Grounding brush assembly
By using conductive fibers in the ground brush assembly and the holding tab on the mounting plate in contact with the mounting part of the support, the current damage and vibration caused by the potential difference between the rotating shaft and the housing in the electric motor is solved, and the firmness of the assembly is achieved Fixation and current reduction.
Patent Information
- Application Number
- CN202410843185.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-06-30
- Filing Date
- 2024-06-27
- Publication Date
- 2024-12-31
AI Technical Summary
In electric motors or electric machines, the potential difference between the rotating shaft and the housing causes the current between the inner and outer rings of the rolling bearings to be damaged and discharged, resulting in vibration, and existing ground brush components are difficult to effectively solve these problems.
Using a ground brush assembly including conductive fibers, a retaining tab on the mounting plate is radially in contact with the mounting portion of the support member, and an axial gap is present between the tab formed by the bending and the second side edge of the support member. , realize the firm fixation of the brush and the mounting plate to ensure the installation and maintenance of the conductive fibers.
Effectively reduce or eliminate problematic discharge through rolling bearings, prevent current damage, reduce vibration, and are simple and economical to assemble.
Smart Images
Figure CN119231280A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of grounding devices for controlling shaft voltage generated in electric motors or machines, and in particular to grounding brush assemblies. Background Art
[0002] In an electric motor or an electric machine, at least one rolling bearing is installed between a casing of the electric motor or the electric machine and a rotating shaft to support the shaft.
[0003] During operation, when the shaft rotates, a potential difference may exist between the shaft and the housing of the electric motor or electric machine, which causes a current to flow between the inner ring of the rolling bearing (rigidly fixed to the shaft) and the outer ring (rigidly fixed to the housing).
[0004] The current flowing through the components of the rolling bearing may damage the components, particularly the rolling elements and the raceways formed on the inner and outer rings. The discharge may also generate vibrations.
[0005] To overcome these drawbacks, it is known practice to use a grounding brush comprising conductive fibers to ground or connect the rotating shaft to ground or earth. The grounding brush is usually mounted in a hole in the housing of the electric motor so that the free end of the fibers is in radial contact with the outer surface of the rotating shaft.
[0006] Due to the conductivity of the fibers, the brushes are kept at the same electrical potential as the housing of the electric motor. The inner and outer rings of the rolling bearing are also at the same electrical potential, which reduces or even eliminates problematic discharges through the rolling bearing.
[0007] US-A1-2021 / 0021180 discloses a grounding brush assembly, which includes: a grounding brush provided with a support and a plurality of conductive fibers installed in the support; and an annular mounting plate provided with a plurality of tabs and an annular outer flange, wherein the plurality of tabs are used to radially and axially hold the support of the grounding brush, and the annular outer flange radially surrounds the brush and the tabs. The tabs are formed by plastic deformation of the mounting plate.
[0008] The present invention seeks to provide an alternative attachment for attaching a grounding brush to a mounting plate. Summary of the invention
[0009] The invention relates to a method for assembling a grounding brush assembly, the grounding brush assembly comprising a grounding brush and a mounting plate for the brush, the brush being provided with a plurality of conductive fibers and a support in which the conductive fibers are accommodated.
[0010] The support member comprises a mounting portion, a first lateral rim extending from the mounting portion on one side and a second lateral rim extending from the mounting portion on the other side, the first lateral rim and the second lateral rim gripping the conductive fiber in an axial direction.
[0011] The mounting plate is provided with a main body and a plurality of retaining tabs ( / tabs) for retaining a support member of the brush, each retaining tab being provided with: an axial portion extending axially from the main body, partially radially surrounding the support member of the brush and radially contacting the support member; and a radially inwardly bent portion ( / a radially inwardly bent portion) located at a free end of the axial portion.
[0012] According to the general characteristics, the method comprises the following steps:
[0013] - a positioning step in which a support of the brush is brought into axial contact with the body of the mounting plate in the axial direction, the mounting portion of the support having an outer diameter in the free state;
[0014] - a step of forming the retaining tabs of the mounting plate by partially cutting the mounting plate and by bending; and
[0015] - an assembly step in which the retaining tabs of the mounting plate are brought into radial contact with the mounting part of the support of the brush, the outer diameter of the mounting part of the support being strictly smaller than the outer diameter of the mounting part of the support in the free state in the assembled state and in the region of the axial portion of each retaining tab.
[0016] Thus, the brush and the mounting plate are simply and cheaply fixed together rigidly in the axial direction and in the radial direction by means of the retaining tabs of the support for retaining the brush. The brush and the mounting plate are also simply and cheaply fixed together rigidly in the circumferential direction by means of the retaining tabs of the support for retaining the brush which locally deform the mounting portion to an outer diameter smaller than its initial diameter in the free state.
[0017] The retaining tabs may be brought into contact with the mounting portion of the support of the brush such that there is an axial gap between the curved portion of each of the tabs and the second lateral edge of the support.
[0018] The retaining tabs may be brought into contact with the mounting portion of the support of the brush such that the outer diameters of the mounting portion of the support are the same.
[0019] The present invention also relates to a grounding brush assembly, which comprises a grounding brush and a brush mounting plate, wherein the brush is provided with a plurality of conductive fibers and a support member, wherein the conductive fibers are accommodated in the support member.
[0020] The support member includes a mounting portion, a first lateral edge extending from the mounting portion on one side, and a second lateral edge extending from the mounting portion on the other side, the first lateral edge and the second lateral edge clamping the conductive fiber in an axial direction.
[0021] The mounting plate is provided with a main body and a plurality of retaining tabs for retaining a support member of the brush, each retaining tab being provided with: an axial portion extending axially from the main body, partially radially surrounding the support member of the brush and radially contacting the support member; and a radially inward bent portion located at a free end of the axial portion.
[0022] Such an assembly can be obtained by implementing the method as defined above.
[0023] According to the overall characteristics, the mounting portion of the support is corrugated in the circumferential direction, and the mounting portion of the support includes alternating segments of small outer diameter and segments of large outer diameter, and the axial portion of each retaining protrusion is in radial contact with the segment of small outer diameter of the mounting portion.
[0024] There may be an axial gap between the curved portion of each tab and the second lateral edge of the support member.
[0025] The mounting plate may include at least one centring portion extending at least axially from a body of the mounting plate, the at least one centring portion being radially outwardly offset relative to the support and having an outer surface defining an outer diameter of the mounting plate.
[0026] The 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 the assembly being in contact with the shaft and the mounting plate being in radial contact with the aperture of the casing. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] 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:
[0028] [ Figure 1 ] is an axial cross-sectional view of a grounding brush assembly installed in a radial direction between a rotating shaft and a housing of an electric motor according to an exemplary embodiment of the present invention;
[0029] [ Figure 2 ]yes Figure 1 An end view of a grounding brush assembly;
[0030] [ Figure 3 ]yes Figure 2 A cross-sectional view of the assembly along axis III-III;
[0031] [ Figure 4 ] schematically depicts a method for assembling a grounding brush assembly according to the present invention;
[0032] [ Figure 5 ] schematically depicts Figure 4 The positioning step of the method;
[0033] [ Figure 6 ] schematically depicts Figure 4 the forming steps of the method; and
[0034] [ Figure 7 ] schematically depicts Figure 4 The assembly steps of the method. DETAILED DESCRIPTION
[0035] 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.
[0036] The motor 2 comprises a grounding brush assembly 10 which is mounted radially between a bore 12 of the housing and a cylindrical outer surface 14 of the shaft. For example, the assembly 10 is force-fitted in the bore 12 of the housing.
[0037] like Figure 2 and Figure 3 As more clearly shown in FIG. 1 , the assembly 10 has a generally annular shape.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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.
[0042] In the present case, the mounting portion 24 extends in the axial direction. In a variant, the mounting portion 24 extends obliquely.
[0043] 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.
[0044] 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.
[0045] 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 .
[0046] 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.
[0047] The centering portions 32 of the mounting plate 18 are spaced apart from each other in the circumferential direction of the assembly 10 , and a notch 38 is left between two consecutive centering portions 32 in the circumferential direction.
[0048] 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 bore of the housing 12 of the associated electric motor 2.
[0049] In the present case, each centering portion 32 extends obliquely outwards, at least partially surrounding the mounting portion 24 of the brush 16 and being radially spaced a certain distance from the mounting portion 24 of the brush 16 and the support 22. In one variant, each centering portion 32 may extend only in the axial direction. In another variant, each centering portion 32 may extend at least in the axial direction relative to the support 22 of the brush 16.
[0050] The mounting plate 18 also includes a plurality of retaining tabs 40 for rigidly securing the support 22 of the brush 16 axially relative to the mounting plate 18 .
[0051] Each tab 40 is provided with an axial portion 42 extending axially from the body 30 of the mounting plate 18, partially radially surrounding the support 22 of the brush 16, and in radial contact with the support 22 of the brush 16. More specifically, each tab 40 is in radial contact with the mounting portion 24 of the support 22. The tabs 40 of the mounting plate 18 interact by radially contacting the support 22 of the brush 16 to axially hold the support 22 of the brush 16 relative to the mounting plate 18.
[0052] The axial portion 42 of each tab 40 is radially spaced apart from the centering portion 32 of the mounting plate 18 .
[0053] Each tab 40 is also provided with a radially inwardly bent portion 44 at the free end of the axial portion 42 of the tab 40 .
[0054] The bent portion 44 of each tab 40 is axially spaced apart from the second lateral edge 28 of the support 22 of the brush 16 , so that an axial gap 46 exists between said bent portion 44 and the second lateral edge 28 of the support 22 .
[0055] 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.
[0056] The mounting portion 24 of the support 22 of the brush 16 is corrugated in the circumferential direction of the assembly 10. The mounting portion 24 of the support 22 includes alternating segments of small outer diameter and segments of large outer diameter.
[0057] The axial portion 42 of each tab 40 of the mounting plate 18 is in radial contact with a section of smaller outer diameter of the mounting portion 24 of the support 22 .
[0058] In the exemplary embodiment shown, the mounting plate 18 includes protrusions 40 and centering portions 32a that alternate in the circumferential direction of the assembly 10. Each protrusion 40 is spaced a certain distance from two centering portions 32 that are directly adjacent ( / adjacent) to it in the circumferential direction of the assembly 10. As another option, the mounting plate 18 may have a different number of protrusions 40 and a different number of centering portions 32. In a variation, the protrusion 40 may contact one or two centering portions 32 that are directly adjacent to it in the circumferential direction of the assembly 10.
[0059] The mounting plate 18 and the support 22 of the brush 16 are two separate components.
[0060] 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.
[0061] 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.
[0062] In another variation, the mounting plate 18 may include a single annular centering portion 32 forming a flange.
[0063] In the example shown, the mounting plate 18 comprises a plurality of tabs 40 regularly spaced apart in the circumferential direction of the assembly 10. In a variant, the mounting plate 18 may comprise a plurality of tabs 40 irregularly spaced apart in the circumferential direction of the assembly 10.
[0064] Figure 4 A method for assembling the assembly 10 is schematically depicted.
[0065] This method from Figure 5 The illustrated positioning step 48 begins, in which the support 22 of the brush 16 is brought into axial contact with the body 30 of the mounting plate 18, the first lateral edge 26 of the support bearing axially against the body 30 of the mounting plate 18. In the free state, the mounting portion 24 of the support 22 has an outer diameter D1 of constant value. In other words, in the unassembled state, the mounting portion 24 of the support has a single outer diameter D1.
[0066] During the positioning step 48 , the support 22 of the brush 16 is not yet rigidly fixed to the mounting plate 18 .
[0067] Next is the step 50 of forming the tabs 40, in which the mounting plate 18 is cut and bent to form the tabs 40. This step is Figure 6 In a variant, the forming step 50 can be performed before the positioning step 48 .
[0068] During step 50 , the centering portion 32 and the notch 38 may also be formed.
[0069] This is followed by an assembly step 52 in which the tabs 40 of the mounting plate 18 are brought into radial contact with the mounting portion 24 of the support 22 of the brush 16 , causing a local deformation of the support 22 of the brush 16 .
[0070] exist Figure 7 During this step shown, the lugs 40 of the mounting plate 18 are brought into radial contact with the mounting portion 24 of the support, so that the mounting portion locally (in the area where each lug 40 bears) has an outer diameter D2 that is strictly smaller than the outer diameter D1. Thus, sections of small outer diameter D2 are formed for the mounting portion 24 of the support 22. After assembly, the mounting portion 24 of the support 22 has a shape that is wavy in the circumferential direction, wherein sections (or areas) of small outer diameter D2 in the areas with lugs 40 alternate with sections (or areas) of large outer diameter D1 in the areas without lugs 40.
[0071] Advantageously, the section of the small outer diameter D2 of the mounting portion 24 of the support 22 is formed in such a way that an axial gap 46 remains between the radially inwardly bent portion 44 of the tab 40 of the mounting plate 18 and the second lateral edge 28 of the support 22 .
[0072] In the example shown, the tabs 40 of the mounting plate 18 are brought into radial contact with the mounting portion 24 of the support 22 so that their outer diameters D2 are identical. As another alternative, a different outer diameter D2 for the mounting portion 24 of the support 22 can be envisaged, strictly smaller than the outer diameter D1 of the mounting portion 24 of the support 22 in the free state.
Claims
1. A method for assembling a grounding brush assembly (2), the grounding brush assembly (2) 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 member (22), the conductive fibers (20) being accommodated in the support member (22), the support member (22) comprising 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, the first lateral edge (26) and the second lateral edge (28) being sandwiched in the axial direction. The conductive fiber (20) is held by the mounting plate (18), the mounting plate (18) being provided with a main body (30) and a plurality of retaining protrusions (40) for retaining the support member (22) of the brush (16), each retaining protrusion (40) being provided with an axial portion (42) and a radially inwardly bent portion (44), the axial portion (42) extending axially from the main body (30), partially radially surrounding the support member (22) of the brush (16), and being in radial contact with the support member (22), the radially inwardly bent portion (44) being located at the free end of the axial portion (42), characterized in that: The method comprises the following steps: - a positioning step (48) in which the support (22) of the brush (16) is brought into axial contact with the body (30) of the mounting plate (18) in the axial direction, the mounting portion (24) of the support (22) having an outer diameter (D1) in a free state; - a step (50) of forming the retaining tabs (40) of the mounting plate (18) by partially cutting the mounting plate (18) and by bending; and - an assembly step (52), in which the retaining tabs (40) of the mounting plate (18) are brought into radial contact with the mounting portion (24) of the support (22) of the brush (16), wherein, in the assembled state and in the region of the axial portion (42) of each retaining tab (40), the outer diameter (D2) of the mounting portion (24) of the support (22) is strictly smaller than the outer diameter (D1) of the mounting portion (24) of the support (22) in the free state.
2. The method according to claim 1, characterized in that The retaining tabs (40) are brought into contact with the mounting portion (18) of the support (22) of the brush (16) such that an axial gap (46) exists between the curved portion (44) of each of the tabs (40) and the second lateral edge (28) of the support (22).
3. The method according to any one of claims 1 and 2, characterized in that The retaining tab (40) is brought into contact with the mounting portion (18) of the support (22) of the brush (16) such that the outer diameter (D2) of the mounting portion (24) of the support is the same.
4. A grounding brush assembly (2), 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), and 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 in the axial direction. (20), the mounting plate (18) is provided with a main body (30) and a plurality of retaining tabs (40) for retaining the support member (22) of the brush (16), each retaining tab (40) is provided with an axial portion (42) and a radially inward bent portion (44), the axial portion (42) extends axially from the main body (30), partially radially surrounds the support member (22) of the brush (16), and is in radial contact with the support member (22), the radially inward bent portion (44) is located at the free end of the axial portion (42), characterized in that, The mounting portion (24) of the support member (22) is wavy in the circumferential direction, and the mounting portion (24) of the support member (22) includes alternating sections with a small outer diameter (D2) and sections with a large outer diameter (D1), and the axial portion (42) of each retaining tab (40) is in radial contact with the section with a small outer diameter (D2) of the mounting portion (24).
5. The grounding brush assembly (2) according to claim 4, characterized in that: An axial gap (46) exists between the curved portion (44) of each tab (40) and the second lateral edge (28) of the support member (22).
6. The grounding brush assembly (2) according to any one of claims 4 and 5, characterized in that: The mounting plate (18) includes at least one centering portion (32) extending at least axially from a body (30) of the mounting plate (18), the at least one centering portion (32) being radially outwardly offset relative to the support member (22) and having an outer surface defining an outer diameter of the mounting plate (18).
7. An electric motor, comprising a housing (4), a shaft (6) and a grounding brush assembly (2) according to any one of claims 4 to 6, wherein the grounding brush assembly (2) is radially mounted between the housing (4) and the shaft (6), the conductive fibers (20) of the grounding brush assembly (2) are in contact with the shaft (6), and the mounting plate (18) is in radial contact with the hole (12) of the housing.