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 relative to each other, and a bridging device (5) forming an electrical contact between the rings (3, 4) spaced apart from the rolling elements (2), wherein the bridging device (5) has at least one spring element (6), an axial, annular contact element (7) and a conductive sleeve (8) and is in 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).

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 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 bridging device has at least one spring element, an axial, annular contact element, and a conductive sleeve, and 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.

[0006] The bridging device can thus be installed compactly within the bearing. The arrangement, consisting of at least one spring element, an axial ring-shaped contact element, and a conductive sleeve, ensures reliable contact throughout its entire operation. Therefore, 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, thus reliably diverting the current around them during operation.

[0007] A further advantage of the proposed arrangement is that only minimal axial forces are required to establish electrical contact. Remarkably, this solution has proven to achieve extremely low electrical resistance, even in contact with oil or grease. Another significant advantage over the prior art is that this system is completely maintenance-free and wear-free, thus eliminating any limitations on its lifespan.

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

[0009] Accordingly, it is also advantageous if the bridging device is supported via a first step on the smaller diameter bearing ring and via the conductive sleeve attached to the larger diameter bearing ring. This ensures an ideal, reproducible, and permanent preload.

[0010] Furthermore, it is advantageous if the annular contact element has an annular outer contour and a corrugated inner contour. The annular outer contour allows the contact element to fit ideally against the inner diameter of the outer bearing ring. The corrugated inner contour limits the lubricant film thickness and establishes contact via mixed friction or, if necessary, additionally via an electrically conductive fluid. This ensures consistent dissipation even at higher speeds. At the same time, the system operates with very low friction and no conductive wear is generated.

[0011] For uniform preload, it has been found that it is particularly advantageous if the spring element is designed as a coil spring or wave spring that encloses the circumference of the smaller diameter ring. This prevents any detrimental change in the position of the spring element during operation.

[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 contact element is fixed to the smaller diameter bearing ring, it is compactly and particularly functionally integrated into the bearing. By selecting an appropriate material for the conductive sleeve, the contact can be optimally designed.

[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] If the retaining ring is arranged radially between the two-part ring and the contact elements, it is compactly housed.

[0018] In this regard, it is also advantageous if the retaining ring is positively connected to the two partial rings. This results in easier assembly.

[0019] 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.

[0020] The invention will now be explained in more detail below with reference to figures, in which context various embodiments are indicated.

[0021] 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, as well as Fig. 2 the warehouse Fig. 1 as an exploded view in partial section.

[0022] The figures are purely schematic and serve solely to illustrate the invention. The same elements are identified by the same reference symbols.

[0023] The bearing 1 according to the invention is in Fig. 1 illustrates an exemplary embodiment. Fig. Figure 2 shows the same bearing in an exploded view for better understanding. Due to the identical embodiment, both figures are discussed together below.

[0024] The figures show that the bearing 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 motor vehicle's drive system. 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)).

[0025] The bearing 1 has a first ring 3, which is configured here as a (radial) inner ring. A second ring 4 of the bearing 1 is thus implemented as a (radial) outer ring. 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 designated by reference numeral 2a; the rolling elements of the second row 12 by reference numeral 2b.

[0026] It is also evident that the first ring 3 is formed in two parts and has two partial rings 13, 14 which are axially (that is, in a direction parallel to the longitudinal axis 18) abutting each other / supported after the mounting of the bearing 1.

[0027] 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 first ring 3. Preferably, this retaining ring 15 is positively connected to both partial rings 13, 14, thus fixing the two partial rings 13, 14 to each other.

[0028] A bridging device 5 is provided axially between the two rows 11, 12 of rolling elements 2; 2a, 2b. The bridging device 5 serves for the direct electrical contacting of the two rings 3, 4 with each other. In operation, the bridging device 5 is designed and has a lower electrical resistance than the rolling elements 2; 2a, 2b such that a 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).

[0029] 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.

[0030] The bridging device 5 has at least one spring element 6, an axial, annular contact element 7 and a conductive sleeve 8 and is arranged 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 and is in contact with the rings 3, 4.

[0031] The bridging device 5 is supported via a shoulder 9 on the smaller diameter ring 3 and via the conductive sleeve 8 attached to the larger diameter ring 4 and is thus in permanent electrical contact with the rings 3, 4.

[0032] Out of Fig. Figure 2 shows that the annular contact element 7 can have an annular outer contour and a wave-shaped inner contour. The spring element 6 is designed as a helical spring or wave spring, which encloses the circumference of the smaller diameter ring 3.

[0033] 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 ring 3. 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.

[0034] 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.

[0035] For current transmission, the bridging device 5 is positioned between rows 11 and 12. A further special feature is that this device must always establish contact between the outer ring (second ring 4) and the inner ring (first ring 3). The spring element thus pre-tensions the annular contact element 7 against the conductive sleeve 8. Due to the low tension, the friction of the bridging device 5 is negligible. 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. Reference symbol list 1 warehouse 2 rolling elements 2a first row of rolling elements 2b second row of rolling elements 3 first ring 4 second ring 5 Bridging device 6 spring element 7 ring-shaped contact element 8 conductive sleeves Paragraph 9 10 - 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 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

[1] Bearing (1) with two rings (3, 4) supported relative to each other by means of several rolling elements (2) and a bridging device (5) forming an electrical contact between the rings (3, 4), spaced apart from the rolling elements (2), characterized by , that the bridging device (5) has at least one spring element (6), an axial, annular contact element (7) and a conductive sleeve (8) and 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). [2] Bearing (1) according to claim 1, characterized by , that the bridging device (5) is supported via a shoulder (9) on the smaller diameter ring (3) and via the conductive sleeve (8) attached to the larger diameter ring (4). [3] Bearing (1) according to claim 1 or 2, characterized by, that the ring-shaped contact element (7) has a ring-shaped outer contour and a wave-shaped inner contour. [4] Bearing (1) according to any one of claims 1 to 3, characterized by , that the spring element (6) is designed as a coil spring or wave spring which encloses the circumference of the smaller diameter ring (3). [5] Bearing (1) according to any one of claims 1 to 4, characterized by , that the two rings (3, 4) are spaced apart in a radial direction, forming a radial bearing. [6] Bearing (1) according to claim 5, characterized by , that the bridging device (5) is arranged axially between the two rows (11, 12) of rolling elements (2) and the annular contact element (7) is arranged non-rotatably on the smaller diameter bearing ring (3). [7] Bearing (1) according to any one of claims 1 to 6, characterized by, that one of the two rings (3, 4) is formed in two parts and two partial rings (13, 14) of this ring (3, 4) are connected to each other by means of a retaining ring (15). [8] Bearing (1) according to claim 7, characterized by , that the retaining ring (15) is arranged on a radial inner side (16) or a radial outer side (17) of the two-part ring (3, 4). [9] Bearing (1) according to claim 7 or 8, characterized by , that the retaining ring (15) is arranged radially between the two-part ring (3, 4) and the contact elements (7, 9). [10] Bearing (1) according to any one of the preceding claims, characterized by , 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.

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