Bearing with integrated bridging device

Abstract

The invention relates to a bearing (1) with two rings (3, 4) supported relative to each other by means of several rolling elements (2) so as to be rotatable, and a bridging device (5) forming an electrical contact between the rings (3, 4) at a distance from the rolling elements (2), wherein the bridging device (5) comprises at least one centering element (6) surrounding the inner bearing ring (3.1), which is supported on the outer bearing ring (4.1) and includes an oval support ring (10) and a radial, annular contact element (7) having a cylindrical inner surface (8) formed on its inner diameter (7.1), and wherein the centering element (6) can apply a radial force to the oval support ring (10). The bearing ring (3.1) forms an inner surface (8) on its outer diameter (3.2), which is spaced apart from the cylindrical inner surface (8). The cylindrical outer surface (9) of the bearing ring (3.1) and the cylindrical inner surface (8) of the ring-shaped contact element (7) make electrical contact with each other section by section. The bridging device is located between a first row (11) of rolling elements (2a) and a second row (12) of rolling elements (2b) with the rings (3, 4) arranged at a distance from the first row (11).

Description

[0001] The invention relates to a bearing with two rings supported relative to each other by means of several rolling elements so as to be rotatable, and a bridging device forming an electrical contact between the rings, spaced apart from the rolling elements. The bearing is preferably used in an electric machine, in particular in a drive unit of a motor vehicle, such as a car, truck, bus, or other commercial vehicle. Alternatively, the bearing can be used in any vehicle, but also in an electrically powered bicycle (pedelec), motorcycle (electric motorcycle), e-scooter, or the like.

[0002] Various methods already exist in the prior art for transmitting electrical currents in the operating area of ​​bearings, bypassing the rolling elements and passing between the bearing rings. For example, DE 10 2016 209 399 A1 discloses, in addition to a support bearing serving the bearing, a so-called sacrificial bearing, which is smaller than the support bearing and primarily designed to transmit the current in order to prevent current flow in the support bearing. Furthermore, so-called "shunt bearings" are known, in which a discharge device is integrated.

[0003] However, it has become apparent that the bridging devices implemented so far are relatively complex in their design and / or manufacture. Furthermore, they usually require additional installation space.

[0004] It is therefore an object of the present invention to provide a bearing whose bridging device reliably protects the components surrounding it in the operating area, such as the components of a gearbox, from current passages even at higher currents, while at the same time being integrated as compactly as possible and being durable in terms of its construction.

[0005] This is achieved by the bearing having two rings supported relative to each other by several rolling elements, one ring being the inner bearing ring and the other the outer bearing ring, and a bridging device forming an electrical contact between the rings, spaced apart from the rolling elements. The bridging device comprises at least one centering element surrounding the inner bearing ring, which is supported on the outer bearing ring, and a radial, annular contact element having an inner surface formed on its inner diameter, as well as an oval support ring arranged radially outside the contact element and held by the centering element with respect to the longitudinal axis of the bearing, or exerting a radial force on the support ring.The inner bearing ring has a cylindrical outer surface formed on its outer diameter and spaced apart from the inner surface of the contact element. The inner surface of the annular contact element makes electrical contact with the cylindrical outer surface of the bearing ring. The bridging device is located between a first row of rolling elements and a second row of rolling elements, spaced apart from the first row, with the rings in electrical contact. The annular contact element is designed and dimensioned such that jamming cannot occur. Instead, electrical contact is achieved around the circumference by means of the radial force exerted by the centering element on the oval carrier ring, and indirectly on the annular contact element.This force, and thus the gap that essentially migrates around the circumference, can also force out or displace lubricant located in the gap, so that the system then operates in the mixed friction regime. Large lubrication gap heights are thus effectively avoided.

[0006] The bridging device can thus be installed compactly within the bearing. This arrangement ensures reliable current transmission throughout the entire service life. No additional axial installation space is required, and the bridging device can be integrated into the existing bearing. The bridging device always exhibits lower electrical resistance than the rolling elements, ensuring reliable current flow around them during operation.

[0007] Surprisingly, it has been found that the proposed solution enables the permanent realization of an electrical conductor with extremely low electrical resistance in contact with oil or grease. A further major advantage over the prior art is that this system is maintenance-free and virtually wear-free, thus eliminating its service life limitations. No additional mounting elements are required, allowing for a simple design with few components. Furthermore, no axial forces are needed to establish the electrical contact.

[0008] Further advantageous embodiments are claimed in the dependent claims and are explained in more detail below.

[0009] To further enhance this effect, at least one groove can be provided in the inner surface of the discharge element. This has the advantage of further reducing the lubrication gap height, which could impede the transmission of electrical currents.

[0010] In an advantageous embodiment, it is also conceivable that at least one continuous relief bore is provided on the inner surface of the discharge element, which extends through the inner surface, i.e., the contact surface, of the contact element and the support ring. These measures can further improve current dissipation in the lubricant contact.

[0011] Furthermore, it is also advantageous if the centering element has a wave-like shape, whereby the outer bearing ring and the carrier ring are contacted at intervals along its circumference. This allows a radial force to be generated between the contact element and the inner bearing ring in a particularly suitable manner.

[0012] In this regard, it is also advantageous if the two rings are spaced apart radially, forming a radial bearing. This allows the bridging device to be conveniently positioned radially between the existing rings.

[0013] Preferably, the bearing is designed as a double-row (angular contact) ball bearing. This provides a stable bearing.

[0014] If the bridging device is arranged axially between the two rows of rolling elements and the centering element is fixed to the outer bearing ring, the bearing is compactly and particularly functionally integrated. The bridging device allows for ideal contact design.

[0015] For easier assembly, it is also advantageous if one of the two rings is made in two parts and two partial rings of this two-part ring are connected to each other by means of a retaining ring.

[0016] The installation of the retaining ring is simplified if it is located on a radial outer side of the two-part ring.

[0017] In this regard, it is also advantageous if the retaining ring is positively connected to the two partial rings. This results in easier assembly.

[0018] In a further preferred embodiment of the bearing, the space between the first and second rows of rolling elements is at least partially filled with an electrically conductive fluid. This electrically conductive fluid, which can be based on, for example, oil, grease, liquid metal, or an ionic liquid, establishes direct contact between the dissipation element and the conductive sleeve. This path of least resistance reliably dissipates induced currents within the bearing, from the outer to the inner ring. Bearings of any connected assemblies, such as the gearbox, are also reliably protected in this way.

[0019] The invention will now be explained in more detail below with reference to figures, in which context various embodiments are indicated.

[0020] They show: Fig. 1 a longitudinal sectional view of a bearing according to the invention, wherein a retaining ring connecting two partial rings of a two-part ring / bearing ring of the bearing is inserted on a radial outer side, Fig. 2 the warehouse Fig. 1 on average AA, as well as Fig. 3 the warehouse Fig. 1 and Fig. 2 as an exploded view in partial section.

[0021] The figures are purely schematic and serve solely to illustrate the invention. The same elements are identified by the same reference symbols.

[0022] The bearing 1 according to the invention is illustrated in the figures with regard to an exemplary embodiment. Fig. Figure 3 shows the same warehouse in an exploded view for better understanding. Therefore, the figures will be discussed together in some of the following sections.

[0023] The figures show that this is designed as a rolling bearing, specifically a radial bearing. By further designing the bearing 1 as a double-row bearing, namely a double-row ball bearing (here an angular contact ball bearing), it can also be configured as a combination of radial and axial bearings. The bearing 1 is preferably used to support a drive component / shaft of a drive device in a motor vehicle. For example, the bearing can be used as a so-called engine bearing to support a motor shaft / output shaft of an engine (electric motor or internal combustion engine (crankshaft)).

[0024] The bearing 1 has a first ring 3, which here is designed as a (radial) inner bearing ring 3.1. A second ring 4 of the bearing 1 is thus realized as a (radial) outer bearing ring 4.1. The second ring 4 is therefore arranged radially (i.e., in a direction perpendicular to the longitudinal axis 18) outside the first ring 3 with respect to a longitudinal axis 18 / axis of rotation of the bearing 1. Radially between the two rings 3, 4, two rows 11, 12 of rolling elements 2, which are designed as balls, are inserted. Each row 11, 12 has a plurality of rolling elements 2 arranged circumferentially on an axial plane, which serve for the radial support (and preferably also for the axial support) of the two rings 3, 4. The rolling elements of the first row 11 are delimited by the reference numeral 2a; the rolling elements of the second row 12 with the reference numeral 2b.

[0025] It is also evident that the first ring, i.e. the inner bearing ring 3.1, is formed in two parts and here has two partial rings 13, 14 which are axially (i.e. in a direction parallel to the longitudinal axis 18) abut each other / supported after the assembly of the bearing 1.

[0026] To ensure ease of assembly and facilitate the transport of the bearing 1, a retaining ring 15 is used, which axially connects / fixes the two partial rings 13, 14 to each other. In this embodiment, the retaining ring 15 is inserted on a radial outer surface 17 of the inner bearing ring 3. Preferably, this retaining ring 15 is positively connected to both partial rings 13, 14, fixing the two partial rings 13, 14 to each other. The bearing can be sealed on one or both sides with a seal 22.

[0027] A bridging device 5 is provided axially between the two rows 11, 12 of rolling elements 2 and 2a, 2b, respectively. The bridging device 5 serves to electrically connect the two rings 3, 4. In operation, the bridging device 5 is designed and has a lower electrical resistance than the rolling elements 2, 2a, 2b such that any potential difference between the two rings 3, 4 is always predominantly, preferably completely, conducted via the bridging device 5 (instead of via the rolling elements 2, 2a, 2b).

[0028] For this purpose, it is particularly advantageous if the bridging device 5 is predominantly made of components of steel / metal / carbon with high electrical conductivity. The rolling elements 2 should be designed with lower conductivity. It is also conceivable to make them from a ceramic material as an alternative to steel.

[0029] The bridging device 5 comprises at least one centering element 6 surrounding the inner bearing ring 3.1 and supported on the outer bearing ring 4.1, an oval support ring 10, and a radial, annular contact element 7, which has a cylindrical inner surface 8 formed on its inner diameter 7.1, and a cylindrical outer surface 9 formed on the outer diameter 3.2 of the inner bearing ring 3.1 and spaced apart from the inner surface 8. The centering element 6 applies a radial force to the oval support ring 10. The cylindrical outer surface 9 of the bearing ring 3.1 and the inner surface 8 of the annular contact element 7 make electrical contact with each other section by section. The bridging device is located between a first row 11 of rolling elements 2a and a second row 12 of rolling elements 2b, spaced apart from the first row 11, with rings 3, 4 in electrical contact.The centering element 6, fixed to the cylindrical inner surface 23 of the outer bearing ring 4.1, allows an ideal radial force to be applied to the support ring 10. The inner surface 8 preferably has at least one continuous relief bore 21 through the contact element 7 and the support ring 10.

[0030] From the Fig. 2 and Fig. Figure 3 shows that the centering element 6 has a wave-like shape and can thus contact the support ring 10 and the outer bearing ring 4.1 at intervals along its circumference.

[0031] It can also be seen in the figures that it is possible to insert the retaining ring 15 on a radial outer surface 17 of the two-part inner bearing ring 3.1. In this respect, it is advantageous if the retaining ring 15 is electrically conductive so that electrical contact can also be made between the partial rings 13 and 14.

[0032] It would also be conceivable to design the two load-bearing rows 11, 12 in the bearing 1 according to the invention as ceramic rolling elements. This would protect the load-bearing rows 11, 12 from current flow.

[0033] For current transmission, the bridging device 5 is placed between rows 11 and 12. To further improve conductivity, the space 19 between the first row 11 of rolling elements 2a and the second row 12 of rolling elements 2b can be at least partially filled with an electrically conductive liquid. A liquid metal or an ionic liquid is particularly suitable.

[0034] Out of Fig. Figure 3 shows that the inner surface 8 may have a groove which can further reduce the lubrication gap height. Reference symbol list 1 warehouse 2 rolling elements 2a first row of rolling elements 2b second row of rolling elements 3 first ring 3.1 inner bearing ring 3.2 Outer diameter of the inner bearing ring 3.1 4 second ring 4.1 outer bearing ring 5 Bridging device 6 Centering element 7 ring-shaped contact element 7.1 Inner surface of the ring-shaped contact element 7 8 cylindrical inner surfaces 9 cylindrical outer surfaces 10 carrier rings 11 first row 12 second row 13 first partial ring 14 second partial ring 15 retaining ring 16 Inside 17 Outside 18 Longitudinal axis 19 Space between the first row 11 of rolling elements 2a and the second row 12 of rolling elements 2b 20 Nut 21 Continuous relief borehole 22 Seal 23 cylindrical inner surface of the outer bearing ring QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2016 209 399 A1

[0002]

Claims

Bearing (1) with two rings (3, 4) supported relative to each other by means of several rolling elements (2) so as to be rotatable relative to each other, wherein one ring (3) is designed as the inner bearing ring (3.1) and the other ring (4) as the outer bearing ring (4.1), and a bridging device (5) forming an electrical contact between the rings (3, 4) spaced apart from the rolling elements (2), characterized in that the bridging device (5) comprises at least one centering element (6) surrounding the inner bearing ring (3.1), which is supported on the outer bearing ring (4.1) and comprises an oval support ring (10) and a radial, annular contact element (7) which has an inner surface (8) formed on its inner diameter (7.1) and wherein the centering element (6) can apply a radial force to the oval support ring (10), and the bearing ring (3.1) has a contact surface on its outer diameter (3.1).2) has a cylindrical outer surface (9) formed and spaced apart from the inner surface (8), and the cylindrical outer surface (9) of the bearing ring (3.1) and the inner surface (8) of the annular contact element (7) make electrical contact with each other section by section, and wherein the bridging device is in electrical contact with the rings (3, 4) between a first row (11) of rolling elements (2a) and a second row (12) of rolling elements (2b) arranged spaced apart from the first row (11). Bearing (1) according to claim 1, characterized in that the inner surface (8) of the annular contact element (7) has at least one groove. Bearing (1) according to claim 1 or 2, characterized in that the bridging device (5) has at least one continuous relief bore through the inner surface (8) of the contact element (7) and the support ring (10). Bearing (1) according to one of claims 1 to 3 or 2, characterized in that the centering element (6) has a wave-like shape and contacts the outer bearing ring (4.1) and support ring (10) at intervals along the circumferential course. Bearing (1) according to one of claims 1 to 4, characterized in that the two rings (3, 4) are spaced apart in a radial direction, forming a radial bearing. Bearing (1) according to claim 4, characterized in that the bridging device (5) is arranged axially between the two rows (11, 12) and between the rolling elements (2a, 2b) and the centering element (6) is arranged non-rotatably on the outer bearing ring (4.1). Bearing (1) according to one of claims 1 to 5, characterized in that the inner bearing ring (3.1) is formed in two parts and two partial rings (13, 14) of this ring (3.1) are connected to each other by means of a retaining ring (15). Bearing (1) according to one of the preceding claims, characterized in that the space (19) between the first row (11) of rolling elements (2a) and the second row (12) of rolling elements (2b) is at least partially filled with an electrically conductive liquid. Bearing (1) according to claim 8, characterized in that the electrically conductive liquid comprises a liquid metal. Bearing (1) according to claim 8, characterized in that the electrically conductive liquid comprises an ionic liquid.

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