Rotary encoder and method of operating rotary encoder

Abstract

To provide a rotary encoder for a machine such as a hoist, or crane and a method for operating the rotary encoder.SOLUTION: A rotary encoder 10 has a rotary encoder shaft 12 which can connect to a shaft of a machine for detecting a rotation of the shaft, the rotary encoder 10 has a frame 11 which can be mounted on the machine, the frame 11 has an encoder element 13 disposed on the frame 11 for detecting a rotation of the rotary encoder shaft 12 and a signal output element 14 for outputting a rotation angle signal and / or a speed signal, the rotary encoder 10 has a bearing device 20 for mounting the rotary encoder shaft 12 on the frame 11 rotatably, and the rotary encoder 10 has an insulating device which electrically insulates the rotary encoder shaft 12 and the bearing device 20 from the frame 11.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates, in particular, to a rotary encoder for machines such as hoists, cranes, etc., and a method for operating the rotary encoder. The rotary encoder can be connected to a machine shaft to detect the rotation of the shaft. The rotary encoder comprises a frame that can be attached to the machine. The frame includes an encoder element arranged on the frame to detect the rotation of the rotary encoder shaft, and a signal output element for outputting a rotary encoder signal and / or a speed signal. The rotary encoder comprises a bearing device as means for rotatably attaching the rotary encoder shaft to the frame.

Background Art

[0002] This type of rotary encoder and method is well known in the prior art and is basically used to detect the position and speed of an axle or shaft. The rotary encoder comprises at least a rotary encoder shaft that can be coupled to a machine, and a mechanical, optical, capacitive, inductive or magnetic encoder element or detection element. The encoder element can form, for example, an incremental encoder or an absolute encoder. In an embodiment using a machine, the encoder element can be a switch or a meter. The encoder element can generate a signal such as a rotation angle signal or a speed signal about the rotation of the shaft. A corresponding signal that can be converted or adjusted according to technical standards via the signal output element can thus be output by the signal output element based on these signals. The signal output element is generally connected to an evaluation device, machine control, etc. by means of a cable for signal transmission or wirelessly. This type of rotary encoder is known from DE 10 2013 204 399 A1.

[0003] Rotary encoders are used, for example, in large machinery or equipment and are subjected to significant stress during operation. Therefore, the housing of a rotary encoder is generally made of metal to ensure that it is relatively resistant to mechanical and thermal influences. The rotary encoder is fixed, for example, by connecting the housing to the machine with screws. Because it is connected to the machine, a compensation current or shaft current flows to the rotary encoder connected to the shaft, which can cause problems such as bearing failure, particularly in rolling bearings. To avoid such bearing damage, it is known to connect a so-called grounding contact to the shaft to ensure that the shaft is grounded via a grounding contact and / or that the induced current is discharged in a controlled manner substantially through the grounding contact instead of the bearing. Since the grounding contact is an additional component, it is not always available and incurs unnecessary costs. In addition, high shaft currents cause unnecessary power loss and high operating temperatures. It is also known to electrically isolate the machine shaft from the rotary encoder shaft via a coupling. However, in this type of insulating coupling, the corresponding insulating adapter shaft or insulating bushing must be manufactured and assembled with high precision to minimize concentricity errors. Such solutions may require more mounting space in the design of the mounting interface and may impose corresponding constraints. Furthermore, the resulting forces may increase bearing wear. Depending on the design, only small loads may be applied to the insulated coupling. [Overview of the project] [Problems that the invention aims to solve]

[0004] In such connections, foreign matter contamination and moisture can reduce the resistance of the insulating connection, potentially diminishing its protective function against axial current. Furthermore, while insulated bearings are known, they are not available for all standard sizes and designs of bearings. Different materials used in so-called hybrid bearings, such as steel and ceramics, have different coefficients of thermal expansion, thus limiting their operating temperature range. In hybrid bearings, the balls may be made of ceramic, and the insulation of the bearing shell may also be formed by a ceramic coating. [Means for solving the problem]

[0005] Therefore, the object of the present invention is to propose a rotary encoder, a rotary encoder device, and a method for operating a rotary encoder that prevents bearing damage by a simple method.

[0006] This objective is achieved by a rotary encoder having the features of claim 1, a rotary encoder device having the features of claim 12, and a method having the features of claim 13.

[0007] The rotary encoder according to the present invention, particularly for machines such as hoists and crimps, has a rotary encoder that can be connected to the shaft of the machine to detect the rotation of the shaft, the rotary encoder has a frame that can be mounted on the machine, the frame has an encoder element positioned on the frame to detect the rotation of the rotary encoder shaft, and a signal output element for outputting a rotation angle signal and / or a speed signal, the rotary encoder has a bearing device for rotatably mounting the rotary encoder shaft to the frame, and the rotary encoder has an insulating device for electrically insulating the rotary encoder shaft and the bearing device from the frame.

[0008] Therefore, the rotary encoder shaft is rotatably mounted on a shaft of a machine, which could be, for example, an electric motor. For the purposes of the present invention, the shaft may also be understood to mean an axle. The shaft may be directly coupled to the drive unit of the machine. However, generally, the rotary encoder shaft may also be rotatably connected to an axle. The frame helps to fix the encoder element to the machine, and the encoder element is positioned on the rotary encoder shaft so that a rotation angle signal and / or speed signal can be generated when the rotary encoder shaft is rotating, and this rotation angle signal and / or speed signal may also be transmitted and processed by a signal output element. The encoder element and signal output element may be designed as encoder elements and signal output elements known in the prior art. Furthermore, the rotary encoder shaft is rotatably mounted on the frame by a bearing device. The rotary encoder has an insulating device that electrically isolates the rotary encoder shaft and the bearing device from the frame, so that the compensation current or shaft current of the shaft and / or rotary encoder shaft can be prevented from flowing through the bearing device to the frame and / or components of the machine. This eliminates the need for an insulating adapter shaft between the rotary encoder shaft and the shaft, specific bearings, couplers, or ground contacts. While a potential may be generated between the frame and the rotary encoder shaft and / or bearing device, it cannot be easily offset by the bearing device and / or flow as a current due to the insulating device. Thus, the insulating device alone can easily prevent damage to the bearings of the rotary encoder and machine, for example, without adding complex technical measures. Furthermore, the insulating device opens up the possibility of inputting and / or detecting electrical signals and / or potentials between the rotary encoder shaft and the frame, between the machine shaft and the frame, between the bearing device and the frame, and / or between the bearing device and the rotary encoder shaft.Depending on the measuring element, changes in electrical signals and / or potentials can be measured, and physical quantities such as damage values ​​to the bearings of the rotary encoder shaft, the shafts of the machine, and / or bearing devices can be determined. In particular, physical quantities or damage values ​​of encoder attachments including the rotary encoder and / or coupler, adapter shaft, or torque support, and furthermore, damage values ​​to the bearings of the machine, for example, can be determined. By isolating the bearing devices, all methods for monitoring the electrical condition of the entire drive train can be integrated into the rotary encoder, reducing the number of mounting locations to one.

[0009] The isolation device may be configured to prevent current induced or input to the shaft and / or rotary encoder shaft from discharging to the frame. Since the frame is generally grounded by the machine while mounted, the isolation device can prevent current from flowing to the frame through the bearing device or rotary encoder shaft. Thus, condition monitoring of the rotary encoder bearing device and / or other parts of the drive train through the machine's bearings can be achieved, and each can also be isolated. If, for example, an isolated coupler is used between the rotary encoder shaft and the machine's shaft, contact with the machine's shaft can be affected by appropriate additional devices.

[0010] The frame may be formed as a housing in which an encoder element, a signal output element, and a bearing device can be housed. This housing may be self-contained or may be realized by multiple parts. The housing may be designed to include flanges for fixing to a machine. The base for the bearing device may be formed within the housing. The encoder element may be formed by a plate having increments surrounding a rotary encoder shaft, such that rotation angle signals and / or speed signals can be generated, and a detector for detecting these increments. The signal output element may be formed by discrete circuits for processing and transmitting the respective signals. The encoder element and the signal output element may be fixed to the housing.

[0011] The bearing device may have at least one bearing, preferably a rolling bearing, more preferably two or more rolling bearings. It is important that the rolling bearings are standardized and / or normalized, inexpensive, readily available, and non-insulated rolling bearings. The rolling bearings may be, for example, deep groove ball bearings. Alternatively, the bearing device may have at least one plain bearing, preferably two or more plain bearings.

[0012] A bearing or rolling bearing can be directly connected to the rotary encoder shaft. For example, a fit such as an intermediate fit or interference fit can be formed between the outer diameter of the rotary encoder shaft and the inner diameter of the bearing or rolling bearing. Thus, the bearing or rolling bearing can directly contact the rotary encoder shaft.

[0013] The bearing device may include a support element that supports and at least partially encloses a bearing or a rolling bearing, or a plurality of bearings or rolling bearings. This support element may be formed, for example, as a sleeve into which the bearing or a plurality of bearings or rolling bearings are inserted. In this case, the outer diameter of the bearing or rolling bearing may be directly connected to the inner diameter of the sleeve by a fit, such as an in-between fit, interference fit, or adhesive connection. Thus, mounting the bearing or rolling bearing can be significantly facilitated, regardless of the frame. The support element and / or sleeve may form a flange through which the support element can be fixed to the frame. The isolation device enables electrical isolation of the support element from the housing while ensuring safe and easy mounting of the bearing or rolling bearing. At the same time, inexpensive rolling bearings can be used, as no special rolling bearing design is required. The support element may enable a modular design for rotary encoders, so that the support element can be used for different types of rotary encoders. Furthermore, the support element significantly facilitates electrical connections to wires for signal input or potential measurement via bearings or rolling bearings.

[0014] The insulating device can be formed from a dielectric material that can be placed between the frame and the bearing device. Such a dielectric material allows the insulating device to be relatively thin, and as a result, it does not require much mounting space.

[0015] This dielectric material may be plastic, insulating paper, mica, or ceramic. Furthermore, other known dielectric materials such as laminated fabric or printed circuit board material may also be used. The insulating device may have voids. The dielectric material may also have a surface coating, such as paint or an anode coating.

[0016] The insulating device may be formed by multiple insulating elements, through which the bearing device is firmly connected to the frame. The insulating elements may be positioned between the bearing device and the frame, where the bearing device is mounted to the frame, or otherwise in contact with the frame.

[0017] The insulating device may be formed as at least one sleeve and / or plate. If the bearing device forms at least partially a sleeve, the insulating device may surround the bearing device. If the surface of the shaft of the bearing device is in contact with the frame, the insulating device may also be partially formed as a plate in contact with the surface of the shaft. If the insulating device comprises multiple insulating elements, these insulating elements may be formed as rings or as a single plate, for example, as screw washers. This is particularly advantageous when the bearing device and / or support elements are bolted to the frame.

[0018] Alternatively, the insulating device may be formed from a dielectric material, and the support element may form the insulating device. Therefore, the support element may be made solely from a dielectric material such as plastic. Thus, a separate insulating device and / or separate insulating element is no longer necessary. This embodiment is particularly advantageous when large forces are not transmitted through the support element.

[0019] The rotary encoder device according to the present invention comprises a rotary encoder according to the present invention and a machine such as a hoist or crane, wherein the rotary encoder is connected to the shaft of the machine to detect the rotation of the shaft. The shaft of the machine can be directly connected to the rotary encoder shaft of the rotary encoder without the need to provide an adapter shaft or other method of electrically insulating the shafts from each other.

[0020] In a method according to the present invention for operating a rotary encoder, particularly for machinery such as hoists and cranes, the rotary encoder shaft of the rotary encoder detects the rotation of the shaft, the rotary encoder is connected to the shaft of the machine, the encoder elements of the rotary encoder are arranged in the frame of the rotary encoder, the frame is fixed to the machine, the rotary encoder signal and / or speed signal are output by the signal output element of the rotary encoder, the rotary encoder shaft is rotatably mounted to the frame via a bearing device of the rotary encoder, and the rotary encoder shaft and bearing device are electrically isolated from the frame by an insulating device of the rotary encoder. For further details of the advantages of the method according to the present invention, refer to the description of the advantages of the rotary encoder according to the present invention.

[0021] Furthermore, at least one electrical signal and / or potential is input or detected by the measuring element of the rotary encoder between the rotary encoder shaft and the frame, between the bearing device and the frame, between the machine shaft and the frame, and / or between the bearing device and the rotary encoder shaft. The measuring element of the rotary encoder may be integrated, for example, within the rotary encoder housing, where the housing is formed by the frame. Since the rotary encoder shaft and the machine shaft are electrically insulated from the frame by an insulating device, a potential can be generated between the rotary encoder shaft and / or the machine shaft and the frame. The value of this potential can be detected and / or measured via the measuring element. In this way, the measuring element can input and / or detect an electrical signal, for example, an electrical signal having a fixed or variable frequency or any signal pattern. In this case, the input signal specifically means the potential generated by the measuring element. The input signal may be DC-isolated from the machine ground. This prevents interference of the signal by induced or coupled shaft voltages, and thus improves the accuracy and sensitivity of the measuring element. If detection is performed on signals transmitted between the bearing device and the frame, advantageously, a measurement of the signal can be generated for the bearing device. This detection can also be performed on signals transmitted between the machine's shaft and the frame, and advantageously, a measurement of the signal for the shaft's bearings and / or drive train can be generated. By using different signals in each case, simultaneous measurement becomes possible. The measuring elements can be connected to a signal output element, and the respective measurements can be output through the signal output element. These measurements can be evaluated so that the rotary encoder itself can be used as a measuring instrument for potential and / or signals. The potential and / or signals can be used to determine the operating state of the machine and / or rotary encoder.

[0022] An electrical signal can be generated by a measuring element and can be conducted and measured via at least one bearing of the bearing device, preferably at least one rolling bearing, and / or a bearing of a machine shaft. Thus, the operating state of each bearing can be monitored in a simple manner. The signal strength can be determined so that the bearing is not damaged by the signal. By insulating the bearing device from the frame, individual bearings of the bearing device or all bearings of the bearing device can be monitored simultaneously. The measuring element can thus be electrically connected directly to an individual bearing or to the support element of the bearing device. For example, in the case of a rolling bearing, the signal can be transmitted via the inner ring, rolling elements and outer ring of the rolling bearing.

[0023] The measuring element can detect and / or store changes in potential and electrical signals over an operating period, and this measuring element can determine and output a damage assessment that is dependent on the load of a physical quantity, for example, a bearing of a machine shaft, a bearing device and / or a machine attachment (including all parts involved in an attachment such as a coupler, adapter shaft or torque support). Depending on the state of each bearing and / or the associated parts of the machine, the signal and / or the potential can undergo more or less significant changes. If the measuring element generates an electrical signal, the electrical signal can be generated continuously or at intervals. This signal and / or these interference signals and / or changes in potential can be easily determined by measurements over an operating period. This measurement can be used to determine a damage assessment and thus can predetermine damage to the machine and / or the bearing(s). Thus, the measuring element can also serve to monitor the operating state of the machine.

[0024] Advantageous embodiments of the method can be derived below from the description of the features of the dependent claims that refer back to claim 1 of the device.

Brief Description of the Drawings

[0025] [Figure 1] FIG. 1 shows a longitudinal cross-sectional view of a rotary encoder 10.

Embodiments for Carrying Out the Invention

[0026] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in more detail.

[0027] The figure shows a longitudinal sectional view of a rotary encoder 10 essentially formed by a frame 11, a rotary encoder shaft 12, an encoder element 13, and a signal output element 14 (only schematically shown). The frame 11 is formed as a housing 15 that can be connected to a machine (not shown) via a flange of the first housing portion 17. The second housing portion 18 is screwed to the first housing portion 17.

[0028] The rotary encoder 10 also includes an insulating device 19 and a bearing device 20 for supporting the rotary encoder shaft 12. The insulating device 19 is configured to electrically insulate the rotary encoder shaft 12 and the bearing device 20 from the frame 11. The bearing device 20 comprises two rolling bearings 21 directly connected to the rotary encoder shaft 12. The bearing device 20 also comprises a support element 22 that houses the rolling bearings 21 and is partially formed in a sleeve shape. The rolling bearings 21 are directly connected to the support element 22 and are spaced apart via a ring 23. The support element 22 also forms a flange 24, and the support element 22 is screwed to the first housing portion 17 via the flange 24 by screws 25. The insulating device 19 is formed of a dielectric material such as plastic, in this case, and is formed by a first ring 26, a second ring 27, a plate 28, and a plurality of washers 29 for the screws 25. In this way, the support element 22 is completely electrically insulated from the frame 11. Therefore, the discharge of any current that could be induced from the machine shaft (not shown) and / or the rotary encoder shaft 12 to the frame 11 is interrupted. The encoder element 13, in this case, is formed by a plate 30 having a notch (not shown) and mounted on the rotary encoder shaft 12, and a detector (not shown) located on a circuit board 31 for detecting the notch, but the design of this encoder element 13 is not affected by the design of the bearing device 20 and the insulating device 19.

Claims

1. A rotary encoder (10), in particular for machines such as hoists, cranes, etc., The rotary encoder has a rotary encoder shaft (12) connectable to a shaft of a machine to detect rotation of the shaft; The rotary encoder has a frame (11) that can be attached to a machine, The frame (11) has an encoder element (13) arranged on the frame (11) for detecting the rotation of the rotary encoder shaft, and a signal output element (14) for outputting a rotation angle signal and / or a speed signal; The rotary encoder has a bearing device (20) for rotatably mounting the rotary encoder shaft to the frame; The rotary encoder has an insulating device (19) that electrically insulates the rotary encoder shaft and the bearing device from the frame. Rotary encoder.

2. 2. The rotary encoder according to claim 1, characterized in that the insulating device (19) can be configured to block currents induced in the shaft and / or the rotary encoder shaft (12) from discharging to the frame (11).

3. 2. The rotary encoder according to claim 1, wherein the frame (11) is formed as a housing (15) in which the encoder element (13), the signal output element (14), and the bearing device (20) are accommodated.

4. 2. A rotary encoder according to claim 1, characterized in that the bearing arrangement (20) comprises at least one bearing, preferably a rolling bearing (21), more preferably two or more rolling bearings.

5. 5. The rotary encoder according to claim 4, characterized in that the bearing is directly connected to the rotary encoder shaft (12).

6. 5. A rotary encoder according to claim 4, characterized in that the bearing arrangement (20) comprises a support element (22) that supports and at least partially surrounds the bearing or bearings.

7. 2. The rotary encoder according to claim 1, wherein the isolating device (19) is formed by a dielectric material arranged between the frame (11) and the bearing device (20).

8. 8. The rotary encoder according to claim 7, wherein the dielectric material is plastic, insulating paper, mica, or ceramic.

9. The insulating device (19) is formed by a plurality of insulating elements (26, 27, 28, 29), 2. The rotary encoder according to claim 1, wherein the bearing device (20) is rigidly connected to the frame (11) via the insulating element.

10. 2. The rotary encoder according to claim 1, wherein the insulating device (19) is formed at least as a sleeve and / or a plate.

11. the isolating device is formed of a dielectric material; 7. A rotary encoder according to claim 6, characterized in that the support element forms the isolation device.

12. A rotary encoder device comprising a rotary encoder (10) according to claim 1 and a machine, in particular a hoist, a crane, etc., the rotary encoder is connected to the shaft of the machine to detect rotation of the shaft; Rotary encoder device.

13. A method of operating a rotary encoder (10), particularly for a machine such as a hoist, crane, etc., comprising: The rotary encoder shaft (12) of the rotary encoder detects the rotation of the shaft; The rotary encoder shaft (12) is connected to the shaft of the machine, an encoder element (13) of the rotary encoder is disposed on the frame (11) of the rotary encoder and detects the rotation of the rotary encoder shaft; The frame (11) is fixed to the machine, The rotation angle signal and / or the speed signal is output by the signal output element (14) of the rotary encoder; The rotary encoder shaft is rotatably mounted to the frame via a rotary encoder bearing device (20); The method according to claim 1, wherein the rotary encoder shaft and the bearing arrangement are electrically isolated from the frame by an isolating arrangement (19) of the rotary encoder.

14. 14. The method according to claim 13, characterized in that electrical signals and / or potentials at least between the rotary encoder shaft (12) and the frame (11), between the bearing arrangement (20) and the frame, between the shaft of the machine and the frame and / or between the bearing arrangement and the rotary encoder shaft are detected by measuring elements of the rotary encoder (10).

15. An electrical signal is generated by the measuring element; 15. The method according to claim 14, characterized in that the electrical signal is conducted and measured via at least a bearing, preferably at least a rolling bearing (21) of the bearing arrangement (20) and / or a bearing of the shaft of the machine.

16. the measuring element detects changes in an electrical signal over a period of operation; 15. The method according to claim 14, characterized in that the measuring element determines and outputs a physical quantity, preferably a load-dependent damage assessment of the bearing of the shaft of the machine, the bearing arrangement (20) and / or an attachment of the machine.

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