rolling bearing device

Abstract

Rolling bearing device (1) which is formed from at least one set of cylindrical rollers (5), a bearing ring (2) and a bypass device (20) and also comprises a first machine element (30) and a second machine element (31), wherein: - the cylindrical roller set (5) comprises a plurality of cylindrical rollers (8), and - the cylindrical rollers (8) of the cylindrical roller set (5) are arranged radially between the bearing ring (2) and the second machine element (31), and are directed radially transversely to the axis of rotation (16), - the bearing ring (2) is arranged concentrically on an axially aligned axis of rotation (16) of the rolling bearing device (2), - at least one electrical connection is formed between the first machine element (30) and the second machine element (31) via the bypass device (20), - the bypass device (20) comprises a holder (21) and at least one electrically conductive bypass conductor (23), wherein the holder (21) and bypass conductor (23) are electrically connected to each other, - the holder (21) is radially attached to the bearing ring (2) by means of force and / or form fit and holds the bypass conductor (23), wherein the bearing ring (2) is attached to the first machine element (30), - the bearing ring (2) is secured against axial displacement on a first axial side against a shoulder (4) in the first machine element (30), - the bearing ring (2) is secured against axial displacement on a second axial side by means of an elastically pre-tensioned retaining ring (10) which engages in a groove (12) in the first machine element (30). - the elastically pre-stressed retaining ring (10) is positioned in the same axial length section x of the machine element (30) in which the bearing ring (2) receives the holder (21). - wherein the bearing ring (2) has a greater axial extension x1 from the center of the bearing in the direction of the bypass device (20) than in the opposite direction x2.

Description

Field of invention

[0001] The invention relates to a rolling bearing device which is formed from at least one first and one second machine element, a set of cylindrical rollers, a bearing ring and a bypass device. Background of the invention

[0002] Rotor shafts in electric machines are usually supported by rolling bearings. Unwanted voltage potentials often arise between the rotor shafts and the housings of electric motors and generators. Without countermeasures, these voltage potentials discharge through the rolling bearings. The current flowing through the affected rolling bearing can generate sparks in the rolling contact between the rolling elements and the raceways. The rolling raceways are damaged by melt pitting or erosion pitting.

[0003] Measures are already known to prevent the build-up or dissipation of voltage potentials via the rolling bearings. For example, bypass devices are used, which divert discharges around the rolling bearings of the electric motor via so-called shaft grounding rings. Such a bypass device, consisting of a shaft grounding ring, is disclosed in DE 10 2016 010 926 A1. This shaft grounding ring has a disc-shaped, electrically conductive bypass conductor, which is clamped between two conductive angle brackets on the housing side and bears against a shaft with elastic preload. The angle brackets forming the holder for the bypass conductor are inserted into a housing at any suitable location. The bypass conductor is made of a conductive material that has a lower resistance to current flow than, for example, steel.The advantage of such a bypass device is that the shaft grounding ring is simple and inexpensive to manufacture. Further implementation possibilities for bypass conductors are disclosed in DE 10 2021 114 965 A1 and DE 10 2019 133 886 A1.

[0004] Bypass conductors are also frequently integrated into sealing devices by experts. An example of a pre-seam seal designed as a bypass conductor is disclosed in DE 10 2014 010 269 B4. The pre-seam seal is connected in series upstream of a main seal and simultaneously establishes an electrically conductive connection between two machine elements as a bypass conductor. The disc-shaped bypass conductor is intended to protect the sealing lip of the main seal from environmental contamination and is attached to the main seal. The main seal is mounted in the housing with a holder formed from an angle bracket.

[0005] Generally, rolling bearing manufacturers are interested in using such bypass conductors in the direct and immediate vicinity of the rolling bearings, which can be exposed to the damage described above due to the reduction of stress potentials. Furthermore, the bypass conductors should be installed in the most space-saving way possible. Therefore, such bypass conductors are integrated, for example, into the main seals of rolling bearings. Such a device is disclosed in DE 10 2015 224 042 A1. The main seal used in this device is impregnated with a conductive filler.

[0006] Due to their primary application in electric motors and the resulting requirements for high relative speeds, bypass devices are mostly used with ball bearings in the prior art. However, implementations with cylindrical roller bearings are also known, as described in DE 10 2021 114 964 A1.

[0007] One possibility for securing a cylindrical roller bearing against axial displacement is discussed as an example in JP 2010 - 43 726 A. Description of the invention

[0008] The object of the invention is to create an improved rolling bearing device with bypass.

[0009] The problem is solved according to the subject matter of claim 1. The rolling bearing device comprises at least one first machine element and one second machine element, as well as a cylindrical roller assembly, a bearing ring, and a bypass device. The cylindrical roller assembly comprises a plurality of cylindrical rollers. The cylindrical rollers of the cylindrical roller assembly are arranged radially between the bearing ring and the second machine element and are oriented radially transversely to the axis of rotation. The bearing ring is arranged concentrically on an axially aligned axis of rotation of the rolling bearing device. At least one electrical connection is formed between the first machine element and the second machine element via the bypass device. The bypass device comprises a holder and at least one electrically conductive bypass conductor and forms an electrical connection between the first and the second machine element.The holder can have one or more retaining rings and can also have one or more retaining discs.

[0010] The holder is radially attached to the bearing ring by means of a force-fit or form-fit connection and holds the bypass conductor. The bearing ring is in turn attached to the first machine element.

[0011] According to the invention, the bearing ring is secured against axial displacement on a first axial side against a shoulder on the machine element and on a second axial side by means of an elastically preloaded retaining ring that engages in a groove in the first machine element. The groove can be designed as a circumferential annular groove. The elastically preloaded retaining ring is positioned at the same axial length x of the machine element as the bearing ring accommodates the holder. Generally, bearing rings are designed to be relatively narrow in the radial direction due to weight and cost considerations. However, the invention accepts that the bearing ring must be wider in the radial direction to accommodate both the mounting of the bypass device and the mounting of the bearing ring with an elastically preloaded ring, for example, a snap ring, at the same axial length x.This has the advantage that, firstly, no additional axial installation space for the rolling bearing device needs to be provided by arranging the holder of the bypass device and the retaining ring next to each other, and secondly, by avoiding the arranging of the components next to each other, impairments of function or service life are avoided.

[0012] The bearing ring of the rolling bearing assembly exhibits a larger axial extension x from the center of the bearing only at a distance z from the bearing seat in the direction of the bypass device. Thus, the seat of the bearing ring in contact with the first machine element is, as is known for rolling bearing rings, symmetrical in the x-direction with respect to the center of the rolling bearing. In contrast, only the area of ​​the bearing ring that has the seat of the holder is emphasized by this extension in the x-direction, i.e., axially.

[0013] It is conceivable that another bearing ring is present, or that the cylindrical rollers roll directly on the shaft or hollow shaft.

[0014] The bypass device is arranged axially on one side of the rolling elements. At least one electrical connection is formed between the first and second machine elements via the bypass device. It is therefore also conceivable that further electrically conductive connections between other machine elements are permanently or even preferably switchable on and off via the bypass device.

[0015] The design of the bypass device focuses solely on electrical conductivity and installation, not on sealing. When bypass conductors are integrated into sealing systems, compromises must be made regarding the choice of material properties for both the seals and the bypass conductor. When designing the bypass conductor of a bypass device, it is advantageous to consider only the requirements for electrical conductivity and wear resistance when selecting and designing the material.

[0016] The bypass device consists of one or more holders and one or more electrically conductive bypass conductors. Preferably, the holder of the bypass device is attached to the bearing ring between the bearing ring and the radially outer machine element. The holder is a component of any design suitable for holding the bypass conductor within the rolling bearing. The properties of the bypass conductor can be precisely tailored to the through-resistance or discharge resistance of the rolling bearing.

[0017] The respective holder and the bypass conductor are electrically connected. The holder itself is conductive, or the bypass conductor and the machine element are connected via a separate electrical conductor – for example, a conductive sleeve. Generally, the bypass device is designed so that voltage potentials are discharged via this bypass device and not via the cylindrical roller assembly.

[0018] Two machine elements are rotatably mounted relative to each other using at least one set of cylindrical roller bearings. Either one or the other machine element is mounted so that it can rotate about the axis of rotation of the rolling bearing by means of the cylindrical roller bearing set, or one or the other machine element is fixed to the housing. Alternatively, both machine elements are arranged so that they can rotate relative to each other about the axis of rotation of the cylindrical roller bearing set. Machine elements include shafts, for example, rotor shafts of an electric machine; housings, for example, bearing shields or housings or housing sections or bearing shields of an electric machine; gears or shafts or housings of a gearbox; or any other machine elements suitable for being mounted relative to each other by means of rolling bearings.

[0019] In the cases considered, the axis of rotation of the cylindrical roller set is always axially oriented, but can run horizontally, vertically, or obliquely in space. Radial orientation is perpendicular to the axis of rotation.

[0020] The cylindrical roller set serves for the rotatable mounting of machine parts, elements and assemblies and has cylindrical rolling elements to reduce friction, which roll between the bearing ring and another contact partner, for example a second bearing ring or a shaft, thus reducing friction in the rotatable mounting.

[0021] The cylindrical roller assembly can include a cage to guide the rolling elements and, as previously explained, is assembled with a bearing ring and another rolling partner, for example, another bearing ring or a shaft, to form a rolling bearing arrangement. Alternatively, the rolling bearing arrangement can also have more than one inner and / or outer ring. Furthermore, the bearing ring(s) can also be split and have a raceway or a portion thereof. The radially inner contact partner, i.e., the shaft or the inner ring, usually has one or more outer raceways, and the outer ring accordingly has one or more inner raceways. The rolling elements that roll on the raceways are roller-shaped. As mentioned previously, the rollers are often guided and held in cages.The rolling elements are either arranged one behind the other in a row in the circumferential direction, or alternatively, the arrangement has several rows of rolling elements arranged next to each other.

[0022] In the context of the invention, a bypass is understood to mean the diversion of a current or voltage around one or more rolling bearings and / or machine components. The rolling elements and the bearing ring are usually made of bearing steel and contact each other at the raceway(s). The contact zones formed are potential pathways for currents, at which the dreaded discharges lead to the damage to the raceways already described in the chapter "Background of the Invention".

[0023] The bypass, or bypass device, is intended to divert the currents. This can be achieved, firstly, by ensuring that the bypass device, or at least the bypass conductor, has comparatively lower electrical or specific electrical resistances than the rolling bearing.

[0024] It is conceivable that the cylindrical roller assembly is insulated against current flow. For example, an insulator or insulating layer could be applied between the bearing ring(s) and the machine element on / in which the bearing ring sits. In this case, the bypass route diverts the discharges only via the bypass elements of the bypass device located on the rolling bearing, bypassing the cylindrical roller assembly but not passing through it. In this case, the holder sits on or against the insulated bearing ring but maintains conductive contact with the machine element. For example, the holder sits on the outer ring and is electrically connected to the housing by means of a contact wire or tongue, or in some other way. Alternatively, or in combination with other measures, it is also conceivable that the rolling elements are made of a non-conductive material such as ceramic. In this case, the bypass device only needs to divert the current.

[0025] As previously explained, the bypass device consists of one or more holders and one or more electrically conductive bypass conductors. In a preferred embodiment, the holder is attached to the bearing ring between the bearing ring and the radially outer machine element. This ensures a particularly secure fit of the bypass device to the bearing ring by means of elastic preload or a combination of elastic preload and positive locking.

[0026] To provide a particularly space-saving rolling bearing assembly, the bypass conductor in a preferred embodiment is inclined at an angle to the bearing center that deviates from the perpendicular to the bearing's axis of rotation. This can be achieved either by the bypass conductor itself or, in a particularly advantageous design, by a corresponding inclination of the bypass device's holder. This has the advantage of optimally utilizing the axial installation space towards the bearing center. Furthermore, this design allows for the creation of a preload on the bypass conductor, ensuring electrical conduction through the bypass device throughout the entire service life of the rolling bearing assembly.

[0027] In a further preferred embodiment, especially for so-called "wet" applications, i.e., in which the lubricant of an entire system also serves as rolling bearing lubrication, the holder of the bypass device has media-permeable openings. These can be designed with different geometries and allow the passage of lubricant while simultaneously preventing excessively high, damaging contact pressure of the bypass conductor on the second machine element in the event of pressure differences that may occur in the system.

[0028] In a further advantageous embodiment, the bypass conductor also has media-permeable openings whose positions are superimposed on those of the media-permeable openings of the holder. Thus, the lubricant can also pass through the bypass device in a radially central position, almost centered on the rolling element face centers.

[0029] Furthermore, it is conceivable that in another preferred embodiment, the bypass conductor is secured against rotation to the holder by means of a positive locking mechanism. This has the advantages that the bypass conductor is prevented from rotating, that the bypass device constitutes a captive unit, and that any flow-enhancing features provided on the bypass conductor are held in their position.

[0030] To maintain a particularly stable preload on the bypass conductor of the bypass device throughout its entire service life, the bypass device of the rolling bearing assembly can, in a further advantageous embodiment, also feature an additional retaining disc that holds the bypass conductor in position and engages with the holder via a positive locking mechanism. Such an arrangement is advantageously and easily assembled. Furthermore, the individual parts of the holder can be manufactured cost-effectively from sheet metal. This thus represents an efficient and cost-effective way to provide a captive unit.The holder of the bypass device in combination with the retaining disc represents a particularly advantageous way to hold the bypass conductor in a predetermined position by means of positive locking, also conceivable in combination with elastic preload, with regard to rotation and displacement as well as the position of flow-promoting features in the bypass conductor.

[0031] While any material and design of the bypass conductor are conceivable, in a further embodiment of the rolling bearing device, the bypass conductor is formed from loop-stitched fibers. The term "stitched fibers" used below refers to individual fibers as well as fiber pairs or fiber bundles. The term "stitching" describes any joining of the fibers, fiber pairs, or fiber bundles that utilizes an additional thread for connection. Sewing, crocheting, or similar techniques can be considered equivalent. The bypass conductor constructed in this way represents an ideal method of current transmission, even in contact with lubricants. Furthermore, it enables the flow of lubricant without causing pressure differences in the bearing or the overall system.

[0032] In a preferred embodiment, the looped, interwoven fibers of the bypass conductor of the rolling bearing device comprise components of carbon or carbon derivatives. These components are particularly suitable for conducting current in a bypass conductor of a rolling bearing device because they are characterized by high elasticity with high elongation at break and very good electrical conductivity. Description of the drawings

[0033] The invention is explained in more detail below using exemplary embodiments. The figures show: - Fig. 1 - a partial section as an embodiment of a rolling bearing device 1 in a partial section along the axis of rotation 16; - Fig. 2 - a detailed representation of the rolling bearing device made of Fig. 1 in a slanted partial section; - Fig. 3 - a section of the rolling bearing device in a possible embodiment of the bypass device - Fig. 4 - an embodiment of the bypass conductor 23 with loop-shaped embroidered fibers,

[0034] Fig. 1 - The rolling bearing device 1 is formed from the cylindrical roller assembly 5, a bearing ring 2, and a bypass device 20 and comprises a first machine element 30 and a second machine element 31. The first machine element 30 can, for example, be designed as a housing, and the second machine element 31, for example, as a shaft, a hollow shaft 9, or a bearing inner ring. The cylindrical roller assembly 5 comprises a plurality of cylindrical rollers 8 and can have a cage 7. The bearing ring 2 is arranged concentrically on an axially oriented axis of rotation 16 of the cylindrical roller assembly 5. The cylindrical roller assembly 5 is provided with cylindrical rollers 8 arranged radially between the bearing ring 6 and the second machine element 31, the latter being oriented radially transversely to the axis of rotation 16. An electrical connection between the first machine element 30 and the second machine element 31 is formed via the bypass device 20.The bypass device 20 comprises a holder 21 and at least one electrically conductive bypass conductor 23, wherein the holder 21 and the bypass conductor 23 are electrically connected to each other. The holder 21 is radially attached to the bearing ring 2 by means of a force-fit and / or positive fit. Fig. 1 between the bearing ring (2) and the machine element 30. The holder 21 holds the bypass conductor 23, with the bearing ring 2 being attached to the first machine element 30. The bypass conductor 23 can be made of loop-stitched fibers, as in Fig. The bearing ring 2 is formed as shown in Figure 4. On a first axial side 3, the bearing ring 2 is secured against axial displacement against a shoulder 4 in the first machine element 30. On a second axial side 6, the bearing ring 2 is secured against axial displacement by means of an elastically preloaded retaining ring 10, which engages in a groove 12 in the first machine element 30. The elastically preloaded retaining ring 10 is positioned in the same axial length x of the machine element 30 in which the bearing ring 2 receives the holder 21. Fig. Figure 1 also shows that the bearing ring 2, spaced only from the bearing seat 13, has a larger axial extension x1 from the center of the bearing in the direction of the bypass device 20, i.e., in the z-direction, than in the opposite axial direction x2. The bypass conductor 23 is inclined at an angle α to the perpendicular of the bearing axis of rotation in the direction of the bearing center z. Fig. 2 clarifies the previously mentioned in Fig. The features mentioned in point 1 are shown in a slanted partial section as a detailed representation.

[0035] Fig. 3 - Fig. Figure 3 shows a part of the rolling bearing device 1, in which the bypass device 20, in the illustrated case seated on the inner diameter of the bearing ring 2 and inclined at an angle α towards the bearing center (deviating from the perpendicular to the bearing axis of rotation), as well as the bearing ring 2 and the cylindrical roller set 5 are visible. The holder 21 has media-permeable openings 17. These can be provided at different radial and axial positions. If these are formed in the area of ​​the bypass line, the flow can be further improved in an embodiment not shown by superimposing the media-permeable openings 15 of the bypass line 23 over the media-permeable openings 17 of the holder 21.The bypass conductor 23 can either be designed in such a way that it is secured against rotation by a positive locking mechanism, for example by engaging in the openings 17 of the holder, or it can also have a retaining disc 18 which positively locks and prevents its rotational movement as well as the rotational movement of the bypass conductor 23 relative to the holder.

[0036] Fig. 4 - The bypass conductor 23 of the bypass device 20 is represented as a circular ring disk with a through hole 24 centrally pierced by the axis of rotation 16. Fig.Figure 4 shows a possible embodiment of the bypass conductor 23, which is formed from loop-stitched fibers 25. This design particularly favors the suitability of the bypass conductor 23 for use with lubricating media. With regard to the media flow through the openings 17 of the holder 21, this represents an ideal way to ensure media passage through the bypass conductor 23. The loops 26 also have the advantage that they form virtually no open fiber cross-sections in the contact area, which would promote the breakage of individual fibers. The bypass conductor 23 is shown schematically with regard to its structure. Here, the loop-stitched fibers 25 of the bypass conductor 23 can, for example, be stitched in a meandering pattern as shown. The loops 26 can be formed on both the distal and proximal sides of the bypass conductor's center.The cohesion of the loops can be achieved, for example, by concentrically arranged, embroidered fiber bundles 27 or by sewing them onto a carrier material, which serves to improve fiber cohesion. Reference sign 1 rolling bearing device 2 bearing rings 3 First axial side Paragraph 4 in the first machine element 5 cylinder roller set 6 Second axial side 7 cage 8 cylinder rollers 9 Hollow shaft 10 retaining ring 11 - 12 Groove / Ring groove 13 bearing seat 14 - 15 media-permeable openings of the bypass duct 16 Rotation axis 17 Media-permeable openings of the holder 18 Retaining washer 19 - 20 Bypass device 21 holders of the bypass device 22 - 23 bypass conductors 24 through hole 25 fibers 26 loops 27 fiber bundles 28 - 29 - 30 first machine element 31 second machine element a Angle deviating from the perpendicular of the bearing axis of rotation x length segment x1, x2, xn Axial extent from the center of the bearing

Claims

[1] Rolling bearing device (1) which is formed from at least one set of cylindrical rollers (5), a bearing ring (2) and a bypass device (20) and also comprises a first machine element (30) and a second machine element (31), wherein: - the cylindrical roller set (5) comprises a plurality of cylindrical rollers (8), and - the cylindrical rollers (8) of the cylindrical roller set (5) are arranged radially between the bearing ring (2) and the second machine element (31), and are directed radially transversely to the axis of rotation (16), - the bearing ring (2) is arranged concentrically on an axially aligned axis of rotation (16) of the rolling bearing device (2), - at least one electrical connection is formed between the first machine element (30) and the second machine element (31) via the bypass device (20), - the bypass device (20) comprises a holder (21) and at least one electrically conductive bypass conductor (23), wherein the holder (21) and bypass conductor (23) are electrically connected to each other, - the holder (21) is radially attached to the bearing ring (2) by means of force and / or form fit and holds the bypass conductor (23), wherein the bearing ring (2) is attached to the first machine element (30), - the bearing ring (2) is secured against axial displacement on a first axial side against a shoulder (4) in the first machine element (30), - the bearing ring (2) is secured against axial displacement on a second axial side by means of an elastically pre-tensioned retaining ring (10) which engages in a groove (12) in the first machine element (30). - the elastically pre-stressed retaining ring (10) is positioned in the same axial length section x of the machine element (30) in which the bearing ring (2) receives the holder (21). - wherein the bearing ring (2) has a greater axial extension x1 from the center of the bearing in the direction of the bypass device (20) than in the opposite direction x2. [2] Rolling bearing device (1) according to claim 1, wherein the holder (21) is attached to the bearing ring (2) between the bearing ring (2) and a machine element (30). [3] Rolling bearing device (1) according to one of the preceding claims, wherein the bypass conductor (23) is inclined at an angle α to the perpendicular of the bearing axis of rotation (16) in the direction of the bearing center. [4] Rolling bearing device (1) according to one of the preceding claims, wherein the holder (21) has media-permeable openings (17). [5] Rolling bearing device (1) according to one of the preceding claims, wherein the bypass conductor (23) has media-permeable openings (15) whose position is superimposed on that of the media-permeable openings (17) of the holder (21). [6] Rolling bearing device (1) according to one of the preceding claims, wherein the bypass conductor (23) is secured against rotation by means of a positive locking mechanism on the holder (21). [7] Rolling bearing device (1) according to one of claims 1 to 6, wherein the bypass device (20) also has a further retaining disc (18) which holds the bypass conductor (23) in position and engages in the holder (21) by means of a positive fit. [8] Rolling bearing device (1) according to claim 1, wherein the bypass conductor (23) is formed from loop-shaped stitched fibers (26). [9] Rolling bearing device (1) according to one of the preceding claims, wherein the loop-shaped knitted fibers of the bypass conductor (23) comprise components of carbon or derivatives of carbon.

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