Combined insulator and conductor assembly for bearings with encapsulated insulators
By using a combined insulator and conductor assembly in the bearing, the damage caused by current through the bearing is solved, and the safe guide of current and the protection of bearings are achieved.
Patent Information
- Application Number
- CN202110340556.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2020-04-03
- Filing Date
- 2021-03-30
- Publication Date
- 2025-08-26
- Estimated Expiration
- 2041-03-30
AI Technical Summary
Current or charge flowing through the bearing raceway will cause damage to the bearing. Existing devices such as ground brushes have limitations that cannot effectively prevent current from passing through the bearing.
A combined insulator and conductor assembly is adopted, which is formed of an electrically insulating material, and the conductor comprises a conductive carrier and a conductive fiber brush assembly, providing a conductive path between the shaft and the seat to prevent current from passing through the bearing.
Effectively prevent current from passing through the bearing, protecting the bearing from damage, and providing alternative paths to ensure safe current flow to the seat and avoid voltage difference.
Smart Images
Figure CN113494521B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to bearings, and more particularly to a grounding device for preventing current or charge from flowing through a bearing. Background Art
[0002] If an electric current or charge flows through bearings used in electrical machinery such as motors, generators, and the like, which is particularly detrimental to the bearing raceways, the bearings may be damaged. Devices such as grounding brushes have been developed to provide an alternative path for the electric current, thereby preventing such current from passing through the bearings. These devices typically include a plurality of conductive fibers spaced circumferentially around the entire outer surface of the shaft to form a relatively solid fiber ring, such that the current passes through the fibers between the shaft and the housing. To prevent the current from passing through the bearings, other devices or mechanisms are provided to electrically insulate the bearings, and these other devices or mechanisms may include insulating coatings or coverings. Summary of the Invention
[0003] In one aspect, the present invention is a combined electrical insulator and conductive assembly for a bearing that can be arranged between a shaft and a housing. The bearing has an inner ring, an outer ring with opposing first and second axial ends, and a plurality of rolling elements located between the rings, the shaft has a circumferential outer surface, and the housing has a circumferential inner surface. The assembly includes an annular insulator that can be arranged around the outer ring of the bearing and has a circumferential inner surface and a circumferential outer surface. The insulator is formed of an electrically insulating material or has an insulating layer provided on at least one of the inner and outer surfaces to substantially prevent current from flowing between the inner and outer rings. The annular conductor has a radially outer end and a radially inner end, the outer end being arranged at least partially around the insulator and engageable with the inner surface of the housing, and the radially inner end being engageable with the outer surface of the shaft to provide a conductive path between the shaft and the housing through the radially inner and radially outer ends of the conductor.
[0004] Preferably, the conductor includes a conductive carrier, the conductive carrier including a cylindrical portion and a disk portion, the cylindrical portion having a circumferential inner surface arranged around the outer surface of the insulator and a circumferential outer surface arranged against the inner surface of the seat. The disk portion extends radially inward from the cylindrical portion to be axially adjacent to the inner and outer rings of the bearing, the disk portion having radial inner ends that are radially spaced outward from the shaft and define a central opening. In addition, an annular conductive brush subassembly is coupled to the disk portion of the carrier, has a centerline, and includes a plurality of conductive fibers. The conductive fibers are circumferentially spaced around the centerline and extend radially inward from the inner end of the disk portion of the carrier. Each conductive fiber has an inner end that can contact the outer surface of the shaft to provide a conductive path between the shaft and the carrier, the path extending through the carrier to the seat. BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The foregoing summary of the invention and the detailed description of the preferred embodiments of the invention will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the invention, there are shown in the accompanying drawings presently preferred schematic embodiments. However, it should be understood that the invention is not limited to the precise arrangements and implementations shown. In the drawings:
[0006] Figure 1 is a perspective view of an assembly of a combined insulator and conductor according to the present invention, shown mounted on a bearing;
[0007] Figure 2 is an axial cross-sectional view of an assembly of a combined insulator and conductor, shown mounted on a shaft and within a housing;
[0008] Figure 3 is an axial cross-sectional view of an assembly comprising an insulator and a conductor;
[0009] Figure 4 yes Figure 3 An enlarged sectional view of the upper portion;
[0010] Figure 5 is an axial cross-sectional view of an insulator;
[0011] Figure 6 is a cutaway axial cross-sectional view of a conductive carrier and a brush assembly;
[0012] Figure 7 is an enlarged cross-sectional view of an assembly of a combined insulator and conductor, illustrating an alternative configuration of the insulator;
[0013] Figure 8is an enlarged cross-sectional view of a brush assembly taken through a set of relatively short conductive fibers; and
[0014] Figure 9 is another enlarged cross-sectional view of the brush assembly taken through a group of relatively large conductive fibers. DETAILED DESCRIPTION
[0015] Certain terminology is used in the following description for convenience only and is not intended to be limiting. The words "inward," "inwardly," and "outwardly" refer to directions toward and away from, respectively, a designated centerline or geometric center of the elements being described, with particular meanings apparent from the context of the specification. Additionally, as used herein, the words "connected" and "coupled" are each intended to encompass a direct connection between two components without any intervening components, and an indirect connection between components with one or more intervening components. The terminology includes the words specifically mentioned above, their derivatives, and words of similar import.
[0016] Referring now in detail to the drawings, wherein like reference numerals are used to refer to like elements throughout, Figures 1 to 9 FIG. 1 shows an assembly 10 of an electrical insulator and a conductor for a bearing 1 which can be arranged between a shaft 2 and a housing 3 (e.g. Figure 2 The bearing 1 comprises an inner ring 4, an outer ring 5 having opposite first and second axial ends 5a and 5b, and a plurality of rolling elements 6 located between the rings 4 and 5. The shaft 2 can be rotated about a central axis A. C The bearing 1, shaft 2, and seat 3 are preferably components of a motor, other electrical machine (e.g., a generator), or any other machine having a rotating component that can accumulate charge or carry current. The combined insulator and conductor assembly 10 generally comprises an annular insulator 12 that can be arranged around the outer race 5 of the bearing and is configured to prevent current from flowing between the outer race 5 and the seat 3; and an annular conductor 11 that is at least partially arranged around the insulator 12 and is configured to provide a conductive path between the shaft 2 and the seat 3.
[0017] More specifically, insulator 12 has a circumferential inner surface 13A and a circumferential outer surface 13B, and is formed from an electrically insulating material (e.g., a polymer, ceramic, etc.), or has an insulating layer (e.g., aluminum having anodized layer(s)) provided on at least one of inner surface 13A and outer surface 13B. In this manner, insulator 12 substantially prevents current from flowing between outer ring 5 and seat 3, thereby preventing current from flowing through bearing inner ring 4 and bearing outer ring 5, as such current would be particularly detrimental to the bearing raceway (not depicted). Ring conductor 11 has a radially outer end 11a, which is at least partially disposed around insulator 12 and engageable with seat inner surface 3a, and a radially inner end 11b, which is engageable with shaft outer surface 2a, to provide a conductive path between shaft 2 and seat 3 via conductor radially inner end 11b and conductor radially outer end 11a, respectively. Additionally or alternatively, as described below, one or more conductive paths may be provided by engaging a portion of conductor 11 (positioned between radially outer end 11a and radially inner end 11b) with a portion of seat 3 or a machine component disposed within seat 3 (e.g., a spring, pin, etc.).
[0018] Preferably, the conductor 11 includes: a conductive carrier 14 coupled to the insulator 12; and a brush subassembly 16 coupled to the carrier 14 and having a plurality of conductive fibers 18 that can contact the shaft 2, the carrier 14 and the brush subassembly forming the conductor 11. The conductive carrier 14 has a centerline 14a and includes a cylindrical portion 20 and a disk portion 22, the cylindrical portion 20 being arranged around the outer ring 5 of the bearing, the disk portion 22 extending radially inward from the cylindrical portion 20 to be axially adjacent to the inner ring 4 and the outer ring 5 of the bearing. The cylindrical portion 20 of the carrier has a circumferential inner surface 21A disposed about the insulator outer surface 13B such that the insulator 12 is encased by the conductor 11, and a circumferential outer surface 21B displaceable against the seat inner surface 3a, preferably frictionally engageable, to axially secure the bearing 1 relative to the seat 3. The circumferential outer surface 21B of the carrier is also "conductively engageable" (i.e., engageable to permit current flow) with the seat inner surface 3a to provide a portion of an electrically conductive path from the shaft 2 to the seat 3. In addition, the disc portion 22 has a radially outer end 22a formed integrally with the cylindrical portion 20, and a radially inner end 22b spaced radially outwardly from the shaft 2 and defining a central opening 23 for receiving a portion of the shaft 2. Figure 2 ).
[0019] Furthermore, an annular conductive brush assembly 16 is coupled to the carrier disk portion 22 and includes a centerline 16a, with a plurality of conductive fibers 18 spaced circumferentially about the centerline 16a. The conductive fibers 18 are preferably formed of carbon and extend radially inward from an inner end 22b of the carrier disk portion 22. Each conductive fiber 18 has an inner end 18a that can contact the outer surface 2a of the shaft to provide a conductive path between the shaft 2 and the carrier 14. Because the carrier 14 is configured to provide a conductive path between the brush assembly 16 and the seat 3, any current or charge on the shaft 2 is directed through the assembly 10 rather than through the bearing 1. Thus, the assembly 10, which combines an insulator and a conductor, serves to protect the bearing 1 by preventing direct current from flowing through the bearing 1 (i.e., due to the insulator 12) and by providing an alternative path for current near the bearing 1 via the brush assembly 16 and the conductive carrier 14. Having described the primary structure and function above, these and other components of the assembly are discussed in detail below.
[0020] Now refer to Figure 4 、 Figure 5 and Figure 7 The insulator 12 preferably includes a main cylindrical body 26 and an end ring 28 connected to the cylindrical body 26. The cylindrical body 26 provides the insulator inner surface 13A and the insulator outer surface 13B, and has opposing first and second axial ends 26a and 26b. A flange 27 extends radially inward from the main body first axial end 26a and can be arranged between the first axial end 5a of the outer ring 5 of the bearing and the disk portion 22 of the carrier 14 to prevent current flowing through the carrier 14 from flowing into the outer ring 5. The end ring 28 can be arranged against the second axial end 5b of the outer ring 5 of the bearing to insulate the end 5b from the seat 3 or another machine component (not depicted) arranged in the seat 3.
[0021] Preferably, if Figure 4 and Figure 5 As best shown in FIG, the cylindrical body 26 has an annular groove 29 adjacent the second axial end 26b, and the end ring 28 has an annular protrusion 30 disposed within the annular groove 29 to couple the end ring 28 to the cylindrical body 26. Alternatively, as Figure 7As depicted, the insulator 12 can be formed without the grooves and protrusions, wherein the carrier cylindrical portion 20 is configured to retain the insulator end ring 28 coupled to the insulator cylindrical body 26, particularly by forming or "deforming" the cylindrical portion 20 tightly around the two components 26, 28. Furthermore, the insulator cylindrical body 26 is preferably formed of aluminum having at least one anodized layer, and the end ring 28 is preferably formed of a rigid polymeric material (e.g., nylon, PVC, etc.). However, the cylindrical body 26 or the end ring 28 may be formed of any other suitable material capable of preventing the flow of electrical current.
[0022] Now refer to Figure 1 、 Figure 4 、 Figure 6 and Figure 7 The cylindrical portion 20 of the conductive carrier 14 is preferably formed from a relatively thin circular shell 32 having opposed first and second axial ends 32a, 32b, the first axial end 32a being integrally formed with the outer end 22a of the plate portion (as described above), and the second end 32b being disposed about the end ring 28. The carrier disc portion 22 is preferably formed as a relatively thin circular plate 34, with the two portions 20, 22 preferably being formed as a one-piece stamping. Furthermore, the disc portion 22 has opposed first and second end surfaces 35A, 35B extending radially between the radially inner end 22b and the radially outer end 22a, the brush assembly 16 being connected to the first end surface 35A, and the second end surface 35B being disposed against the insulator flange 27. In addition, the carrier pan portion 22 preferably includes a plurality of mounting tabs 36 spaced circumferentially about the carrier centerline 14 a, each mounting tab 36 engaging the brush assembly 16 to couple the subassembly 16 to the carrier 14 .
[0023] Preferably, each mounting tab 36 is formed by cutting (e.g., by die punching) through the disk portion 22 to form a rectangular tab 36 and a clearance opening 38 that is bent around a retaining member 40 (described below) of the brush assembly 16 such that each mounting tab 36 is generally C-shaped. The clearance opening 38 provides a passage for a fluid (e.g., lubricant, air, etc.) to flow through the carrier 14 and thereby through the bearing 1 or from the bearing 1 through the carrier 14. Furthermore, the carrier 14 is preferably formed of a metallic material, most preferably aluminum, but may be formed of any other metallic material (e.g., steel), a conductive polymer, etc.
[0024] Now refer to Figure 1 、 Figure 4 as well as Figures 6 to 9 , the conductive brush assembly 16 preferably includes an annular retainer 40 that is connected to the carrier 14 (described above) and has an open radial inner end 40a and a closed outer end 40b, the radial inner end 40a having an annular groove 42. Each of the plurality of conductive fibers 18 has a radial outer end 18b disposed within the groove 42 and extends radially inward from the retainer 40 toward the shaft 2. More specifically, the retainer 40 has an axial outer base 44 and two opposing radial legs 46, so that the retainer 40 generally has a C-shaped axial cross-section. The retainer legs 46 preferably clamp the outer ends 18b of the conductive fibers 18 to retain the fibers 18 within the groove 42.
[0025] In addition, the brush assembly 16 preferably includes a circular hoop 48 disposed within the holder slot 42, and each of the plurality of conductive fibers 18 is bent around the hoop 48. Thus, each conductive fiber 18 is preferably generally U-shaped or V-shaped and has two inner ends 18a that can contact the outer surface 2a of the shaft. However, each of the conductive fibers 18 can be configured as a generally straight strand (not shown) extending from a radially outer end 18b to a radially inner end 18a.
[0026] Furthermore, the plurality of conductive fibers 18 of the brush assembly 16 are configured as a generally continuous loop of fibers (not shown), or preferably as a plurality of discrete groups 19 of circumferentially spaced fibers 18 (e.g., Figure 1 and Figure 9In the latter preferred embodiment, the groups 19 of fibers 18 are preferably formed by die-cutting a brush assembly 16 comprising a continuous loop of fibers 18, such that the groups 19 of fibers that can contact the shaft 2 are separated by groups 21 of shorter lengths of fibers 18. In addition, the size of each conductive fiber 18 preferably has a diameter in the range of five micrometers (5 μm) to one hundred micrometers (100 μm). Although, as discussed above, each conductive fiber 18 is preferably formed of carbon, alternatively, the fibers 18 may be made of any suitable conductive material, such as a metallic material, a conductive polymer, etc.
[0027] Although conductor 11 preferably includes carrier 14 and brush assembly 16 as described above and depicted in the accompanying drawings, conductor 11 may alternatively be formed in any other suitable manner that is both coupled to insulator 12 and capable of providing one or more conductive paths between shaft 2 and seat 3. For example, conductor 11 may include a solid ring (not shown) of conductive material (instead of brush assembly 16) attached to carrier 14 and conductively engageable with shaft 2, the ring having a continuous inner circumferential contact surface or a plurality of arcuate contact surface sections provided by radially inwardly extending protrusions. As another alternative, disk portion 22 of conductive carrier 14 may be formed to have an inner end portion 22b that is contactable with outer surface 2a of the shaft to provide a direct conductive path between shaft 2 and disk portion 22. The scope of the present invention includes these and all other suitable configurations of conductor 11 capable of functioning as generally described herein.
[0028] Before assembling the bearing 1 into the seat 3, the insulator and conductor assembly 10 is mounted on the bearing 1 as follows. The insulator 12 is mounted on the outer ring 5 of the bearing by inserting the ring first axial end 5a into the second axial end 26b of the cylindrical body 26 and sliding the inner surface 13A of the body 26 over the ring outer surface 5c until the flange 27 is arranged against the ring first axial end 5a. The end ring 28 is then positioned on the second axial end 5b of the outer ring 5 of the bearing and, in some embodiments, the ring protrusion 30 is inserted into the groove 29 of the cylindrical body 26 to couple the ring 28 to the body 26 (e.g., Figure 5 Next, the conductive carrier 14 of the conductor 11, with the brush assembly 16 pre-mounted thereon, is coupled to the insulator 12 by inserting the first axial end 26a of the insulator into the second axial end 32b of the carrier cylindrical portion 20 and sliding the inner surface 21A of the carrier cylindrical portion 20 over the insulator outer surface 13B until the carrier disc portion 22 is positioned against the insulator flange 27. At this point, the bearing 1 with the insulator and conductor assembly 10 can be mounted on the shaft 2 and within the seat 3.
[0029] Compared to previously known arrangements, the insulator / conductor assembly 10 of the present invention is more effective in protecting the bearing 1 from damage caused by electrical current. The insulator 12 effectively prevents a voltage differential from developing between the shaft 2 and the seat 3 through the bearing 1, thereby preventing current from flowing through the inner and outer races 4 and 5 and the rolling elements 6. To further ensure that current does not flow through the bearing 1, the conductive bearing 14 and brush assembly 16 provide an alternative path for any charge or current on the shaft 2 to pass through the conductive fibers 18 to the retainer 40, through the retainer 40 and into the bearing disc portion 22, then through the bearing cylindrical portion 20 and into the seat 3. This additional or alternative conductive path into the seat 3 can be provided by axial contact between a portion of the seat 3 (e.g., a radial shoulder) or a component of a machine disposed within the seat 3 (e.g., a spring, pin, etc.) and a surface of the bearing disc portion 22 (e.g., radial end surface 35A, tab 36, etc.) or / and a surface of the annular retainer 40. Thus, any charge or current on the shaft 2 in the area of the bearing 1 is not only prevented from passing through the bearing 1 by the insulator 12, but is also shunted to flow through the brush assembly 16 and the conductive carrier 14 of the conductor 11. Furthermore, the assembly 10 can be mounted on the bearing 1 by the manufacturer or distributor so that the bearing 1 with the assembly 10 combined with the insulator and conductor can be provided to the customer or end user as a complete assembly ready for installation on the shaft 2 and within the seat 3.
[0030] Those skilled in the art will appreciate that changes may be made to the above-described embodiments without departing from the broad inventive concept thereof. It should therefore be understood that the present invention is not limited to the particular embodiments disclosed, but is intended to cover modifications within the spirit and scope of the invention as generally defined in the appended claims.
Claims
1. An assembly of a combined insulator and conductor for a bearing arrangeable between a shaft and a seat, the bearing having an inner ring, an outer ring with opposite first and second axial ends, and a plurality of rolling elements located between the rings, the shaft having a circumferential outer surface and the seat having a circumferential inner surface, the assembly comprising: an annular insulator displaceable about an outer race of the bearing and configured to prevent current from flowing between the outer race and the seat; as well as an annular conductor having a radially outer end portion disposed at least partially around the insulator and engageable with the inner surface of the seat, and a radially inner end portion engageable with the outer surface of the shaft such that a conductive path is provided between the shaft and the seat through the radially inner and outer ends of the conductor, The conductor includes: a conductive carrier having a cylindrical portion providing a radially outer end portion of the conductor and a disk portion extending radially inward from the cylindrical portion; and an annular conductive brush assembly connected to the disk portion of the carrier.
2. The assembly according to claim 1, characterized in that The insulator has a circumferential inner surface and a circumferential outer surface, and the insulator is formed of an electrically insulating material or has an insulating layer provided on at least one of the inner surface and the outer surface.
3. The assembly according to claim 1, characterized in that The insulator comprises: a cylindrical body having opposite first and second axial ends and a flange extending radially inwardly from the first axial end so as to be arrangeable between the first axial end of the outer ring of the bearing and the disk portion of the carrier; and An end ring is connected to the second axial end of the cylindrical body and can be placed against the second axial end of the outer ring of the bearing.
4. The assembly according to claim 3, characterized in that The cylindrical body has an annular groove adjacent to the second axial end, and the end ring has an annular protrusion disposed within the annular groove to couple the end ring to the cylindrical body.
5. The assembly according to claim 1, characterized in that the cylindrical portion having a circumferential inner surface and a circumferential outer surface, the circumferential inner surface of the cylindrical portion being disposed about the outer surface of the insulator, the circumferential outer surface of the cylindrical portion being displaceable against and conductively engageable with the inner surface of the seat, the disk portion being axially adjacent the inner and outer races of the bearing, the disk portion having a radially inner end portion spaced radially outwardly from the shaft and defining a central opening for receiving a portion of the shaft, The annular conductive brush assembly includes a centerline and a plurality of conductive fibers circumferentially spaced about the centerline and extending radially inward from an inner end of the disk portion of the carrier, each conductive fiber having an inner end capable of contacting an outer surface of the shaft so as to provide a conductive path between the shaft and the carrier.
6. The assembly according to claim 1 or 5, characterized in that The carrier has a centerline, and the disc portion of the carrier includes a plurality of mounting tabs spaced circumferentially about the carrier centerline, each mounting tab engaging the brush assembly to couple the subassembly to the carrier.
7. The assembly according to claim 1 or 5, characterized in that The cylindrical portion of the carrier is formed from a relatively thin shell having a circumferential outer surface which is frictionally engageable with the inner surface of the seat to retain the bearing axially within the seat.
8. The assembly according to claim 1 or 5, characterized in that The cylindrical portion of the carrier is configured to retain an end ring of the insulator coupled to the cylindrical body of the insulator.
9. The assembly according to claim 5, characterized in that The conductive brush assembly includes an annular holder connected to the carrier and having a radially inner end with an annular groove, each of the plurality of conductive fibers having a radially outer end disposed within the groove and extending radially inward from the holder and toward the shaft.
10. The assembly according to claim 5, characterized in that At least one of the following: The brush assembly further includes a circular hoop disposed within the holder, and each of the plurality of conductive fibers is bent about the hoop such that each fiber has two ends capable of contacting the outer surface of the shaft; and The plurality of conductive fibers of the brush assembly are arranged in a plurality of circumferentially spaced discrete fiber groups.
Citation Information
Patent Citations
Method and system for reducing bearing fluting in electromechanical machine
US20030086630A1