Patent ID: 12249880

DETAILED DESCRIPTION OF THE INVENTION

FIG.1shows, in axial section, part of an electric motor10or machine comprising a fixed housing12and a rotary shaft14rotatable about a central axis X-X, which is supported radially by a rolling bearing16. In this instance, the bearing is of the ball type. Alternatively, the bearing16may include other types of rolling elements (e.g., cylindrical rollers, needles, etc.) or be formed as a journal bearing.

The motor10further comprises a grounding brush assembly20which is mounted radially between the bore12aof the housing12and the outer cylindrical surface14aof the rotary shaft14.

The grounding brush assembly20serves to continuously dissipate the electrical charge accumulating on the shaft14of the motor10when the motor10is in operation, by transferring this charge to the housing12.

With reference toFIGS.2to5, a grounding brush assembly20according to a first example or embodiment of the invention will now be described.

As illustrated inFIGS.2and3, the grounding brush assembly20has a generally annular shape. The assembly20comprises a grounding brush30and a brush mounting plate40which is configured to axially and radially retain the brush30.

The brush30comprises a plurality of conductive individual fibers31which are intended to come around or be disposed about the rotary shaft14of the motor10. The conductive fibers31may be made of carbon, stainless steel, conductive plastics, such as fibers made of acrylic or nylon, etc.

The brush30further comprises a holding or support member32, in the interior of which the conductive fibers31are mounted. In the exemplary embodiment illustrated, the support32is in the form of an open ring.

As illustrated more clearly inFIG.4, the support32comprises an annular axial portion32aand two annular lateral portions32b,32cextending radially inwards in order to grip the conductive fibers31. The axial portion32aand the two lateral portions32b,32cdelimit a channel which is radially open on the inside and in the interior of which one end of the conductive fibers31is positioned.

In the example illustrated, the lateral portions32b,32cextend obliquely inwardly from the axial portion32a. As a variant, the lateral portions32b,32ccould extend substantially radially. In the example illustrated, the conductive fibers31are bent around a connecting wire33of the support32.

The free distal end of the conductive fibers31is intended to come into radial contact with the outer surface14aof the rotary shaft14of the motor10.

The brush30is in the form of an open ring having a first end which is circumferentially spaced apart from a second end which is circumferentially opposite the first end, as shown inFIGS.2and3. Such a circumferential spacing between two ends of the brush30allows the brush30to adapt to various diameters of the shaft14of the motor10.

Generally, the first end of the brush30and the second end are not attached to one another, but may be in contact with one another. As a variant, it remains possible to attach the first end and the second end of the brush30to one another.

The mounting plate40of the brush30comprises an annular radial main body42and a plurality of “retainer” tongues44extending from the main body42for axially and radially retaining the brush30.

As will be described in more detail below, the mounting plate40also comprises a plurality of mounting and centering sectors or tabs46extending from the main body42. The tabs46form a means for centering the mounting plate40.

As will also be described below, the mounting plate40also comprises at least one and preferably a plurality of “mounting” tongues52protruding radially outwardly with respect to the tabs46.

Referring again toFIG.4, the body42comprises two opposite front faces42a,42bwhich delimit the axial thickness of the body. The body42also comprises a cylindrical bore42cand a cylindrical axial outer surface42d(FIG.2) radially opposite to the bore42c.

Each retainer tongue44extends from the cylindrical outer surface42dof the body42. Each tongue44protrudes axially with respect to the front face42bof the body42. Each tongue44locally radially surrounds the support32of the brush30and is in radial contact with the axial portion32aof the support32. The support32of the grounding brush30is held axially bearing against the front face42bof the body42by the tongues44. As such, the tongues44serve for axially and radially retaining the grounding brush30.

Each retainer tongue44includes an axial portion44aextending axially from the cylindrical outer surface42dof the body42, and a radially inwardly folded portion44bwhich is provided at the free end of the axial portion44a. The axial portion44aof each tongue44is in the form of a cylindrical portion. The folded portion44bof each tongue44serves for axially retaining the grounding brush30. The folded portion44bof each tongue44is in axial contact against the lateral portion32cof the support32. The tongues44are in this case identical or substantially identically formed.

As illustrated inFIGS.2and3, the tongues44of the mounting plate40are spaced apart from one another in the circumferential direction, in a regular or evenly spaced manner. As an alternative, it could be possible to provide an irregular circumferential spacing (i.e., circumferentially staggered). The tongues44are distributed circumferentially around the main body42.

As indicated above, the mounting plate40also comprises a plurality of centering tabs46extending from the main body42. The tabs46extend from the cylindrical outer surface42dof the body42.

Referring toFIG.5, each centering tab46protrudes axially with respect to the front face42bof the body42. Each tab46locally radially surrounds the support32of the brush30while remaining separated therefrom (i.e., radially spaced apart from the brush30). The centering tabs46are at least partially offset radially outwardly with respect to the tongues44.

The tabs46extend axially from the same side of the body42as the tongues44. As an alternative, the centering tabs46could extend axially from the opposite side of the body42from the tongues44. Each tab46is preferably formed at least generally identical to each other tab46.

Each centering tab46includes a radial portion46aextending radially outwardly from the body42and a centering portion46bextending axially from the radial portion46aand locally radially surrounding the support32while remaining radially separated therefrom (i.e., spaced radially apart from the support32). The centering portions46bof the tabs46collectively define the outer diameter of the mounting plate40.

The radial portion46aof each centering tab46forms a connecting portion which connects the associated centering portion46bto the body42. The radial portion46aof each tab46extends radially outwardly from the outer surface of the body42.

The centering portion46bextends axially from a large-diameter edge of the associated radial portion46a. The centering portion46bextends generally axially. The centering portion46bof each tab46is in the form of a cylindrical portion. The bore in the centering portion46bof each tab46is radially spaced apart from the support32of the brush30by a non-zero radial distance. The outer surfaces of the centering portions46bof the tabs46collectively define the outer surface of the tabs46, which defines the outer diameter of the mounting plate40. The outer surface of each centering portion46bis radially opposite to the bore in each portion46b. In this exemplary embodiment, the centering portions46bof the tabs46are offset radially outwardly with respect to the tongues44.

Referring again toFIG.2, the centering portion46bof each centering tab46includes two opposite front or “axial” faces48,50(i.e., the faces48,50extend along a central axis) which delimit the centering portion46bin the circumferential direction. The centering portion46bof each tab46extends in a continuous manner in the circumferential direction between its two front faces48,50. The front/axial faces48,50of each centering portion46bare free. There is no connection between the centering portion46bof each centering tab46and either the body42or the tongues44.

As illustrated inFIGS.2and3, the centering tabs46are spaced apart from one another in the circumferential direction, in a regular or evenly spaced manner. As an alternative, it could be possible to provide an irregular or staggered circumferential spacing. The tabs46are distributed circumferentially around the main body42.

Each centering tab46is positioned in the circumferential direction between two immediately successive retaining tongues44so as to be spaced apart in the circumferential direction from the two immediately adjacent tongues44. That is, a circumferential space is formed between each centering tab46and each immediately adjacent retaining tongue44. As such, there is no portion which connects a tab46to an adjacent tongue44in the circumferential direction.

In the exemplary embodiment, each centering tab46has a circumferential dimension greater than that of the retaining tongues44. By way of indication, the circumferential dimension of the tabs46may be, for example, between 10° and 45°. In the exemplary embodiment illustrated, the number of centering tabs46is equal to the number of retaining tongues44. As an alternative, it is possible to provide a number of tabs46which differs from the number of the tongues44.

In the exemplary embodiment illustrated, the centering tabs46have an axial dimension substantially equal to the retaining tongues44. Alternatively, the tabs46may each be formed with an axial dimension different than the axial dimension of each tongue44.

As indicated above, the mounting plate40also comprises at least one and preferably a plurality of mounting tongues52protruding radially outwardly with respect to the centering tabs46, as best shown inFIG.5. Each mounting tongue52is formed on a separate one of the centering tabs46, specifically on the central portion46bof the associated tab46. Each tongue52protrudes radially outwardly with respect to the outer surface of the centering portion46bof the associated tab46. Each tongue52preferably extends obliquely outwardly and is flexible or deflectable in the radial direction.

In the exemplary embodiment illustrated, the root of each mounting tongue52is positioned axially on the side of the radial portion46aof the associated centering tab46. As an alternative, it could be possible to make provision for the root of each tongue52to be positioned axially on the side of the free end of the associated centering portion46b.

Each tongue52is formed by cutting and bending of the centering portion46bof the associated tab46. During this cutting operation, a window54is formed on the centering portion46bin such a way as to allow the associated tongue52to remain. Each window54is a through-window and each tongue52both extends inside the window54and protrudes radially outwardly from the window54.

In the exemplary embodiment illustrated, the mounting plate40comprises three mounting tongues52which are spaced apart from one another in the circumferential direction in a regular or evenly spaced manner.

As an alternative, it is possible to provide a greater or smaller number of tongues52, for example, one or two tongues52or four or more tongues52. Preferably, the number of tongues52is at least two. Also preferably, in the case of a plurality of tongues52, the tongues52are regularly or evenly spaced apart in the circumferential direction.

Each mounting tongue52has a circumferential dimension substantially smaller than that of the associated centering tab46. By way of indication, the circumferential dimension of the tongues52may, for example, be between 3° and 10°. The tongues52in the exemplary embodiment are identical to each other.

The mounting plate40is preferably produced by cutting and stamping. The mounting plate40is made of a conductive material such as aluminum, stainless steel, bronze, copper or another appropriate material.

Each mounting tongue52of the mounting plate40is intended to protrude into and engage with a groove formed in the bore12aof the housing12of the associated electric motor10. The groove may be a single annular groove engaged by all of the mounting tongues52or alternatively a plurality of discrete grooves, each groove receiving a separate one of the tongues52of the mounting plate40.

When the grounding brush assembly20is installed axially into the housing12of the associated electric motor10, the free ends of the mounting tongues52of the mounting plate40move or deflect radially inwardly, counter to their elasticity, due to the radial contact between the tongues52and the bore12aof the housing12. Once the tongues52of the mounting plate40are positioned opposite the groove in the bore12aof the housing12, the tongues52of the mounting plate40, due to their elasticity, at least partially resume their original position in the free state and serve to axially retain the assembly20relative to the housing12. The axial retention is obtained by the axial contact between the free ends of the tongues52of the mounting plate40and one of the edges of the groove in the housing12.

In this exemplary embodiment, the centering portions46bof the tabs46of the mounting plate40extend only axially. As a variant, at least some or all of the centering portions46bof the tabs46may extend obliquely outwardly, that is to say both axially and radially.

The exemplary embodiment illustrated inFIGS.6to9, in which identical elements bear the same references, differs from the first example by the design of the mounting plate40of the assembly20.

In this example, the centering tabs46of the mounting plate40of the first example are replaced by an annular flange60and the body42has an increased or greater radial dimension. In this embodiment, the body42extends radially beyond the retaining tongues44. The flange60forms a means for centering the mounting plate40.

The flange60extends axially from the body42, preferably from a large-diameter edge of the body42. The flange60extends axially, specifically protruding axially with respect to the front face42bof the body42. The flange60radially surrounds the support32of the brush30while remaining separated or spaced therefrom. The flange60is offset radially outwardly with respect to the retaining tongues44. Preferably, the flange60extends axially from the same side of the body42as the retaining tongues44. Alternatively, the flange60may extend axially from the opposite side of the body42as the tongues44. The bore in the flange60is radially spaced apart from the support32of the brush by a non-zero radial distance. The outer surface of the flange60, radially opposite to the bore in the flange60, defines the outer diameter of the mounting plate40.

In this embodiment, the body42is provided with a plurality of through-openings62which are formed in its thickness and which are spaced apart from one another in the circumferential direction. These openings62are formed during the partial cutting of the body42to form the retaining tongues44.

The mounting tongues52are formed on the flange60. The tongues52are preferably identical to those of the first exemplary embodiment. Each tongue52protrudes radially outwardly with respect to the flange60, specifically radially outwardly with respect to the outer surface of the flange60. Each tongue52preferably extends obliquely outwardly, i.e., both radially and axially. Each tongue52is flexible or deflectable in the radial direction.

In the depicted exemplary embodiment, the root of each tongue52is positioned axially on the body42. As an alternative, the root of each tongue52may be positioned axially on the side of the free end of the flange60.

Each tongue52is preferably formed by cutting and bending of the flange60. During this cutting operation, the associated window54is formed on the flange60in such a way as to allow the associated tongue52to remain, each window54being a through-window. Each tongue52both extends inside the window54and protrudes radially outwardly.

In the exemplary embodiment as depicted, the mounting plate40comprises four mounting tongues52which are spaced apart from one another in the circumferential direction in a regular or evenly spaced manner. As an alternative, it is possible to provide a greater or smaller number of tongues52.

Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention.

Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter. The invention is not restricted to the above-described embodiments, and may be varied within the scope of the following claims.