Grounding brush assembly

The grounding brush assembly with a mounting plate design featuring radial and axial portions, flanges, and hooks/lugs ensures easy disassembly, addressing the disassembly challenge of existing assemblies and enhancing maintenance efficiency.

FR3144895B1Active Publication Date: 2024-12-20AB SKF SKF PATENT DEPARTMENT
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Patent Information

Application Number
FR2023000094
Authority / Receiving Office
FR · FR
Patent Type
Patents
Current Assignee / Owner
Filing Date
2023-01-05
Publication Date
2024-12-20
Estimated Expiration
2043-01-05

AI Technical Summary

Technical Problem

Existing grounding brush assemblies for electric motors are difficult to disassemble due to force-fitting, which complicates maintenance and replacement.

Method used

A grounding brush assembly with a mounting plate that includes radial and axial portions, flanges, and hooks or lugs, allowing for axial and radial retention of conductive fibers while providing clearance for easy disassembly through axial play or clearance, facilitating tool insertion for dismantling.

Benefits of technology

Enables easy disassembly and maintenance of the grounding brush assembly by allowing tool access, reducing maintenance complexity and improving serviceability.

✦ Generated by Eureka AI based on patent content.

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Abstract

[Grounding Brush Assembly] This grounding brush assembly (10) comprises a grounding brush (16) and a brush (16) mounting plate (18), said brush (16) being provided with a plurality of conductive fibers (20) and a support (22) within which the conductive fibers (20) are housed, the mounting plate (18) being integral with the support (22) and having a radial portion (36) extending radially outwards from the support (22), and an axial portion (38) extending axially from said radial portion (36) and radially surrounding at least part of the support (22) while being radially spaced from said support (22), the mounting plate (18) comprising at least one collar (40) extending radially outwards from the distal end of said axial portion (38). Figure for the abridged version: Fig 4.
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Description

Title of invention: Grounding brush assembly Technical field of the invention

[0001] The present invention relates to the field of grounding devices for controlling the shaft current generated in electric motors or machines, and in particular grounding brush assemblies. State of the prior art

[0002] In an electric motor or machine, at least one rolling bearing is mounted between the housing of the electric motor or machine and the rotating shaft in order to support this shaft.

[0003] In operation when the shaft is rotating, an electrical potential difference may appear between it and the casing of the motor or the electric machine, which generates an electric current between the inner ring of the rolling bearing which is integral with the rotating shaft, and the outer ring integral with the casing.

[0004] Electric current passing through rolling bearing components can damage these components, including rolling elements and raceways on the inner and outer rings. Electrical discharges can also generate vibrations.

[0005] To overcome these drawbacks, it is known to ground or earth the rotating shaft using a grounding brush or broom comprising conductive fibers. The grounding brush is generally mounted in the bore of the electric motor housing such that the free ends of the fibers are in radial contact with the outer surface of the rotating shaft.

[0006] Due to the conductivity of the fibers, the brush is maintained at the same electrical potential as the electric motor housing. The inner and outer rings of the rolling bearing are also at the same electrical potential, which reduces or even eliminates problematic electrical discharges through the rolling bearing.

[0007] Document US-A1-2021 / 0021180 discloses a grounding brush assembly comprising a grounding brush provided with a support and a plurality of conductive fibers mounted in this support, and an annular mounting plate provided with a plurality of radial and axial retaining tabs for the support of the grounding brush, and an annular outer flange radially surrounding the brush and the tabs. The tabs are formed by plastic deformation of the mounting plate.

[0008] Such a grounding brush assembly is force-fitted into the bore of the housing, the grounding brush assembly being therefore difficult to disassemble.

[0009] The present invention aims to remedy this drawback. Summary of the invention

[0010] A grounding brush assembly comprising a grounding brush and a brush mounting plate, said brush being provided with a plurality of conductive fibers and a holder within which the conductive fibers are housed.

[0011] The mounting plate is integral with the support and is provided with a radial portion extending radially outwardly relative to the support, and an axial portion axially extending said radial portion and radially surrounding at least in part the support while being radially spaced from said support.

[0012] According to a general characteristic of the invention, the mounting plate comprises at least one collar extending radially outwards the distal end of said axial portion.

[0013] The axial portion of the mounting plate may be annular.

[0014] In one embodiment, the flange of the mounting plate may be annular.

[0015] Alternatively, the mounting plate may comprise a plurality of flanges spaced apart from each other in the circumferential direction.

[0016] The mounting plate may comprise at least one attachment tab axially extending said axial portion and provided at its distal end with a hook extending radially, said hook being able to be axially offset relative to said collar on the side opposite the radial portion.

[0017] Said hanging tab of the mounting plate may comprise two opposing edges each extending the hook of said hanging tab and each connecting to a directly adjacent flange of the plurality of flanges.

[0018] A circumferential clearance may remain between said attachment tab of the mounting plate and each directly adjacent flange of the plurality of flanges.

[0019] The invention also relates to an electric machine or motor comprising a casing, a shaft, a grounding brush assembly as defined previously mounted radially at least in part between the casing and the shaft, the conductive fibers of said assembly being in contact with the shaft.

[0020] An axial clearance may remain between the casing and said collar of the mounting plate.

[0021] The mounting plate may comprise a plurality of radial portions spaced apart from each other in the circumferential direction, an axial clearance possibly remaining between the casing and said radial portions.

[0022] An axial clearance may remain between the casing and said hooks. Brief description of the figures

[0023] The present invention will be better understood upon studying the detailed description of embodiments, taken as non-limiting examples and illustrated by the appended drawings in which:

[0024] [Fig-1] is an axial sectional view of a grounding brush assembly mounted radially partly between a rotating shaft and an electric motor housing according to a first exemplary embodiment of the invention;

[0025] [Fig.2] is a perspective view of the grounding brush assembly of [Fig.l];

[0026] [Fig.3] is a front view of the grounding brush assembly of [Fig.l];

[0027] [Fig.4] is a sectional view of the whole of [Fig.l] along axis IV-IV;

[0028] [Fig.5] is a sectional view of the whole of [Fig.l] along the VV axis;

[0029] [Fig.6] is an axial sectional view of a second assembly of the entire [Fig.l];

[0030] [Fig.7] is a perspective view of a grounding brush assembly according to a second exemplary embodiment of the invention;

[0031] [Fig.8] is a perspective view of a grounding brush assembly according to a third exemplary embodiment of the invention;

[0032] [Fig.9] is a front view of the grounding brush assembly of [Fig.l 1];

[0033] [Fig.10] is a sectional view of the assembly of [Fig.11] along the axis XX mounted radially in part between the rotating shaft and the casing;

[0034] [Fig.11] is a sectional view of the assembly of [Fig.11] along the axis XI-XI mounted radially in part between the rotating shaft and the casing;

[0035] [Fig. 12] is a perspective view of a grounding brush assembly according to a fourth exemplary embodiment of the invention;

[0036] [Fig. 13] is a front view of the grounding brush assembly of [Fig. 15];

[0037] [Fig.14] is a sectional view of the whole of [Fig.15] along the XIV-XIV axis mounted radially partly between the rotating shaft and the housing; and

[0038] [Fig.15] is a sectional view of the assembly of [Fig.15] along the axis XV-XV mounted radially in part between the rotating shaft and the casing. Detailed description of the invention

[0039] [Fig.l] represents, in axial section, a part of an electric motor or machine 2 comprising a fixed casing 4, a rotating shaft 6, of axis XX, supported radially by a bearing 8. The bearing 8 is for example a rolling bearing of the ball type. As a variant, it is possible to provide other rolling elements, for example rollers. In another variant, it is also possible to provide a plain bearing.

[0040] The motor 2 comprises a grounding brush assembly 10 mounted ra- dially partly between the bore 12 of the casing and the external cylindrical surface 14 of the shaft. The assembly 10 is for example force-fitted into the bore 12 of the casing.

[0041] As more visibly illustrated in Figures 2 to 5, the grounding brush assembly 10 has a generally annular shape. The assembly 10 includes a grounding brush 16 and a brush mounting plate 18.

[0042] The grounding brush 16 comprises a plurality of conductive fibers 20 and a support 22, the conductive fibers being housed inside the support 22 of the brush 16. The conductive fibers 20 are for example made of carbon, stainless steel, conductive plastic, such as acrylic fibers or nylon. The plurality of conductive fibers 20 is in the form of an open ring. In the example illustrated, the conductive fibers 20 are folded around a connecting wire 24. The free distal end of the conductive fibers 20 is intended to come into radial contact with the external surface 14 of the shaft 6.

[0043] To ensure the mounting and retention of the conductive fibers 20, the support 22 comprises a mounting portion 26, a first lateral rim 28 extending the mounting portion 26 on the one hand and a second lateral rim 30 extending the mounting portion 26 on the other hand.

[0044] The mounting plate 18 is integral with the support 22. The mounting plate 18 comprises a main body 32 axially bearing against the first rim 28 of the support, a plurality of tabs 34 for axial and radial retention of the brush 16, and a plurality of radial portions 36.

[0045] Said radial portions 36 of the mounting plate 18 extend radially outwardly from the main body 32 of the mounting plate 18 and are spaced apart from each other in the circumferential direction. Alternatively, it could be possible to provide that the mounting plate 18 comprises an annular radial portion 36.

[0046] The retaining tabs 34 extend from the main body 32 of the mounting plate 18 and are spaced apart from each other in the circumferential direction, each retaining tab 34 being located in the circumferential direction between two successive radial portions 36 of the mounting plate 18. Each retaining tab 34 extends from the main body 32 of the mounting plate 18 such that the retaining tab 34 locally radially surrounds the support 22 of the brush 16 while being in radial and axial contact with the support 22. The support 22 is thus held axially and radially by the retaining tabs 34.

[0047] In the example shown, the mounting plate 18 comprises six radial portions 36 and six retaining tabs 34 regularly spaced in the circumferential direction. Alternatively, the mounting plate comprises a different number of radial portions 36 and a different number of retaining tabs 34.

[0048] The mounting portion 26 of the support 22 is in radial contact against the retaining tabs 34 and the second lateral rim 30 is in axial contact against said tabs. The mounting portion 26 extends the large diameter edge of the first lateral rim 28. The mounting portion 26 here extends axially. Alternatively, the mounting portion 26 extends obliquely.

[0049] The second lateral rim 30 of the support 22 extends the mounting portion 26 radially inward. The second lateral rim 30 extends the mounting portion 26 on the side opposite the first lateral rim 28. The mounting portion 26 and the first and second lateral rims 28, 30 are annular in shape and delimit a channel open radially on the inner side inside which one end of the conductive fibers 20 is located. The first and second lateral rims 28, 30 axially enclose the conductive fibers 20. The conductive fibers 20 are axially supported on either side against the first and second lateral rims 28, 30.

[0050] In the illustrated embodiment, the conductive fibers 20 come to bear radially against the mounting portion 26, the first and second lateral rims 28, 30 extending obliquely inwards from the mounting portion 26. Alternatively, the first and second lateral rims 28, 30 could extend radially.

[0051] In the illustrated embodiment, the mounting plate 18 and the support 22 are two separate parts. Alternatively, the mounting plate 18 could be made in a single piece with the support 22, for example made by cutting and stamping. In this case, the main body 32 of the mounting plate 18 extends the small diameter edge of the first lateral flange 28.

[0052] The mounting plate 18 and the grounding brush 16 comprise an electrically conductive material, such as, for example, aluminum, stainless steel, bronze, copper, or other material.

[0053] The mounting plate 18 further comprises an annular axial portion 38 axially extending the large diameter edge of the radial portions 36 of the mounting plate 18. Said axial portion 38 radially surrounds the mounting portion 26 of the support 22 and is radially spaced therefrom. Said axial portion 38 here extends purely axially. Alternatively, said axial portion 38 could extend both axially and radially, i.e. obliquely, inwards or outwards.

[0054] Alternatively, the mounting plate 18 could comprise, instead of the annular axial portion, a plurality of axial portions 38 spaced apart from each other in the circumferential direction.

[0055] The mounting plate 18 also comprises an annular collar 40 extending radially outwardly the distal end of the annular axial portion 38 of the mounting plate 18. The proximal end of the axial portion 38 is connects to the radial portions 36.

[0056] In the example shown, the collar 40 has a portion for connection to the curved axial portion 38, and a radially extending portion extending this connection portion. Alternatively, the collar 40 could extend purely radially. In another alternative, the collar 40 could radially extend inwardly the distal end of the annular axial portion 38 of the mounting plate 18.

[0057] Referring again to [Fig. 1], the assembly 10 is mounted radially in part between the bore 12 of the housing and the external cylindrical surface 14 of the shaft so that the plurality of radial portions 36 of the mounting plate 18 bear axially against a shoulder of the housing 4. The radial portions 30 of the mounting plate 18 bear radially against the bore 12 of the housing. The radial portions 36 extend axially outwardly relative to the casing 4. Thus, the annular collar 40 of the mounting plate 18 of the assembly 10 is axially spaced from the casing 4. An axial clearance 42 remains between the casing 4 and the annular collar 40 of the mounting plate 18 of the assembly 10. This axial clearance 42 allows the insertion of a tool (not shown) making it possible to easily disassemble the assembly 10, the tool making it possible to pull axially on the annular collar 40 of the mounting plate 18 by exerting a force on the side opposite the casing 4.

[0058] [Fig. 6] shows another mounting of the assembly 10 inside the engine. The annular collar 40 of the mounting plate 18 is here in axial contact with the casing 4 and the radial portions 36 are axially spaced from the shoulder of the casing 4. An axial clearance 44 remains between the radial portions 36 and the casing 4.

[0059] In a similar manner to the previous embodiment, the axial clearance 44 allows the insertion of a tool making it possible to dismantle the assembly 10, here by axial thrust against the radial portions 36 of the mounting plate 18 and / or against the main body 32 of the mounting plate 18.

[0060] The embodiment illustrated in [Fig. 7], in which identical elements bear the same references, differs from the example illustrated in FIGS. 1 to 6 in that the mounting plate 18 of the assembly 10 comprises a plurality of flanges 40 spaced apart from each other in the circumferential direction. A plurality of notches 45 is formed at the distal end of the axial portion 38 to form the plurality of flanges 40. In the illustrated embodiment, the flanges 40 are spaced evenly apart from each other. Alternatively, it is possible to provide an irregular spacing.

[0061] The embodiment illustrated in Figures 8 to 11, in which identical elements bear the same references, differs from the example illustrated in Figures 1 to 6 in that the mounting plate 18 of the assembly 10 comprises a plurality of collars collars 40 spaced apart from each other in the circumferential direction, and a plurality of hooking tabs 46 spaced apart from each other in the circumferential direction, each of said hooking tabs 46 being located in the circumferential direction between two successive collars 40.

[0062] The hooking tabs 46 of the mounting plate 18 axially extend the distal end of the annular axial portion 38 of the mounting plate 18 and are each provided at their distal end with a hook 48 extending radially outwards. Alternatively, said hooks 48 could extend radially inwards.

[0063] Said hooks 48 are axially offset relative to the collars 40 on the side opposite to said plurality of radial portions 36.

[0064] In the example shown, the attachment tabs 46 of the mounting plate 18 each comprise two rims 50 opposite in the circumferential direction and each extending the hook 48 of said attachment tab 46 and each connecting to a directly adjacent collar 40.

[0065] Figures 10 and 11 show the assembly 10 mounted radially in part between the bore 12 of the casing and the external cylindrical surface 14 of the shaft. The collars 40 of the mounting plate 18 are in axial contact with the casing 4. The hooking tabs 46 extend axially outwardly relative to the casing 4. Thus, the hooks 48 of the hooking tabs 46 are axially spaced from the casing 4. An axial clearance 52 remains between the hooks 48 and the casing 4, this axial clearance 52 allowing the insertion of a tool making it possible to dismantle the assembly 10 by axial traction on said hooks 48.

[0066] The embodiment illustrated in Figures 12 to 15, in which identical elements bear the same references, differs from the example illustrated in Figures 8 to 11 in that the mounting plate 18 does not include the flanges 50 and in that a plurality of notches 45 is formed at the distal end of the axial portion 38 so that a circumferential clearance is formed between each of said attachment tabs 46 and the two directly adjacent collars 40. Alternatively, it is possible to form the notches 45 so that a circumferential clearance is formed between a portion of said attachment tabs 46 and at least one of the two directly adjacent collars 40.

Claims

Claims

1. Grounding brush assembly (10) comprising a grounding brush (16) and a mounting plate (18) for the brush (16), said brush (16) being provided with a plurality of conductive fibers (20) and a support (22) inside which the conductive fibers (20) are housed, the mounting plate (18) being integral with the support (22) and provided with a radial portion (36) extending radially outwardly relative to the support (22), and an axial portion (38) axially extending said radial portion (36) and radially surrounding at least in part the support (22) while being radially spaced from said support (22), characterized in that the mounting plate (18) comprises at least one collar (40) extending radially outwardly the distal end of said axial portion (38).

2. An assembly (10) according to claim 1, wherein the flange (40) of the mounting plate (18) is annular.

3. An assembly (10) according to claim 1, wherein the mounting plate (18) comprises a plurality of flanges (40) spaced apart from each other in the circumferential direction.

4. Assembly (10) according to any one of claims 1 to 3, in which the mounting plate (18) comprises at least one hooking tab (46) axially extending said axial portion (38) and provided at its distal end with a hook (48) extending radially, said hook (48) being axially offset relative to said collar (40) on the side opposite the radial portion (36).

5. An assembly (10) according to claim 4 dependent on claim 3, wherein said hooking tab (46) of the mounting plate (18) comprises two opposed flanges (50) each extending the hook (48) of said hooking tab (46) and each connecting to a directly adjacent flange (40) of the plurality of flanges (40).

6. An assembly (10) according to claim 4 dependent on claim 3, wherein a circumferential clearance remains between said gripping tab (46) of the mounting plate (18) and each directly adjacent flange (40) of the plurality of flanges (40).

7. Electric motor (2) comprising a casing (4), a shaft (6), an assembly (10) of grounding brushes according to any one of the preceding claims mounted radially at least in part between the casing (4) and the shaft (6), the conductive fibers (20) of said assembly being in contact with the shaft (6).

8. Motor (2) according to claim 7, wherein an axial clearance (42) remains between the casing (4) and said collar (40) of the mounting plate (18).

9. Motor (2) according to one of claims 7 and 8, wherein the mounting plate (18) comprises a plurality of radial portions (36) spaced from each other in the circumferential direction, an axial clearance (44) remaining between the casing (4) and said radial portions (36).

10. Motor (2) according to any one of claims 7 to 9 dependent on any one of claims 4 to 6, in which an axial clearance (52) remains between the casing (4) and said hooks (48).