Grounding brush assembly
By designing a ground brush assembly with conductive fibers and retaining hooks in the electric motor, the current damage and vibration caused by the potential difference between the rotating shaft and the shell is solved, and a more stable grounding effect is achieved.
Patent Information
- Application Number
- CN202410843205.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-06-30
- Filing Date
- 2024-06-27
- Publication Date
- 2024-12-31
AI Technical Summary
In electric motors or electric machines, the potential difference between the rotating shaft and the housing causes current damage and discharge between the inner and outer rings of the rolling bearings, resulting in vibration, and existing ground brush assemblies are insufficient in installation and support.
A ground brush assembly including conductive fibers is designed, and its support member interacts with the mounting plate through the mounting part and the retaining hook to achieve axial firm fixation, ensuring stable contact between the conductive fibers and the shaft and the mounting plate, and reducing discharge.
Through the design of this component, current damage and discharge between rolling bearings is reduced, stability and firmness of the ground brush are improved, and vibration risks are reduced.
Smart Images
Figure CN119231267A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of grounding devices for controlling shaft voltage generated in electric motors or machines, and in particular to grounding brush assemblies. Background Art
[0002] In an electric motor or an electric machine, at least one rolling bearing is installed between a casing of the electric motor or the electric machine and a rotating shaft to support the shaft.
[0003] During operation, when the shaft rotates, a potential difference may exist between the shaft and the housing of the electric motor or electric machine, which causes an electric current to flow between the inner ring of the rolling bearing (rigidly fixed to the shaft) and the outer ring (rigidly fixed to the housing).
[0004] The current flowing through the components of the rolling bearing may damage the components, particularly the rolling elements and the raceways formed on the inner and outer rings. The discharge may also generate vibrations.
[0005] To overcome these drawbacks, it is known practice to use a grounding brush comprising conductive fibers to ground or connect the rotating shaft to ground or earth. The grounding brush is usually mounted in a hole in the housing of the electric motor so that the free end of the fibers is in radial contact with the outer surface of the rotating shaft.
[0006] Due to the conductivity of the fibers, the brushes are kept at the same electrical potential as the housing of the electric motor. The inner and outer rings of the rolling bearing are also at the same electrical potential, which reduces or even eliminates problematic discharges through the rolling bearing.
[0007] US-A1-2021 / 0021180 discloses a grounding brush assembly, which includes: a grounding brush provided with a support and a plurality of conductive fibers installed in the support; and an annular mounting plate provided with a plurality of tabs and an annular outer flange, wherein the plurality of tabs are used to radially and axially hold the support of the grounding brush, and the annular outer flange radially surrounds the brush and the tabs. The tabs are formed by plastic deformation of the mounting plate.
[0008] The present invention seeks to provide an alternative attachment for attaching a grounding brush to a mounting plate. Summary of the invention
[0009] The invention relates to an assembled grounding brush assembly, which comprises a grounding brush and a mounting plate for the brush, wherein the brush is provided with a plurality of conductive fibers and a support, wherein the conductive fibers are accommodated in the support.
[0010] The support member comprises a mounting portion, a first lateral rim extending from the mounting portion on one side and a second lateral rim extending from the mounting portion on the other side, the first lateral rim and the second lateral rim gripping the conductive fiber in an axial direction.
[0011] According to the overall characteristics of the present invention, the brush support also includes at least one retaining portion, which extends from the first lateral edge and is provided with a mounting portion and at least one retaining hook, the mounting portion extends in the hole of the mounting plate, and the at least one retaining hook extends radially outward from the mounting portion and is capable of interacting with the mounting plate to axially retain the brush support relative to the mounting plate, and the retaining hook is axially located on the side opposite to the first lateral edge relative to the mounting plate.
[0012] Thus, the brush and the mounting plate are simply and inexpensively fixed together axially rigidly by means of the hook or hooks of the brush support.
[0013] The mounting plate may be provided with a main body.
[0014] The body of the mounting plate may be annular.
[0015] The mounting plate may include at least one centring portion extending at least axially from a body of the mounting plate, the at least one centring portion being radially offset outwardly relative to the support member and having an outer surface defining an outer diameter of the mounting plate.
[0016] The mounting portion of the retaining portion may extend within a hole in the body of the mounting plate.
[0017] The hook of the retaining portion is capable of interacting with the body of the mounting plate.
[0018] The hook of the retaining portion may be located on a side opposite to the first lateral edge in the axial direction relative to the main body of the mounting plate.
[0019] The retaining portion of the brush support may extend from a small diameter edge of a first lateral rim of the brush support.
[0020] The hooks of the retaining portion may interact by axial contact with the mounting plate to retain the support of the brush in the axial direction relative to the mounting plate.
[0021] The hooks of the retaining portion may interact by axial contact with the body of the mounting plate to retain the brush support axially relative to the mounting plate.
[0022] The hook of the retaining portion may be in axial contact with the mounting plate.
[0023] A first lateral edge of the brush support may be in axial contact with the mounting plate.
[0024] According to one particular design, the support of the brush comprises a single holding portion having a mounting extending over an angular sector greater than 300°, in particular greater than 350°, and at least one holding hook.
[0025] According to another design, the brush support comprises at least two retaining portions, each retaining portion comprising a mounting extending over a limited angular sector and at least one retaining hook.
[0026] The invention also relates to an electric motor comprising a casing, a shaft and a grounding brush assembly as defined above and mounted radially between the casing and the shaft, the conductive fibers of the assembly being in contact with the shaft and the mounting plate being in radial contact with the aperture of the casing. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The invention will be more clearly understood on reading the detailed description of embodiments provided by way of non-limiting example and illustrated by the accompanying drawings, in which:
[0028] [ Figure 1 ] is an axial cross-sectional view of a grounding brush assembly installed in a radial direction between a rotating shaft and a housing of an electric motor according to an exemplary embodiment of the present invention;
[0029] [ Figure 2 ]yes Figure 1 an end view of a grounding brush assembly; and
[0030] [ Figure 3 ]yes Figure 2 A cross-sectional view of the assembly along axis III-III. DETAILED DESCRIPTION
[0031] Figure 1A portion of an electric motor or electric machine 2 is shown in axial section, comprising a fixed casing 4, a shaft 6 (in particular a rotating shaft) with an axis XX supported radially by a bearing 8. The bearing 8 is, for example, a rolling bearing, such as a ball bearing. In a variant, other rolling elements, for example rollers, can be envisaged. In another variant, a sliding bearing can also be envisaged.
[0032] The motor 2 comprises a grounding brush assembly 10 which is mounted radially between a bore 12 of the housing and a cylindrical outer surface 14 of the shaft. For example, the assembly 10 is force-fitted in the bore 12 of the housing.
[0033] like Figure 2 and Figure 3 As more clearly shown in FIG. 1 , the assembly 10 has a generally annular shape.
[0034] The assembly 10 includes a grounding brush 16 and a mounting plate 18 for the brush. The brush 16 includes a plurality of conductive fibers 20 and a support 22 in which the conductive fibers 20 are housed. The conductive fibers 20 are made, for example, of carbon, stainless steel, conductive plastics such as acrylic or nylon fibers. The plurality of conductive fibers 20 are in the form of an open ring. In the example shown, the conductive fibers 20 are bent around a connecting wire. The free distal end of the conductive fibers 20 is in radial contact with the cylindrical outer surface 14 of the shaft.
[0035] To ensure mounting and retention of the conductive fibers 20 , the support 22 of the brush 16 comprises a mounting portion 24 , a first lateral rim 26 extending from the mounting portion 24 on one side and a second lateral rim 28 extending from the mounting portion 24 on the other side.
[0036] The mounting portion 24 extends from a large diameter edge of the first lateral rim 26. The first lateral rim 26 extends from the mounting portion 24 inwardly in the radial direction.
[0037] The mounting portion 24 extends from a large diameter edge of the second lateral edge 28. The second lateral edge 28 extends radially inward from the mounting portion 24. The second lateral edge 28 extends from the mounting portion 24 on a side opposite to the first lateral edge 26.
[0038] In the present case, the mounting portion 24 extends in the axial direction. In a variant, the mounting portion 24 extends obliquely.
[0039] The mounting portion 24 and the first and second lateral edges 26, 28 have a generally annular shape and define a radially inwardly open channel in which the end of the conductive fiber 20 is located. The first and second lateral edges 26, 28 axially clamp the conductive fiber 20. The conductive fiber 20 bears against the first and second lateral edges 26, 28 on both sides in the axial direction.
[0040] In the exemplary embodiment shown, the conductive fiber 20 bears radially against the mounting portion 24, and the first lateral edge 26 and the second lateral edge 28 extend obliquely inwardly from the mounting portion 24. In a variant, the first lateral edge 26 and the second lateral edge 28 may extend radially.
[0041] As will be described in more detail below, the brush support 22 also includes a plurality of retaining hooks 44 for rigidly securing the support in the axial direction relative to the mounting plate 18 .
[0042] The mounting plate 18 comprises an annular body 30 bearing axially against the first lateral edge 26 of the support 22 of the brush 16 and a plurality of centring portions 32 extending obliquely outwards from the large diameter edge of the body 30 .
[0043] The centering portions 32 of the mounting plate 18 are spaced apart from each other in the circumferential direction of the assembly 10, leaving a notch 34 between two consecutive centering portions 32 in the circumferential direction. The centering portion 32 is formed, for example, by cutting an annular portion in such a way that the notch 34 is formed.
[0044] The centering portion 32 defines the outer diameter of the mounting plate 18. The outer surface of the centering portion 32 defines the outer diameter of the mounting plate 18. The centering portion 32 makes it possible to center the mounting plate after installation in the hole 12 of the housing of the associated electric motor 2.
[0045] In the present case, each centering portion 32 extends obliquely outwards, at least partially surrounding the mounting portion 24 of the brush 16 and being radially spaced a certain distance from the mounting portion 24 of the brush 16 and the support 22. In one variant, each centering portion 32 may extend only in the axial direction. In another variant, each centering portion 32 may extend at least in the axial direction relative to the support 22 of the brush 16.
[0046] The mounting plate 18 and the support 22 of the brush 16 are two separate components.
[0047] The mounting plate 18 and the grounding brush 16 include a conductive material, such as aluminum, stainless steel, bronze, copper ( / red copper), or another material.
[0048] The body 30 of the mounting plate 18 comprises two opposite end faces 35, 36 which delimit the axial thickness of the body 30 of the mounting plate 18. The first lateral edge 26 of the support of the brush bears against the end face 36 of the body 30 in the axial direction.
[0049] The support 22 of the brush 16 also comprises a plurality of retaining portions 38 extending from the first lateral edge 26. The retaining portions 38 are identical to one another. In the present case, the retaining portions 38 are in the form of lugs. The retaining portions 38 are spaced apart from one another in the circumferential direction of the assembly 10, in the present case regularly spaced apart from one another.
[0050] Each retaining portion 38 comprises an annular mounting portion 40 extending radially inwardly from the small diameter edge of the first lateral rim 26 and axially in a hole 42 of the mounting plate, more specifically, in the hole of the body 30 of the mounting plate 18 .
[0051] The mounting portion 40 of each holding portion 38 is in radial contact with the hole 42 of the mounting plate. In a variant, there may be a slight radial gap between each holding portion 38 and the hole 42 of the mounting plate. The mounting portion 40 of each holding portion 38 is held at a distance from the shaft 6 of the electric motor 2 in the radial direction.
[0052] Each retaining portion 38 further includes a retaining hook 44 extending radially outward from the mounting portion 40 on the side opposite to the first lateral edge 26. The hooks 44 are identical to one another. The hooks 44 are axially located on the side opposite to the first lateral edge 26 relative to the mounting plate 18, and more specifically, on the side opposite to the first lateral edge 26 relative to the body 30 of the mounting plate 18.
[0053] The hook 44 of the retaining portion 38 interacts by axial contact with the mounting plate 18 to axially retain the support 22 of the brush 16 relative to the mounting plate 18. More specifically, the hook 44 of the retaining portion 38 interacts by axial contact with the body 30 of the mounting plate 18. The hook 44 axially contacts the end face 35 of the mounting plate. In a variant, there may be a slight axial play between the hook 44 and the end face 35 of the mounting plate.
[0054] In the example shown, the brush support 22 comprises a plurality of retaining portions 38 spaced apart from one another in the circumferential direction for mounting on a mounting plate. Alternatively, the brush support 22 may comprise an annular retaining portion 38 provided with an annular hook 44 or with a plurality of hooks 44 spaced apart from one another in the circumferential direction. In another variant, the brush support 22 may comprise a retaining portion 38 in the form of an open ring and provided with one or more hooks 44.
[0055] In the exemplary embodiment shown, the brush support 22 is made in one piece. Alternatively, the holding portion 38 can be a separate component formed separately and attached to the support 22 by any suitable means (e.g., by welding or adhesive bonding).
[0056] In the example shown, the mounting plate 18 comprises a plurality of centering portions 32 regularly spaced apart in the circumferential direction of the assembly 10. In a variant, the mounting plate 18 may comprise a plurality of centering portions 32 irregularly spaced apart in the circumferential direction of the assembly 10.
[0057] In another variation, the mounting plate 18 may include a single annular centering portion 32 forming a flange.
Claims
1. A grounding brush assembly (10), comprising a grounding brush (16) and a brush mounting plate (18), wherein the brush (16) is provided with a plurality of conductive fibers (20) and a support member (22), wherein the conductive fibers (20) are accommodated in the support member (22), wherein the support member (22) comprises a mounting portion (24), a first lateral edge (26) extending from the mounting portion (24) on one side, and a second lateral edge (28) extending from the mounting portion (24) on the other side, wherein the first lateral edge and the second lateral edge clamp the conductive fibers (20) in the axial direction, wherein: The support member (22) of the brush (16) further comprises at least one retaining portion (38), the at least one retaining portion (38) extending from the first lateral edge (26) and provided with a mounting portion (40) and at least one retaining hook (44), the mounting portion (40) extending in a hole (42) of the mounting plate, the at least one retaining hook (44) extending radially outward from the mounting portion (40) and being capable of interacting with the mounting plate (18) so as to axially retain the support member (22) of the brush (16) relative to the mounting plate (18), the retaining hook (44) being axially located on a side opposite to the first lateral edge (26) relative to the mounting plate (18).
2. The grounding brush assembly (10) according to claim 1, characterized in that: The mounting plate (18) is provided with a main body (30) and at least one centering portion (32) extending at least axially from the main body (30), the at least one centering portion (32) being offset radially outward relative to the support member (22) and having an outer surface defining an outer diameter of the mounting plate (18), the mounting portion (40) of the retaining portion (38) extending in a hole (42) of the main body of the mounting plate (18), the retaining hook (44) of the retaining portion (38) being capable of interacting with the main body (30).
3. The grounding brush assembly (10) according to any one of claims 1 and 2, characterized in that: The retaining portion (38) of the support (22) of the brush (16) extends from a small diameter edge of a first lateral rim (26) of the support (22) of the brush (16).
4. The grounding brush assembly (10) according to any one of the preceding claims, characterized in that The retaining hooks (44) of the retaining portion (38) interact by axial contact with the mounting plate (18) so as to retain the support (22) of the brush (16) axially relative to the mounting plate (18).
5. The grounding brush assembly (10) according to any one of the preceding claims, characterized in that The support (22) of the brush (16) comprises a single retaining portion (38) having a mounting portion (40) extending over an angular sector greater than 300° and at least one retaining hook (44), in particular, the mounting portion (40) extending over an angular sector greater than 350°.
6. The grounding brush assembly (10) according to any one of claims 1 to 4, characterized in that: The support (22) of the brush (16) comprises at least two retaining portions (38), each retaining portion (38) comprising a mounting portion (40) extending over a limited angular sector and at least one retaining hook (44).
7. An electric motor (2), comprising a housing (4), a shaft (6) and a grounding brush assembly (10) according to any one of the preceding claims, wherein the grounding brush assembly (10) is radially mounted between the housing (4) and the shaft (6), the conductive fibers (20) of the grounding brush assembly (10) are in contact with the shaft (6), and the mounting plate (18) is in radial contact with the hole (12) of the housing.