Guidance device for creating an electrically conductive connection between two components that can rotate relative to each other.

Abstract

Guide device (7; 26) for producing an electrically conductive connection between two components rotatable relative to each other, in particular between a shaft (2) and a grounding hub (6) provided for the purpose of grounding the shaft (2), comprising a holder (14; 29) which is provided for electrically conductive attachment to one component and is equipped with a recess (15; 32), wherein a contact element (16; 31) is guided axially displaceably to the holder (14; 29) in the recess (15; 32) and is in electrically conductive contact with the holder (14; 29), wherein the contact element (16; 31) is brought out of a first axial side (17) of the holder with an end face (20) which is provided for forming an electrically conductive sliding contact (12) of the contact element (16; 31) with the other component, and wherein at least one Supply channel (23;33 to 36) is configured, each opening at the first axial side (17) of the holder (14; 29) and serving to supply lubricant and / or coolant to the sliding contact (12), wherein the at least one supply channel (23; 33 to 36) runs at least sectionally along the recess (15; 32) overlapping spatially with the recess (15; 32), characterized in that at least one aperture is provided in the at least one supply channel (23; 33 - 36) along its respective course, in particular in a respective inlet area (24) and / or in a respective outlet area (25).

Description

[0001] The invention relates to a conducting device for establishing an electrically conductive connection between two components that are rotatable relative to one another, in particular between a shaft and a grounding hub provided for the purpose of grounding the shaft, comprising a holder that is provided for electrically conductive attachment to one component and is equipped with a recess, wherein a contact element is guided in the recess so as to be axially displaceable relative to the holder and is thereby electrically conductively connected to the holder, wherein the contact element is led out of a first axial side of the holder with an end face that is provided for forming an electrically conductive sliding contact of the contact element with the other component, and wherein at least one supply channel is formed in the holder,which opens at the first axial side of the holder and serves to supply lubricant and / or coolant to the sliding contact. Furthermore, the invention relates to an arrangement for grounding a shaft, an electric axle drive unit, and an electric machine.

[0002] In the motor vehicle sector, electrical machines are used to design the respective vehicle as a hybrid or electric vehicle. For example, electrical machines are sometimes also provided in motor vehicle transmissions in order to make the respective motor vehicle transmission suitable for use in a hybrid or electric vehicle. While other components of the respective transmission are encapsulated and shielded by the surrounding transmission housing, the shafts leading out of the transmission housing can cause electromagnetic interference, which can lead to malfunctions in other electronic components in the motor vehicle. In addition, a potential difference can build up between the respective shaft and the transmission housing, which can cause breakdowns in the bearings of the respective shaft and thus reduce the service life of these bearings.For this reason, the affected shaft must be earthed if possible. Even with electrical machines otherwise provided in a motor vehicle, such as electric axle drive units, a respective shaft must be earthed to eliminate or reduce electromagnetic interference and prevent the build-up of a potential difference. This earthing is usually achieved by an electrically conductive connection between the shaft to be earthed and a ground, which is usually a housing, whereby the electrically conductive connection is usually made as a sliding contact via a conducting device. In addition, arrangements for earthing a shaft are also known in which lubricant and / or coolant are specifically directed into the area of ​​the sliding contact in order to minimize wear in this area and to cool the sliding contact.

[0003] For example, WO 2022 / 135715 A1 discloses an arrangement for grounding a shaft, which may be a rotor shaft of an electric machine. In this arrangement, an electrically conductive connection is established between the shaft and a ground in the form of a housing to ground the shaft, this connection being implemented as a sliding contact via an intermediate conductor device. The conductor device comprises a holder which is electrically conductively fastened on the ground side. A contact element is guided in the holder for axial displacement in a recess and protrudes with an end face on one axial side of the holder in order to establish sliding contact with the shaft located there on the end face.In order to minimize thermal component stress, a liquid can also be guided into the area of ​​the sliding contact, for which purpose the holder of the guide device is equipped with a supply channel in a variant of WO 2022 / 135715 A1, which runs at a distance from the recess in the holder.

[0004] WO 2023 / 247006 A1 discloses a diverting device for diverting electrical currents from a rotor part of a machine formed with a shaft, comprising a contact element that is at least partially received in a guide device and is particularly axially displaceable to form an electrically conductive sliding contact. The contact element is electrically conductively connected to the guide device and / or the holding element of the machine and is preloaded by a spring element in the direction of the shaft contact surface.

[0005] DE 10 2019 133 677 A1 discloses an electric drive unit comprising an electric machine with a rotor and a lance electrically conductively connected to the rotor shaft, which lance is supported on the rotor shaft and floatingly mounted on the housing, wherein the lance and the housing are electrically conductively coupled to one another by at least one radially resilient, electrically conductive connecting element. Based on the prior art described above, the object of the present invention is to provide a guide device for establishing an electrically conductive connection between two components rotatable relative to one another, wherein this guide device should enable a reliable supply of a sliding contact with a lubricant and / or coolant while simultaneously achieving a compact design.

[0006] This object is achieved based on the preamble of claim 1 in conjunction with its characterizing features. The dependent claims that follow each of these claims provide advantageous developments of the invention. An arrangement for grounding a shaft, in which a guide device according to the invention is provided, is further the subject of claims 16 and 17. Furthermore, claim 18 relates to an electric axle drive unit, and claim 19 relates to an electric machine.

[0007] According to the invention, a guide device designed to establish an electrically conductive connection between two components rotatable relative to one another comprises a holder provided for electrically conductive attachment to one component and equipped with a recess. A contact element is guided in the recess so as to be axially displaceable relative to the holder and is electrically conductively connected to the holder, wherein the contact element has an end face extending outward on a first axial side of the holder, which end face is provided for forming an electrically conductive sliding contact between the contact element and the other component. In addition, at least one supply channel is formed in the holder, which opens out on the first axial side of the holder and serves to supply lubricant and / or coolant to the sliding contact.

[0008] The guide device according to the invention is thus intended to establish an electrically conductive connection between two components that rotate or can rotate relative to each other. One component is preferably a stationary grounding hub, which is electrically connected to a shaft via the guide device in order to ground this shaft. In particular, the shaft to be grounded is a rotor shaft, which is intended for a rotationally fixed connection to the rotor of an electrical machine.

[0009] For the purposes of the invention, an "electrically conductive" or "electrically conductive" connection is understood to mean a connection that allows a current to flow between the connected components. This connection can be realized directly through a direct contact or indirectly via additional, intermediate components.

[0010] The guide device according to the invention comprises a holder which, when the guide device is installed, is designed to be electrically conductively attached to one of the components to be electrically connected. A contact element is guided axially displaceably in the holder, with this guidance taking place in a recess in the holder. For this purpose, the recess in the holder defines, in particular, an inner contour which corresponds at least substantially to an outer contour of the displaceably guided contact element. In the sense of the invention, “axial” means an alignment parallel to an axis along which the contact element is displaceably guided in the holder.

[0011] The contact element has an end face extending from a first axial side of the holder, such that the contact element projects with this end face relative to the first axial side of the holder. For this purpose, the contact element is preferably prestressed in the direction of the first axial side of the holder, wherein this prestressing is carried out in particular via a spring element which can be placed axially between the contact element and a section of the holder delimiting the recess. When the guide device is installed, an electrically conductive sliding contact with the other component is established on the end face of the contact element, wherein the contact element is also electrically conductively connected to the holder, whereby the electrically conductive connection between the two components is formed via the holder and the contact element together.

[0012] Furthermore, in the guide device in the holder, at least one supply channel is defined, via which lubricant and / or coolant can be guided to the first axial side of the holder, in that the at least one supply channel opens out on the first axial side of the holder, i.e. has an outlet opening on each of the first axial sides of the holder. In this case, the at least one supply channel is provided for the purpose of further supplying the lubricant and / or coolant supplied to the at least one supply channel to the sliding contact of the contact element with the other component. This is done in order to reduce wear on the components that are in sliding contact with one another and to mitigate thermal stress on the components by cooling this area.Accordingly, the at least one supply channel opens on the first axial side in such a way that the lubricant and / or coolant can reach the sliding contact between the contact element and the other component. The lubricant and / or coolant is preferably a liquid, in particular oil, such as a transmission oil.

[0013] The invention now encompasses the technical teaching that the at least one supply channel runs at least partially along the recess, spatially intersecting with the recess. In other words, at least one respective partial section of the at least one supply channel is guided directly along the recess in such a way that the at least one supply channel and the recess spatially intersect, and accordingly, the at least one supply channel is open, at least in the respective partial section, toward an interior region defined by the recess.

[0014] Such a design of a guide device has the advantage that, due to the at least partially spatially overlapping course of the at least one supply channel with the recess in this area, the extension of the guide device according to the invention in the transverse direction relative to the axial guide of the contact element can be reduced, thereby enabling an overall compact design of the guide device. This also makes it possible to make smaller components mounted externally on the holder, such as a bearing to be provided here, when the guide device according to the invention is installed.

[0015] Because the at least one supply channel spatially overlaps with the recess at least in sections, the lubricant and / or coolant guided via the at least one supply channel also reaches the guide of the contact element in the holder. When designed as a lubricant, this lubricates the guide of the contact element in the holder, which reduces friction in the guide and can therefore possibly reduce a hysteresis effect when the contact element is preloaded via a spring element. Due to the spatial overlap of the at least one supply channel with the recess, the at least one supply channel is also delimited by the contact element guided in the recess, as a result of which the lubricant and / or coolant guided via the at least one supply channel flows along the contact element in this area.In this way, the supply of the lubricant and / or coolant to the front side of the contact element can be significantly improved in the case of spatial overlap in the area of ​​the mouth of the supply channel on the first axial side.

[0016] For the purposes of the invention, the at least one supply channel running at least sectionally along the recess means that the at least one supply channel also runs parallel to the recess at least in the respective section and is accordingly also axially aligned here. In addition, the at least one supply channel overlaps with the recess in the region of its running along it, which, for the purposes of the invention, means that in the respective section a respective line volume defined by the at least one supply channel is partially covered by an internal volume defined by the recess. Thus, the at least one supply channel is open towards the recess in this respective section, whereby the lubricant and / or coolant guided via the at least one supply channel can be guided along the contact element running in the recess.

[0017] In contrast, the supply channel of the guide device in WO 2022 / 135715 A1 is designed at a distance from the recess in which the contact element is guided for axial displacement. As a result, the guide device of WO 2022 / 135715 A1 has a greater extension in the transverse direction to the guide.

[0018] Preferably, the guide device according to the invention provides a plurality of supply channels, each of which extends at least partially along the recess, spatially overlapping with the recess. In particular, the supply channels are arranged in a uniform arrangement around the guide of the contact element in the holder.

[0019] According to one embodiment of the invention, the at least one supply channel runs entirely along an axial extent of the recess in the holder, intersecting with the recess. This advantageously allows a compact design of the guide device to be achieved over the entire axial extent of the recess.

[0020] According to an alternative or supplementary embodiment of the invention to the aforementioned embodiment, the at least one supply channel is spatially connected to a second axial side, which is located on the holder facing away from the first axial side. Thus, the at least one supply channel can be supplied with the lubricant and / or coolant from the second axial side of the holder, which allows for good accessibility.

[0021] In a further development of the aforementioned design option, the recess is delimited towards the second axial side by a section, wherein at least one opening is formed in the section, which opening connects the at least one supply channel to the second axial side. This has the advantage that, by designing a respective cross-section of the at least one opening, a volume flow of lubricant and / or coolant supplied to the at least one supply channel can be adjusted. In this respect, the at least one opening can function as a throttle point. The connection via the at least one opening is preferably established in that the at least one opening, starting from the second axial side, opens into an inner region of the recess, which indeed overlaps with the at least one supply channel over its axial extent.This allows the at least one supply channel to be easily fed from the interior. Alternatively or additionally, several openings are preferably provided in the section bordering the recess.

[0022] In particular, the holder can have a housing part in which the recess is formed, with a disc being attached to the housing part, in which the at least one opening is formed. In this case, the holder is designed in several parts, which can reduce the manufacturing and assembly costs of the guide device. Alternatively, the holder of the guide device can also be designed in one piece.

[0023] In a further embodiment of the invention, the at least one supply channel is designed with a constant cross-section along its respective course. Alternatively, however, the at least one supply channel can also be designed to have a variable cross-section along its respective course, wherein the at least one supply channel widens or narrows in cross-section, in particular along its respective course, in a respective inlet region and / or in a respective outlet region. As a result, a throttling of a volume flow of lubricant and / or coolant guided via the at least one supply channel can be implemented directly by appropriately designing the at least one supply channel.

[0024] In a further development of the invention, the at least one supply channel has an oval cross-section, at least in sections. This advantageously allows for additional installation space to be saved in the transverse direction to the axial guide of the contact element in the holder. However, the at least one supply channel can also have another round cross-section, in particular a circular cross-section, or another cross-section.

[0025] According to one possible embodiment of the invention, the contact element has a rectangular cross-section, wherein the at least one supply channel runs in the region of one side of the rectangular cross-section of the contact element, spatially overlapping the recess. In a further development of this possible embodiment, a supply channel runs on each side of the rectangular cross-section, spatially overlapping the recess. This realizes an advantageous arrangement of several supply channels, via which a suitable volume flow of lubricant and / or coolant can be guided to the sliding contact. The arrangement of the supply channels on each side of the rectangular cross-section enables uniform placement of the supply channels around the guide of the contact element in the holder.

[0026] However, the contact element can also have a different angular cross-section, with the at least one supply channel extending at each corner of the angular cross-section of the contact element, spatially overlapping the recess. This also allows for a suitable arrangement of one or more supply channels.

[0027] In a further development of the invention, the contact element consists of an electrically conductive material, in particular carbon, an electrically conductive plastic or felt, or an electrically conductive material combination. The contact element is particularly preferably made of carbon, which achieves high electrical conductivity. If necessary, another material, such as silver, can be applied to the end face to improve the electrically conductive sliding contact. However, a composite material composed of several suitable materials can also be used as the material combination.

[0028] According to the embodiment of the invention, at least one orifice plate is introduced into the at least one supply channel along its respective course, in particular in a respective inlet region and / or in a respective outlet region. This achieves a throttling of the volume flow of lubricant and / or coolant guided via the at least one supply channel, which is made possible in a simple manner by introducing a corresponding orifice plate. This can be carried out alternatively or in addition to a corresponding design of at least one opening in the holder.

[0029] Particularly preferably, a bearing seat is provided in the region of the respective spatially overlapping course of the at least one supply channel with the recess on the holder. This bearing seat is designed to accommodate a bearing for rotatably supporting the components relative to one another. This has the advantage that, due to the compact design of the holder in this area, the bearing to be placed there can also be designed to be compact.

[0030] The invention further relates to an arrangement for grounding a shaft. This arrangement comprises a grounding hub that is electrically connected to a ground, preferably a housing. The grounding hub is also electrically connected to the shaft to be grounded via a sliding contact formed on a guide device, wherein the guide device is designed according to one or more of the preceding variants. Lubricant and / or coolant can be supplied to the sliding contact at least partially via the guide device.

[0031] The shaft to be grounded is preferably a rotor shaft intended for a rotationally fixed connection to the rotor of an electrical machine. The rotor and rotor shaft can be constructed as a single piece or as separate, rotationally fixed components. The electrical machine can be part of a motor vehicle transmission. However, the component to be grounded can, in principle, also be another shaft, such as a transmission shaft, or another, particularly rotating, component.

[0032] In the arrangement according to the invention, the grounding hub is provided for electrically connecting the shaft to be grounded to ground by electrically connecting the grounding hub at a first axial end to the shaft to be grounded and also electrically connecting it to ground at a second axial end. The grounding hub consists of an electrically conductive material at least in contact areas with the ground and the shaft to be grounded, as well as in an intermediate area connecting these contact areas. Preferably, however, the grounding hub is formed entirely from an electrically conductive material, which is in particular a metallic material, such as steel or aluminum.

[0033] The ground, to which the electrically conductive connection of the shaft to be grounded is established via the intermediate grounding hub, is, within the meaning of the invention, an electrically conductive body, to which, in particular, the potential zero is assigned as the reference potential. This ground is preferably in the form of a housing, whereby the electrically conductive connection of the grounding hub can be established specifically on this housing, a housing part, or a component permanently electrically connected thereto.

[0034] On the other hand, the grounding hub also preferably serves within the arrangement to supply the lubricant and / or coolant to the guide device. For the supply of the lubricant and / or coolant, the grounding hub is designed at least in sections as a tube through which an axial supply line is defined, and thus in the longitudinal direction of the grounding hub. This supply line opens at one end of the grounding hub, to which the guide device is attached to the grounding hub. This allows the lubricant and / or coolant to reach the guide device along the supply line formed by the grounding hub, via which it is then further supplied to the sliding contact with the shaft. The grounding hub can have further openings, from which other areas can be supplied with lubricant and / or coolant.

[0035] According to the invention, the grounding hub has, in particular, a rod-like shape, i.e., it is designed as an elongated component similar to a shaft, in order to establish the electrically conductive connection between the shaft to be grounded and the ground, preferably axially, within the arrangement according to the invention. Furthermore, the grounding hub is preferably designed to be rotationally symmetrical. As already described above, the grounding hub is preferably tubular over at least part of its axial extent to enable the supply of the lubricant and / or coolant to the guide device.

[0036] An arrangement according to the invention for grounding a shaft can be a component of an electric axle drive unit for a motor vehicle or an electric machine.

[0037] Advantageous embodiments of the invention, which are explained below, are illustrated in the drawings. It shows: Fig. 1 is a sectional view of a shaft grounding arrangement according to a preferred embodiment of the invention; Fig. 2 a schematic representation of a control device of the arrangement of Fig. 1, according to a first embodiment of the invention; Fig. 3 another illustration of the guidance system from Fig. 2; Fig. 4 to 6 show different views of a guide device according to a second embodiment of the invention; Fig. 7 a schematic representation of a drive train of a motor vehicle; and Fig. 8 a schematic view of an electrical machine.

[0038] Out of Fig. Figure 1 shows a sectional view of an arrangement 1 for grounding a shaft 2, this arrangement 1 being implemented according to a preferred embodiment of the invention. The shaft 2 is a rotor shaft 3 of an electric machine (not shown in detail), wherein the rotor shaft 3 is connected in a rotationally fixed manner to a rotor of the electric machine. Within the arrangement 1, the rotor shaft 3 is electrically conductively connected to a ground 4 in the form of a housing cover 5 in order to ground the rotor shaft 3 to the housing cover 5 and thus to a housing (not shown in detail here).

[0039] The electrically conductive connection of the rotor shaft 3 to the housing cover 5 is made via a grounding hub 6 and a guide device 7, wherein the grounding hub 6 is located coaxially to the rotor shaft 3 and is predominantly formed by a tubular body. The grounding hub 6 extends axially from the housing cover 5 through a further shaft 8 designed as a hollow shaft into the rotor shaft 3, which is designed as a hollow shaft in this area for this purpose. The shaft 8 is also arranged coaxially to the rotor shaft 3 and is also connected to the rotor shaft 3 in a rotationally fixed manner, wherein the shaft 8 can be a gear shaft of a gearbox via which the electric machine is or can be integrated.

[0040] The grounding hub 6 is made of an electrically conductive material, preferably metal. In the area of ​​an axial end 9 of the grounding hub 6, the grounding hub 6 is mounted in a floating manner on the side of the housing cover 5. At this end 9, in addition to establishing the electrically conductive connection between the grounding hub 6 and the housing cover 5, an axial preload of the grounding hub 6 in the direction of the rotor shaft 3 is also provided.

[0041] At an end 10 opposite the axial end 9, the guide device 7 is also fastened to the grounding hub 6, the guide device 7 being pressed into the grounding hub 6. Furthermore, a bearing 11 is arranged on the guide device 7, which is designed as a rolling bearing and via which the permanently stationary grounding hub 6 and the permanently stationary guide device 7 are mounted in the rotor shaft 3, which rotates relative to it. A sliding contact 12 to the rotor shaft 3 is established via the guide device 7 in order to electrically conductively contact the guide device 7 with the rotor shaft 3 and to ground the latter via the electrically conductive connection of the guide device 7 to the grounding hub 6 and further via the electrically conductive connection of the grounding hub 6 to the housing cover 5.

[0042] Apart from establishing the electrically conductive connection between the rotor shaft 3 to be grounded and the housing cover 5, the grounding hub 6 also serves to supply lubricant and / or coolant to an area of ​​the sliding contact 12 in order to cool this area and, subsequently, also the rotor shaft 3 and, in particular, the rotor of the electric machine. The lubricant and / or coolant is preferably oil. The lubricant and / or coolant is introduced from the axial end 9 into an internal volume 13 of the grounding hub 6, with this introduction preferably taking place in the area of ​​the housing cover 5.

[0043] Along the grounding hub 6, the lubricant and / or coolant introduced into the inner volume 13 then reaches the axial end 10, wherein at the end 10 of the grounding hub 6, a further supply to the sliding contact 12 is then carried out by supplying the lubricant and / or coolant via the guide device 7, which is designed for this purpose according to a first embodiment of the invention and in the Fig. 2 and Fig. 3 is shown in more detail.

[0044] As particularly in Fig. 2, the guide device 7 comprises a holder 14, which is attached to the axial end 10 of the earthing hub 6. For this purpose, the holder 14, as shown in Fig. 3, it is provided with a cylindrical outer contour, at least in the area where the holder 14 is attached to the grounding hub 6. The electrically conductive connection between the holder 14 of the conducting device 7 and the grounding hub 6 is established via the attachment, with the holder 14 being made of an electrically conductive material.

[0045] Furthermore, a recess 15 is formed in the holder 14, which is designed as a blind bore with a circular cross-section. A contact element 16 is guided in the recess 15 so as to be axially displaceable relative to the holder 14 and is prestressed in the direction of a first axial side 17 of the holder 14. This prestressing is preferably carried out via a spring element, which is arranged in particular between the contact element 16 and a section 18 by which the recess 15 is delimited in the direction of a second axial side 19 of the holder 14. Due to the prestressing, the contact element 16 is guided out of the holder 14 with an end face 20, wherein the sliding contact 12 with the rotor shaft 3 is formed on the end face 20 of the contact element 16.

[0046] Due to the circular cross-section design of the recess 15, the contact element 16 also has a circular cross-section. Furthermore, the contact element 16 is made of carbon, although another material, such as silver, can also be applied in the area of ​​the end face 20. Due to the guidance of the contact element 16 in the holder 14 and the sliding contact 12 with the rotor shaft 3, the contact element 16 establishes the electrically conductive connection between the grounding hub 6 via the holder 14 and the rotor shaft 3, which rotates relative to it.

[0047] For the supply of the lubricant and / or coolant introduced into the inner volume 13 of the earthing hub 6 to the sliding contact 12, the holder 14 is provided at its section 18 with an opening 21, via which the lubricant and / or coolant can pass from the inner volume 13 into an inner region 22 defined by the recess 15, as indicated by the arrow in Fig. 2 indicated.

[0048] From the inner area 22, the lubricant and / or coolant can then pass via a supply channel 23 to the axial side 17 of the holder 14 and there into the area of ​​the sliding contact 12.

[0049] As a special feature, the supply channel 23 runs as in Fig. 2, along the recess 15, whereby this running along the supply channel 23 is carried out over the complete axial extent of the recess 15. In addition, the supply channel 23 spatially overlaps with the recess 15, which is particularly evident in Fig. 3, so that the supply channel 23 is open towards the recess 15. This has the result that the lubricant and / or coolant can easily pass from the inner region 22 into the supply channel 23, flow between the holder 14 and the contact element 15 and exit the holder 14 on the axial side 17, whereby the lubricant and / or coolant can continue to flow along the contact element 16 and finally reach the area of ​​the sliding contact 12. By flushing around the contact element 16, better cooling can be brought about in the area of ​​the contact element 16. In addition, due to the course of the supply channel 23 along the guide, the guide of the contact element 16 in the holder 14 is also lubricated and thus the friction in this area is reduced.

[0050] Due to the arrangement of the supply channel 23 directly adjacent to the recess 15 and the spatial overlap with the recess 15, the holder 14 can be designed compactly, and thus the guide device 7 itself can also be designed compactly. This also means that the bearing 11, which is mounted on a bearing seat on the outside of the holder 14, can be designed with a smaller diameter, resulting in lower friction and thus lower drag losses in the area of ​​the bearing 11.

[0051] The supply channel 23 has an oval cross-section, which allows for additional space savings in the transverse direction to the guide of the contact element 16 in the holder 14. The supply channel 23 is designed with a constant cross-section along its length; alternatively, however, the cross-section of the supply channel 23 can also be widened or narrowed in an inlet region 24 and / or an outlet region 25 of the supply channel 23.

[0052] The opening 21 also has an oval cross-section, whereby the design of this cross-section regulates the volume flow of lubricant and / or coolant directed into the interior area 22. Alternatively or additionally, a separate aperture could also be incorporated into the opening 21 of section 18 or into the supply channel 23.

[0053] The Fig. 4 to 6 show views of a guide device 26 according to a second embodiment of the invention. This guide device 26 essentially corresponds to the guide device 7 according to the Fig. 2 and Fig. 3 and can alternatively be used to the guide device 7 in the arrangement 1 from Fig. 1. The difference is that several openings 27 are designed in a section 28, through which, as in the variant according to Fig. 2 and Fig. 3, a recess in a holder 29 of the guide device 26 is delimited. The openings 27 are formed in a disc 30, which is part of the multi-part holder 29 and forms the section 28.

[0054] As also in Fig. 5 and also in Fig. 6, a contact element 31 of the guide device 26 has a rectangular cross-section, wherein the Fig. 5 and Fig. 6, correspondingly, the recess 32 is also rectangular in shape. Furthermore, the guide device 26 now has a plurality of supply channels 33, 34, 35 and 36, which each run along the recess 32 and spatially overlap with the recess 32. The individual supply channel 33 or 34 or 35 or 36 is placed on a respective side 37 or 38 or 39 or 40 of the rectangular contact element 31. Otherwise, the embodiment according to the Fig. 4 to 6 of the variant according to the Fig. 2 and Fig. 3, so that reference is made to what has been described in this regard.

[0055] Fig. 7 shows a schematic view of a purely electric drive train of a motor vehicle, which has an electric axle drive unit 41. The electric axle drive unit 41 comprises an electric machine 42, the power of which is transmitted to drive wheels 45 and 46 of a motor vehicle via a reduction gear set 43 and a differential gear 44. For this purpose, the electric machine 42 is connected to the reduction gear set 43 on the output side via a rotor shaft 47. Output shafts 48 and 49 of the differential gear 44 are connected to the drive wheels 45 and 46. The electric machine 42, the reduction gear set 43, and the differential gear 44 are enclosed in a housing 50. An inverter 51 is attached to the housing 50. The inverter 51 is connected on the one hand to the electric machine 42 and on the other hand to a battery 52.The converter 51 serves to convert the direct current from the battery 52 into an alternating current suitable for operating the electric machine 42 and has several power semiconductors for this purpose. The conversion between direct current and alternating current is achieved by a controlled pulsed operation of the power semiconductors.

[0056] In the present case, the rotor shaft 47 is earthed in an arrangement which is analogous to the variant according to Fig. 1. Here, too, a grounding hub 53 is provided, which is electrically connected to the rotor shaft 47 via an intermediate guide device (not shown here) by means of a sliding contact. The structure of this guide device corresponds to the guide device 7 according to the Fig. 2 and Fig. 3 or the control device 26 according to the Fig. 4 to 6. Lubricant and / or coolant are also supplied to the area of ​​the sliding contact via the grounding hub 53 and the guide device.

[0057] Finally, Fig. 8 shows a schematic view of an electric machine 54. The electric machine 54 has a housing 55 that accommodates a stator 56 and a rotor 57. The stator 56 is fixed in the housing 55 for rotation. The rotor 57 is coupled to a rotor shaft 58, which is rotatably supported by two rolling bearings 59 and 60 supported on the housing 55. One end of the rotor shaft 58 protrudes from the housing 55.

[0058] The rotor shaft 58 is earthed in the present case within the framework of an arrangement according to the invention, which in principle is designed in an analogous manner to the variant according to Fig. 1. Here, too, a grounding hub 61 is provided, which is in sliding contact with the rotor shaft 58 via an intermediate guide device in order to become the rotor shaft 58. The intermediate guide device can either be made according to the guide device 7 from the Fig. 2 and Fig. 3 or according to the control device 26 according to the Fig. 4 to 6. In addition, a supply of lubricant and / or coolant to the sliding contact is realized via the grounding hub 61 and the intermediate guide device.

[0059] By means of the embodiments according to the invention, a compact design of a guide device can be achieved while at the same time reliably supplying a sliding contact with lubricant and / or coolant. Reference symbol 1 arrangement 2nd wave 3 Rotor shaft 4 Mass 5 Housing cover 6 Grounding hub 7 Guidance device 8 Wave 9 End 10 End 11 camps 12 sliding contact 13 internal volume 14 Bracket 15 Recess 16 Contact element 17 axial side Section 18 19 axial side 20 front side 21 Breakthrough 22 Interior 23 supply channel 24 Entrance area 25 Exit area 26 Guidance device 27 breakthroughs Section 28 29 Bracket 30 slices 31 Contact element 32 recess 33 supply channel 34 supply channel 35 supply channel 36 supply channel 37 page 38 page 39 pages 40 pages 41 Axle drive unit 42 electric machine 43 Reduction gear set 44 differential gears 45 drive wheel 46 Drive wheel 47 Rotor shaft 48 Output shaft 49 Output shaft 50 housings 51 inverters 52 Battery 53 Grounding hub 54 electric machine 55 housings 56 Stator 57 Rotor 58 Rotor shaft 59 rolling bearings 60 rolling bearings 61 Grounding hub

Claims

[1] Conducting device (7; 26) for establishing an electrically conductive connection between two components which can be rotated relative to one another, in particular between a shaft (2) and an earthing hub (6) provided for the purpose of earthing the shaft (2), comprising a holder (14; 29) which is provided for an electrically conductive attachment to one component and is equipped with a recess (15; 32), wherein a contact element (16; 31) is guided in the recess (15; 32 so as to be axially displaceable relative to the holder (14; 29) and is electrically conductively connected to the holder (14; 29), wherein the contact element (16; 31) is led out of a first axial side (17) of the holder with an end face (20) which is provided for forming an electrically conductive sliding contact (12) of the contact element (16; 31) with the other component, and wherein in the holder (14; 29) at least one supply channel (23;33 to 36) which opens out at the first axial side (17) of the holder (14; 29) and serves to supply lubricant and / or coolant to the sliding contact (12), wherein the at least one supply channel (23; 33 to 36) runs at least in sections along the recess (15; 32) spatially overlapping with the recess (15; 32); characterized by that at least one aperture is introduced into the at least one supply channel (23; 33 - 36) along its respective course, in particular in a respective input area (24) and / or in a respective output area (25). [2] Guide device (7; 26) according to claim 1, characterized by that the at least one supply channel (23; 33 to 36) runs completely along an axial extent of the recess (15; 32) in the holder (14; 29), overlapping with the recess (15; 32). [3] Guide device (7; 26) according to claim 1 or 2, characterized bythat the at least one supply channel (23; 33 to 36) is spatially connected to a second axial side (19) which is located on the holder (14; 29) facing away from the first axial side (17). [4] Guide device (7; 26) according to claim 3, characterized by that the recess (15; 32) is delimited towards the second axial side (19) by a section (18; 28), wherein at least one opening (21; 27) is formed in the section (18; 28), which opening connects the at least one supply channel (23; 33 to 36) to the second axial side (19). [5] Guide device (7; 26) according to claim 4, characterized by that the connection is established via the at least one opening (21; 27) in that the at least one opening (21; 27) opens into an inner region (22) of the recess (15; 32) starting from the second axial side (19). [6] Guide device (26) according to claim 4 or 5, characterized bythat the holder (29) has a housing part in which the recess (32) is formed, wherein a disc (30) is fastened to the housing part, in which the at least one opening (27) is formed. [7] Guide device (7; 26) according to one of the preceding claims, characterized by that the at least one supply channel (23; 33 to 36) is designed with a constant cross-section along its respective course. [8] Guide device (26) according to one of claims 1 to 6, characterized by that the at least one supply channel (23; 33 to 36) widens or narrows in cross-section along its respective course in a respective input region (24) and / or in a respective output region (25). [9] Guide device (7; 26) according to one of the preceding claims, characterized by that the at least one supply channel (23; 33 to 36) has an oval cross-section at least in sections. [10] Guide device (26) according to one of the preceding claims, characterized by that the contact element (31) has a rectangular cross-section, wherein the at least one supply channel (33 to 36) runs in the region of one side (37 to 40) of the rectangular cross-section of the contact element (31) spatially overlapping with the recess (32). [11] Guide device (26) according to claim 10, characterized by that on each side (37 to 40) of the rectangular cross-section a supply channel (33 to 36) runs spatially overlapping with the recess (32). [12] Guide device (26) according to one of the preceding claims, characterized by that the contact element (16) has a square cross-section, wherein the at least one supply channel (33 to 36) runs at each corner of the square cross-section of the contact element (16) spatially overlapping with the recess (32). [13] Guide device (7; 26) according to one of the preceding claims, characterized by that the contact element (16; 31) consists of an electrically conductive material, in particular of carbon, of an electrically conductive plastic or felt, or of an electrically conductive material combination. [14] Guide device (7; 26) according to one of the preceding claims, characterized by in that in the region of the respective spatially overlapping course of the at least one supply channel (23; 33 to 36) with the recess (15; 32) on the holder (14; 29), a bearing seat is designed to receive a bearing (11) for the rotatable mounting of the components relative to one another. [15] Arrangement (1) for earthing a shaft (2), in particular a rotor shaft (3) of an electrical machine, comprising an earthing hub (6) which is electrically conductively connected to a ground (4), preferably a housing, wherein the earthing hub (6) is also electrically conductively connected to the shaft (2) to be earthed via a sliding contact (12) which is formed on a guide device (7; 26), wherein the guide device (7; 26) is designed according to one or more of claims 1 to 15, and wherein lubricant and / or coolant can be supplied to the sliding contact (12) at least partially via the guide device (7; 26). [16] Arrangement (1) according to claim 15, characterized bythat the holder (14; 29) of the guide device (7; 26) is fastened to the earthing hub (6) on the end face of the earthing hub (6), wherein the earthing hub (6) is at least partially tubular and an inner volume (13) of the earthing hub (6) formed thereby defines a supply line for supplying lubricant and / or coolant to the guide device (7; 26). [17] Electric axle drive unit (41) for a motor vehicle, characterized by a shaft (2) earthed according to an arrangement according to claim 15 or 16. [18] Electric machine (54) with a rotationally fixed stator (56) and a rotatable rotor (57), wherein the rotor (57) is coupled to a rotor shaft (58), characterized by that the rotor shaft (58) is earthed according to an arrangement according to claim 15 or 16.

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