Grounding brush assembly

Abstract

A ground brush assembly. The ground brush assembly (10) comprises a ground brush (16) and a mounting plate (18) for the brush (16), the brush (16) being provided with a plurality of electrically conductive fibers (20) and a support (22), the electrically conductive fibers (20) being housed inside the support, a mounting plate (18) is fixed to the support (22) and provided with a radially extending body (32), a retaining tongue (34) for axially and radially retaining the support (22), and an axially extending centering portion (36), the mounting plate (18) comprising at least one flange (40) extending radially inward from a distal end of the axial portion (36).

Description

Technical Field

[0001] This invention relates to the field of grounding devices for controlling shaft current generated in electric motors or machines, and particularly to grounding brush assemblies. Background Technology

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

[0003] During operation, when the shaft rotates, a potential difference may occur between the shaft and the housing of the electric motor or machine, thereby generating a current between the inner ring (fixed to the shaft) and the outer ring (fixed to the housing) of the rolling bearing.

[0004] Current flowing through the components of a rolling bearing can damage these components, particularly the rolling elements and the raceways formed on the inner and outer rings. Discharge can also generate vibration.

[0005] To overcome these drawbacks, a known practice is to ground the rotating shaft using a grounding brush that includes conductive fibers. The grounding brush is typically installed in a hole in the motor mount, such that the free end of the fiber makes radial contact with the outer surface of the rotating shaft.

[0006] Thanks to the conductivity of the fibers, the brush maintains the same potential as the motor housing. The inner and outer rings of the rolling bearing also operate at the same potential, which reduces or even eliminates problematic discharges through the rolling bearing.

[0007] Document US-A1-2021 / 0021180 discloses a grounding brush assembly including a grounding brush and an annular mounting plate. The grounding brush is provided with a support and multiple conductive fibers mounted in the support. The annular mounting plate is provided with multiple tongues for holding the grounding brush support in the radial and axial directions, and an annular outer flange surrounding the brush and tongues in the radial direction. The tongues are formed by plastic deformation of the mounting plate.

[0008] This grounding brush assembly is force-fitted into the hole of the seat, making it difficult to remove.

[0009] The present invention aims to overcome this shortcoming. Summary of the Invention

[0010] The present invention relates to a grounding brush assembly for an electric motor, the electric motor having a rotating shaft, a fixed housing, and bearings.

[0011] The component includes a grounding brush with multiple conductive fibers and a support member, the conductive fibers being installed inside the support member. The component also includes a brush mounting plate fixed to the brush support member.

[0012] The mounting plate includes: a body formed of a radially outwardly extending radially relative to the support member; a plurality of centering tongues projecting axially relative to the radially extending portion, each tongue partially radially surrounding and radially contacting the support member of the brush, the support member being held by the tongues to axially bear against the radially extending portion of the mounting plate; and a centering portion extending axially at least from the body, extending axially on the same side as the tongues, radially offset relative to the support member and the tongues, and having an outer surface defining the outer diameter of the mounting plate to center the mounting plate after it is installed in a hole in the seat of an associated electric motor.

[0013] According to a general feature of the invention, the centering portion includes at least one flange extending radially inward from the distal end of the axial portion.

[0014] In one embodiment, the centering portion may be annular. Alternatively, the centering portion may include a plurality of axial portions spaced apart from each other in the circumferential direction.

[0015] In one embodiment, the flange is annular. Alternatively, the mounting plate includes a plurality of flanges spaced apart from each other on a circumferential portion, each flange extending radially inward from the distal end of the axial portion of the centering portion.

[0016] The present invention also relates to an electric machine or motor, comprising a base, a shaft, and a grounding brush assembly as defined above, the grounding brush assembly being at least partially radially mounted between the base and the shaft, the conductive fibers of the assembly being in contact with the shaft.

[0017] According to a preferred embodiment of the invention, the flange of the mounting plate of the component is received radially within a hole in the seat. The centering portion extends axially within the hole without extending beyond the end of the hole. Attached Figure Description

[0018] The invention will be better understood by studying the detailed description of the embodiments given by way of non-limiting example and illustrated in the accompanying drawings, in which:

[0019] Figure 1 This is an axial cross-sectional view of a grounding brush assembly, at least partially mounted radially between the rotating shaft and the seat of an electric motor, according to an exemplary embodiment of the present invention.

[0020] Figure 2 yes Figure 1 A 3D view of the grounding brush assembly in the image;

[0021] Figure 3 yes Figure 1 Front view of the grounding brush component in the middle;

[0022] Figure 4 yes Figure 3 The component in the cross-sectional view along line II; and

[0023] Figure 5 yes Figure 3 The component in the diagram is shown in the cross-sectional view along line II-II. Detailed Implementation

[0024] Figure 1 A portion of an electric motor or machine 2 is shown in axial section. The electric motor or machine 2 includes a fixed base 4 and a rotating shaft 6 having an axis XX, which is radially supported by a bearing 8. The bearing 8 is, for example, a spherical rolling bearing. As a variation, other rolling elements, such as rollers, can be envisioned. In another variation, a sliding bearing can be envisioned.

[0025] Motor 2 includes a grounding brush assembly 10, which is at least partially mounted radially between a bore 12 in the housing and an outer cylindrical surface 14 of the shaft. The assembly 10 is, for example, force-fitted into the bore 12 in the housing.

[0026] In the remainder of the specification, the adjectives "axial" and "radial," and the adverbs "in the axial direction" and "in the radial direction," are defined relative to the central axis X. Therefore, the axial portion or component is parallel to the axis X, while the radial portion or component is perpendicular to and surrounds the axis. Furthermore, the radial portion is provided with an "inner" surface oriented toward the axis X and an "outer" surface oriented away from the axis X.

[0027] like Figures 2 to 5 As can be seen more clearly, the grounding brush assembly 10 has a generally annular shape. The assembly 10 includes a grounding brush 16 and a mounting plate 18 for the brush 16.

[0028] The grounding brush 16 includes multiple conductive fibers 20 and a support 22, with the conductive fibers housed within the support 22. The conductive fibers 20 can be made of, for example, carbon, stainless steel, or conductive plastics (such as acrylic fibers or fibers made of nylon). The multiple conductive fibers 20 are in the form of open rings. In the example shown, the conductive fibers 20 are bent around a connecting wire 24. The distal free ends of the conductive fibers 20 are intended to make radial contact with the outer surface 14 of the shaft 6.

[0029] To ensure the mounting and retention of the conductive fiber 20, the support 22 includes a cylindrical portion 26, a first lateral edge 28 extending from a portion of the cylindrical portion 26, and a second lateral edge 30 extending from another portion of the cylindrical portion 26. The first edge 28 is axially positioned towards the outside of the assembly, while the second edge 30 is axially positioned towards the bearing 8, and the edges 28 and 30 are axially opposite to the cylindrical portion 26 and the fiber 20.

[0030] Mounting plate 18 is fixed to support member 22. Mounting plate 18 includes a body 32, a plurality of tongues 34 and an axial centering portion 36. The body 32 is formed by a radial portion that axially abuts against a first edge 28 of the support member. The plurality of tongues 34 are used to hold brush 16 in the axial and radial directions.

[0031] The centering portion 36 of the mounting plate 18 extends axially from the body 32 in a direction away from the bearing 8. Figures 1 to 5 In the embodiment shown, the centering portion 36 is composed of an annular cylindrical portion. As a variation, it is conceivable that the centering portion includes a plurality of axial portions spaced apart from each other on the circumferential portion.

[0032] The centering portion 36 is provided with an outer surface 38 that defines the outer diameter of the mounting plate 18, so as to center the mounting plate after it is installed in the hole 12 of the associated electric motor 2 seat 4. The centering portion 36 is preferably press-fitted into the hole 12 of the seat 4 to create diametrical interference, thereby ensuring the mechanical retention of the mounting plate 18 in the seat 4.

[0033] The tongues 34 extend from the body 32 of the mounting plate 18 and are spaced apart from each other in the circumferential portion. The tongues 34 protrude from the body 32 in the axial direction away from the bearing 8.

[0034] Each retaining tongue 34 extends from the body 32 of the mounting plate 18 such that the retaining tongue 34 partially surrounds the support 22 of the brush 16 radially, while simultaneously contacting the support 22 radially. The support 22 is held axially by the tongue 34. Furthermore, each tongue 34 has a curved edge on the support 22 to create axial contact. The support 22 is held by the tongue 34 to axially support the radial portion 32 of the mounting plate 18. Thus, the support 22 is held both axially and radially by the retaining tongue 34.

[0035] In the example shown, the mounting plate 18 includes eight retaining tongues 34 that are regularly spaced apart in the circumferential region. As a variation, the mounting plate includes a different number of retaining tongues 34. If the mounting plate 18 includes multiple centering portions, the positions of the tongues 34 may alternate with the centering portions in the circumferential direction.

[0036] The centering portion 36 extends axially from the body 32, extends axially on the same side as the support 22 and the tongue 34, and is radially offset outward relative to the support 22 and the tongue 34.

[0037] The cylindrical portion 26 of the support 22 is in radial contact with the retaining tongue 34, and the second lateral edge 30 is in axial contact with the tongue. The cylindrical portion 26 extends from the large-diameter boundary of the first lateral edge 28. The cylindrical portion 26 extends axially here.

[0038] The second lateral edge 30 of the support 22 extends radially inward from the cylindrical portion 26. The second lateral edge 30 extends from the cylindrical portion 26 on the side opposite to the first lateral edge 28. The cylindrical portion 26, the first lateral edge 28, and the second lateral edge 30 are annular in shape and define a radially inwardly open channel in which one end of the conductive fiber 20 is positioned. The first lateral edge 28 and the second lateral edge 30 axially clamp the conductive fiber 20. The conductive fiber 20 axially abuts against the first lateral edge 28 and the second lateral edge 30 on each side.

[0039] In the exemplary embodiment shown, the conductive fiber 20 radially abuts against the cylindrical portion 26, and the first lateral edge 28 and the second lateral edge 30 extend inwardly at an angle from the cylindrical portion 26. As a variation, the first lateral edge 28 and the second lateral edge 30 may extend radially.

[0040] In the exemplary embodiment shown, the mounting plate 18 and the support member 22 are two separate pieces. As a variation, the mounting plate 18 and the support member 22 can be manufactured as a single piece, for example, by cutting and pressing. In this case, the body 32 of the mounting plate 18 extends from the first side toward the small-diameter boundary of the edge 28.

[0041] Mounting plate 18 and grounding brush 16 comprise conductive materials such as aluminum, stainless steel, bronze, copper, or another material.

[0042] According to the invention, the mounting plate 18 further includes an annular flange 40 extending radially inward from the distal end of the axial and annular centering portion 36 of the mounting plate 18.

[0043] In the example shown, flange 40 has a connecting portion for connecting to the curved centering portion 36 and a radially extending portion extending from the connecting portion. As a variation, flange 40 may extend purely radially.

[0044] Refer again Figure 1 The component 10 is partially mounted radially between the hole 12 of the housing and the outer cylindrical surface 14 of the shaft, such that the radial portion 32 of the mounting plate 18 is axially supported against the shoulder of the housing 4. The centering portion 36 of the mounting plate 18 is radially supported against the hole 12 of the housing.

[0045] With this invention, the grounding brush assembly 10 can be installed in the seat 4 and on the rotating shaft 6 in a simple manner without the risk of deformation.

[0046] In practice, according to existing technology (e.g., US-A1-2021 / 0021180), the grounding brush assembly is press-fitted into the hole of the seat by an installation tool that axially abuts against the edge of the tongue and applies force in the axial direction of insertion. This installation method requires proper design of the grounding brush assembly, in particular, the tongue and support 22 need to have sufficient radial dimensions to withstand the applied force.

[0047] Using this invention, the grounding brush assembly 10 is press-fitted into the hole 12 of the seat by an installation tool (not shown) that axially abuts against the lateral surface of the flange 40 and applies force in the axial direction of insertion. Therefore, the tongue no longer functions as a support tool and can be appropriately dimensioned solely for its function of holding the support member 22. The tongue 34 and the support member 22 can be dimensioned in a reduced manner relative to prior art assemblies, allowing the assembly 10 to achieve radial compactness. The flange, in itself, is dimensioned in a suitable manner to provide support for the installation tool without affecting the radial compactness of the assembly 10.

[0048] Therefore, the tongue 34 and the support 22 are no longer subjected to direct forces applied by the installation tool, thereby eliminating the risk of deformation of the components during the insertion of the assembly 10 into the seat 4.

[0049] According to the embodiment shown, the annular flange 40 of the mounting plate 18 of the assembly 10 is radially received within the bore 12 of the seat 4. The centering portion 36 extends axially inside the bore 12 without extending beyond the end of the bore. Thus, the assembly 10 maintains optimal axial compactness. According to a variation not shown, and depending on possible needs, the centering portion 36 may extend axially beyond the bore 12, in which case the flange 40 will be outside the bore 12.

[0050] Flange 40 extends radially inward, thereby allowing removal of assembly 10 from seat 4 using a removal tool (not shown). This tool can be designed to enter the space defined between the radial portion 32 of the plate and flange 40, axially abutting against the inner surface of the flange. Thus, the removal tool can apply axial force on opposite sides of seat 4 in a direction opposite to the insertion direction. In this way, assembly 10 can be easily installed and then removed. Maintenance operations can be easily performed to replace assembly 10 according to the invention.

[0051] Finally, the flange allows for increased rigidity of the centering portion 36, which is forcibly mounted in the seat 4. The risk of deformation of this portion 36 during assembly or removal of component 10 is ultimately reduced.

[0052] Furthermore, all or some of the technical features of the various embodiments can be combined with each other. Therefore, the grounding brush assembly can be adapted in terms of cost, performance, and ease of use.

Claims

1. A grounding brush assembly (10) for an electric motor (2), the electric motor (2) having a shaft (6) rotatable about an axis (X), a fixed seat (4), and a bearing (8), and the grounding brush assembly (10) including a grounding brush (16) and a brush mounting plate (18), the grounding brush (16) having a plurality of conductive fibers (20) and a support member (22), the conductive fibers being installed inside the support member (22), the brush mounting plate (18) being fixed to the support member (22) of the brush, the mounting plate (18) comprising: -The main body (32) is formed by a radial portion extending radially outward relative to the support member (22). - A plurality of centering tongues (34) projecting axially relative to the body (32), each tongue (34) partially radially surrounding and in radial contact with a support (22) of the brush (16), the support (22) being held by the tongues (34) to axially support the body (32) abutting against the mounting plate (18), and - The centering portion (36), extending axially from at least the body (32), extending axially on the same side as the tongue (34), radially offset outward relative to the support (22) and the tongue (34), and provided with an outer surface (38) defining the outer diameter of the mounting plate (18) to center the mounting plate (18) after it is installed in the hole (12) of the seat (4) of the associated electric motor (2). The mounting plate (18) is characterized in that it includes at least one flange (40) extending radially inward from the distal end of the centering portion (36).

2. The component (10) according to claim 1, characterized in that, The centering portion (36) is annular.

3. The component (10) according to claim 1, characterized in that, The centering portion (36) includes a plurality of axial portions spaced apart from each other in the circumferential direction.

4. The component (10) according to any one of the preceding claims, characterized in that, The flange (40) is annular.

5. The component (10) according to any one of claims 1 to 4, characterized in that, The mounting plate (18) includes a plurality of flanges (40) spaced apart from each other in the circumferential direction.

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

7. The motor (2) according to claim 6, characterized in that, The flange (40) of the mounting plate (18) of the component (10) is radially accommodated in the hole (12) of the seat (4).

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