Grounding Brush Set

Abstract

[Grounding brush assembly] This grounding brush assembly (10) comprises a brush (16) and a mounting plate (18), the brush (16) being provided with a plurality of conductive fibers (20) and a support (22) inside which the conductive fibers (20) are housed, the support (22) comprising a mounting portion (24), first and second lateral flanges (26, 28) axially enclosing said conductive fibers (20), the support (22) of the brush (16) comprising at least one tab (40) distinct from the first and second lateral flanges (26, 28) and axially bearing against the mounting plate (18), the assembly (10) comprising at least one means (42) for securing said tab (40) to the mounting plate (18), said securing means (42) being distinct from the support (22) and mounting plate (18). Figure for 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] The present invention aims to provide an alternative attachment for a grounding brush. ground to a mounting plate. Summary of the invention

[0009] The invention provides a grounding brush assembly comprising a grounding brush and a brush mounting plate, the brush being provided with a plurality of conductive fibers and a holder within which the conductive fibers are housed.

[0010] The support comprising a mounting portion, a first lateral edge extending on the one hand the mounting portion, and a second lateral edge extending on the other hand the mounting portion, the first and second lateral edges axially enclosing said conductive fibers.

[0011] According to a general characteristic, the brush support comprises at least one tab distinct from the first and second lateral edges and axially bearing against the mounting plate, the assembly further comprising at least one means for securing said tab to the mounting plate, said securing means being distinct from the support and the mounting plate.

[0012] Thus, the axial and radial connection of the brush and the mounting plate is achieved in a simple and economical manner using the tab(s) of the brush support and the means for connecting said tab to the mounting plate.

[0013] The mounting plate may be provided with a main body.

[0014] The mounting plate may be provided with at least one pro centering portion extending at least axially along the main body, offset radially outwards relative to the support and provided with an outer surface defining the outer diameter of the mounting plate.

[0015] Said tab of the support can be axially supported against the main body of the mounting plate.

[0016] According to a first design, said tab of the brush support is axially in direct contact with the mounting plate.

[0017] According to a second alternative design, said securing means is interposed axially between the mounting plate and said tab of the support. Said tab of the support is axially in indirect support against the mounting plate with axial interposition of said securing means.

[0018] Said tab of the brush holder may extend from the mounting portion of the brush holder.

[0019] Said tab of the brush holder may extend from the first side edge of the brush holder.

[0020] Said securing means may be electrically conductive.

[0021] Said securing means may be made of electrically conductive material driver.

[0022] The first lateral edge of the support may be in axial contact with the mounting plate.

[0023] Said securing means may comprise glue and / or an adhesive and / or a weld and / or a brazing.

[0024] The brush holder may comprise a plurality of tabs axially bearing against the mounting plate and spaced from each other in the circumferential direction in a regular or irregular manner.

[0025] The assembly may comprise a plurality of means for securing said tabs to the mounting plate which may or may not each be electrically conductive. The securing means may be identical or different.

[0026] The present 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 said assembly being in contact with the shaft, the mounting plate being in radial contact with the bore of the casing.

[0027] The present invention also relates to a method of assembling a grounding brush assembly as defined above, comprising the following steps:

[0028] - a step of forming said tab of the support by partially cutting the brush holder and folding;

[0029] - a positioning step in which the setting brush is brought axially to ground against the mounting plate; and

[0030] - an assembly step during which said tab is secured to the support with the mounting plate with said securing means. Brief description of the figures

[0031] 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:

[0032] [Fig-1] is an axial sectional view of a grounding brush assembly mounted radially between a rotating shaft and an electric motor housing according to a first exemplary embodiment of the invention;

[0033] [Fig.2] is a front view of the grounding brush assembly of [Fig.l];

[0034] [Fig.3] is a sectional view of the whole of [Fig.2] along the axis III-III;

[0035] [Fig.4] is a detail view of [Fig.3];

[0036] [Fig.5] schematically illustrates a method of assembling the brush assembly grounding figures 1 to 4,

[0037] [Fig.6] is a sectional view of a grounding brush assembly according to a second exemplary embodiment of the invention; and

[0038] [Fig.7] is a detail view of [Fig.6]. Detailed description of the invention

[0039] [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.

[0040] The motor 2 comprises a grounding brush assembly 10 mounted radially 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.

[0041] As illustrated more visibly in Figures 2 and 3, the assembly 10 has a generally annular shape.

[0042] The assembly 10 comprises a grounding brush 16 and a brush mounting plate 18. The 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 illustrated example, 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 cylindrical surface of the shaft 14.

[0043] 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.

[0044] The mounting portion 24 extends the large diameter edge of the first lateral flange 26. The first lateral flange 26 extends the mounting portion 24 radially inward.

[0045] The mounting portion 24 extends the large diameter edge of the second lateral flange 28. The second lateral flange 28 extends the mounting portion 24 radially inward. The second lateral flange 28 extends the mounting portion 24 on the side opposite the first lateral flange 26.

[0046] The mounting portion 24 here extends axially. Alternatively, the mounting portion 24 extends obliquely.

[0047] The mounting portion 24 and the first and second side flanges 26, 28 are generally annular shape and delimit a channel open radially on the inner side inside which is located one end of the conductive fibers 20. The first and second lateral edges 26, 28 axially enclose the conductive fibers 20. The conductive fibers 20 are axially supported on either side against the first and second lateral edges 26, 28.

[0048] 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.

[0049] As will be described in more detail later, the brush holder 22 also includes a plurality of tabs 40 to ensure its attachment relative to the mounting plate 18.

[0050] The mounting plate 18 comprises an annular main body 30 axially bearing against the first lateral edge 26 of the support 22 of the brush 16, and a plurality of centering portions 32 extending obliquely outwards the large diameter edge of the main body 30.

[0051] The main body 30 of the mounting plate 18 comprises two opposite front faces 34, 36 which delimit the axial thickness of the main body 30 of the mounting plate 18. The first lateral edge 26 of the brush support is axially supported against the front face 36 of the main body 30.

[0052] 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 38 in the circumferential direction between two directly successive centering portions 32. The centering portions 32 are, for example, formed by cutting out an annular portion so as to form the notches 38.

[0053] The centering portions 32 define the outer diameter of the mounting plate 18. The outer surfaces of the centering portions 32 define the outer diameter of the mounting plate 18. The centering portions 32 allow the centering of the mounting plate after mounting in the bore of the casing 12 of the associated electric motor 2.

[0054] Each centering portion 32 here extends obliquely outwards, at least locally surrounding the mounting portion 24 of the brush 16 and remaining radially at a distance from the mounting portion 24 of the support 22 of the brush 16. As a variant, each centering portion 32 may extend purely axially. In another variant, each centering portion 32 may extend at least axially opposite the support 22 of the brush 16.

[0055] As previously indicated, the support 22 of the brush 16 also comprises the plurality of tabs 40.

[0056] Each blade 40 of the support 22 extends radially outward from the mounting portion 24 of the support 22 of the brush 16, each blade 40 extending the mounting portion 24 of the support 22 on the side opposite the second lateral edge 28. Each blade 40 extends in the radial extension of the first lateral edge 26. Each blade 40 of the support extends substantially parallel to the main body 30 of the mounting plate 18.

[0057] Each blade 40 of the support 22 is axially supported against the mounting plate 18. More precisely, each blade 40 of the support 22 is axially supported against the front face 36 of the main body 30 of the mounting plate 18.

[0058] In the example shown, each tab 40 of the support 22 is arranged so as to extend towards one of the centering portions 32 of the mounting plate 18, the free end of each tab 40 remaining radially at a distance from said centering portion 32. Alternatively, all or part of the tabs 40 of the support 22 may extend towards a notch 38 of the mounting plate 18. As a variant, all or part of the tabs 40 of the support 22 may also extend against a centering portion 32 of the mounting plate 18.

[0059] The tabs 40 are offset relative to each other in the circumferential direction of the assembly 10, here in a regular manner. In the illustrated embodiment, there are eight tabs 40. Alternatively, it is of course possible to provide a different number of tabs 40, for example lower or higher.

[0060] The assembly 10 also comprises a securing means 42 ([Fig.4]) associated with each of the tabs 40 of the support 22 to ensure securing with the mounting plate 18. The number of securing means 42 is therefore equal to the number of tabs 40.

[0061] The securing means 42 are elements distinct from the support 22 and the mounting plate 18, and attached to them.

[0062] In the illustrated embodiment, each securing means 42 is provided between the free end edge of the associated tab 40 and the front face 36 of the main body 30 of the mounting plate 18. The securing means 42 covers the free end edge of the associated tab 40 and locally covers the front face 36 of the main body 30 of the mounting plate 18. Each securing means 42 here comprises a weld, and each tab 40 of the support 22 bears directly against the mounting plate 18 by being welded to the main body 30 of the mounting plate 18.

[0063] Alternatively, the securing means 42 may comprise at least one of: a glue, an adhesive or a solder. In this case, the tab 40 of the support 22 is in indirect support against the mounting plate 18, the securing means 42 being interposed axially between the mounting plate 18 and each tab 40 of the support 22.

[0064] In the example shown, each tab 40 of the support 22 extends radially. Alternatively, all or part of the tabs 40 of the support 22 may extend obliquely.

[0065] In the example shown, the support 22 of the brush 16 is made in a single piece. Alternatively, the tabs 40 of the support 22 could be separate pieces formed separately and fixed to the support 22 by any suitable means, for example by welding or gluing.

[0066] The mounting plate 18 and the support 22 of the brush 16 are two separate parts.

[0067] The mounting plate 18 and the grounding brush 16 comprise a material electrically conductive, such as aluminum, stainless steel, bronze, copper or other material.

[0068] Advantageously, each securing means 42 is also made of electrically conductive material to further promote the dissipation of electrical charges. Thus, the electrical charges which accumulate on the shaft 6 during operation of the electric machine 2 are dissipated towards the casing 4 through the conductive fibers 20, the support 22 of the brush 16, the securing means 42 and the mounting plate 18. It remains possible, however, to provide for the securing means 42 to be made of a non-electrically conductive material.

[0069] In the example shown, the mounting plate 18 comprises a plurality of centering portions 32 spaced regularly in the circumferential direction of the assembly 10. Alternatively, the mounting plate 18 may comprise a plurality of centering portions 32 spaced irregularly in the circumferential direction of the assembly 10.

[0070] In another variant, the mounting plate 18 may comprise a single annular centering portion 32 forming a flange.

[0071] In the example shown, the support of the brush 16 comprises a plurality of tabs 40 spaced regularly in the circumferential direction of the assembly 10. Alternatively, the support 22 of the brush 16 may comprise a plurality of tabs 40 spaced irregularly in the circumferential direction of the assembly 10. As a variant, the support 22 of the brush 16 comprises a single tab 40.

[0072] [Fig.5] schematically illustrates a method of assembling the assembly 10.

[0073] We begin with a step 44 of forming the tabs 40 in which the first lateral edge 26 of the support 22 is cut and folded to form the tabs 40.

[0074] Then, a positioning step 46 is carried out in which axially the support 22 of the brush 16 in axial contact against the mounting plate 18. More precisely, the support 22 of the brush 16 is brought against the main body 30 of the mounting plate 18, the first lateral edge 26 of the support and the tabs 40 being in axial contact against the main body 30.

[0075] Finally, an assembly step 48 is carried out in which the tabs 40 of the support 22 are secured to the mounting plate 18 with the securing means 42.

[0076] In the embodiment example which has just been described, the tabs 40 of the support 22 of the brush 16 extend from the mounting portion 24 of the support 22. Alternatively, as illustrated in FIGS. 6 and 7, in which identical elements bear the same references, the tabs 40 of the support 22 of the brush 16 may extend from the first lateral edge 26 of the support 22. The tabs 40 here extend from the large diameter edge of the first lateral edge 26 of the support 22.

Claims

Claims

1. Grounding brush assembly (10) comprising a grounding brush (16) and a brush mounting plate (18), the brush (16) being provided with a plurality of conductive fibers (20) and a support (22) inside which the conductive fibers (20) are housed, the support (22) comprising a mounting portion (24), a first lateral flange (26) extending on the one hand the mounting portion (24), and a second lateral flange (28) extending on the other hand the mounting portion (24), the first and second lateral flanges (26, 28) axially enclosing said conductive fibers (20), characterized in that the support (22) of the brush (16) comprises at least one tab (40) distinct from the first and second lateral flanges (26, 28) and axially bearing against the mounting plate (18), the assembly (10) further comprising at least one means (42) for securing said tab (40) with the mounting plate (18),said securing means (42) being distinct from the support (22) and the mounting plate (18).,

2. An assembly (10) according to claim 1, wherein the mounting plate (18) is provided with a main body (30) and at least one centering portion (32) extending at least axially the main body (30), offset radially outwardly relative to the support (22) and provided with an outer surface defining the outer diameter of the mounting plate (18), said tab (40) of the support (22) being axially in abutment against the main body (30) of the mounting plate (18).

3. Assembly (10) according to one of claims 1 and 2, in which said tab (40) of the brush support is axially in direct contact with the mounting plate (18), or in which said tab (40) of the support (22) is axially in indirect contact with the mounting plate (18) with axial interposition of said securing means (42).

4. An assembly (10) according to any preceding claim, wherein said tab (40) of the brush holder extends from the mounting portion (24) of the holder, or extends from the first flange (26) of the holder.

5. An assembly (10) according to any preceding claim, wherein said securing means (42) is made of a material electrically conductive.

6. An assembly (10) according to any preceding claim, wherein the first lateral flange (26) of the support (22) is in axial contact with the mounting plate (18).

7. An assembly (10) according to any preceding claim, wherein said securing means (42) comprises glue and / or adhesive and / or solder and / or brazing.

8. Assembly (10) according to any one of the preceding claims, in which the support (22) of the brush (16) comprises a plurality of tabs (40) axially bearing against the mounting plate (18) and spaced apart from each other in the circumferential direction, the assembly (10) comprising a plurality of means (42) for securing said tabs (40) to the mounting plate (18).

9. An electric motor (2) comprising a housing (4), a shaft (6) and a grounding brush assembly (10) according to any preceding claim mounted radially between the housing (4) and the shaft (6), the conductive fibers (20) of said assembly (10) being in contact with the shaft (6), the mounting plate (18) being in radial contact with the bore of the housing (12).

10. Method for assembling a grounding brush assembly (10) according to any one of claims 1 to 8, characterized in that it comprises the following steps: - a step (44) of forming said tab (40) of the support (22) by partially cutting the support (22) of the brush (16) and by folding, - a positioning step (46) in which the grounding brush (16) is brought axially against the mounting plate (18), and - an assembly step (48) during which said tab (40) of the support (22) is secured to the mounting plate (18) with said securing means.

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