Bearings with conductive media

Abstract

A bearing assembly with a conductive medium, capable of being assembled on a shaft, comprises a bearing unit, the bearing unit including a radially inner bearing ring, the radially inner bearing ring including a radially inner raceway, and the radially inner bearing ring being capable of rotating with the shaft. The bearing unit further comprises a radially outer bearing ring and a plurality of rolling elements: the radially outer bearing ring including a radially outer raceway, the radially outer bearing ring being stationary relative to the shaft; the plurality of rolling elements being supported between the radially inner raceway of the radially inner bearing ring and the radially outer raceway of the radially outer bearing ring, capable of rolling. An annular cavity is disposed adjacent to the bearing unit, and the conductive medium is disposed within the cavity.

Description

Technical Field

[0001] The present invention relates generally to bearing technology and, more particularly, although not exclusively, to a bearing assembly including an electrically conductive medium. Background Art

[0002] Rolling bearings used in motors cause current to flow. Pulses from the inverter induce electromotive force between the bearing races. This current can cause persistent electrical damage to the rolling elements and bearing raceways due to sparks or electrical erosion. Electrical erosion can also cause damage to contact surfaces caused by the current flow, such as material shedding. Consequently, the bearings can fail prematurely, leading to failure of the entire machine. This leads to significant repair costs and downtime.

[0003] Known solutions include hybrid bearings, coated bearings and insulated bushings. Separate grounding rings are also frequently used, such as spring-loaded graphite brushes and wave grounding systems such as carbon fiber rings. These serve to protect the rolling bearings from damage. These are separate components, often attached to the housing by clamping or screwing. These components work alongside the graphite brushes and are only partially designed for a full lifespan. Partly because they can fail due to contamination in the machine, these systems always require additional assembly work, space and cost. Graphite brushes increase friction and exacerbate contamination when performance degrades, while also limiting speed. Summary of the Invention

[0004] The present invention is achieved by a bearing assembly capable of being assembled on a shaft, as described below. The bearing assembly capable of being assembled on a shaft comprises: a bearing unit, the bearing unit including: a radially inner bearing ring including a radially inner raceway, the radially inner bearing ring being rotatable together with the shaft; a radially outer bearing ring including a radially outer raceway, the radially outer bearing ring being stationary relative to the shaft; and a plurality of rolling elements supported so as to roll between the radially inner raceway of the radially inner bearing ring and the radially outer raceway of the radially outer bearing ring; an annular cavity constructed adjacent to the bearing unit; and a conductive medium disposed within the cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 is a cross-sectional view of a bearing assembly and a shaft according to an exemplary embodiment;

[0006] Figure 2 is a cross-sectional view of a bearing assembly and a shaft according to another exemplary embodiment;

[0007] Figure 3 is a cross-sectional view of a bearing assembly according to another exemplary embodiment;

[0008] Figure 4 is a cross-sectional view of a bearing assembly according to another exemplary embodiment;

[0009] Figure 5 is a cross-sectional view of a bearing assembly according to another exemplary embodiment, wherein the bearing assembly includes a disk-shaped laminar brush. DETAILED DESCRIPTION

[0010] The bearing assembly disclosed in the present invention is suitable for use in bearing units, particularly rolling bearings. The exemplary embodiments disclosed herein are particularly, though not exclusively, suitable for use in motor bearing units such as automotive traction motors. The bearing unit is disposed on a shaft.

[0011] The exemplary embodiments disclosed herein reduce friction particles and friction, thereby extending the life of the bearing unit. Due to the reduced friction, the exemplary embodiments can also operate at higher speeds.

[0012] The inventive concepts of exemplary embodiments will now be described, by way of non-limiting example only, with reference to a bearing assembly on a rotating shaft.Exemplary embodiments create electrical conductivity between a rotating component and a non-rotating component.

[0013] Reference Figure 1 The bearing assembly of the exemplary embodiment is generally designated by the numeral 10 and includes a bearing unit 12 mounted on a rotatable shaft 14. Throughout this specification and the claims, words and expressions such as "radial" and "axial" referring to positions and orientations should be understood as referring to the central rotation axis X (not shown) of the bearing unit 12 and the shaft 14. The accompanying drawings illustrate structural details by way of example.

[0014] Bearing unit 12 includes a radially inner bearing ring (hereinafter referred to as the "inner bearing ring") 16, which is mounted on shaft 14 and is capable of rotating with shaft 14. Bearing unit 12 further includes a radially outer bearing ring (hereinafter referred to as the "outer bearing ring") 18. Outer bearing ring 18 is stationary relative to inner bearing ring 16 and shaft 14 (meaning that outer ring 18 does not rotate with inner ring 18 and shaft 14). Inner bearing ring 16 includes a raceway 20 located radially inward of the bearing (hereinafter referred to as the "inner ring raceway"), and outer bearing ring 18 includes a raceway 22 located radially outward of the bearing (hereinafter referred to as the "outer ring raceway") 22. A plurality of rolling elements 24 are supported between inner ring raceway 20 and outer ring raceway 22 and are capable of rolling. Rolling elements 24 may be stainless steel balls or similar components. The first seal 26 and the second seal 27 are fixed to the bearing inner ring 16 or formed integrally with the bearing inner ring 16, and extend radially outward from the bearing inner ring 16 to the bearing outer ring 18 on both sides of the inner ring raceway 20 and the outer ring raceway 22. Alternatively, the first seal 26 and the second seal (or seal member) 27 may also be fixed to the bearing outer ring 18 or formed integrally with the bearing outer ring 18, and extend radially inward from the bearing outer ring 18 to the bearing inner ring 16.

[0015] Figure 1 The illustrated embodiment further includes an annular case 28 that can be assembled onto the shaft 14 adjacent to the bearing unit 12. Case 28 has an interior cavity formed by its housing 30. Housing 30 is stationary relative to the shaft 14 (meaning that housing 30 does not rotate with the shaft 14). Housing 30 may include a first body portion 32 and a second body portion 38. These two body portions 32 and 38 are designed to engage with each other via an openable locking member 31, which allows them to be releasably connected to each other. First body portion 32 has a first radial wall portion 34 and a first axial wall portion 36, while second body portion 38 has a second radial wall portion 40 and a second axial wall portion 42. Second radial wall portion 40 may be designed to include a fitting portion 44 configured to be press-fitted onto the bearing outer ring 18 so as to remain stationary therewith. The entire bearing assembly (or entire bearing assembly) 20, including the bearing unit 12 and the cartridge 28, can be press-fitted onto the shaft 14 as a unit after the housing 30 is press-fitted onto the bearing assembly 10, or can be press-fitted onto the shaft 14 separately. The housing 30 can be made of any suitable material, including conductive materials such as stainless steel, steel, and aluminum.

[0016] The cartridge 28 further includes an annular flinger ring 46 disposed within the housing 30. The flinger ring 46 is constructed to have an L-shaped cross-section, having an axial flinger portion 48 and a radial flinger portion 50. The axial flinger portion 48 is designed to be press-fit onto the shaft 14, thereby enabling the flinger ring 46 to rotate therewith. The flinger ring 46 further includes two sealing lips 52 extending at an angle from opposite sides of the radial flinger portion 50. The sealing lips 52 can be made of any suitable material, such as vulcanized rubber, and attached to the radial flinger portion 50 by overmolding or bonding. Depending on performance requirements, the sealing lips 52 can also be made of any suitable polymer. For example, when used for lower performance (low speed / low temperature 125°C), the sealing lip 52 can be made of nitril rubber and hydrogenated nitril rubber; when used for high performance (high speed / high temperature 150°C), the sealing lip 52 can be made of fluoroelastomers or fluorocarbons; when used for very high performance (very high speed / high temperature 175°C), the sealing lip 52 can be made of polytetrafluoroethylene (PTFE).

[0017] The box 28 is designed to accommodate a conductive medium 58. The conductive medium 58 can be a conductive paste, fluid, grease, particles, gel, or other medium. The conductive medium 58 can further be an ionic liquid, a conductive fat, or an oil-based matrix. The conductive material can be a poor lubricant because good lubricants typically have low conductivity. Therefore, a balance can be achieved by using a non-conductive material with conductive particles dispersed throughout. The conductive medium 58 is held within the box 28 by the sealing lip 52, above the sealing lip 52.

[0018] Figure 2Another exemplary embodiment of a bearing assembly 110 is shown. For the sake of simplicity, similar components in the alternative embodiment will be given the same reference numerals as in the previous embodiment, but preceded by multiples of 100. A cassette 128 is integrally formed with the bearing unit 112. The cassette 128 includes a cassette housing 130 and is stationary relative to the shaft 114 (does not rotate with the shaft 114). The housing 130 may include a first body portion 132 and a second body portion 138. The first body portion 132 has a first radial wall portion 134 and a first axial wall portion 136, and the second body portion 138 has a second radial wall portion 140 and a second axial wall portion 142. The first radial wall portion 134 may be constructed with an adapter portion 145 designed to be press-fitted onto the bearing outer ring 118 so as to remain stationary therewith. The entire bearing assembly 110 may be press-fitted onto the shaft 114 as a single unit. The first seal 126 is fixed to the bearing inner ring 116 or is formed integrally with the bearing inner ring 116. A second seal is not provided. As before, the box 128 further includes an annular oil flinger 146, a sealing lip 152 and a conductive medium 158.

[0019] Figure 3 Another embodiment of a bearing assembly 210 is shown assembled on a shaft 214. In this embodiment, the bearing assembly 210 includes a sealed cavity 228 integrally formed with the bearing unit 212. The cavity 228 is separated from the bearing unit 212 by a seal 227. The sealed cavity 228 is an annular chamber at least partially filled with a conductive medium 258.

[0020] Figure 4 Another exemplary embodiment of a bearing assembly 310 is shown. The bearing assembly 310 includes a sealed cavity 328 integrally formed with the bearing unit 312. The sealed cavity 328 is an annular chamber at least partially filled with a conductive medium 358. The sealed cavity 328 further includes an inner annular ring 347 that is rotatable with the shaft 314.

[0021] exist Figure 3 and 4 In the illustrated embodiment, the bearing assemblies 210 and 310 can be used in compact spaces because no additional components require space. The sealed cavities 228 and 328 can be used to seal and retain the conductive medium 258 and 358. Additional seals 229 and 329 can be used to cover the inner walls 231 and 331 of the sealed cavities 228 and 328. The additional seals 229 and 329 can also contain a conductive medium such as copper, aluminum, or silver to provide additional conductivity.

[0022] Figure 5A bearing assembly 410 is shown in another exemplary embodiment. The bearing assembly 410 includes a sealed cavity 428 formed integrally with the bearing unit 412. The sealed cavity 428 is separated from the bearing unit 412 by a seal 427 and may include the previously Figure 3 and 4 An additional seal is depicted. A disk-shaped device, such as a laminar grounding brush 460, similar to a grounding ring, is disposed in the sealing cavity 428 and is capable of rotating with the shaft 414. The grounding brush 460 may include conductive brush filaments 462 sandwiched between conductive rings 464, and may be of the type disclosed in U.S. Patent No. 9,790,995, entitled "Bearing Seal with Integrated Grounding Brush." ​​The contents of this U.S. patent are incorporated herein by reference. Alternatively, the sealing cavity 428 may be filled with metallic wool, such as copper wool or silver wool, to ensure a conductive connection between the rotating and stationary portions of the bearing unit 412. To increase the electrical conductivity of the bearing unit, the rotating and stationary components of the bearing unit may also be coated with a conductive material, such as silver.

[0023] Further preferred and / or particularly advantageous exemplary embodiments of the inventive concept are defined according to the characterizing features indicated in the appended dependent claims.

Claims

1. A bearing assembly capable of being assembled on a shaft, comprising: A bearing unit, comprising: a radially inner bearing ring, the radially inner bearing ring including a radially inner raceway, the radially inner bearing ring being rotatable with the shaft; a radially outer bearing ring including a radially outer raceway, the radially outer bearing ring being stationary relative to the shaft; and a plurality of rolling elements supported so as to roll between a radially inner raceway of the radially inner bearing ring and a radially outer raceway of the radially outer bearing ring; an annular cavity constructed adjacent to the bearing unit; A conductive medium is disposed in the cavity, The cavity is constituted by an outer shell of an annular box, which is stationary relative to the shaft.

2. The bearing assembly according to claim 1, characterized in that: The annular box is configured to be press-fitted to the bearing unit.

3. The bearing assembly according to claim 1, wherein: The annular case includes a first body portion and a second body portion configured to be attached to the first body portion.

4. The bearing assembly according to claim 3, characterized in that: The first body portion has a first radial wall portion and a first axial wall portion, and the second body portion has a second radial wall portion and a second axial wall portion.

5. The bearing assembly according to claim 4, characterized in that: One of the first radial wall portion and the second radial wall portion is configured to be press-fitted with the bearing unit.

6. The bearing assembly according to claim 4, characterized in that: One of the first axial wall portion and the second axial wall portion is configured to be press-fitted with the bearing unit.

7. The bearing assembly according to claim 1, characterized in that: The bearing assembly further includes an oil slinger disposed in the housing and configured to rotate together with the shaft.

8. The bearing assembly according to claim 7, characterized in that: The oil slinger includes an axial oil slinger portion and a radial oil slinger portion, wherein the axial oil slinger portion is configured to be press-fitted onto the shaft.

9. The bearing assembly according to claim 8, characterized in that: The bearing assembly further includes at least one sealing lip disposed on the radial oil slinger portion.

10. The bearing assembly according to claim 1, characterized in that: The bearing assembly further includes a seal disposed between the cavity and the bearing unit.

11. The bearing assembly according to claim 10, characterized in that: The cavity has an inner wall covered with a conductive seal.

12. The bearing assembly according to claim 1, wherein: The conductive medium is a fluid.

13. The bearing assembly according to claim 1, wherein: The conductive medium is selected from conductive paste, grease, particles, ionic liquid, fat and oil-based matrix.

14. The bearing assembly according to claim 1, wherein: The conductive medium is formed of a non-conductive material with a conductive material distributed throughout.

15. The bearing assembly according to claim 1, wherein: The conductive medium is formed by conductive brush filaments of a grounding brush disposed in the cavity and configured to rotate with the shaft.

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