Internally diverted ground brush assembly with axial brush and centering bearing
By forming a conductive path in the electric motor through conductive base components and conductive brush assemblies, the problem of damage caused by current passing through the bearing is solved, thus protecting the bearing and reducing friction and wear.
Patent Information
- Application Number
- CN202510916235.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-10-24
- Filing Date
- 2025-07-03
- Publication Date
- 2026-01-13
AI Technical Summary
In electric motors, when charge accumulates on the shaft and enters the housing through the bearing, it can cause bearing damage. Existing grounding brush assemblies may not be able to effectively shunt current, leading to damage to rolling elements and raceways.
The system employs a conductive base component and a conductive brush assembly. The conductive base component includes a cylindrical body and a centering bearing. Conductive fibers extend radially outward from the outer surface of the base component and engage with the rotating shaft to form a conductive path, diverting current from the bearing to the fixed shaft and preventing current from passing through the bearing.
It effectively avoids damage to the bearing rolling elements and raceways, while strengthening and preventing vibration of the fixed shaft and reducing friction and wear of the conductive fibers.
Smart Images
Figure CN121332243A_ABST
Abstract
Description
[0001] Citation of relevant applications
[0002] This application claims priority to Italian patent application No. 102024000016090, filed on July 11, 2024, the contents of which are incorporated herein by reference in their entirety. Technical Field
[0003] The present invention relates to a grounding device for bearings, and more particularly to a grounding brush assembly for shunting current away from the bearing. Background Technology
[0004] In electric machinery (such as electric motors, generators, etc.), the machine typically includes a shaft rotatable about a central axis, an outer housing, and at least one bearing connecting the shaft to the housing. This bearing typically includes an inner ring mounted on the rotatable shaft, an outer ring arranged around the inner ring and engaging the housing, and multiple rolling elements arranged between the inner and outer rings. During operation, electrical charge may accumulate on the shaft, potentially generating currents that flow from the shaft through the bearing and into the housing. These currents can damage the raceways of the inner and outer rings, as well as the rolling elements.
[0005] To prevent damage to bearings, a grounding brush assembly is known to provide a conductive path between the shaft and the housing to shunt current away from bearing(s). Such a grounding brush assembly typically includes a bracket or holder connected to the housing and a brush attached to the bracket / holder, comprising multiple conductive fibers extending radially inward from the holder and contacting an outer surface of the shaft or a sleeve or other component mounted on the shaft. Alternatively, the holder may be mounted on the shaft and have multiple radially outward-pointing fibers engaging an inner circumferential surface of the housing. Summary of the Invention
[0006] In one aspect, the invention provides a grounding brush assembly for an electric machine, the electric machine including a rotatable shaft, an outer housing, at least one bearing rotatably connecting the shaft to the housing, and a fixed shaft. The rotatable shaft is rotatable about a central axis and has an inner circumferential surface defining a hollow hole. The fixed shaft extends through the hole of the rotatable shaft and is electrically grounded. The grounding brush assembly includes a conductive base member comprising a cylindrical body having a hole sized to receive a portion of the fixed shaft and a centerline coaxially alignable with the central axis. The cylindrical body has a main body portion and at least one end body portion. The main body portion has an outer circumferential surface and a first outer diameter, and the at least one end body portion has a second outer diameter, the value of which is smaller than the value of the first outer diameter. At least one centering bearing includes an inner ring and an outer ring, the inner ring being arranged around at least one end body portion of the cylindrical body of the base member, and the outer ring being capable of engaging the inner circumferential surface of the rotatable shaft to center the rotatable shaft about the fixed shaft. At least one conductive brush is coupled to the conductive base member and includes multiple conductive fibers extending radially outward from the outer surface of the main body portion of the base member and axially along the centerline. Each conductive fiber has an inner radial end coupled to the base member and an outer radial end capable of engaging the inner circumferential surface of the rotatable shaft, such that at least one conductive path extends from the rotatable shaft, through the brush and the base member, and reaches the fixed shaft.
[0007] Preferably, the main body portion of the cylindrical body has a first axial end and an opposing second axial end, and at least one end body portion of the cylindrical body includes a first end body portion extending axially from the first axial end of the main body portion and a second end body portion extending axially from the second axial end of the main body portion. In this configuration, the at least one centering bearing includes a first centering bearing and a second centering bearing, the first centering bearing being arranged around the first end body portion of the cylindrical body of the base member, and the second centering bearing being arranged around the second end body portion of the cylindrical body of the base member.
[0008] Furthermore, the main body portion of the cylindrical body of the base member preferably has at least one axial groove, which extends radially inward from the outer circumferential surface of the main body portion and extends axially between a first axial end and a second axial end of the main body portion. The inner end of each of the plurality of conductive fibers is disposed within the at least one axial groove, and the plurality of conductive fibers are spaced apart axially along the at least one axial groove. Preferably, the at least one conductive brush comprises a plurality of conductive brushes, each of which is disposed within a separate one of the plurality of axial grooves in the main body portion of the cylindrical body. Attached Figure Description
[0009] The foregoing description of the invention and its preferred embodiments will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the invention, currently preferred illustrative embodiments are shown in the drawings. However, it should be understood that the invention is not limited to the precise configurations and means shown. In the drawings:
[0010] Figure 1 This is an axial cross-sectional view of an electric machine including the grounding brush assembly according to the present invention;
[0011] Figure 2 This is an axial cross-sectional view of a grounding brush assembly. The grounding brush assembly has a base component, which has two end body parts and two centering bearings.
[0012] Figure 3 This is an axial cross-sectional view of a grounding brush assembly, which has a base member, a single end body portion, and a centering bearing; and
[0013] Figure 4 It is a perspective view of a base component with a single end body portion. Detailed Implementation
[0014] The use of certain terms in the following description is for convenience only and not as a limitation. The terms “inner,” “inward,” and “outer,” “outward,” respectively refer to directions toward and away from the specified centerline or geometric center of the described element, their specific meanings readily understood from the context of the description. Furthermore, as used herein, the terms “connection” and “linkage” are each intended to include a direct connection between two components without any other component between them, and an indirect connection between components with one or more other components between them. Terms include those specifically mentioned above, their derivatives, and terms with similar meanings.
[0015] Now refer to the accompanying drawings for details, in which the same numbers are always used to indicate the same elements. Figures 1 to 4 The image shows a grounding brush assembly 10 for an electric motor 1. The electric motor 1 includes a shaft 2, a housing 4, at least one bearing 5 rotatably connecting the shaft 2 to the housing 4, and a fixed shaft 6, the shaft 2 being rotatable about a central axis A. C The rotating shaft 6 extends through the hole 3 of the rotatable shaft 2 and is electrically grounded. The grounding brush assembly 10 basically includes a conductive base member 12, at least one conductive brush 14 connected to the base member 12 and having multiple conductive fibers 40, and at least one centering bearing 18 arranged around the end portion 28 of the base member 12.
[0016] More specifically, the base member 12 includes a cylindrical body 22 having an inner circumferential surface 24 defining a hole 25 sized to receive a portion of the fixed shaft 6 and capable of being aligned with the central axis A. C Centerline L aligned coaxially C Preferably, the grounding brush assembly 10 is mounted to the fixed shaft 6 via a frictional fit between the inner surface 24 of the cylindrical body 22 and the outer circumferential surface (not shown) of the shaft 6. Furthermore, as... Figure 2 As indicated, the cylindrical body 22 includes a main body portion 26 and at least one end body portion 28. The main body portion 26 has an outer circumferential surface 27 and a first outer diameter D1, and the at least one end body portion 28 has a second outer diameter D2, the value of which is smaller than the value of the first outer diameter D1. Therefore, the at least one end body portion 28 is stepped inward relative to the main body portion 26. Furthermore, the cylindrical body 22 is formed of a conductive material (such as steel, aluminum, a conductive polymer, or any other suitable conductive material).
[0017] At least one centering bearing 18 includes an inner ring 30 and an outer ring 32, and preferably includes a plurality of rolling elements 34 arranged between the inner ring 30 and the outer ring 32. The inner ring 30 is arranged around at least one end body portion 28 of the cylindrical body 22 of the base member 12, and the outer ring 32 is capable of engaging the inner circumferential surface 2a of the rotatable shaft 2. At least one centering bearing 18 is used to connect the rotatable shaft 2 to the fixed shaft 6, such that the centering bearing(s) 18 reinforces and prevents vibration of the fixed shaft 6, and does not provide a load for supporting the two shafts 2, 6.
[0018] Furthermore, at least one conductive brush 14 includes a plurality of conductive fibers 40, which extend radially outward from the outer surface 27 of the main body portion 26 of the base member 12 and axially along the centerline L. C Extended, and as an alternative, multiple conductive fibers 40 are axially aligned along the centerline L. C And around the center line L in the circumferential direction C Extension. Each conductive fiber 40 has an inner radial end 40a that connects to the main body portion 26 of the base member 12 and an outer radial end 40b that can engage with the inner circumferential surface 2a of the rotatable shaft 2.
[0019] Therefore, at least one conductive path extends from the rotatable shaft 2, through the brush 14 and the base member 12, and reaches the fixed shaft 6. Using this grounding brush assembly 10, any charge accumulated on the rotatable shaft 2 flows as current through the assembly 10, rather than through the bearing(s) 5 of the electric machine 1. This avoids damage to the rolling elements and raceways (not indicated) of the bearings 5, while simultaneously strengthening and preventing vibration of the fixed shaft 6 by the centering bearing(s) 18. The basic elements and functions have been described above; these and other components of this grounding brush assembly 10 are further described in detail below.
[0020] Reference Figures 2 to 4 The main body portion 26 has a first axial end 26a and an opposing second axial end 26b, and preferably includes at least one axial groove 50 extending radially inward from the outer surface 27 of the main body portion 26. The at least one groove 50 extends axially between the first axial end 26a and the second axial end 26b of the main body portion 26. Furthermore, the inner end 40a of each of a plurality of conductive fibers 40 is disposed within the at least one axial groove 50, and the plurality of conductive fibers 40 are spaced apart along the at least one axial groove 40. Preferably, the at least one axial groove 50 includes a plurality of axial grooves 50, each axial groove 50 extending axially between the first end 26a and the second end 26b of the main body portion 26 and circumferentially around a centerline L. CSpacing apart. Alternatively, the main body portion 26 may include only a single spiral groove (not depicted), formed in the outer surface 27 of the main body portion 26 and extending axially between the first axial end 26a and the second axial end 26b and circumferentially around the centerline L. C extend.
[0021] like Figure 2 As depicted, the cylindrical body 22 preferably includes two end body portions 28, specifically a first end body portion 29A extending axially from a first axial end portion 26a of the main body portion 26a and a second end body portion 29B extending axially from a second axial end portion 26b of the main body portion 26. Using this body structure, at least one centering bearing 18 includes a first centering bearing 19A arranged around the first end body portion 29A of the cylindrical body 22 and a second centering bearing 19B arranged around the second end body portion 19A of the cylindrical body 22.
[0022] Especially referencing Figure 4 At least one conductive brush 14 preferably comprises a plurality of conductive brushes 14, each of which is arranged in a separate axial groove 50 in the main body portion 26 of the cylindrical body 22. Each brush 14 preferably includes a retainer 60 having a base wall 62 and two spaced-apart sidewalls 64, 66 extending from the base wall 62 to define an axial channel 61. A plurality of conductive fibers 40 of each brush 14 are arranged between and engaged by the two sidewalls 64, 66 to retain the conductive fibers 40 within the axial channel 61. Preferably, the retainer 40 is formed of a conductive material (such as steel, aluminum, conductive polymer, etc.), and each conductive fiber 40 is a stranded conductive material (preferably carbon, but may also be formed of steel, aluminum, conductive polymer, etc.).
[0023] In a preferred cylindrical body 22 having two end body portions 29A, 29B and two centering bearings 19A, 19B, each brush 14 is held within an associated axial groove 50 of the main body portion 26 by the two bearings 19A, 19B. However, as Figure 3As depicted, the cylindrical body 22 may have only a single end body portion 28 extending from the first axial end portion 26a of the main body portion 26. In this case, the conductive base member 12 further includes an annular retainer clip 70 that engages with the second axial end portion 26b of the main body portion 26. The retainer clip 70 is configured to retain each brush 14 disposed within an associated axial groove 50 of the main body portion 26 of the cylindrical body 22. Preferably, the cylindrical body 22 has an annular groove 72 positioned adjacent to the second axial end portion 26b of the main body portion 26, and the retainer clip 70 is a C-shaped clip disposed within the annular groove 72 and against the axial end portion (not indicated) of each brush 14.
[0024] Using the grounding brush assembly 10 of the present invention, the conductive fiber 40 contacts the inner surface 2a of the rotating shaft 2, and the magnitude of the linear velocity (i.e., tangential to surface 2a) of the inner surface 2a is less than the magnitude of the linear velocity at the outer surface 2b of the shaft 2. Therefore, compared with known grounding brush assemblies in which the conductive fiber contacts the outer surface of the rotating shaft, the friction and wear of the conductive fiber 40 are reduced.
[0025] Representative, non-limiting examples of the invention have been described in detail above with reference to the accompanying drawings. This detailed description is intended only to teach those skilled in the art further details for practicing the preferred aspects of this teaching, and is not intended to limit the scope of the invention.
[0026] Furthermore, the combinations of features and steps disclosed in the detailed description above may not be necessary for practicing the invention in the broadest sense, but are merely representative examples taught to specifically describe the invention. Moreover, the aforementioned representative examples, along with the features of the appended independent and dependent claims, can be combined in ways not specifically and explicitly enumerated to provide other useful embodiments of this teaching.
[0027] For the purposes of the original written disclosure and for the purpose of limiting the claimed subject matter, all features disclosed in the specification and / or claims are intended to be disclosed individually and independently of each other, without dependence on combinations of features in the embodiments and / or claims. Furthermore, for the purposes of the original written disclosure and for the purpose of limiting the claimed subject matter, all value ranges or indications for entity groups are intended to disclose every possible intermediate value or intermediate entity. The invention is not limited to the embodiments described above and may vary within the scope of the appended claims.
Claims
1. A grounding brush assembly for an electric motor, the electric motor including a rotatable shaft, a housing, at least one bearing rotatably connecting the shaft to the housing, and a fixed shaft, the rotatable shaft being rotatable about a central axis and having an inner circumferential surface defining a hollow hole, the fixed shaft extending through the hole of the rotatable shaft and electrically grounded, the grounding brush assembly comprising: A conductive base component includes a cylindrical body having a hole sized to receive a portion of the fixed shaft and a centerline capable of being coaxially aligned with the central axis. The cylindrical body has a main body portion and at least one end body portion. The main body portion has an outer circumferential surface and a first outer diameter, and the at least one end body portion has a second outer diameter, the value of which is smaller than the value of the first outer diameter. At least one centering bearing, comprising an inner ring and an outer ring, the inner ring being arranged around at least one end body portion of a cylindrical body of the base member, the outer ring being capable of engaging an inner circumferential surface of the rotatable shaft to center the rotatable shaft about the fixed shaft; and At least one conductive brush is coupled to the conductive base member and includes a plurality of conductive fibers extending radially outward from the outer surface of the main body portion of the base member and axially along the centerline. Each conductive fiber has an inner radial end coupled to the base member and an outer radial end capable of engaging the inner circumferential surface of the rotatable shaft, such that at least one conductive path extends from the rotatable shaft, through the brush and the base member, and reaches the fixed shaft.
2. The grounding brush assembly according to claim 1, characterized in that: The main body portion of the cylindrical body has a first axial end and an opposing second axial end, and at least one end body portion of the cylindrical body includes a first end body portion extending axially from the first axial end of the main body portion and a second end body portion extending axially from the second axial end of the main body portion; and The at least one centering bearing includes a first centering bearing and a second centering bearing, the first centering bearing being arranged around a first end body portion of the cylindrical body of the base member, and the second centering bearing being arranged around a second end body portion of the cylindrical body of the base member.
3. The grounding brush assembly according to claim 1, characterized in that, The main body portion of the cylindrical body of the base member has at least one axial groove, the at least one axial groove extending radially inward from the outer peripheral surface of the main body portion and extending axially between a first axial end and a second axial end of the main body portion, the inner end of each of the plurality of conductive fibers being disposed within the at least one axial groove, and the plurality of conductive fibers being axially spaced along the at least one axial groove.
4. The grounding brush assembly according to claim 3, characterized in that: At least one axial groove in the main body portion of the cylindrical body includes a plurality of axial grooves, each axial groove extending axially between a first end and a second end of the main body portion and spaced circumferentially around the centerline of the base member; and The at least one conductive brush includes a plurality of conductive brushes, each of which is arranged in a separate axial groove in the main body portion of the cylindrical body.
5. The grounding brush assembly according to claim 3, characterized in that, The at least one conductive brush includes a retainer having a base wall and two spaced-apart sidewalls extending from the base wall to define an axial channel, wherein the plurality of conductive fibers are arranged between and joined by the two sidewalls to retain the conductive fibers within the axial channel.
6. The grounding brush assembly according to claim 3, characterized in that: The main body portion of the cylindrical body of the conductive base component has a first axial end and an opposing second axial end, wherein at least one end body portion extends axially from the first axial end; and The conductive base component further includes a retaining clip that engages with a second axial end of the main body portion and is configured to retain at least one conductive brush disposed within an axial groove of the main body portion of the cylindrical body.
7. The grounding brush assembly according to claim 6, characterized in that, The cylindrical body has an annular groove positioned adjacent to a second axial end of the main body portion, and the retaining clip is a C-shaped clip arranged within the annular groove and capable of abutting against the axial end of the at least one conductive brush.
8. A grounding brush assembly for an electric machine, the electric machine including a rotatable shaft, a housing, at least one bearing rotatably connecting the shaft to the housing, and a fixed shaft, the rotatable shaft being rotatable about a central axis and having an inner circumferential surface defining a hollow hole, the fixed shaft extending through the hole of the rotatable shaft and electrically grounded, the grounding brush assembly comprising: A conductive base component includes a cylindrical body having a hole sized to receive a portion of the fixed shaft and a centerline capable of being coaxially aligned with the central axis. The cylindrical body has a main body portion and at least one end body portion. The main body portion has an outer circumferential surface and a first outer diameter, and the at least one end body portion has a second outer diameter, the value of which is smaller than the value of the first outer diameter. At least one centering bearing, comprising an inner ring and an outer ring, the inner ring being arranged around at least one end body portion of a cylindrical body of the base member, the outer ring being capable of engaging an inner circumferential surface of the rotatable shaft to center the rotatable shaft about the fixed shaft; and A plurality of conductive brushes are each connected to a main body portion of the conductive base member and spaced circumferentially around the centerline. Each of the plurality of conductive brushes includes a plurality of conductive fibers extending radially outward from the outer surface of the main body portion of the base member and axially along the centerline. Each conductive fiber has an inner radial end that connects to the cylindrical body of the base member and an outer radial end that engages with the inner circumferential surface of the rotatable shaft, such that at least one conductive path extends from the rotatable shaft, through each of the plurality of brushes and the base member, and reaches the fixed shaft.
9. The grounding brush assembly according to claim 8, characterized in that: The main body portion of the cylindrical body has a first axial end and an opposing second axial end, and at least one end body portion of the cylindrical body includes a first end body portion extending axially from the first axial end of the main body portion and a second end body portion extending axially from the second axial end of the main body portion; and The at least one centering bearing includes a first centering bearing and a second centering bearing, the first centering bearing being arranged around a first end body portion of the cylindrical body of the base member, and the second centering bearing being arranged around a second end body portion of the cylindrical body of the base member.
10. The grounding brush assembly according to claim 8, characterized in that, The main body portion of the cylindrical body of the base member has a plurality of axial grooves spaced apart circumferentially around the center line. Each axial groove extends radially inward from the outer circumferential surface of the main body portion and extends axially between a first axial end and a second axial end of the main body portion. The inner radial ends of a plurality of conductive fibers of each of the plurality of brushes are arranged in a single axial groove and spaced apart axially along the single axial groove.
11. The grounding brush assembly according to claim 8, characterized in that, Each of the plurality of conductive brushes includes a retainer having a base wall and two spaced-apart sidewalls extending from the base wall to define an axial channel, wherein the plurality of conductive fibers are arranged between and joined by the two sidewalls to retain the conductive fibers within the axial channel.
12. The grounding brush assembly according to claim 8, characterized in that: The main body portion of the cylindrical body of the conductive base component has a first axial end and an opposing second axial end, wherein at least one end body portion extends axially from the first axial end; and The conductive base component further includes a retaining clip that engages with a second axial end of the main body portion and is configured to retain at least one conductive brush disposed within an axial groove of the main body portion of the cylindrical body.
13. The grounding brush assembly according to claim 12, characterized in that, The cylindrical body has an annular groove positioned adjacent to a second axial end of the main body portion, and the retaining clip is a C-shaped clip arranged within the annular groove and capable of abutting against the axial end of the at least one conductive brush.