interrupted. When the bearing arrangement 220 fails, the rotation of the bushing is mechanically introduced. The increased displacement between the rotor 250 and the stator 260 is introduced at an early stage of the failure, which can reduce the impact. Method step S430 may include the following steps: displacing the bushing 230 and the bearing arrangement 220 together with the rotor 250 in the second axial direction by a distance suitable for the detection method of the rotary encoder 200. By designing the recesses and the corresponding pins, sufficient interruption of the detection of the operating parameters is provided. After method step S430, subsequent method step S440 may be performed.

[0126] Method step S440 may include the following steps: generating an alarm signal when the interruption of the detection by the rotary encoder 200 is imminent. Thereby, the operator can be notified at an early stage of a failure of the bearing arrangement 220. Thereby, the operator can manually interrupt the operation of the encoder 200 and / or the operation of the assembly 100, for example, by controlling the engine 120 to stop or by controlling the clutch 140 of the assembly 100 to disengage and reducing the torque provided by the engine 120. After method step S440, subsequent method step S450 may be performed.

[0127] Method step S450 may include the step of automatically interrupting the operation of the assembly 100 connected to the rotary encoder 200. This may be performed by means of the first control device 201, the second control device 202 or the rotation measurement circuit of the stator 260. Thereby, the control device may be arranged to automatically control the engine 120 to stop or control the clutch 140 of the assembly 100 to disengage from the engine 120 and reduce the provided torque. According to one example, operating the braking unit of the assembly to reduce the rotational speed of the shaft of the assembly 100 and / or the shaft 210 of the rotary encoder. This may be performed by means of the first control device 201, the second control device 202 or the rotation measurement circuit of the stator 260.

[0128] According to an example, the interruption operation of the component 100 connected to the rotary encoder 200 is performed by turning off the power supply, thereby at least partially turning off the component. This can be performed by means of the first control device 201, the second control device 202, or the rotation measurement circuit of the stator 260.

[0129] After the method step s450, the method ends.

[0130] Figure 5 is a view of a version of the device 500. Refer to Figure 2 and Figure 3a The described control devices 201 and 202 may include the device 500 in one version. According to an example, the rotation measurement circuit of the stator 260 may include the device 500. The device 500 includes a non-volatile memory 520, a data processing unit 510, and a read / write memory 550. The non-volatile memory 520 has a first memory element 530 in which a computer program (such as an operating system) is stored for controlling the functions of the device 500. The device 500 further includes a bus controller, a serial communication port, I / O tools, an A / D converter, a time and date input and transmission unit, an event counter, and an interrupt controller (not shown). The non-volatile memory 520 also has a second memory element 540.

[0131] According to an example embodiment, a computer program is provided, which includes a routine for determining a fault of the rotary encoder 200, the rotary encoder including a rotor 250, a stator 260, and a shaft 210 having a bearing configuration 220.

[0132] The computer program P may include a routine for detecting that the detectability of the angular position of the shaft 210 detected by the rotary encoder 100 is reduced to a level below a predetermined threshold.

[0133] The computer program P may include a routine for detecting an interruption in the detection of the angular position of the shaft 210 provided by the rotary encoder 200 due to an increased distance between the rotor 250 and the stator 260 caused by a fault in the bearing configuration 220.

[0134] The computer program P may include a routine for generating an alarm signal when the detectability of the angular position of the shaft 210 detected by the rotary encoder 100 is reduced to a level below a predetermined threshold.

[0135] The computer program P may include a routine for automatically interrupting the operation of the component 100 connected to the rotary encoder 200 when the detectability of the angular position of the shaft 210 detected by the rotary encoder 100 is about to be reduced to a level below a predetermined threshold.

[0136] The computer program P may include routines for generating an alarm signal when an interruption in the detection of the angular position of the shaft 210 provided by the rotary encoder 200 is imminent. The computer program P may include routines for automatically interrupting the operation of the component 100 connected to the rotary encoder 200 when an interruption in the detection of the angular position of the shaft 210 provided by the rotary encoder 200 is imminent.

[0137] The computer program P may include routines for performing any one of the processing steps described in detail with reference to the present disclosure.

[0138] The program P may be stored in the memory 560 and / or the read / write memory 550 in an executable form or a compressed form.

[0139] In the case where it is stated that the data processing unit 510 performs a specific function, it means that the data processing unit 510 executes a specific part of the program stored in the memory 560 or a specific part of the program stored in the read / write memory 550.

[0140] The data processing device 510 may communicate with the data port 599 via the data bus 515. The non-volatile memory 520 is intended to communicate with the data processing unit 510 via the data bus 512. The separate memory 560 is intended to communicate with the data processing unit via the data bus 511. The read / write memory 550 is arranged to communicate with the data processing unit 510 via the data bus 514. For example, the links L201, L202, and L120 may be connected to the data port 599 (see Figure 1 , Figure 2 and Figure 3a ).

[0141] When data is received on the data port 599, they are stored in the second memory element 540. When the received input data has been stored, the data processing unit 510 will be ready to perform the code execution as described above.

[0142] The device 500 may perform a part of the method described herein by means of the data processing unit 510, which runs a program stored in the memory 560 or the read / write memory 550. When the device 500 runs the program, the method steps and process steps described herein are performed.

[0143] The relevant method steps described herein may be performed by means of, for example, the device 500. Any suitable processing circuit may be used to perform the disclosed method steps. The processing circuit may be arranged in the rotary encoder 200 or outside the rotary encoder 200, such as at the component 100.

[0144] The computer program product includes a computer-readable medium, such as, for example, a Universal Serial Bus (USB) memory, an insertion card, an embedded drive, or a Read-Only Memory (ROM). The computer-readable medium stores thereon a computer program including program instructions. The computer program can be loaded into a processing circuit included in any one of the rotation measurement circuits of the first control device 201, the second control device 202, or the stator 260. When loaded into the processing circuit, the computer program can be stored in a memory associated with or included in the processing circuit and executed by a processor. According to some embodiments, when the computer program is loaded into the processing circuit and run by the processing circuit, the computer program can cause the execution of method steps according to, for example Figure 4a and Figure 4b the method steps shown or otherwise described herein.

[0145] According to one example, there is provided a computer program product including instructions that, when executed by a computer (such as the first control device 201 and / or the second control device 202), cause the computer to perform the following steps: detecting an increased distance between the rotor 250 and the stator 260 due to a fault in the bearing configuration 220, such as a reduction in the detectability of the angular position of the shaft 210 detected by the rotary encoder 200 to a level below a predetermined threshold.

[0146] According to one example, there is provided a computer-readable storage medium including instructions that, when executed by a computer (such as the first control device 201 and / or the second control device 202), cause the computer to perform the following steps: detecting an increased distance between the rotor 250 and the stator 260 due to a fault in the bearing configuration 220, such as a reduction in the detectability of the angular position of the shaft 210 detected by the rotary encoder 200 to a level below a predetermined threshold.

[0147] For illustrative purposes, a description of example embodiments provided herein has been given. The description is not intended to be exhaustive or to limit the example embodiments to the precise form disclosed, and modifications and variations are possible in light of the above teachings, or may be obtained from practice of various alternatives to the provided embodiments. The examples discussed herein are chosen and described in order to explain the principles and nature of various example embodiments and their practical application, so that those skilled in the art can utilize the example embodiments in various manners and with various modifications suitable for particular contemplated uses. The features of the embodiments described herein can be combined in all possible combinations of methods, devices, modules, systems, and computer program products. It should be understood that the example embodiments presented herein can be practiced in any combination with each other.

[0148] Exemplary embodiments have been disclosed in the accompanying drawings and the specification. However, many variations and modifications can be made to these embodiments. Therefore, although specific terms are employed, they are used in a general and descriptive sense only and not for purposes of limitation, and the scope of the embodiments is defined by the appended claims.

Claims

1. A method for determining a fault of a rotary encoder (200), the rotary encoder (200) comprising a rotor (250), a stator (260), and a shaft (210) having a bearing arrangement (220), the method comprising the following steps: - Providing (s401) an axial bushing (230) that is internally connected to the bearing arrangement (220) and rotatably arranged in the housing (280) of the rotary encoder, the rotary encoder (200) comprising a spacer device arranged to change an axial distance between the rotor (250) and the stator (260); - Applying a prestress (s402) to the bushing (230) and the bearing arrangement (220) in a first axial direction by means of a spring member (270); - Displacing (s403) the bushing (230) and the bearing arrangement (220) together with the rotor (250) in a second axial direction opposite to the first axial direction by means of rotation of the bushing (230) caused by a fault of the bearing arrangement (220), and by means of an increased distance generated between the rotor (250) and the stator (260) by the spacer device, the increased distance being sufficient to reduce the detectability of the angular position of the shaft (210) detected by the rotary encoder (100) to a level below a predetermined threshold.

2. The method according to claim 1, comprising the following steps: - Displacing the bushing (230) and the bearing arrangement (220) together with the rotor (250) in the second axial direction by a distance suitable for the detection method of the rotary encoder (200).

3. The method according to claim 1 or 2, comprising the following steps: - Generating (s440) an alarm signal when the detectability of the angular position of the shaft (210) detected by the rotary encoder (100) is about to drop below the predetermined threshold; and / or - Automatically interrupting (s450) the operation of a component (100) connected to the rotary encoder (200) when the detectability of the angular position of the shaft (210) detected by the rotary encoder (100) is about to drop below the predetermined threshold.

4. The method according to claim 1 or 2, comprising the following steps: - Generating an alarm signal when the detection interruption of the angular position of the shaft / rotor detected by the rotary encoder is about to occur; and / or - Automatically interrupting the operation of a component connected to the rotary encoder when the detection interruption of the angular position of the shaft / rotor detected by the rotary encoder is about to occur.

5. The method according to claim 1 or 2, comprising the following steps: - Providing (s410) at least one recess (245a, 245b) to the bushing (230), each of the recesses (245a, 245b) being arranged to receive a corresponding pin (240a, 240b).

6. A rotary encoder (200) includes means (250, 260; 201; 202; 500) for detecting a fault of the rotary encoder (200). The rotary encoder (200) includes a rotor (250), a stator (260), and a shaft (210) having a bearing arrangement (220). The rotary encoder (200) further includes: - An axial bushing (230) internally connected to the bearing arrangement (220) and rotatably arranged in a housing (280) of the rotary encoder (200); - Spring means (270) arranged to prestress the bushing (230) and the bearing arrangement (220) in a first axial direction; - Spacing means arranged to change an axial distance between the rotor (250) and the stator (260), wherein the bushing (230) and the bearing arrangement (220) together with the rotor (250) are arranged such that, by rotation of the bushing (230) due to a fault of the bearing arrangement (220), and by means of an increased distance generated between the rotor (250) and the stator (260), displacement (s403) occurs in a second axial direction opposite to the first axial direction, the increased distance being sufficient to reduce the detectability of the angular position of the shaft (210) detected by the rotary encoder (100) to a level below a predetermined threshold.

7. The rotary encoder (200) according to claim 6, includes: - Means (245a; 245b; 240a, 240b) arranged to displace the bushing (230) and the bearing arrangement (220) together with the rotor (250) in the second axial direction by a distance adapted to a detection method of the rotary encoder (200).

8. The rotary encoder (200) according to claim 6 or 7, includes: - Means (201; 202; 500) arranged to generate an alarm signal when the detectability of the angular position of the shaft (210) detected by the rotary encoder (100) is about to drop below the predetermined threshold; and / or - Means (201; 202; 500) arranged to automatically interrupt the operation of a component (100) connected to the rotary encoder (200) when the detectability of the angular position of the shaft (210) detected by the rotary encoder (100) is about to drop below the predetermined threshold.

9. The rotary encoder (200) according to claim 6 or 7, includes: - Means (201; 202; 500) arranged to generate an alarm signal when an interruption of the detection of the angular position of the shaft (210) detected by the rotary encoder is about to occur, and; and / or - Means (201; 202; 500) arranged to automatically interrupt the operation of a component connected to the rotary encoder when an interruption of the detection of the angular position of the shaft (210) detected by the rotary encoder is about to occur.

10. The rotary encoder (200) according to claim 6 or 7, wherein the rotary encoder (200) includes more than one recess (245a, 245b) of the bushing (230), and each of the recesses (245a, 245b) is arranged to receive a corresponding pin (240a, 240b).

11. An assembly (100) comprising the rotary encoder (200) according to any one of claims 6-10.

12. A computer program product comprising instructions which, when executed by a computer (201; 202; 500), cause the computer (201; 202; 500) to perform the method according to any one of claims 1-5 using the rotary encoder (200) according to any one of claims 6-10.

13. A computer-readable storage medium comprising instructions which, when executed by a computer (201; 202; 500), cause the computer (201; 202; 500) to perform the method according to any one of claims 1-5 using the rotary encoder (200) according to any one of claims 6-10.

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