Grounding brush assembly

Abstract

Ground brush assembly (10) comprising a brush (16) and a mounting plate (18), said brush (16) being provided with a plurality of electrically conductive fibers (20) and a support (22) within which the electrically conductive fibers (20) are housed, the support (22) comprising a mounting portion (24), a first lateral rim (26) and a second lateral rim (28) axially clamping the electrically conductive fibers (20), the support (22) of said brush (16) comprising at least one tab (40), the ground brush assembly (10) comprises a support (22), at least one tab (40) distinct from the first lateral rim (26) and the second lateral rim (28) and bearing axially against a mounting plate (18), the ground brush assembly (10) comprising at least one fixing member (42) for rigidly fixing the tab (40) to the mounting plate (18), the fixing member (42) distinct from the support (22) and the mounting plate (18).

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 fibers in an axial direction.

[0011] According to the general characteristics, the support of the brush comprises at least one tab, the at least one tab being different from the first lateral edge and the second lateral edge and bearing against the mounting plate in the axial direction, and the grounding brush assembly further comprises at least one securing means for rigidly securing the tab to the mounting plate, the securing means being different from the support and the mounting plate.

[0012] Thus, the brush and the mounting plate are simply and inexpensively fixed together axially and radially rigidly by means of the tab or tabs of the brush support and by means of one or more fixing means for rigidly fixing said tab to the mounting plate.

[0013] The mounting plate may be provided with a 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 tabs of the support may bear axially against the body of the mounting plate.

[0016] According to a first design, the tabs of the brush support directly abut against the mounting plate in the axial direction.

[0017] According to a second design as another option, the fixing member is axially interposed between the mounting plate and the protruding piece of the support member. In such a manner that the fixing member is interposed axially, the protruding piece of the support member indirectly abuts against the mounting plate axially.

[0018] The tab of the brush support may extend from a mounting portion of the brush support.

[0019] The tab of the brush support may extend from a first lateral edge of the brush support.

[0020] The fixing member may be electrically conductive.

[0021] The fixing member may be made of a conductive material.

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

[0023] The fixing means may include glue and / or adhesive and / or welding (weld) and / or brazing (braze).

[0024] The support of the brush may comprise a plurality of tabs which bear against the mounting plate in the axial direction and are regularly or irregularly spaced from one another in the circumferential direction.

[0025] The grounding brush assembly may include a plurality of fixing members (all of which may or may not be conductive) for rigidly fixing the tab to the mounting plate. The fixing members may be the same 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 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.

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

[0028] - a step of partially cutting the support of the brush and forming said tabs of said support by bending;

[0029] - a positioning step, in which the grounding brush is brought axially against the mounting plate; and

[0030] - an assembly step in which said tabs of said support are rigidly fixed to a mounting plate using said fixing means. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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:

[0032] [ 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 a first exemplary embodiment of the present invention;

[0033] [ Figure 2 ]yes Figure 1 An end view of a grounding brush assembly;

[0034] [ Figure 3 ]yes Figure 2 A cross-sectional view of the assembly along axis III-III;

[0035] [ Figure 4 ]yes Figure 3 Detailed picture of

[0036] [ Figure 5 ] schematically depicts the assembly process Figures 1 to 4 A method for grounding a brush assembly;

[0037] [ Figure 6 ] is a cross-sectional view of a grounding brush assembly according to a second exemplary embodiment of the present invention; and

[0038] [ Figure 7 ]yes Figure 6 Detail picture of. DETAILED DESCRIPTION

[0039] Figure 1 A portion of an electric motor or electric machine 2 is shown in axial section, comprising a fixed casing 4, a shaft 6 (in particular a rotating shaft) with an axis XX supported radially by a bearing 8. The bearing 8 is, for example, a rolling bearing, such as a ball bearing. In a variant, other rolling elements, for example rollers, can be envisaged. In another variant, a sliding bearing can also be envisaged.

[0040] 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 press-fitted into the bore 12 of the housing.

[0041] like Figure 2 and Figure 3 As more clearly shown in FIG. 1 , the assembly 10 has a generally annular shape.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] In the present case, the mounting portion 24 extends in the axial direction. In a variant, the mounting portion 24 extends obliquely.

[0047] 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.

[0048] 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.

[0049] As will be described in greater detail below, the brush support 22 also includes a plurality of tabs 40 for rigidly securing it to the mounting plate 18 .

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

[0051] The body 30 of the mounting plate 18 comprises two opposite end faces 34, 36 which delimit the axial thickness of the body 30 of the mounting plate 18. The first lateral edge 26 of the support of the brush bears against the end face 36 of the body 30 in the axial direction.

[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 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 38 is formed.

[0053] 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.

[0054] 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 at a distance from the mounting portion 24 of the support 22 of the brush 16. In one variant, each centering portion 32 may extend only in the axial direction. In another variant, each centering portion 32 may extend at least in the axial direction relative to the support 22 of the brush 16.

[0055] As mentioned above, the support 22 of the brush 16 also includes a plurality of tabs 40 .

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

[0057] Each tab 40 of the support member 22 bears against the mounting plate 18 in the axial direction. More specifically, each tab 40 of the support member 22 bears against the end surface 36 of the main body 30 of the mounting plate 18 in the axial direction.

[0058] In the example shown, each tab 40 of the support 22 is configured to extend toward one of the centering portions 32 of the mounting plate 18, with the free end of each tab 40 being radially spaced a distance from the centering portion 32. Alternatively, all or some of the tabs 40 of the support 22 may extend in the direction of (towards) the notch 38 of the mounting plate 18. In a variant, all or some of the tabs 40 of the support 22 may also extend against the centering portion 32 of the mounting plate 18.

[0059] The tabs 40 are offset from one another in the circumferential direction of the assembly 10, in this case, regularly offset from one another. In the exemplary embodiment shown, there are eight tabs 40. As another alternative, a different number (e.g., more or less) of tabs 40 may of course be provided.

[0060] The assembly 10 also includes a securing means 42 ( Figure 4 ), a fixing member 42 is associated with each of the lugs 40 of the support 22 for rigid fixing to the mounting plate 18. Therefore, the number of fixing members 42 is equal to the number of lugs 40.

[0061] The fixing member 42 is an element that is different from (distinct from) the support member 22 and the mounting plate 18 , and is added to the support member 22 and the mounting plate 18 .

[0062] In the exemplary embodiment shown, each fixing part 42 is arranged between the free end edge of the associated tab 40 and the end face 36 of the body 30 of the mounting plate 18. The fixing part 42 covers the free end edge of the associated tab 40 and partially covers the end face 36 of the body 30 of the mounting plate 18. In the present case, each fixing part 42 comprises a weld, and each tab 40 of the support 22 bears directly against the mounting plate 18 and is welded to the body 30 of the mounting plate 18.

[0063] Alternatively, the fixing member 42 may include at least one of: glue, adhesive or brazing. In this case, the tabs 40 of the support 22 are indirectly supported against the mounting plate 18, so that the fixing member 42 is axially interposed 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 in the radial direction. In a variant, all or some 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 one piece. Alternatively, the tabs 40 of the support 22 may be separate components formed separately and attached to the support 22 by any suitable means (e.g., by welding or adhesive bonding).

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

[0067] The mounting plate 18 and the grounding brush 16 include a conductive material, such as aluminum, stainless steel, bronze, copper ( / red copper), or another material.

[0068] Advantageously, each fixing part 42 is also made of a conductive material to further promote the dissipation of electric charges. Thus, the electric charges accumulated on the shaft 6 during operation of the electric machine 2 are dissipated toward the housing 4 through the conductive fibers 20, the support 22 of the brush 16, the fixing parts 42 and the mounting plate 18. However, it is possible to provide fixing parts 42 made of non-conductive material.

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

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

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

[0072] Figure 5 A method for assembling the assembly 10 is schematically depicted.

[0073] The method begins with a step 44 of forming the tab 40 , in which the first lateral edge 26 of the support member 22 is cut and bent to form the tab 40 .

[0074] Next comes a positioning step 46 in which the support 22 of the brush 16 is brought into axial contact with the mounting plate 18. More specifically, the support 22 of the brush 16 is brought into abutment against the body 30 of the mounting plate 18, the first lateral edge 26 of the support and the tabs 40 bearing against the body 30 in the axial direction.

[0075] This is followed by an assembly step 48 in which the tabs 40 of the support 22 are rigidly secured to the mounting plate 18 using the securing members 42 .

[0076] In the exemplary embodiment just described, the tabs 40 of the support 22 of the brush 16 extend from the mounting portion 24 of the support 22. As another alternative, Figure 6 and Figure 7 As shown in FIG. 1 (wherein like elements have like reference numerals), the tab 40 of the support 22 of the brush 16 can extend from the first lateral edge 26 of the support 22. In the present case, the tab 40 extends from the large diameter edge of the first lateral edge 26 of the support 22.

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: The support (22) of the brush (16) includes at least one tab (40), which is different from the first lateral edge (26) and the second lateral edge (28) and is axially supported against the mounting plate (18), and the grounding brush assembly (10) also includes at least one fixing member (42) for rigidly fixing the tab (40) to the mounting plate (18), the fixing member (42) being different from the support (22) and 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 protrusion (40) of the support member (22) being supported axially against 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 protrusion (40) of the brush support member directly abuts against the mounting plate (18) in the axial direction, or, wherein the protrusion (40) of the support member (22) indirectly abuts against the mounting plate (18) in the axial direction in a manner that the fixing member (42) is inserted in the axial direction.

4. The grounding brush assembly (10) according to any one of the preceding claims, characterized in that The tab (40) of the brush support extends from a mounting portion (24) of the support, or from a first lateral edge (26) of the support.

5. The grounding brush assembly (10) according to any one of the preceding claims, characterized in that The fixing component (42) is made of conductive material.

6. A 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).

7. A grounding brush assembly (10) according to any one of the preceding claims, characterized in that The fixing member (42) comprises glue and / or adhesive and / or welding and / or brazing.

8. The grounding brush assembly (10) according to any one of the preceding claims, characterized in that The support (22) of the brush (16) includes a plurality of lugs (40) which bear against the mounting plate (18) in the axial direction and are spaced apart from each other in the circumferential direction, and the grounding brush assembly (10) includes a plurality of fixing members (42) for rigidly fixing the lugs (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 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.

10. A method for assembling a grounding brush assembly (10) according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: - a step (44) of forming said tabs (40) of said support (22) of said brush (16) by partially cutting said support (22) and by bending; - a positioning step (46), in which the grounding brush (16) is brought into axial contact with the mounting plate (18); and - an assembly step (48) in which the tab (40) of the support (22) is rigidly fixed to the mounting plate (18) using the fixing means.

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