Rolling bearing device

Abstract

The invention relates to a rolling bearing device (1) which is formed from at least one set of cylinder rollers, an outer bearing ring (2) and a bypass device (20), and also has a first machine element (30) and a second machine element (31). 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 outer bearing ring (2) is secured against axial movement on the second end face (St2) by means of a securing ring (10) which engages in a groove (12) in the second machine element (30). The clamping plate (21.2) of the holder (21) is connected to the holding plate (21.1) at the radial height (h) of the shoulder (6) of the outer bearing ring by means of a form fit. The clamping plate (21.2) provides a contact surface (24) at the radial height of the end face (3) of the outer bearing ring (2), which contact surface is raised in relation to the plane Y-Z with respect to the base surface of the clamping plate (21.2).

Description

[0001] Title of the invention

[0002] Rolling bearing device

[0003] Field of the invention

[0004] The invention relates to a rolling bearing arrangement which is formed from at least a first and a second machine element, a cylindrical roller set, an outer bearing ring and a bypass device.

[0005] Background of the invention

[0006] Rotor shafts in electrical machines are usually supported by rolling bearings. Unwanted voltage potentials often arise between the rotor shafts and housings of electric motors and generators. If countermeasures are not taken, 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 pits or erosion pits.

[0007] Measures are already known to prevent the buildup or reduction of voltage potentials across the rolling bearings. For example, bypass devices are used, with which discharges are guided "around" the rolling bearings of the electric motor via so-called shaft grounding rings. DE 10 2016 010 926 A1 discloses such a bypass device consisting of a shaft grounding ring. This shaft grounding ring has a disk-shaped, electrically conductive bypass conductor, which is clamped toward the housing between two conductive angle plates and which rests against a shaft with elastic prestress on the inside. The angle plates forming the holder of 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 flowing currents than, for example, steel.The advantage of such a bypass device is that the shaft grounding ring is simple and inexpensive to manufacture.

[0008] In the automotive sector, bypass conductors are also often integrated into sealing devices. An example of an upstream seal designed as a bypass conductor is disclosed in DE 10 2014 010 269 B4. The upstream seal is connected in series upstream of a main seal and, as a bypass conductor, simultaneously establishes an electrically conductive connection between two machine elements. The disc-shaped bypass conductor also protects the sealing lip of the main seal against environmental contaminants and is attached to the main seal. The main seal is mounted in the housing with a holder formed from an angled sheet.

[0009] Due to their primary application in electric motors and the resulting requirement for high relative speeds, the aforementioned bypass devices proposed in the prior art are generally used with ball bearings. The bypass devices are either provided within the bearing or are located at any point on the shaft. Cylindrical roller bearings, due to their design characteristics, are more suitable for higher loads and lower speeds and are increasingly used in industrial applications. Since the currents are greater in these applications, bypass devices for industrial applications are installed at a cost-effective location in the system, contacting the shaft.

[0010] Description of the invention

[0011] The object of the invention is to create an improved rolling bearing assembly with a bypass for higher-speed cylindrical roller bearings. This object is achieved according to the subject matter of claim 1. The rolling bearing assembly has at least one cylindrical roller set, an outer bearing ring, a first machine element and a second machine element, as well as a bypass device. The cylindrical roller set comprises a plurality of cylindrical rollers. The cylindrical rollers of the cylindrical roller set are arranged radially between the inner and outer bearing rings and are directed radially transversely to the axis of rotation; the outer bearing ring is arranged concentrically on an axially aligned axis of rotation of the rolling bearing assembly. 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, which are conductively connected to one another.

[0012] The holder of the bypass device is constructed in several parts and comprises a retaining disk and a clamping disk, wherein the retaining disk of the holder is fastened radially between the outer bearing ring and the second machine element to the outer bearing ring and holds the bypass conductor. The outer bearing ring is fastened to the second machine element. In order to provide the best possible protection for the rolling bearing against the passage of current, the holder of the bypass device is thus in direct contact with the outer bearing ring, wherein the holder is also arranged axially between the first end face of the outer bearing ring and the second machine element and is secured against axial displacement by a shoulder on the second machine element. This provides reliable protection for the rolling bearing with a lower electrical resistance of the bypass device and enables a particularly space-saving arrangement.The outer bearing ring is secured against axial movement on the second end face by a retaining ring that engages a groove in the second machine element. The clamping disc of the holder is positively connected to the retaining disc at the radial height of the shoulder of the outer bearing ring. The clamping disc provides a contact surface at the radial height of the end face of the outer bearing ring, which is raised relative to the base surface of the clamping disc relative to the YZ plane. In the prior art, axial securing is usually achieved by frictional locking, i.e., by pressing the bearing ring into a designated installation space, sometimes with retaining rings.If a bypass conductor consists of a multi-part structure, it cannot be attached flat against a shoulder in a second machine element in the area where the components are connected due to the connection options, for example by caulking, pressing, riveting, screwing, or similar. In this case, the holder is sometimes simply clamped between the first end face of the outer bearing ring and the second machine element. However, this can lead to increased assembly effort and / or slipping during operation. If a connection between the clamping and retaining discs of the holder is nevertheless necessary, a small contact surface must be accepted for assembly.Surprisingly, it has been found that raised contact surfaces on the contact disc of the holder of the bypass device with respect to the base surface of the clamping disc relative to the YZ plane provide sufficient contact for a rolling bearing with a bypass device to stop against a shoulder on the second machine element. In the context of the invention, the base surface of the clamping disc relative to the YZ plane is understood to be the surface formed by the undeformed part of the clamping disc, in which the connection to the holding disc also takes place. The contact surface is understood to be the contact surface of the holding disc in its entirety with the adjacent machine element or outer bearing ring. In this sense, the surface is therefore not limited to a single, closed partial surface, but to the entire contact surface. It is therefore also conceivable that the contact surface can consist of individual partial surfaces.

[0013] Preferably, the contact surfaces can be formed from axially resilient shaped elements from the clamping disc. This is particularly suitable if it also provides preload of the outer bearing ring against the retaining ring on the second end face of the outer bearing ring. This can compensate for tempering-related ring creep or enable a loose bearing arrangement. In a preferred embodiment, the contact surfaces are formed from circular segment-shaped shaped elements. This is easy to manufacture, and it also creates a particularly uniform contact surface that makes the best possible use of the available space.

[0014] In order to make the contact surface even more uniform, the axially spring-loaded shaped elements can ideally be evenly distributed over the circumference of the clamping disc.

[0015] It is further preferred to form the contact surface of the clamping disc in the direction of the outer bearing ring. Surprisingly, it has been found to be advantageous to provide the smooth contact surface on the shoulder of the second machine element, so that the raised portions can rest against the outer bearing ring.

[0016] In a further preferred embodiment, the first machine element is designed as an inner bearing ring. This allows for particularly easy machining of the rolling element's running surface. Furthermore, the contact area contacted by the bypass conductor can have particularly advantageous properties. For example, a particularly low electrical resistance can be achieved in this area at the transition to the bypass conductor. For example, a coating can be provided to reduce the electrical or mechanical resistance.

[0017] Preferably, a particularly secure and simple attachment of the bypass device can be achieved by the holder of the bypass device also engaging radially in a groove-shaped undercut between the outer bearing ring and the second machine element. This makes the attachment particularly space-saving and only minimal axial installation space needs to be provided for the bypass device to ensure ideal positioning in the seating area. To prevent the rotational mobility of the bypass conductor, in a further preferred embodiment at least one axially flared shaped element, for example a notch in the clamping disk, can be provided to secure the bypass conductor against rotation. This is particularly suitable for ensuring the positioning accuracy of the bypass conductor over its entire service life and for ensuring uniform and permanent contact, as well as for keeping wear to a minimum.

[0018] Independently of the above or in combination with it, the holder of the bypass device of the rolling bearing assembly can have media-permeable, annular openings in the area of ​​the bypass conductor. This is particularly advantageous for so-called "wet" applications, i.e., in which the lubricant of an entire system also serves as rolling bearing lubrication. In this context, annular is understood to mean any round shape that describes a closed circumference. These can be designed in different geometric forms, i.e., in different annular segments or sub-segments distributed over the circumference of the holder, or as annular holes. They allow the passage of lubricant while simultaneously preventing any pressure differences that may occur in the system, which would lead to excessive, damaging, contact pressure of the bypass conductor on the second machine element.Due to the multi-part design of the holder, openings must be provided on all elements, such as the retaining plate and a clamping disc. This allows the lubricant to flow through the bypass device in an ideal manner.

[0019] At least one electrical connection is formed at least between the first and the second machine element via the bypass device. The design of the bypass device is focused exclusively on current conductivity and the installation situation, not on a sealing function. When bypass conductors are integrated into sealing systems, compromises must be made regarding the choice of material properties of the seals and also of the bypass conductor. When designing the bypass conductor of a bypass device, it is advantageous to only consider the requirements for current conductivity and wear resistance when selecting and designing the material. The bypass device is composed of a holder and an electrically conductive bypass conductor. The holder is any component designed to hold the bypass conductor. The properties of the bypass conductor can be precisely tailored to the throughput or bypass requirements.Discharge resistance of the rolling bearing must be adjusted.

[0020] As mentioned above, the holder and the bypass conductor are electrically connected. Generally, the bypass device is designed so that voltage potentials are discharged via this bypass device and not via the cylindrical roller set.

[0021] Two machine elements are mounted so as to be rotatable relative to one another by means of at least one cylindrical roller set. In the present case, the first machine element is arranged closer to the axis of rotation and the second machine element further away from the axis of rotation of the rolling bearing. Ideally, the second machine element is mounted so as to be rotatable by means of the cylindrical roller set. However, it is not excluded that the first machine element is mounted so as to be rotatable by means of the cylindrical roller set. Machine elements are generally shafts, for example rotor shafts of an electrical machine, housings, for example bearing shields or housings or housing sections or bearing shields of an electrical machine, gears or shafts or housings of a gearbox or any other machine elements that are suitable for being mounted on or against one another by means of rolling bearings.

[0022] In the cases considered, the rotation axis of the cylindrical roller set is always axially aligned. Radial is perpendicular to the rotation axis.

[0023] The cylindrical roller set is used for the rotatable mounting of machine parts, elements and assemblies and has cylindrical rolling elements to reduce friction, which roll between the first machine element, which can be designed as an inner bearing ring, and the outer bearing ring and thus reduce friction in the rotatable bearing.

[0024] The cylindrical roller set can have a cage to guide the rolling elements and, as already explained, is installed with at least one outer bearing ring and a second machine element to form a rolling bearing. Alternatively, the rolling bearing can also have more than just an inner and / or outer ring. In addition, the bearing ring, or the bearing rings, are alternatively split and have a raceway or part of a raceway. One or more outer raceways are formed on the radially inner contact partner, i.e. the inner ring, and correspondingly one or more inner raceways are formed on the outer ring. The rolling elements rolling on the raceways are roller-shaped bodies. As already mentioned, the rollers are often guided and held in cages. The rolling elements are either arranged in a row one behind the other in the circumferential direction or, alternatively, the arrangement comprises several rows of rolling elements arranged next to one another.The bearing rings can be designed with or without rims.

[0025] In the context of the invention, a bypass is understood to mean the redirection of a current or voltage around one or more rolling bearings and / or machine parts. The rolling elements and the bearing ring are usually made of rolling bearing steel and touch each other at the raceway(s). The contact zones formed are potential passageways for currents, where the dreaded discharges lead to the damage to the raceways already described in the "Background of the Invention" chapter.

[0026] The currents are to be redirected through the bypass or bypass device. This can be "controlled" by ensuring that the bypass device, or in any case the bypass conductor, has comparatively lower electrical or specific electrical resistance than the rolling bearing. It is conceivable that the rolling elements are made of a non-conductive material such as ceramic. In this case, the bypass device only needs to redirect the current.

[0027] Although any material and design for the bypass conductor is conceivable, it is advantageous to form the bypass conductor from loop-shaped, embroidered fibers. The term "embroidered fibers" used below refers to both individual fibers and fiber pairs or bundles. The term "embroidering" describes any joining of fibers, fiber pairs, or bundles that uses an additional thread for connection. Sewing, crocheting, or similar methods can therefore also be considered equivalent. The bypass conductor formed in this way represents an ideal means of power transmission, even in contact with lubricants. Furthermore, it enables the flow of lubricants without causing pressure differences in the bearing or the overall system.

[0028] The looped, interwoven fibers of the bypass conductor of the rolling bearing device advantageously comprise 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 a high elongation at break and very good electrical conductivity.

[0029] Description of the drawings

[0030] The invention is explained in more detail below using exemplary embodiments. They show:

[0031] Figure 1 - a partial section as an embodiment of a rolling bearing arrangement 1 in a partial section along the rotation axis 16;

[0032] Figure 2 - a detailed illustration of an exemplary embodiment of a bypass device 20; Figure 3 - a detailed illustration of the bypass device 20 from Figure 2 in an oblique partial section;

[0033] Figure 4 - a representation of the clamping disc 21.2 of the bypass device 20 from Figure 2;

[0034] Figure 1 - The rolling bearing assembly 1 is formed from the cylindrical roller set 5, an outer bearing ring 2, and a bypass device 20, and has a first machine element 30 and a second machine element 31. The second machine element 31 can be designed, for example, as a housing, and the first machine element 30, for example, as a shaft, a hollow shaft, or a bearing ring. The cylindrical roller set 5 comprises a plurality of cylindrical rollers 8 and can have a cage 11. The bearing ring 2 is arranged concentrically on an axially aligned axis of rotation 16 of the cylindrical roller set 5. The cylindrical roller set 5 is provided with cylindrical rollers 8 arranged radially between the first machine element 30 and the outer bearing ring 2, wherein the outer bearing ring 2 is directed radially transversely to the axis of rotation 16. An 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 in Figure 1 has a holder 21 and an electrically conductive bypass conductor 23, wherein the holder 21 and bypass conductor 23 are electrically conductively connected to one another. The holder 21 of the bypass device 20 is designed in several parts, shown in two parts in the figure, comprising a holding disk 21.1 and a clamping disk 21.2. The holding disk 21.1 of the holder 21 is fastened radially between the outer bearing ring 2 and the second machine element 30 to the outer bearing ring 2 and holds the bypass conductor 23. The outer bearing ring 2 is fastened to the second machine element 30. The holder 21 is also arranged axially between the first end face 18 of the outer bearing ring 2 and the second machine element 30 and is secured against axial displacement by a shoulder 4 on the second machine element 30.The outer bearing ring 2 is secured against axial movement on the second end face 19 by means of a retaining ring 10, which engages in a groove 12 in the second machine element 30. The clamping disc 21.2 of the holder 21 is connected to the retaining disc 21.1 by means of a positive fit at the radial height of the shoulder 6 of the outer bearing ring 2. The clamping disc 21.2 provides a contact surface 24 at the radial height h of the end face 3 of the outer bearing ring 2, which contact surface is raised relative to the base surface of the clamping disc 21.2 with respect to the YZ plane. The media-permeable openings 17 are provided in the clamping disc 21.2, the retaining disc 21.1, and in the bypass conductor 23 as a media-permeable opening of the bypass conductor 15.

[0035] Figure 2: Figure 2 shows a detailed illustration of an exemplary embodiment of a bypass device 20, as is also shown in Figure 1. The clamping disk 21.2 provides a contact surface 24 which is raised with respect to the base surface of the clamping disk 21.2 with respect to the YZ plane. It is also clear that the contact surfaces 24 can also be designed to be resilient as axially resilient shaped elements 32. It is also conceivable that the connection of the exposed contact surfaces is only provided at one point in order to provide low rigidity in the sense of the resilient design. Figure 2 also shows that the bypass conductor 23 is secured against rotation by at least one axially exposed shaped element 27 in the clamping disk 21.2. The holder 21 of the bypass device 20 can also have annular, media-permeable openings 17, as shown. These are shown here as holes.These media-permeable openings 17 can be designed tangentially alternating with the axially flared shaped elements 27 in order to generate a uniform lubricant passage or a uniform clamping.

[0036] Figure 3: Figure 3 shows a detailed view of the bypass device 20 from Figure 2 in an oblique partial section. It shows how the axially flared shaped element 27 in the clamping disc 21.2 secures the bypass conductor 23 against rotation. The contact surface 24, which is raised relative to the base surface of the clamping disc 21.2, is also visible in detail.

[0037] Figure 4: Figure 4 shows the clamping disc 21.2 of the bypass device 20 from Figure 2 as a single component. The contact surface 24 is formed from circular segment-shaped elements 29. These can also act as axially resilient elements 32. Reference numerals

Claims

Patent claims 1. A rolling bearing assembly (1) formed from at least one cylindrical roller set (5), an outer bearing ring (2), and a bypass device (20), and further comprising 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 first machine element (30) and the outer bearing ring (2), and wherein these are directed radially transversely to the rotational axis (16), the outer bearing ring (2) is arranged concentrically on an axially aligned rotational axis (16) of the rolling bearing assembly (1), 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),and wherein the holder (21) and bypass conductor (23) are electrically conductively connected to one another, wherein the holder (21) of the bypass device (20) is designed in several parts, comprising a holding disk (21.1) and a clamping disk (21.2), wherein the holding disk (21.1) of the holder (21) is fastened radially between the outer bearing ring (2) and the second machine element (30) to the outer bearing ring (2) and holds the bypass conductor (23), wherein the outer bearing ring (2) is fastened to the second machine element (30), wherein the holder (21) is also arranged axially between the first end face (18) of the outer bearing ring (2) and the second machine element (30) and is secured against axial displacement by a shoulder (4) on the second machine element (30), wherein the outer bearing ring (2) is secured against axial movement on the second end face (19) by means of a retaining ring (10) which engages in a groove (12) in the second machine element (30), wherein the clamping disc (21.2) of the holder (21) is connected to the holding disc (21.1) by means of a positive fit at the radial height of the shoulder (6) of the outer bearing ring (2), and wherein the clamping disc (21.2) provides a contact surface (24) at the radial height of the end face (3) of the outer bearing ring (2), which contact surface is raised with respect to the base surface of the clamping disc (21.2) with respect to the YZ plane.

2. Rolling bearing arrangement (1) according to claim 1, wherein the contact surface (24) is formed from axially resilient shaped elements (32).

3. Rolling bearing arrangement (1) according to claim 1 or 2, wherein the contact surface (24) is formed from circular segment-shaped elements (29).

4. Rolling bearing arrangement (1) according to claim 2 or 3, wherein the axially resilient shaped elements (32) or the circular segment-shaped shaped elements (29) are uniformly distributed over the circumference of the clamping disc (21.2).

5. Rolling bearing arrangement (1) according to one of the preceding claims, wherein the contact surface is formed in the direction of the outer bearing ring.

6. Rolling bearing arrangement (1) according to one of the preceding claims, wherein the first machine element (31) is designed as an inner bearing ring (7).

7. Rolling bearing arrangement (1) according to one of the preceding claims, wherein the holder (21) of the bypass device (20) also engages radially in a groove-shaped undercut (28) on the outer bearing ring (2) between the outer bearing ring (2) and the second machine element (30).

8. Rolling bearing arrangement (1) according to one of the preceding claims, wherein the bypass conductor (23) is secured against rotation by at least one axially flared shaped element (27) in the clamping disc (21.2).

9. Rolling bearing assembly (1) according to claim 3 to 5, wherein the contact region (14) generates a lower electrical resistance than the outer bearing ring (2).

10. Rolling bearing arrangement (1) according to one of the preceding claims, wherein the holder (21) of the bypass device (20) has annular, media-permeable openings (24).

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