Grounding brush assembly

Abstract

[Grounding Brush Assembly] This grounding brush assembly (10) comprises a brush (16) and a brush 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 provided with at least one radial portion (34) extending radially outwards from the support (22), and at least one centering portion (36) extending at least axially from said radial portion (34) and radially surrounding at least part of the support (22) while being radially spaced from said support (22), at least one orifice (38) being formed on said centering portion (36), said orifice (38) remaining at a distance from the proximal and distal ends of said centering portion (36). Figure for the abstract: Fig 1.

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 at least one radial portion extending radially outwardly relative to the support, and at least one centering portion extending at least axially said radial portion and radially surrounding at least in part the support while being radially spaced from said support, said centering portion being provided with a proximal end connecting to said radial portion and a distal end, said proximal and distal ends delimiting the axial dimension of said centering portion.

[0012] According to a general characteristic of the invention, at least one orifice is formed on said centering portion of the mounting plate, said orifice remaining at a distance from the proximal and distal ends of said centering portion.

[0013] The term "orifice formed on said centering portion of the mounting plate" means that said orifice extends exclusively over the centering portion of the mounting plate. In other words, said orifice does not extend both over said centering portion and over said radial portion of the mounting plate.

[0014] When the assembly is mounted radially, at least in part, between a casing and a shaft of an electric motor, said orifice allows the insertion of a tool to easily dismantle the assembly, the tool in particular making it possible to pull axially on the mounting plate by exerting a force on the side opposite the casing.

[0015] Said orifice may form a blind hole extending from an inner or outer surface of said centering portion of the mounting plate.

[0016] Alternatively, said orifice may form a hole passing through the thickness of said centering portion of the mounting plate.

[0017] The centering portion of the mounting plate may be annular.

[0018] The centering portion of the mounting plate may be wavy in shape in the circumferential direction, said orifice being formed in a small diameter area of ​​said centering portion.

[0019] According to another variant, the mounting plate comprises a plurality of centering portions spaced apart from each other in the circumferential direction. The centering portions then form tabs.

[0020] The grounding brush assembly may include a curved portion pro extending radially inwardly along the distal end of said centering portion of the mounting plate.

[0021] The mounting plate may further comprise at least one folded reinforcement portion extending the distal end of said centering portion of the mounting plate and bearing against said centering portion of the mounting plate to form a fold and locally obtain a double thickness of material.

[0022] Advantageously, the longitudinal dimension of said folded reinforcement portion is at least three times greater than the thickness of said folded reinforcement portion.

[0023] Preferably, the folded portion of reinforcement remains at a distance from said orifice or is flush with said orifice. Alternatively, the folded portion of reinforcement may cover a portion of said orifice.

[0024] The invention also relates to an electric machine or motor comprising a casing, a shaft, and a grounding brush assembly as defined above mounted radially at least in part between the casing and the shaft, the conductive fibers of said assembly being in contact with the shaft. Brief description of the figures

[0025] 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:

[0026] [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;

[0027] [Fig.2] is a perspective view of the grounding brush assembly of the [Fig.l];

[0028] [Fig.3] is a front view of the grounding brush assembly of [Fig.l];

[0029] [Fig.4] 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 second exemplary embodiment of the invention;

[0030] [Fig.5] 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 third exemplary embodiment of the invention;

[0031] [Fig.6] is an axial sectional view of a grounding brush assembly mounted radially between a rotating shaft and an electric motor housing according to a fourth exemplary embodiment of the invention;

[0032] [Fig.7] is a perspective view of the grounding brush assembly of the [Fig.6] ;

[0033] [Fig.8] is a front view of the grounding brush assembly of [Fig.6];

[0034] [Fig.9] is a sectional view of the whole of [Fig.6] along the axis IX-IX; and

[0035] [Fig. 10] is a sectional view of the whole of [Fig.6] along the axis XX. Detailed description of the invention

[0036] [Fig. 1] represents, in axial section, a part of an electric motor or machine 2 comprising a fixed casing 4, a shaft 6 in particular rotating, 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.

[0037] The motor 2 comprises a grounding brush assembly 10 mounted radially in part between the bore of the casing 12 and the external cylindrical surface of the shaft 14. The assembly 10 is for example force-fitted into the bore of the casing 12.

[0038] As more visibly illustrated in Figures 2 and 3, the grounding brush assembly 10 has a generally annular shape. The assembly 10 includes a grounding brush 16 and a brush mounting plate 18.

[0039] The grounding brush 16 comprises a plurality of conductive fibers 20 and a support 22, the conductive fibers 20 being housed inside the support 22 of the brush 16. The conductive fibers 20 are for example made of carbon, stainless steel, conductive plastics, 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. The free distal end of the conductive fibers 20 is in radial contact with the external surface of the shaft 14.

[0040] To ensure the 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 the mounting portion 24 on the one hand and a second lateral rim 28 extending the mounting portion 24 on the other hand.

[0041] The mounting plate 18 is integral with the support 22 of the brush 16. The mounting plate 18 comprises a main body 30 axially bearing against the first lateral edge 26 of the support 22 of the brush 16, a plurality of tabs 32 for axial and radial retention of the brush 16, and an annular radial portion 34. The radial portion 34 is provided with a plurality of through-openings 35 formed in its thickness and spaced apart from each other in the circumferential direction. These openings 35 are formed during the partial cutting of the radial portion 34 to form the retaining tabs 32.

[0042] The radial portion 34 of the mounting plate 18 extends radially outwardly from the main body 30 of the mounting plate 18.

[0043] The retaining tabs 32 extend from the main body 30 of the mounting plate 18 and are spaced apart from each other in the circumferential direction of the assembly 10. Each retaining tab 32 extends from the main body 30 of the mounting plate 18 such that the retaining tab 32 locally radially surrounds the support 22 of the brush 16 while being in radial and axial contact with the support 22 of the brush 16. The support 22 of the brush 16 is thus held axially and radially by the retaining tabs 32.

[0044] In the example shown, the mounting plate 18 comprises eight retaining tabs 32 spaced regularly in the circumferential direction of the assembly 10. Alternatively, the mounting plate 18 comprises a different number of retaining tabs 32 and / or retaining tabs 32 spaced irregularly.

[0045] The mounting portion 24 of the support 22 is in radial contact against the retaining tabs 32 and the second lateral edge 28 is in axial contact against said retaining tabs 32. The mounting portion 24 extends the large diameter edge of the first lateral edge 26. The mounting portion 24 extends axially here. Alternatively, the mounting portion 24 extends obliquely.

[0046] The second lateral rim 28 of the support 22 extends the mounting portion 24 radially inward. The second lateral rim 28 extends the mounting portion 24 on the side opposite the first lateral rim 26. The mounting portion 24 and the first and second lateral rims 26, 28 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 26, 28 axially enclose the conductive fibers 20. The conductive fibers 20 are axially supported on either side against the first and second lateral rims 26, 28.

[0047] In the illustrated embodiment, the conductive fibers 20 come to bear radially against the mounting portion 24, the first and second lateral edges 26, 28 extending obliquely inwards from the mounting portion 24. Alternatively, the first and second lateral edges 26, 28 could extend radially.

[0048] In the illustrated embodiment, the mounting plate 18 and the support 22 of the brush 16 are two separate parts. Alternatively, the mounting plate 18 could be made in a single piece with the support 22 of the brush 16, for example made by cutting and stamping. In this case, the main body 30 of the mounting plate 18 extends the small diameter edge of the first lateral rim 26.

[0049] 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.

[0050] The mounting plate 18 further comprises an annular centering portion 36 pro running at least axially along the large diameter edge of the radial portion 34 of the mounting plate 18. The centering portion 36 of the mounting plate 18 radially surrounds the mounting portion 24 of the support 22 and is radially spaced therefrom. The centering portion 36 of the mounting plate 18 here extends purely axially. Alternatively, the centering portion 36 of the mounting plate 18 could extend both axially and radially, i.e. obliquely, inwards or outwards.

[0051] Alternatively, the mounting plate 18 could comprise, instead of the annular centering portion 36, a plurality of centering portions 36 spaced apart from each other in the circumferential direction of the assembly 10. Said centering portions 36 of the mounting plate 18 may extend axially or obliquely inwards or obliquely outwards.

[0052] The assembly 10 comprises a plurality of orifices 38 formed on the centering portion 36 of the mounting plate 18. The orifices 38 are here identical to each other and spaced apart from each other in the circumferential direction. Each orifice 38 is axially spaced from the radial portion 34 and the distal free end of the centering portion 36 of the mounting plate 18. The proximal end of the centering portion 36 of the mounting plate 18 connects to the radial portion 34 of the mounting plate 18. The centering portion 36 of the mounting plate 18 is delimited in the axial direction by its proximal end and by its opposite free distal end.

[0053] Each orifice 38 forms a hole passing through the thickness of the centering portion 36 of the mounting plate 18. In other words, each orifice 38 opens onto the inner surface 40 of the centering portion 36 of the mounting plate 18 and onto the outer surface 42 thereof.

[0054] In the example shown, the mounting plate 18 comprises eight orifices 38 spaced regularly in the circumferential direction of the assembly 10. The orifices 38 are here arranged in the same circle. Alternatively, the mounting plate 18 comprises a different number of orifices 38 and / or orifices 38 spaced irregularly and / or orifices 38 formed at different axial positions of the centering portion 36 of the mounting plate 18 or a single orifice 38.

[0055] Alternatively, one or more orifices 38 could form a blind hole extending from the inner surface 40 or from the outer surface 42 of the centering portion 36 of the mounting plate 18.

[0056] Referring again to [Fig. 1], the assembly 10 is mounted radially in part between the bore of the housing 12 and the external surface of the shaft 14 so that the radial portion 34 of the mounting plate 18 is in axial abutment against a shoulder of the housing 4. The radial portion 34 of the mounting plate 18 is radially in abutment against the bore of the casing 12. The radial portion 34 of the mounting plate 18 extends axially outwardly relative to the casing 12.

[0057] The assembly 10 is mounted radially in part between the bore of the casing 12 and the external surface of the shaft 14 so that the centering portion 36 of the mounting plate 18 bears radially against the bore of the casing 12. The centering portion 36 of the mounting plate 18 extends radially inwardly projecting relative to the casing 4.

[0058] The centering portion 36 of the mounting plate 18 here extends axially outside the casing 4, the orifices 38 being formed on the centering portion 36 of the mounting plate 18 so as to be axially offset outwards relative to the casing 4. Alternatively, only a portion of each orifice 38 could extend axially outside the casing 4.

[0059] The holes 38 of the mounting plate allow the insertion of a tool (not shown) allowing the assembly 10 to be easily dismantled, the tool allowing axial pulling on the mounting plate 18 by exerting a force on the side opposite the casing 4.

[0060] In the example shown, the orifices 38 are rectangular in shape. Alternatively, the orifices 38 may be of any shape allowing the insertion of said tool.

[0061] The embodiment illustrated in [Fig. 4], in which identical elements bear the same references, differs from the example illustrated in FIGS. 1 to 3 in that the mounting plate 18 of the assembly 10 comprises a folded portion 44 of annular reinforcement extending the distal end of the centering portion 36 of the mounting plate 18 and bearing against the centering portion 36 on the outer side to form a fold and locally obtain a double thickness of material. In this embodiment, the distal end of the centering portion 36 is therefore not free.

[0062] Alternatively, the folded reinforcement portion 44 could be folded to bear on the inner side of the centering portion 36. In another variant, it could be possible to provide a plurality of folded reinforcement portions spaced apart from each other in the circumferential direction.

[0063] In the example shown, the free end of the folded portion 44 of reinforcement of the mounting plate 18 is flush with the orifices 38. Alternatively, the free end of the folded portion 44 of reinforcement of the mounting plate 18 could remain at a distance from the orifices 38.

[0064] Preferably, the longitudinal dimension of the folded reinforcement portion 44 is at least three times greater than its thickness, in particular in order to increase the mechanical strength of the mounting plate 18 of the assembly 10.

[0065] The embodiment illustrated in [Fig.5], in which identical elements bear the same references, differs from the first example illustrated in that the plate mounting plate 18 of the assembly 10 comprises at least one curved portion 46 extending radially inwards the distal end of the centering portion 36 of the mounting plate 18. In this exemplary embodiment, the distal end of the centering portion 36 is therefore not free.

[0066] The assembly 10 is mounted radially in part between the bore of the casing 12 and the external surface of the shaft 14 so that the curved portion 46 of the mounting plate 18 is in axial support against a shoulder of the casing 4 or against an outer ring of the bearing 8 in particular when the shaft 6 is rotating. The curved portion 46 of the mounting plate 18 is radially in support against the bore of the casing 12. The curved portion 46 of the mounting plate 18 extends axially projecting outwards relative to the casing 4.

[0067] The assembly 10 is mounted radially in part between the bore of the casing 12 and the external surface of the shaft 14 so that the centering portion 36 of the mounting plate 18 bears radially against the bore of the casing 12. The centering portion 36 of the mounting plate 18 and the curved portion 46 of the mounting plate 18 extend radially inwardly projecting relative to the casing 4.

[0068] The assembly 10 is mounted radially in part between the bore of the casing 12 and the external surface of the shaft 14 so that the radial portion 34 of the mounting plate 18 is axially offset outside the casing 4. The plurality of orifices 38 is formed on the centering portion 36 of the mounting plate 18 so that each orifice 38 is axially offset from the casing 4, each orifice 38 extending, at least in part, axially outside the casing 4.

[0069] The embodiment illustrated in Figures 6 to 10, in which identical elements bear the same references, differs from the first example illustrated in that the centering portion 36 of the mounting plate 18 is of undulating shape in the circumferential direction of the assembly 10.

[0070] The centering portion 36 of the mounting plate 18 comprises an alternation of small diameter sections 48 and large diameter sections 50 connected to each other by connecting sections 52. Each of said small diameter sections 48 and large diameter sections 50 of the centering portion 36 is extended on either side in the circumferential direction of the assembly 10 by a connecting section 52.

[0071] In the example shown, the connecting sections 52 are oblique. Alternatively, the connecting sections 52 of the centering portion 36 of the mounting plate 18 may extend purely radially.

[0072] The assembly 10 comprises a plurality of orifices 38 formed in a small diameter area of ​​the centering portion 36 of the mounting plate 18. Each orifice 38 is formed on one of said small diameter sections 48 of said centering portion 36. of the mounting plate 18 and extends partly over the connecting sections 52 directly adjacent to said small diameter sections 48 in the circumferential direction of the assembly 10. Alternatively, each orifice 38 may be formed only on said small diameter sections 48 of said centering portion 36 of the mounting plate 18.

[0073] In the example shown, the mounting plate 18 comprises eight identical orifices 38 spaced regularly in the circumferential direction of the assembly 10. The orifices 38 are here arranged in the same circle. Alternatively, the mounting plate 18 comprises a different number of orifices 38 and / or orifices 38 spaced irregularly and / or orifices 38 formed at different axial positions of small diameter zones of the centering portion 36 of the mounting plate 18 or a single orifice 38.

Claims

Claims

1. A grounding brush assembly (10) comprising a grounding brush (16) and a brush mounting plate (18), 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 at least one radial portion (34) extending radially outwardly relative to the support (22), and at least one centering portion (36) extending at least axially said radial portion (34) and radially surrounding at least in part the support (22) while being radially spaced from said support (22), said centering portion (36) being provided with a proximal end connecting to said radial portion (34) and a distal end, said proximal ends and distal delimiting the axial dimension of said centering portion (36),characterized in that at least one orifice (38) is formed on said centering portion (36) of the mounting plate (18), said orifice (38) remaining at a distance from the proximal and distal ends of said centering portion (36).,

2. An assembly (10) according to claim 1, wherein said orifice (38) forms a blind hole extending from an inner (40) or outer (42) surface of said centering portion (36) of the mounting plate (18).

3. An assembly (10) according to claim 1, wherein said orifice (38) forms a hole passing through the thickness of said centering portion (36) of the mounting plate (18).

4. An assembly (10) according to any one of claims 1 to 3, wherein the centering portion (36) of the mounting plate (18) is annular.

5. An assembly (10) according to any one of claims 1 to 4, wherein the centering portion (36) of the mounting plate (18) is of circumferentially corrugated shape, said orifice (38) being formed in a small diameter area of ​​said centering portion (36).

6. An assembly (10) according to any one of claims 1 to 3, wherein the mounting plate (18) comprises a plurality of centering portions (36) spaced apart from each other in the circumferential direction.

7. An assembly (10) according to any one of claims 1 to 6, comprising a curved portion (46) extending radially inwardly the distal end of said centering portion (36) of the mounting plate (18).

8. An assembly (10) according to any one of claims 1 to 6, wherein the mounting plate (18) further comprises at least one folded reinforcement portion (44) extending the distal end of said centering portion (36) of the mounting plate (18) and bearing against said centering portion (36) of the mounting plate (18) to form a fold and locally obtain a double thickness of material.

9. An assembly (10) according to claim 8, wherein the longitudinal dimension of said folded reinforcing portion (44) is at least three times greater than the thickness of said folded reinforcing portion (44).

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

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