SPLIT BRUSH WITH METAL CLIP

Abstract

A brush device includes: a first and a second flange disposed side by side, each flange extending radially between a rubbing face intended to rub against a moveable element and a flange head intended to be connected electrically to another moveable element, a first plate rigidly fixed to the first flange only and extending tangentially above the head of the second flange, in such a way as to transmit, when this first plate is loaded by pressure unit, pressure forces on the second flange, a second plate, distinct from the first plate, rigidly fixed to the second flange only and extending tangentially above the head of the first flange in such a way as to bear on the first flange in the event of relative motion of the second flange with respect to the first flange towards the first moveable element.

Claims

1-10. (canceled)

11. A brush device (1) for the transmission of electric power between a first and a second element, mobile in relation to one other, comprising: a first (11) and a second (12) wafer disposed side by side, each wafer extending radially between a contact surface intended to slide against the first mobile element and a wafer top (71, 72) intended to be electrically connected to the second element, a first plate (41) rigidly fixed to the first wafer only, and extending tangentially over at least a portion of the top of the second wafer, so as to transmit pressure forces, when pressing means bias said first plate, onto the second wafer so that the contact surfaces of the first and second wafers slide on the first mobile element, said device further comprising: a second plate (42), distinct from the first plate, rigidly fixed to the second wafer only and extending tangentially over at least a portion of the top of the first wafer so as to press on said first wafer in case of relative movement of the second wafer in relation to the first wafer toward the first mobile element.

12. The brush device (1) as claimed in claim 11, said device being designed so that when the first plate (41) transmits the pressure forces onto the second wafer (12), the second plate (42) and the part (31) of, or fixed to, the top (71) of the first wafer (11) susceptible of being abutted against the second plate in case of relative motion of the second wafer with respect to the first wafer is separated by a clearance having a thickness in the radial direction between 100 μm and 1 mm.

13. The brush device (1) as claimed in claim 11, wherein each wafer (11, 12) extends between the contact surface (61, 62) and an top surface (31, 32) at the end of the top (71, 72), wherein the second plate (42) extends above the top surface (31) of the first wafer.

14. The brush device (1) as claimed in claim 13, wherein the second plate (42) extends between the first plate (41) and the top surface (31, 32) of the first wafer (11) and of the second wafer (12).

15. The brush device (1) as claimed in claim 11, wherein the second plate (42) comprises an attachment part (425) rigidly fixed to a side or front face of the second wafer, and a pressing part (426) extending tangentially above the top of the first wafer (11), wherein the wafers (11, 12) define notches (491) to receive the pressing part of the second plate.

16. The brush device (1) as claimed in claim 11, wherein the first plate (41) is cantilevered.

17. The brush device (1) as claimed in claim 11, wherein the first plate (41) and the second plate (42) are fixed to the first wafer (11) and to the second wafer (12), respectively, by riveting.

18. The brush device (1) as claimed in claim 11, wherein the second plate (42) defines, at one end above the first wafer, a flange (435) extending in a direction having a radial component, and the first plate (41) defines a cavity to receive this flange so that the first and the second plate cooperate with each other when the wafers (11, 12) cooperate with one other.

19. A rotating electrical machine comprising a brush device (1) as claimed in claim 11.

20. An aircraft or a spacecraft comprising the brush device (1) of claim 11.

21. The brush device (1) as claimed in claim 12, wherein each wafer (11, 12) extends between the contact surface (61, 62) and an top surface (31, 32) at the end of the top (71, 72), wherein the second plate (42) extends above the top surface (31) of the first wafer.

22. The brush device (1) as claimed in claim 12, wherein the second plate (42) comprises an attachment part (425) rigidly fixed to a side or front face of the second wafer, and a pressing part (426) extending tangentially above the top of the first wafer (11), wherein the wafers (11, 12) define notches (491) to receive the pressing part of the second plate.

23. The brush device (1) as claimed in claim 13, wherein the second plate (42) comprises an attachment part (425) rigidly fixed to a side or front face of the second wafer, and a pressing part (426) extending tangentially above the top of the first wafer (11), wherein the wafers (11, 12) define notches (491) to receive the pressing part of the second plate.

24. The brush device (1) as claimed in claim 14, wherein the second plate (42) comprises an attachment part (425) rigidly fixed to a side or front face of the second wafer, and a pressing part (426) extending tangentially above the top of the first wafer (11), wherein the wafers (11, 12) define notches (491) to receive the pressing part of the second plate.

25. The brush device (1) as claimed in claim 12, wherein the first plate (41) is cantilevered.

26. The brush device (1) as claimed in claim 13, wherein the first plate (41) is cantilevered.

27. The brush device (1) as claimed in claim 14, wherein the first plate (41) is cantilevered.

28. The brush device (1) as claimed in claim 15, wherein the first plate (41) is cantilevered.

29. The brush device (1) as claimed in claim 12, wherein the first plate (41) and the second plate (42) are fixed to the first wafer (11) and to the second wafer (12), respectively, by riveting.

30. The brush device (1) as claimed in claim 13, wherein the first plate (41) and the second plate (42) are fixed to the first wafer (11) and to the second wafer (12), respectively, by riveting.

Description

[0057] The invention shall be better understood when taken in conjunction with the figures, which illustrate the embodiments which are non-limiting and given by way of example.

[0058] FIG. 1 is a perspective view of a part of an example of a brush device according to an embodiment of the invention, in a separated state.

[0059] FIG. 2 is a perspective view of an example of a brush device according to another embodiment of the invention.

[0060] FIG. 3 is a perspective view of an example of a brush device according to an embodiment of the invention, in a separated state.

[0061] FIG. 4 is a view of a side face of an example of a brush device according to an embodiment of the invention.

[0062] FIG. 5 is a top view of an example of a brush device according to an embodiment of the invention.

[0063] Identical references may be used from one figure to another to designate identical or similar elements, in form or in function.

[0064] The brush devices illustrated were designed for brush starters-generators, for an aeronautical application.

[0065] These brush devices, also called brushes, are thus intended to be subjected to relatively strong vibrations, and possibly to relatively high temperatures since electrical machines may be integrated or enclosed. These vibrations are susceptible to cause miscellaneous damage to an electrical machine. For example, there is a risk that the brush becomes detached.

[0066] Advantageously, consideration may be given to riveting the cables to the wafers so as to limit this risk.

[0067] There is also a risk of damaging the cables, or even the insulating sheaths.

[0068] In addition, the front faces of the brush, or sometimes even the side faces, are likely to wear due to the friction of the brush in the brush holder.

[0069] Finally, the contact surface and the edges of the brush are susceptible to experience relatively high electrical wear due to electrical arcing induced by the brush jumping on the commutator, particularly when the bars of the commutator are imperfectly aligned.

[0070] The use of split brushes may largely compensate for this latter disadvantage since the electrical contact with the bars of the commutator may be more effective.

[0071] In reference to FIG. 1, the brush device 1 comprises a first wafer 11 and a second wafer 12, normally placed against one other. In FIG. 1, these wafers 11, 12 are in a separated state.

[0072] The top of the brush 1 is slightly beveled, i.e. that the top surfaces 31, 32 form a light angle with the contact surfaces not visible in FIG. 1. FIG. 4, described below, shows another brush example having such an angle. This may allow for better mechanical stability.

[0073] The cables 21, 21′, 22, 22′ are riveted to wafers 11, 12.

[0074] A first plate 41 is fixed by riveting to the first wafer 11. This first plate 41 comprises an attachment part 415 secured by rivets 419 to the first wafer.

[0075] The first plate 41 further comprises a supporting part 416, of one single piece with the attachment part 415, and extends above the tops of wafers 11 and 12, so that, if a spring (not shown) exerts pressure on an upper planar surface 411 of this pressing part 416, the first wafer 11 is under this pressure due to the rigid attachment to the first plate 41, and the second wafer 12 is also under this pressure since the pressing part 416 abuts against a planar surface 421 of a second plate 42 rigidly fixed to the second wafer 12.

[0076] This second plate 42 comprises an attachment part 425 fixed by rivets 422 to the second wafer 12, and a pressing part 426 in the general shape of a strip. The parts 425, 426 are made in one piece.

[0077] When the wafers 11, 12 are assembled, the pressing part in the shape of a tab 426 becomes housed between the upper surface 31 of the first wafer 11, and a lower planar surface 412 of the pressing part 416 of the first plate 41 opposite the upper planar surface 411. Thus, if the second wafer 12 is driven, for example, due to vibrations, toward a commutator (not shown), such that the second wafer 12 tends to move away from the first wafer 11, the planar surface 421 of the second plate 42 exerts pressure on the upper surface 31 of the first wafer 11, such that the first wafer 11 is driven toward the commutator.

[0078] The invention is in no way limited by the form of the pressing system used. A spring, or other element, may be provided.

[0079] The rivets 419 (422, respectively) used to secure the attachment part 415 (425, respectively) extend tangentially so as to traverse the top 71 of the first wafer 11 (top 72 of the second wafer 12, respectively).

[0080] These rivets 419 (422, respectively) are also used to fix the cables 21, 21′ (cables 22, 22′, respectively). More precisely, during the manufacture of the brush, cavities are formed in the wafers 11, 12 to receive the rivets 419, 422. The cable ends are wrapped around the rivets, then a welding is performed to rigidly secure the cables and platelets on the wafers.

[0081] The first plate 42 is cantilever, such that at the end of service life, the part 416 forming a tab is blocked on a cage of a brush holder (not shown). Owing to the cooperation of the part 426 of the second plate with the first wafer 11, the second wafer 12 also remains suspended.

[0082] This brush 1 is advantageous in relation to the existing split brush with pressing plate, in that the wear of the wafers is more symmetrical than with these existing brushes. For the existing split brushes with pressing plates, the pressure exerted by the spring may be relatively uneven. The second wafer, said free wafer, may be susceptible to receive less pressure thrust than the first wafer, and, as a result, there is a risk of slippage with respect to the first wafer.

[0083] With the brush 1, the risk of friction wear between the two opposing faces of the wafers is thus reduced.

[0084] In addition, the cables 22, 22′ fixed to the second segment will likely be under less stress than in the prior art.

[0085] In addition, electrical wear of the second wafer 12 may be less than in the prior art since, with this brush 1, the relative movements of excessive amplitude are thus prevented. The invention may therefore limit the degradation of the commutator and disconnection of the generator.

[0086] In addition, when the brush 1 reaches the end of its service life, i.e. when the lead wafer 11 is blocked by the cantilever end of the first plate 41 pressing on the cage of the brush holder (not shown), the free wafer 12 is also held suspended, owing to the second plate 42.

[0087] In addition to the upper planar surface 411, the first plate 41 defines two side edges 413, 414 protruding from said surface 411. These edges 413, 414 make it possible to maintain the end of spring on the surface 411.

[0088] The plates 41, 42 occupy a central position on the top surfaces of the wafers 11, 12 thereby freeing up the locations for the attachment of cables 21, 21′, 22, 22′.

[0089] In the embodiment of FIG. 2, notches 491 are provided on the tops of the wafers 11, 12, to receive the pressing part 426 of the plate 42. These notches form a groove having dimensions substantially corresponding to those of the pressing part 426.

[0090] The raising of the pressing part 426, therefore, remains limited, and advantageously the height of the notches (depending on the radial direction) is slightly greater than the thickness of the metal sheet from which the second plate is made, such that the pressing part 426 of the second plate is flush with the upper surface of each of the wafers 11, 12. We may thus consider using a first plate with the same dimensions and the same position relative to the first wafer, as in the prior art.

[0091] Thus, the pressing part 426 is slid into the notch on the top of the lead wafer 11. The two wafers may be relatively well adjusted with respect to one other, and the support of the spring on the free wafer 12 may be improved.

[0092] An additional notch 490 is further provided, extending radially, to receive the attachment part 425 of the second plate 42.

[0093] In the embodiment of FIG. 3, the pressing part 426 of the second plate 42 defines a projecting end 435, and the first plate 41 defines a recess, not visible in FIG. 3, to receive this projecting end 435. The free end of the second plate is thus bent, and an arrangement is provided in the plate 41 of the lead wafer 11 so that the plates 41, 42 fit into one another, thereby improving the fastening of the wafers 11, 12.

[0094] As shown in FIG. 4, a kerf 50 may be provided on one side face, or on both side faces.

[0095] As shown in FIG. 4, the angle formed between the top surfaces and a plane normal to the radial direction (typically the plane of the contact surfaces in the case of planar contact surfaces) may be in the order of 15°.

[0096] Furthermore, it may be noted that in the example illustrated in this figure, the contact surfaces 61, 62 are curved, the wafers 11, 12 being shaped and disposed so that these faces 61, 62 form a surface with relatively little discontinuity between the wafers 11, 12.

[0097] As shown in FIG. 5, a notch 118 extending radially may be defined in the first wafer, to receive the attachment part 415 of the first plate 41.

[0098] The wafers 11, 12 may be made of electrographite or metal-graphite material, for example, copper-graphite or silver-graphite. These brushes may be impregnated, especially for an application in the aeronautics sector.

[0099] The invention may thus help to improve the wear symmetry of the wafers, and thus limit the risk of damage to the generator in a relatively simple and reliable manner and without downgrading the performance characteristics of the brush.

[0100] Furthermore, it may be noted that the brush described above may be compatible with rings known in the prior art. This brush may thus be used in place of an existing brush.