Patent ID: 12249879

DETAILED DESCRIPTION OF THE INVENTION

FIG.1shows, in axial section, part of an electric motor10or machine comprising a fixed housing12, 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. As an alternative, it is possible to provide another type of rolling elements (e.g., cylindrical rollers, needles, etc.) or 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 or functions to continuously dissipate the electrical charge accumulating on the shaft14of the motor when the motor is in operation, by transferring this charge to the housing12.

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 individual conductive 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.

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 inwardly 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 radially. In the example illustrated, the conductive fibers31are bent around a connecting wire33of the support32.

The free distal end31aof 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 brush to adapt to a different diameter of the shaft14of the motor10.

Generally, the first and second ends of the brush30are 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 retaining tongues44for axially and radially retaining the brush30, which extend from the main body42.

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.

Referring again toFIG.4, the body42comprises two opposite front faces42a,42bwhich delimit the axial thickness of the body42. The body42also comprises a cylindrical bore42cand a cylindrical axial outer surface42d(FIG.2) radially opposite to the bore42c.

Each 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. The tongues44serve for axially and radially retaining the grounding brush30.

Each tongue44comprises 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.

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. The tongues44are distributed circumferentially around the main body42. In the exemplary embodiment illustrated, the number of tongues44is six. As an alternative, it is possible to provide a different number of tongues44.

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

Referring toFIG.5, each tab46protrudes axially with respect to the front face42bof the body42. Each tab46locally radially surrounds the support32of the brush30while remaining separated therefrom. The tabs46are partially offset radially outwards with respect to the tongues44. The tabs46preferably extend axially from the same side of the body42as the tongues44. As an alternative, the tabs46could extend axially from the opposite side of the body42to the tongues44. The tabs46are in this case identical.

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 outwardly from the support32). The centering portions46bof the tabs46collectively define the outer diameter of the mounting plate40.

The radial portion46aof each 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 portion46bof each tab46is in the form of a cylindrical portion. The bore in the central portion46bof each tab46is radially spaced apart from the support32of the brush30by a non-zero radial distance. The outer surfaces of the centering portions46bof the tabs46define the outer diameter of the mounting plate40. In this exemplary embodiment, the centering portions46bof the tabs46are offset at least partially radially outwardly with respect to the tongues44.

Referring again toFIG.2, the centering portion46bof each tab46comprises two opposite front faces48,50which delimit the central portion in the circumferential direction. The centering portion46bof each tab46extends in a continuous manner in the circumferential direction between its two front faces48,50. The front faces48,50of each centering portion46bare free. There is no connection between the centering portion46bof each tab46with the body42or with the tongues44.

As illustrated inFIGS.2and3, the 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 circumferential spacing (i.e., circumferentially staggered). The tabs46are distributed circumferentially around the main body42.

Each centering tab46is positioned in the circumferential direction between two immediately successive or adjacent tongues44. Each tab46is spaced apart in the circumferential direction from the two immediately adjacent tongues44. In other words, a circumferential space is formed between each tab46and each immediately adjacent tongue44. There is no portion which connects a tab46to an adjacent tongue44in the circumferential direction.

In this instance, each tab46has a circumferential dimension greater than that of the 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 six. As an alternative, it is possible to provide a different number of tabs46. 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 tongues44.

In the exemplary embodiment illustrated, the tabs46have an axial dimension substantially equal to the tongues44. As an alternative, it is possible to provide the tabs46with axial dimensions different from the axial dimensions of the tongues44.

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.

In this exemplary embodiment, the centering portions46bof the tabs46of the mounting plate40extend only axially.

The exemplary embodiment illustrated inFIGS.6to9, in which identical elements bear the same references, differs in particular from the preceding example in that the centering portions46bof the tabs46extend obliquely outwardly. The centering portions46btherefore extend both axially and radially. The centering portions46bhave a conical or frustoconical shape. In this exemplary embodiment, the centering portions46bof the tabs46are entirely offset radially outwardly with respect to the tongues44.

With respect to the preceding example, the radial height h (FIG.7) separating the outer surface of the tongues44and the outer surface of centering portions46bof the mounting plate40is increased. The radial dimension of the radial portion46aof each tab46is thus also increased. Furthermore, in this example, the number of tongues44and tabs46of the mounting plate is increased with respect to the preceding example.

The exemplary embodiment illustrated inFIGS.10to13, in which identical elements bear the same references, differs primarily from the preceding example in that the radial height h (FIG.11) separating the outer surface of the tongues44and the outer surface of centering portions46bof the mounting plate40is increased. Therefore, the radial dimension of the radial portion46aof each tab46is also increased. In this example, the number of tongues44and tabs46of the mounting plate40is reduced with respect to the preceding example.

The exemplary embodiment illustrated inFIG.14, in which identical elements bear the same references, differs from the second exemplary embodiment in that each tab46of the mounting plate40includes a folded rim52which extends from the centering portion46bradially outwardly from the side opposite to the tongues44. The rim52of each tab46extends radially outwardly. The rim52of each tab46extends from the free end of the centering portion46bof each tab46.

This design of the tabs46of the mounting plate ensures good axial positioning of the assembly20inside the housing12of the associated electric motor10by providing a groove or a shoulder in the bore of the housing12, against which the rims52of the tabs46come into abutment.

The grounding brush assembly20according to the invention is easy to manufacture, for example by stamping, and can be adapted to the variation in diameters of shafts and housings used in electric motors, while being suitable for electric motors having a small or limited radial space between the housing and the rotary shaft.

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.