Sliding contact brush for electrical sliding contact with a rotating sliding contact ring

Abstract

The invention relates to a sliding contact brush (1) with a contact surface (3) for an electrical sliding contact with a rotating sliding contact ring (2), wherein the contact surface (3) is bounded in the direction of rotation by an edge (11, 12) formed with a brush side surface (9, 10), characterized in that, to reduce wear in wet sliding contact operation, a profiled surface contour (14, 20, 21, 22) is provided on at least one brush side surface (9) extending from the edge (11), such that, with progressive wear of the contact surface (3), an obtuse edge angle (α) is formed at least section by section at the edge (11). The invention further relates to a sliding contact arrangement with at least one such sliding contact brush (1).

Description

[0001] The invention relates to a sliding contact brush for electrical sliding contact with a rotating sliding contact ring according to the type defined in more detail in the preamble of claim 1. The invention further relates to a sliding contact arrangement with at least one such sliding contact brush.

[0002] DE 10 2012 218 095 A1 discloses a sliding contact device for an electrical machine. The sliding contact device comprises an annular contact device and at least one contact brush, one end of which is pre-tensioned against the outer surface of the contact device.

[0003] The invention is therefore based on the object of proposing a sliding contact brush and a sliding contact arrangement of the aforementioned type, which enable a reduction of wear on a wet-running sliding contact in a structurally simple and cost-effective manner.

[0004] The problem is solved by the features of claim 1 and alternatively by the features of claim 8. Further advantageous and claimed embodiments emerge from the respective subclaims, the description, and the drawings.

[0005] Thus, a sliding contact brush with a contact surface for the electrical sliding contact with a rotating sliding contact ring is proposed, wherein the contact surface is limited in the direction of rotation and counter to this direction by an edge formed by a brush side surface. To enable a structurally simple and cost-effective reduction in wear on the contact surface of a wet-running sliding contact, a profiled surface contour is provided on at least one brush side surface, starting from the edge, such that, as wear progresses on the contact surface, an obtuse edge angle is created at least in sections.

[0006] Due to progressive wear and material removal at the contact surface, the edge at the transition to the brush side surface follows the profiled surface contour formed on the latter. This counteracts any sharp-edged transition to the brush side surface that may occur during operation by creating a blunt edge angle, preventing wear-prone interaction between the edge and the rotating sliding contact ring.

[0007] This is especially true for a wet-running sliding contact, where the ring contact surface of the sliding contact ring is preferably profiled to improve the electrical sliding contact. The profiled surface contour on the brush side surface reliably prevents extreme wear on the contact surface of the sliding contact brush caused by the profiling of the ring contact surface.

[0008] The obtuse edge angle is preferably greater than or equal to 90°.

[0009] In a preferred, particularly easy-to-manufacture embodiment of the invention, the profiled surface contour on the brush side surface is formed by recesses extending transversely, preferably perpendicular to the direction of wear, and parallel to one another. The recesses are thus particularly easy to produce cost-effectively in a single step, particularly by pressing or embossing. They can be easily implemented in any desired shape on the brush side surface, preferably as grooves.

[0010] The design of the surface contour can be further simplified if the surface contour on the brush side surface in the direction of wear preferably has a cross-sectional profile with uniform depressions arranged one behind the other.

[0011] Preferably, the recesses form a wave-shaped cross-sectional profile. Preferably, rounded portions with identical radii are formed at the respective vertices of the wave shape. In this way, temporary conditions with acute angles occurring at the edge as the contact surface progressively wears can be significantly reduced or completely prevented.

[0012] To adapt to the installation conditions, especially the design of the sliding contact brush and the rotating sliding contact ring, the shape of the profile can be further modified. This also allows temporary conditions with sharp edges between the contact surface and the brush side surface to be further reduced or completely eliminated.

[0013] For this purpose, in the cross-sectional profile, the flanks of the recesses facing the edge are preferably aligned perpendicular to the brush side surface, with the flanks of the recesses facing away from the edge being inclined towards the latter.

[0014] The recesses can also form a sawtooth-shaped cross-sectional profile.

[0015] To further adjust the shape of the profiling, it is also possible to modify the depth of the recesses accordingly.

[0016] The contact surface is preferably curved, corresponding to the sliding contact on the sliding contact ring. Preferably, the contact surface is flattened toward the edges. This ensures that, in an unworn state, the edge at the transition to the brush side surface does not have a sharp shape.

[0017] It is also advantageous if the flattened portions and the flanks of the recesses facing the edge are preferably arranged parallel to one another.

[0018] The object of the invention is also achieved by a sliding contact arrangement with at least one sliding contact brush as described above. The sliding contact brush is in wet-running electrical sliding contact with an annular contact surface of a sliding contact ring arranged in a rotationally fixed manner on a rotor shaft of an electric machine, the annular contact surface being profiled to improve the electrical sliding contact.

[0019] By profiling the ring contact surface, the electrical sliding contact between it and the sliding contact surface of the sliding contact brush can be improved in wet, particularly oily, environments. The previously described profiled surface contour provided on at least one side surface of the brush prevents the extreme wear on the contact surface of the sliding contact brush described above.

[0020] Preferably, several, preferably three, sliding contact brushes are arranged evenly distributed around the circumference of the sliding contact ring.

[0021] Preferably, the profiled surface contour is formed at least on the side surface of the respective sliding contact brush oriented opposite to the direction of rotation of the sliding contact ring. This directly counteracts the risk of a temporary sharp-edged shape at the transition to the brush side surface on the side of the contact surface where the rotating sliding contact ring contacts and which is therefore most exposed to wear.

[0022] Preferably, the ring contact surface on the outer circumference of the sliding contact ring is profiled with radial depressions that run obliquely to the axis of rotation of the sliding contact ring and preferably parallel to one another, which are preferably designed as grooves.

[0023] Particularly advantageously, the contact carrier with the pre-assembled sliding contact brushes can be easily pushed onto the sliding contact ring as a pre-assembled unit for assembly. The unit is modular and structurally identical, particularly as a standardized, cost-saving design with consistently identical or largely identical components and a small number of them. It is flexible in its design, construction, and manufacturing, and can be adapted to specific arrangements and installation conditions, particularly to the design of the sliding contact brushes and the electrical machine, especially the sliding contact ring.

[0024] Further claimed features of the invention will become apparent from the following description and the drawings, which further explain the present invention. They show: Fig. 1 several sliding contact brushes according to the invention in electrical sliding contact with a rotating sliding contact ring, Fig. 2 a sliding contact brush in a single view in a first embodiment, Fig. 3 and Fig. 4 the sliding contact brush Fig. 2 in perspective single view, Fig. 5 to 8 an enlarged section of Fig. 2 in progressive state of wear, Fig. 9 a sliding contact brush according to the invention in a detailed view in a second embodiment, Fig. 10 a sliding contact brush according to the invention in a single view in a third embodiment, Fig. 11 a sliding contact brush according to the invention in a detailed view in a fourth embodiment.

[0025] The figures show various views and embodiments of a sliding contact brush 1 according to the invention for a wet-running electrical sliding contact with a rotating sliding contact ring 2. These illustrations also illustrate the sliding contact arrangement according to the invention.

[0026] In Fig. 1, three identical sliding contact brushes 1, each with a contact surface 3, are in electrical sliding contact with a sliding contact ring 2, which is non-rotatably mounted on a shaft end of a rotor shaft 4 of an electrical machine (not shown). The rotor shaft 4 is guided with its shaft end through a central through-opening 5 on a contact carrier 6, on which the sliding contact brushes 1 are arranged in holders 7, evenly distributed in the circumferential direction around the sliding contact ring 2.

[0027] The contact surfaces 3 of the sliding contact brushes 1 are in sliding contact with the ring contact surface 8 on the outer diameter or circumference of the sliding contact ring 2 and are each designed in a circular arc shape corresponding to the outer diameter or circumference. They are delimited in the direction of rotation of the sliding contact ring 2 and opposite to it by the edges 11, 12 formed by the brush side surfaces 9, 10.

[0028] The sliding contact brushes 1 and the shaft end of the rotor shaft 4 with the sliding contact ring 2 are arranged in a wet space moistened with liquid lubricant, preferably oil. The ring contact surface 8 on the outer circumference of the sliding contact ring 2 is profiled with recesses 13, which preferably run obliquely to the axis of rotation 39 of the sliding contact ring 2 and parallel to one another and are preferably designed as grooves. The axis of rotation 39 coincides with the rotation and center axis of the rotor shaft 4. The recesses 13 serve to tear open the ring contact surface 8 of the sliding contact ring 2, which is moistened with lubricant, and the lubricant film formed thereby on the ring contact surface 8 during operation, and to improve the electrical sliding contact between the sliding contact brushes 1 and the sliding contact ring 2.

[0029] The sliding contact brushes 1 each have a profiled surface contour 14 on a brush side surface 9, starting from the edge 11 formed with the contact surface 3, to reduce wear on the respective contact surface 3 in sliding contact with the profiled ring contact surface 8 of the sliding contact ring 2.

[0030] For clarification, Fig. 2 to 4 one of the sliding contact brushes 1 from Fig. 1 in a single view in a first embodiment. The sliding contact brushes 1 are Fig. 3 and Fig. 4 is rectangular in shape, with a bevel 40 on each of its four longitudinal edges. The bevel 40 serves in particular to prevent jamming of the sliding contact brushes 1, which are slidably arranged in the holders 7.

[0031] The circular arc-shaped contact surface 3 is formed on a narrow end face of the sliding contact brush 1 and, together with the two brush side surfaces 9, 10, forms an edge 11, 12 on each of the narrow longitudinal sides. A profiled surface contour 14 is provided on one brush side surface 9, extending from an edge 11.

[0032] In Fig. 2, the progressive wear during operation on the contact surface 3 of the sliding contact brush 1 is indicated by an arrow as the wear direction S. Starting from the edge 11 in the wear direction S, the surface contour 14 forms a cross-sectional profile with uniform depressions 15 arranged one behind the other.

[0033] These form a wave-shaped cross-sectional profile with equally shaped wave crests and wave troughs, each of which is formed at its apex with roundings 16, 17 with the same radii.

[0034] After Fig. 3 and Fig. 4, the recesses 15 extend transversely, preferably perpendicularly, to the longitudinal direction or to the longitudinal edges of the brush side surface 9 formed on the chamfers 40 on the profiled surface contour 14 of the brush side surface 9, continuously and parallel to one another. The recesses 15 are preferably designed as grooves. They can be produced simply by pressing or stamping without cutting, or by milling. The material for the sliding contact brushes 1 is preferably metal, preferably brass.

[0035] In Fig. 5 to 8, the contour of the worn contact surface 3 on the sliding contact brush 1 is indicated by a dashed line as wear progresses in the wear direction S. With progressive wear of the contact surface 3 and the resulting material removal therefrom, the edge 11 in the transition to the brush side surface 9 follows the wave-shaped cross-sectional profile of the surface contour 14 on the brush side surface 9. This ensures that, with progressive wear on the contact surface 3, an obtuse edge angle α is formed at least in sections on the edge 11. The edge angle α is preferably greater than or equal to 90°.

[0036] In this way, a sharp-edged transition between the contact surface 3 and the brush side surface 9 at the edge 11, which may occur as wear progresses, is repeatedly broken, so that such a condition can only occur temporarily, if at all.

[0037] This reliably prevents extreme wear of the contact surface 3 during operation, particularly due to the engagement of the edge 11 on the contact surface 3 into the recesses 13 on the profiled ring contact surface 8 of the sliding contact ring 2 and the resulting milling effect on the contact surface 3. This applies particularly in the event of any tilting of the sliding contact brushes 1 in the holders 7 due to design-related play.

[0038] The contact surface 3 is preferably provided with a flattening 18, 19 at its end sections toward the edges 11, 12. This serves to create an obtuse edge angle α at the edges 11, 12 in the transition to the brush side surfaces 9, 10 in the unworn state.

[0039] According to Fig. 1, the profiled surface contour 14 on the sliding contact brushes 1 is preferably in each case at the opposite direction to that shown in Fig. 1 is attached to the brush side surface 9 which is aligned with the direction of rotation of the sliding contact ring 2 indicated by an arrow and on which the rotating slip ring starts during operation ( Fig. 1). It is also conceivable to provide a profiled surface contour 14 in a similar manner, starting from the edge 12 on the other brush side surface 10.

[0040] Fig. 9 to 11 show, in further exemplary embodiments, alternative profiled surface contours 20, 21, 22 on the brush side surface 9 for further reducing wear on the contact surface 3 of the sliding contact brushes 1. Furthermore, the various configurations of the surface contours 14, 20, 21, 22 enable simple adaptation to the installation conditions, in particular to the design of the sliding contact brushes 1 and the rotating sliding contact ring 2.

[0041] In contrast to the first embodiment according to Fig. 2 to 8 are in the further embodiments according to the Fig. 9 to 11 in the cross-sectional profile of the surface contours 20, 21, 22, the flanks 23, 24, 25 of the depressions 26, 27, 28 facing the edge 11 are aligned perpendicular to the brush side surface 9 and preferably parallel to the flattening 18 on the contact surface 3, while the flanks 29, 30, 31 of the depressions 26, 27, 28 facing away from the edge 11 are correspondingly more inclined towards the edge 11.

[0042] In the exemplary embodiment according to Fig. 11 in the surface contour 22, the flanks 31 of the depressions 28 facing away from the edge 11 are inclined more towards the edge 11 than the flanks 30 of the depressions 27 in the surface contour 21 from the embodiment according to Fig. 10.

[0043] Furthermore, in the Fig. 10 and Fig. In the cross-sectional profile of the surface contours 21, 22 shown in Figure 11, the radii of the rounded portions 32, 33 at the apex are significantly smaller than in the previously described embodiments. In this way, the surface contours 21, 22 form a sawtooth profile.

[0044] In addition, the depth of the recesses 26 of the surface contour 22 is Fig. 11 lower than in the previously described embodiments of the embodiments according to Fig. 2 to 10.

[0045] After Fig. 1, the sliding contact brushes 1 are slidably guided in housing-like holders 7 on the contact carrier 6. At the ends facing away from the respective contact surface 3, the sliding contact brushes 1 are each pressed against the ring contact surface 8 of the sliding contact ring 2 by springs 34, preferably torsion springs, in order to ensure sliding contact of the contact surfaces 3 with the sliding contact ring 2 as wear progresses.

[0046] The holders 7 and the springs 34 are mounted on a contact plate 35 of the contact carrier 6. The contact plate 35 is made of metal and is connected to a power source, in particular a battery, for electrical current. The sliding contact brushes 1 are electrically connected to the contact plate 35 via stranded wires 36, preferably soldered to it.

[0047] The contact carrier 6 further comprises an electrically insulating base plate 37, preferably made of plastic, to which the illustrated front contact plate 35 with the sliding contact brushes 1, the holders 7, and the springs 32 is attached at the front side. Attached to the rear side of the base plate 37, facing away from the front side, is a rear contact plate (not shown) with the same arrangement of sliding contact brushes as on the front contact plate 35. Several screw connections are preferably provided for attaching the contact plates 35 to the base plate 37.

[0048] The sliding contact ring 2 is made of metal and is mounted on an electrically insulating carrier 38, preferably made of plastic, in a rotationally fixed manner, preferably by injection molding. The carrier 38 is mounted on the shaft end of the rotor shaft 4 in a rotationally fixed manner, preferably by form-fitting.

[0049] The sliding contact ring 2 is electrically connected to a rotor winding (not shown) of the electric machine via a busbar (not shown) arranged within the carrier 38. The rotor winding is electrically connected via another busbar running within the carrier 38 to another sliding contact ring 2 (also not shown) arranged in a rotationally fixed manner on the carrier 38. This ring is in electrical sliding contact with the additional sliding contact brushes arranged on the back of the contact carrier 6.

[0050] The contact carrier 6 with the sliding contact brushes 1 on the front and the sliding contact brushes on the rear, on the one hand, and the carrier 36 with the sliding contact ring 2 on the other, each form a pre-assembled unit. Accordingly, for assembly, the carrier 38 with the sliding contact rings 2 can first be simply slipped onto the shaft end of the rotor shaft 4 in a rotationally fixed manner, preferably with a positive fit and / or by pressing it on in an interference fit. Then, the contact carrier 6 with the sliding contact brushes on the rear is pushed onto the rear sliding contact ring, and the sliding contact brushes 1 on the front are pushed onto the front sliding contact ring 2 to form the sliding contact. The contact carrier 6 can then be fastened to a stationary component, for example the housing of the electrical machine, in particular by a screw connection.

[0051] The modular units formed in this way are all identical in construction, particularly as a standardized, cost-saving design with always identical or largely identical components and a small number of them. They are flexible in design, construction, and manufacture, adaptable to specific arrangements and installation conditions, particularly for the electrical machine, especially for the sliding contact ring 2. List of reference symbols 1 sliding contact brush 2 sliding contact ring 3 Contact surface 4 Rotor shaft 5 passage opening 6 contact carriers 7 Bracket 8 Ring contact surface 9 Brush side surface 10 Brush side surface 11 edge 12 edge 13 recess, groove 14 Surface contour 15 recess, groove 16 Rounding 17 Rounding 18 Flattening 19 Flattening 20 Surface contour 21 Surface contour 22 Surface contour 23 flank 24 flank 25 flank 26 recess, groove 27 recess, groove 28 recess, groove 29 flank 30 flank 31 flank 32 Rounding 33 Rounding 34 Spring, torsion spring 35 Contact plate 36 strands 37 Base plate 38 carriers 39 axis of rotation, central axis 40 chamfer α edge angle QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2012 218 095 A1

[0002]

Claims

[1] Sliding contact brush (1) with a contact surface (3) for electrical sliding contact with a rotating sliding contact ring (2), wherein the contact surface (3) is limited in the direction of rotation by an edge (11, 12) formed with a brush side surface (9, 10), characterized by in that, in order to reduce wear during wet-running sliding contact of the contact surface (3), a profiled surface contour (14, 20, 21, 22) is provided on at least one brush side surface (9), each starting from the edge (11), such that with progressive wear of the contact surface (3), an obtuse edge angle (α) is formed at the edge (11) at least in sections. [2] Sliding contact brush (1) according to claim 1, characterized by that on the brush side surface (9) the profiled surface contour (14, 20, 21, 22) is formed by recesses (15, 26, 27, 28) running perpendicular to the wear direction (S) and parallel to one another. [3] Sliding contact brush (1) according to one of claims 1 or 2, characterized by that on the brush side surface (9) the surface contour (14, 20, 21, 22) has a wave-shaped cross-sectional profile in the wear direction (S) with uniform depressions (15, 26, 27, 28) arranged one behind the other, wherein rounded portions (16, 17, 32, 33) with the same radii are formed at the respective vertices. [4] Sliding contact brush (1) according to one of claims 2 or 3, characterized by that the flanks (23, 24, 25) of the recesses (26, 27, 28) facing the edge (11) run perpendicular to the brush side surface (9). [5] Sliding contact brush (1) according to one of claims 2 to 4, characterized by that the recesses (27, 28) form a sawtooth-shaped cross-sectional profile in the wear direction (S). [6] Sliding contact brush (1) according to one of claims 1 to 5, characterized bythat the contact surface (3) is curved corresponding to the sliding contact on the sliding contact ring (2) and forms flattened areas (18, 19) towards the edges (11, 12). [7] Sliding contact brush (1) according to claim 6, characterized by that the flattened portions (18, 19) and the flanks (23, 24, 25) of the recesses (26, 27, 28) facing the edge (11) are arranged parallel to one another. [8] Sliding contact arrangement with at least one sliding contact brush (1) according to one of the preceding claims in a wet-running electrical sliding contact with an annular contact surface (8) of a sliding contact ring (2) arranged in a rotationally fixed manner on a rotor shaft (4) of an electrical machine, wherein the annular contact surface (8) is profiled to improve the electrical sliding contact. [9] Sliding contact arrangement according to claim 8, characterized bythat the sliding contact brush (1) is formed on at least the brush side surface (9) oriented opposite to the direction of rotation of the sliding contact ring (2) with a profiled surface contour (14, 20, 21, 22) to reduce wear on the contact surface (3). [10] Sliding contact arrangement according to one of claims 8 or 9, characterized by that the sliding contact surface (3) on the outer circumference of the sliding contact ring (2) is profiled with radial grooves (13) running parallel to one another at an angle to the axis of rotation (39) thereof.

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