Grounding brush assembly
By designing a ground brush assembly with a curved free end tab in an electric motor, the current damage and vibration problems caused by the potential difference between the rotating shaft and the shell are solved, and a more stable grounding effect is achieved, reducing the risk of current damage and vibration .
Patent Information
- Application Number
- CN202410843238.4
- 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 the current between the inner and outer rings of the rolling bearings to be damaged and discharged, resulting in vibration, and existing ground brush components are difficult to effectively solve these problems.
A ground brush assembly including conductive fibers is designed, and its support member interacts with the mounting plate by forming a through opening and a curved free end in the thickness of the mounting plate to achieve rigid fixation of the brush and the mounting plate in the axial direction. Ensure stable installation and support of conductive fibers.
Through this design, problematic discharge through rolling bearings is reduced or eliminated, the firmness and stability of the assembly is improved, and the risk of current damage and vibration is reduced.
Smart Images
Figure CN119231271A_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 a 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 a grounding brush assembly, which comprises a grounding brush and a mounting plate of 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 general characteristics, at least one through-opening is formed in the thickness of the mounting plate, and the brush support comprises at least one tab extending through the opening, the tab being provided with a bent free end which is capable of interacting with the mounting plate to axially hold the brush support relative to the mounting plate, the bent free end being axially located on the side opposite to the support 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 tab or tabs of the brush support.
[0013] The mounting plate may be provided with a main body.
[0014] The mounting plate may be provided with at least one centring portion extending at least axially from the body, the at least one centring portion being offset radially outwardly relative to the support and having an outer surface defining an outer diameter of the mounting plate.
[0015] The through opening may be formed in the thickness of the body of the mounting plate.
[0016] The tabs are capable of interacting with the body of the mounting plate.
[0017] The tab of the brush support may extend from a mounting portion of the brush support.
[0018] The tabs may be produced by partially cutting the support of the brush.
[0019] A first lateral edge of the support member may be in axial contact with the mounting plate.
[0020] According to a particular design, a plurality of through openings are formed in the thickness of the mounting plate, said openings being offset from one another in the circumferential direction, and the brush support comprises a plurality of tabs, each tab of the brush support extending through one of said openings, each tab being provided with a bent free end which is capable of interacting with the mounting plate in order to hold the brush support axially relative to the mounting plate, said bent free end being located axially relative to the mounting plate on the side opposite to the brush support.
[0021] The present invention also relates to an electric motor comprising a casing, a shaft and a grounding brush assembly as defined above and radially mounted between the casing and the shaft, the conductive fibers of the grounding brush assembly being in contact with the shaft and the mounting plate being in radial contact with the aperture of the casing.
[0022] The invention also relates to a method for assembling a grounding brush assembly as defined above, said method comprising the following steps:
[0023] - a positioning step, in which the grounding brush is axially brought against the mounting plate and the lug is axially inserted through the opening so that the free end of the lug is axially located on the opposite side of the support relative to the mounting plate; and
[0024] - An assembly step during which the free ends of said tabs of the brush support are bent.
[0025] The method may also comprise a prior step of partially cutting a first lateral edge of the support of the brush so as to form the tab. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] 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:
[0027] [ 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;
[0028] [ Figure 2 ]yes Figure 1 An end view of a grounding brush assembly;
[0029] [ Figure 3 ]yes Figure 2 A cross-sectional view of the assembly along axis III-III;
[0030] [ Figure 4 ]yes Figure 2 A cross-sectional view of the assembly along axis IV-IV;
[0031] [ Figure 5 ] schematically depicts a method for assembling a grounding brush assembly according to the present invention;
[0032] [ Figure 6 ] depicts Figure 5 the positioning step of the method; and
[0033] [ Figure 7 ] depicts Figure 5 The assembly steps of the method. DETAILED DESCRIPTION
[0034] Figure 1 A portion of an electric motor or 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, such as rollers, can be envisaged. In another variant, a sliding bearing can also be envisaged.
[0035] 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.
[0036] like Figures 2 to 4 As more clearly shown in FIG. 1 , the assembly 10 has a generally annular shape.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] In the present case, the mounting portion 24 extends in the axial direction. In a variant, the mounting portion 24 may extend obliquely.
[0042] 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.
[0043] 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.
[0044] As will be described in greater detail below, the brush support 22 also includes a plurality of retaining tabs 48 for rigidly securing the support axially relative to the mounting plate 18 .
[0045] The mounting plate 18 comprises a body 30 of generally annular shape, which bears axially against the first lateral edge 26 of the support 22 of the brush 16 , and a plurality of centring portions 32 which extend obliquely outwardly from the large diameter edge of the body 30 .
[0046] 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.
[0047] 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.
[0048] In the present case, each centering portion 32 extends obliquely outwards so as to at least partially surround the mounting portion 24 of the brush 16 and is 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 opposite to the mounting portion 24 of the support 22 of the brush 16.
[0049] The mounting plate 18 and the support 22 of the brush 16 are two separate components.
[0050] The mounting plate 18 and the grounding brush 16 include a conductive material, such as aluminum, stainless steel, bronze, copper, or another material.
[0051] The body 30 of the mounting plate 18 comprises two opposite end faces 38, 40 which delimit the axial thickness of the body 30 of the mounting plate 18. The first lateral edge 26 of the brush support 22 bears axially against the end face 40 of the body.
[0052] In the thickness of the mounting plate 18, a plurality of through openings 46 are formed. More specifically, each opening 46 is formed in the axial thickness of the body 30 of the mounting plate 18, extending from the end face 38 to the end face 40. The openings 46 open on the end faces 38, 40. The openings 46 are located radially at a distance from the bore of the body 30. The openings 46 are identical to one another.
[0053] In the present case, the openings 46 extend in the axial direction. As another option, the openings 46 may extend obliquely. The openings 46 are offset from one another in the circumferential direction of the assembly 10, in the present case, regularly offset from one another. In the exemplary embodiment shown, there are eight openings 46. As another option, a different number (e.g., more or less) of openings 46 may of course be provided.
[0054] As explained above, the support 22 of the brush 16 comprises a plurality of retaining tabs 48 for rigidly fixing said support 22 in the axial direction relative to the mounting plate 18. The tabs 48 are identical to one another.
[0055] Each tab 48 extends axially from the mounting portion 24 of the brush support opposite its second lateral edge 28. Each tab 48 extends axially through one of the openings 46 formed in the thickness of the mounting plate 18.
[0056] Each tab 48 of the support 22 of the brush 16 is provided with a free end 48 a which is located on the side opposite to the support of the brush 16 in the axial direction with respect to the mounting plate 18 and is bent to protrude with respect to the body 30 of the mounting plate 18 .
[0057] The bent free end 48a of each tab 48 interacts 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. The bent free end 48a of each tab 48 interacts by axial contact with the end face 38 of the mounting plate.
[0058] In the example shown, each curved free end 48a of the tab 48 extends radially outward so as to axially contact the end face 38 of the body 30 of the mounting plate 18. In a variation, all or some of the curved free ends of the tab 48 may extend radially inward and / or be at a certain axial distance from the end face 38 of the body 30 of the mounting plate 18. Alternatively, the curved free ends 48a of the tab 48 may extend obliquely.
[0059] In an exemplary embodiment, the tab 48 extends from the mounting portion 24 of the support 22 of the brush 16. Alternatively, the tab 48 may extend from a rounded portion connecting the mounting portion 24 of the support 22 to the first lateral edge 26. In one variation, the tab 48 may extend from the first lateral edge 26 of the support 22.
[0060] In the exemplary embodiment shown, the support 22 of the brush 16 is made in one piece. Alternatively, the tab 48 may be a separate component formed separately and attached to the support 22 by any suitable means (e.g., by welding or adhesive bonding).
[0061] In the example shown, the second lateral edge 28 , the mounting portion 24 and the first lateral edge 26 are in the form of an open ring and extend over an angular sector greater than 300°, in particular greater than 350°.
[0062] In the example shown, the support 22 of the brush 16 comprises a plurality of retaining tabs 48. In a variant, the support 22 of the brush 16 may comprise a single retaining tab 48 and the mounting plate 18 may then comprise a single through opening 46.
[0063] In the exemplary embodiment 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.
[0064] In another variation, the mounting plate 18 may include a single annular centering portion 32 forming a flange.
[0065] Figure 5 A method for assembling the assembly 10 is schematically depicted.
[0066] The method begins with a step 58 of partially cutting the first lateral edge 26 of the support 22 of the brush 16 to form the tab 48 .
[0067] Next comes a positioning step 60 in which the support 22 of the brush 16 is axially brought against the mounting plate 18 , the first lateral edge 26 of the support 22 of the brush 16 bearing axially against the body 30 of the mounting plate 18 .
[0068] During this step, each tab 48 of the support 22 of the brush 16 is also inserted axially through one of the openings 46 formed in the thickness of the mounting plate 18, so that the free end of each tab 48 of the support 22 of the brush 16 is located on the side opposite to the support 22 of the brush 16 in the axial direction with respect to the mounting plate 18 and protrudes. Figure 6 Shown in.
[0069] Then comes the assembly step 62, in which the free end of each tab 48 of the support 22 of the brush 16 is bent against the mounting plate 18. This step is Figure 7 Thus, the brush 16 and the mounting plate 18 are rigidly fixed together in the axial direction.
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 (26) and the second lateral edge (28) clamp the conductive fibers (20) in an axial direction, wherein: At least one through opening (46) is formed in the thickness of the mounting plate (18), and the support (22) of the brush (16) includes at least one tab (48) extending through the opening (46), the tab (48) being provided with a bent free end (48a), the bent free end (48a) being capable of interacting with the mounting plate (18) so as to axially retain the support (22) of the brush (16) relative to the mounting plate (18), the bent free end (48a) being located axially on the side opposite to the support (22) 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 through opening (46) being formed in the thickness of the main body (30), the tab (48) being capable of interacting with the main body (30) of the mounting plate (18).
3. The grounding brush assembly (10) according to any one of claims 1 and 2, characterized in that: The tab (48) of the brush support extends from a mounting portion (24) of the brush support (22) (16).
4. The grounding brush assembly (10) according to any one of the preceding claims, characterized in that The tabs (48) are produced by partially cutting the support (22) of the brush (16).
5. The grounding brush assembly (10) according to any one of the preceding claims, characterized in that The first lateral edge (26) of the support member (22) is in axial contact with the mounting plate (18).
6. A grounding brush assembly (10) according to any one of the preceding claims, characterized in that A plurality of through openings (46) are formed in the thickness of the mounting plate (18), the openings (46) being offset from one another in the circumferential direction, the support (22) of the brush (16) comprising a plurality of tabs (48), each tab (48) of the support (22) of the brush (16) extending through one of the openings (46), each tab (48) being provided with a bent free end (48a), the bent free end (48a) being capable of interacting with the mounting plate (18) so as to axially retain the support (22) of the brush (16) relative to the mounting plate (18), the bent free end (48a) being axially located on the side opposite to the support (22) of the brush (16) relative to the mounting plate (18).
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 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.
8. A method for assembling a grounding brush assembly (10) according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: - a positioning step (60) in which the grounding brush (16) is axially brought into contact with the mounting plate (18) and the lug (48) is axially inserted through the opening (46) so that the free end of the lug (48) is axially located on the side opposite to the support (22) relative to the mounting plate (18); and - an assembly step (62) in which the free ends of the tabs (48) of the brush support are bent.
9. The method according to claim 8, characterized in that The method comprises a previous step of partially cutting a first lateral edge (26) of the support of the brush so as to form the tab (48).