Device for grounding a rotor carrier

Abstract

The invention relates to a device for grounding a rotor carrier, comprising a grounded housing and a rotatable rotor carrier arranged in the grounded housing and extending in an axial direction, further comprising a grounding device and at least one bearing, the rotor carrier being supported relative to the housing via the at least one bearing, the housing has a housing arm, and wherein the grounding device has an electrically conductive annular carrier element with a central recess, the carrier element being connected to the housing arm by means of the central recess, and wherein an electrically conductive sliding contact is arranged on the carrier element in a radially outwardly directed manner. The rotor carrier has a bearing element for forming an electrically conductive connection with the rotor carrier on an outer side of the sliding contact, such that an electrical connection is established between the rotor carrier and the housing via the sliding contact and the bearing element. The invention further relates to an electric machine and a transmission.

Description

Technical Field

[0001] The invention relates to a device for grounding a rotor carrier, the device comprising a grounded housing and a rotor carrier arranged in the grounded housing and extending in the axial direction, further comprising a grounding device and at least one bearing. The invention also relates to an electric machine and a transmission. Background Art

[0002] For example, an electric drive unit / transmission of an electric vehicle or hybrid vehicle usually has an electric machine, which has a stator and a rotor rotatably supported relative to the stator, and the rotor is in turn connected to the rotor shaft of the electric machine in a rotationally fixed manner. The rotor shaft can be coupled to the transmission of the motor vehicle for torque transmission. The electric machine can be arranged together with the transmission and power electronics in a common housing. During the operation of such an electric machine, the rotor shaft can be excited and emit interference signals.

[0003] In electric machines, so-called bearing currents occur during operation, i.e. capacitive circulating currents that flow through the bearings and cause damage there. This can lead, for example, to wear on the bearings of the rotor shaft and / or to electromagnetic compatibility stresses in certain frequency ranges.

[0004] In order to avoid such bearing currents, it is known to arrange a grounding device, in particular a shaft grounding ring, on the rotor shaft or on a countershaft coupled to the rotor shaft via a transmission element, via which grounding device the bearing currents are diverted away from the bearing.

[0005] It is also known that the rotor of an electric machine generates heat during operation, which must be dissipated, for example, by oil flow, in order to avoid inadmissible high temperatures. In addition, the bearings used for the rotor shaft must also be lubricated and cooled.

[0006] US 2021293279 A1 discloses an electrically conductive structural component for a bearing, which is arranged around a shaft and within a housing, wherein the bearing comprises an inner ring and an outer ring and a plurality of rolling bodies arranged between the rings, wherein the electrically conductive structural component comprises:

[0007] an annular retaining portion coupled to the bearing outer ring or the bearing housing and having a centerline and an open inner end defining an annular groove; and

[0008] At least two conductors, the conductors respectively having radially outer ends arranged in the retaining grooves and radially inner ends capable of contacting the shaft, wherein each conductor is formed of a plurality of conductive fibers arranged such that they extend radially inwardly from the inner end of the retaining portion, wherein the at least two conductors are spaced apart from each other around a center line in a circumferential direction so as to define at least two axial through-portions between the retaining portion and the shaft.

[0009] WO 2020 234148 A1 discloses a device for establishing an electrically conductive connection between a shaft and a housing in which the shaft is rotatably supported, the device comprising an electrically conductive retaining element and an electrically conductive contact element fastened to the retaining element, wherein the contact element is configured to establish an electrically conductive connection between the shaft and the retaining element, wherein the retaining element is configured to establish an electrically conductive connection between the contact element and the housing, wherein the retaining element is fastened to the housing by means of a retaining ring. Summary of the invention

[0010] The object of the present invention is to specify a device for grounding a rotatable rotor carrier arranged in a grounded housing which is also improved overall with regard to oil conduction.

[0011] This object is achieved by a device having the features of claim 1 , as well as a transmission having the features of claim 15 and an electric machine having the features of claim 16 .

[0012] Advantageous embodiments emerge from the dependent patent claims, the description and the drawings.

[0013] The object is achieved by a device for grounding a rotor carrier, comprising a grounded housing and a rotatable rotor carrier arranged in the grounded housing and extending in the axial direction, the device further comprising a grounding device and at least one bearing, wherein the rotor carrier is supported relative to the housing via the at least one bearing, and wherein the housing has a housing arm, wherein the grounding device is arranged on the housing arm on the circumference next to the bearing, and wherein the grounding device has an electrically conductive annular support element with a central recess, wherein the support element is connected to the housing arm by means of the central recess in order to form a permanent electrically conductive connection with the housing arm on the inner side of the support element, and

[0014] An electrically conductive friction contact is arranged on the support element pointing outward in the radial direction for forming an electrically conductive connection with the rotor support on its outer side, thereby establishing an electrical connection between the rotor support and the housing via the friction contact and the support element.

[0015] According to the invention, it has been recognized that in modern electric drives, spark erosion may occur in the rotor bearings. In order to avoid bearing damage, a grounding path must be provided. Conventional grounding rings cannot always be used, because there may not be any contactable, uninterrupted surfaces available.

[0016] The rotor carrier is designed here, for example, as a rotatable shaft which is designed, for example, as a collar shaft or a hub shaft or another shaft.

[0017] The housing arm is, for example, an integrated shoulder / rib / bearing seat or a bearing mount which is formed integrally with the housing / is formed on the housing.

[0018] In this case, annular can be understood to mean an annular body. In this case, the central recess is in particular designed as a recess, in particular an annular recess, which is arranged in particular centrally on the carrier element.

[0019] Here, the term "beside the bearing on the peripheral side" means that the grounding device is arranged beside the bearing. For example, such a bearing can be designed as a radial bearing, wherein the radial bearing is preferably a rolling bearing, and particularly preferably a deep groove ball bearing.

[0020] According to the invention, it is now provided that the grounding device is permanently connected on its inner side (surface pointing radially inwards) to the grounded housing and contacts the rotating rotor carrier / bearing carrier on its outer side.

[0021] Furthermore, the friction contact can directly contact the circumferential surface of the rotor carrier / bearing carrier, or an electrically conductive sleeve / bushing can be provided which is attached to the rotor carrier.

[0022] In this case, the sliding contact can be formed by or include bristles and / or spring blades or the like, for example.

[0023] This means that the friction contacts, such as bristles, do not point radially inwards (as is common in the prior art), but rather radially outwards, where they directly or indirectly (eg via an electrically conductive sleeve) contact the rotor carrier in order to produce the electrically conductive connection.

[0024] By means of such an arrangement, the rotor carrier / bearing carrier has an uninterrupted cylindrical contact surface for producing a permanent electrically conductive connection, thereby ensuring that the current is permanently discharged.

[0025] Due to the central recess, the carrier element can be arranged in a simplified manner on an existing housing arm, on which the bearing is also arranged.

[0026] In this case, the carrier material of the device is made of a conductive material, for example aluminum. The sliding contact also has a high conductivity.

[0027] In particular, the housing arm is designed as a cylinder at least in the region in which it contacts the support element.

[0028] In particular, the housing arm is configured as an internal housing arm that at least partially extends into the rotor carrier, so that the friction contact portion can be in contact with the rotor carrier. Here, the dimensions between the housing arm, the grounding device and the rotor carrier are configured so that the friction contact portion contacts the rotor carrier internally.

[0029] In another embodiment, the grounding device is configured as a grounding ring having an annular support element and an annular friction contact. Here, the support element and the friction contact are both electrically conductive. For example, bristles, springs, etc. are clamped / bonded to the support element as the friction contact.

[0030] As a result, the connection between the sliding contact and the support element is also made conductive in a simple manner in order to produce an electrical connection between the rotor carrier and the housing.

[0031] In a further embodiment, in particular the central recess of the grounding ring is arranged on the housing arm by means of a force-fitting connection (eg an interference fit), thereby achieving a conductive connection to the housing in a simple manner.

[0032] In a further embodiment, the rotor carrier has a circumferential groove between the bearing and the ground contact device. Furthermore, the friction contact has a friction contact diameter extending in the axial direction, wherein the circumferential groove has a groove bottom and a groove bottom diameter extending in the axial direction, and wherein the groove bottom diameter can be greater than or equal to the friction contact diameter.

[0033] In another embodiment, the groove has a groove bottom, wherein a radial opening is provided in the groove bottom in the rotor carrier. The opening can be designed as a radial hole. The groove bottom should be at least as wide as the diameter of the opening or the radial hole.

[0034] This means that the rotating rotor carrier / bearing carrier has a groove with holes or through-holes between the bearing and the grounding device. These holes or through-holes can be distributed equidistantly on the circumference. The groove bottom diameter (i.e. the diameter of the groove bottom) is greater than or equal to the contact diameter or the diameter of the sliding contact, thereby preventing backflow and thus preventing the sliding contact from being contaminated by oil. Due to centrifugal force, the oil that is not used to lubricate the bearing (excess oil) is collected in the groove and transported away through the holes and, for example, delivered to the transmission. It is thus ensured that the excess oil is thrown out and does not affect the conductive contact between the grounding device and the rotor carrier / bearing carrier.

[0035] In another embodiment, the passage (i.e. the hole) has an axial diameter, by means of which the fluid flowing through the groove is transported away without backflow. This allows the accumulated oil to be easily transported away without the contact surface between the sliding contact and the rotor carrier being filled with oil (contaminated).

[0036] In another embodiment, the connection point between the grounding device and the housing arm is in the axial direction, i.e. the grounding device or the housing arm has at least one continuous recess in the axial direction for forming a fluid connection with at least one bearing or groove, so that the bearing is supplied with oil from the outside for lubrication.

[0037] In a further embodiment, at least one continuous recess is arranged in the housing arm.

[0038] In particular, at least one continuous recess in the housing arm is arranged below the support element as a continuous recess, so that a fluid can flow through below the support element.

[0039] Here, the notch can be arranged as an interruption of the press fit / pressing in the housing arm, pointing toward the support element. Thus, a continuous recess is provided in the housing arm.

[0040] In a further alternative embodiment, at least one continuous recess is arranged in the support element. In particular, at least one continuous recess in the support element is arranged as a continuous recess pointing toward the housing arm.

[0041] This arrangement allows the oil to bypass the grounding device by gravity without contaminating the sliding contact (i.e. the contact element). The oil cools and lubricates the bearing. Excess oil can be discharged through the grooves and holes (i.e. the penetrations).

[0042] Furthermore, a plurality of recesses can also be provided at equidistant intervals in the support element.

[0043] In particular, the recess has a cross section, wherein the cross section is designed to allow the fluid (here lubricating oil and cooling oil) flowing through the recess to flow through without backflow, thereby also preventing the grounding device, in particular the sliding contact, from being contaminated by oil.

[0044] In particular, at least one recess is designed such that the fluid (here lubricating oil and cooling oil) flowing through in a defined manner flows without backflow, in particular in a laminar manner. Backflow can also be avoided in this way.

[0045] In another embodiment, the grounding device is arranged on the housing arm on the side of the bearing facing away from the rotor. As a result, a cylindrical, uninterrupted contact surface for the grounding device can be easily provided on the rotor carrier / bearing carrier.

[0046] Furthermore, the object is achieved by a transmission for a motor vehicle having a device as described above for grounding a rotor carrier mounted in a housing of the transmission.

[0047] The proposed device can be a component of a transmission for a motor vehicle, for example an automatic transmission or an automated transmission. A corresponding rotor carrier of the transmission, in particular a rotor shaft, is rotatably supported in a housing of the transmission. Further shafts, for example a cardan shaft leading to a differential transmission or a half shaft leading to a drive wheel of the motor vehicle, can be coupled to the rotor carrier.

[0048] The object is also achieved by an electric machine having a rotationally fixed stator and a rotatable rotor, wherein the rotor is coupled to a rotor carrier, wherein the rotor carrier is mounted in a housing of the electric machine, and the electric machine has the above-described device for grounding the rotor.

[0049] The proposed device can be a component of an electric machine having a rotationally fixed stator and a rotatably mounted rotor. The rotor is coupled to a rotor carrier. The rotor carrier is grounded relative to the housing of the electric machine via the proposed device. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Further features and advantages of the present invention are apparent from the following description with reference to the accompanying drawings. In which:

[0051] Figure 1 : shows the device according to the invention in use;

[0052] Figure 2 : shows details of the device according to the invention. DETAILED DESCRIPTION

[0053] Here, the rotor carrier 3 is particularly configured as a rotor shaft. In the sense of the present invention, a "rotor shaft" is understood in principle as a rotatable component that is configured to transmit rotational motion between components to be coupled. Here, the rotor carrier can also be formed integrally with one or two components to be coupled. Particularly preferably, the rotor carrier to be grounded is the rotor carrier 3 of the motor, which is configured to be connected to the rotor of the motor in a rotationally fixed manner. Here, the rotor and the rotor carrier 3 can also be implemented in one piece, or exist as separate individual components that are connected to each other in a rotationally fixed manner. Here, the motor can be a component of a motor vehicle transmission. In principle, however, the rotor carrier 3 to be grounded can also be other shafts, such as a transmission shaft.

[0054] In this case, the “axial direction A” corresponds to the direction along the axis of rotation of the rotor carrier, while the radial direction (radial direction R) refers to the orientation in the diametric direction proceeding from the axis of rotation.

[0055] In the sense of the invention, an "electrically conductive" connection is understood to be a connection that enables a current flow between the connected components. In the device according to the invention, the electrically conductive connection is provided between the rotor carrier 3 and the housing 5, wherein this can be achieved directly or indirectly via another intermediate component, for example via an electrically conductive sleeve on the rotor carrier 3.

[0056] The bearing 7 which supports the rotor carrier 3 to be grounded in a rotatable manner relative to the housing 5 is in particular a radial bearing, wherein the radial bearing is preferably designed as a rolling bearing and is particularly preferably designed as a deep groove ball bearing. However, within the scope of the invention, the intermediate bearing may also be designed as a rolling bearing of another type, for example as a roller bearing, or also as a sliding bearing.

[0057] It is known that in modern electric drives, spark erosion may occur in the (rotor) bearings. In order to avoid bearing damage, a grounding path must be provided. According to the invention, it has been recognized that conventional grounding rings cannot be used in modern electric drives because there may be no accessible, uninterrupted outer diameter available.

[0058] Figure 1 A detail of a device 1 according to the invention is shown.

[0059] The device is arranged in an electric machine 2 which has a rotor with a rotor carrier 3 which is designed here as a rotor shaft. The rotor carrier 3 can carry a laminated core 4 which is indicated here.

[0060] The device 1 also has a grounded housing 5 with an internal housing arm 6 located in the housing and at least partially in the rotor carrier 3. The housing arm 6 can be designed as a web / shoulder / bearing seat or bearing mount and be formed integrally with the housing 5.

[0061] Furthermore, there is a bearing 7 , via which the rotor carrier 3 to be grounded is rotatably mounted relative to the housing 5 , or via which the rotor carrier 3 can be supported relative to the housing 5 .

[0062] The bearing 7 is arranged here on the rotor side.

[0063] Furthermore, a grounding device is arranged on the circumference of the bearing 7 , which grounding device has an electrically conductive annular support element 8 , wherein the support element 8 has a central recess 9 .

[0064] In this case, the carrier element 8 consists of a conductive material, for example aluminum.

[0065] The central recess 9 allows the support element to be arranged on the housing arm 6, for example by means of an interference fit, pressed together with the housing arm. In this way, a simple electrically conductive connection is established between the support element 8 and the housing 5 from which the discharge takes place. This also makes it possible to simply fasten the annular support element 8 to the housing arm 6 and thus to the housing 5.

[0066] This means that the support element 8 is connected to the housing arm 6 by means of the central recess 9 in order to form a permanent electrically conductive connection with the housing arm 6 on the inner side of the inner diameter 11 of the support element 8 , for example.

[0067] Furthermore, a radially away-directed annular friction contact 10 , such as bristles, tongues, etc., is arranged on the support element 8 . The friction contact 10 contacts the rotor carrier 3 , thereby providing contact with an uninterrupted cylindrical contact surface.

[0068] For example, the friction contact 10 is clamped / adhesively bonded or similarly connected to the support element 8. The connection of the friction contact 10 to the support element 8 has a high conductivity.

[0069] This means that the conductive friction contact 10 is arranged on the support element 8 in a radial direction R pointing radially outward so as to form a conductive connection with the rotor carrier 8 on the outer side or outer diameter 12 of the grounding device, thereby establishing an electrical connection between the rotor carrier 3 and the housing 5 via the friction contact 10 and the support element 8.

[0070] The grounding device is therefore permanently connected to the grounded housing or housing arm 6 at the inner diameter 11. At the outer diameter 12 or the outside, the grounding device is in contact with the rotating rotor carrier / bearing carrier 3.

[0071] As a result, an electrically conductive connection is produced between the rotor carrier 3 and the housing 5 .

[0072] Between the ground contact device and the bearing 7 , a circumferential groove 13 is arranged on the rotor carrier 3 .

[0073] In order to be able to supply oil to the bearing 7 , the housing arm 6 is interrupted below the support element 8 .

[0074] For this purpose, there are continuous recesses in the axial direction A, which are in particular designed as continuous cutouts 14 . In this case, the cutouts 14 in the housing arm 6 are arranged so as to point toward the support element 8 .

[0075] The recess 14 can be designed as a press fit / pressed fit or as an interruption of a press fit surface between the support element 8 and the housing arm 6. In this case, a plurality of recesses 14 can be provided at equidistant intervals in the housing arm 6.

[0076] This arrangement allows the oil to bypass the grounding device by gravity without contaminating the sliding contact 10 (ie the contact element). The oil can cool and lubricate the bearing. Excess oil can be guided into the groove 13 or intercepted through the groove.

[0077] This means that the housing arm 6 has a recess 14 for forming a fluid connection with at least one bearing 7 or groove 13. As a result, the bearing 7 can be supplied with oil from the outside for lubrication.

[0078] In this case, the recess 14 has a cross section which is designed so that the cooling oil flowing through the recess 14 does not flow back.

[0079] For this purpose, the recess 14 is designed in such a way that the cooling oil flowing through forms a laminar flow.

[0080] The laminar gap flow rate for the recess 14 is yes:

[0081]

[0082] in, is equal to the static pressure difference, Equal to viscosity, is equal to the length, and is equal to the height of the cutout 14, and Equal to the cross-sectional diameter of the recess 14 .

[0083] As a result, the oil flowing through is guided under the inner diameter 11 without backflow in order to supply the bearing 7 with oil. Excess oil is collected in the groove 13.

[0084] Furthermore, the groove 13 has a groove bottom, wherein a hole 15 ( Figure 2 ). These holes can be distributed equidistantly on the circumference. The groove bottom diameter is larger than the contact part diameter, thereby preventing oil from flowing back.

[0085] Due to the centrifugal force, the oil that is not used to lubricate the bearing 7 (excess oil) collects in the groove 13 and is transported away through the holes 15 and supplied, for example, to the transmission. This ensures that the excess oil is thrown out and does not impair the conductive contact between the grounding device and the rotor carrier 3.

[0086] The cutout 14 in the press fit surface (outer diameter 12) of the housing arm 6 allows the oil to bypass the grounding device by gravity without contaminating the contact elements, namely the friction contact 10, and thus cool and lubricate the bearing 7. This prevents the grounding device, in particular the friction contact 10, from being contaminated by oil.

[0087] Therefore, the friction contact 10 can be kept at least largely free of oil, thereby improving the electrical contact between the friction contact 10 and the rotor carrier 3 .

[0088] Figure 2The cutout 14 in the press fit surface (outer diameter 12) of the housing arm 6, the friction contact 10 and the groove 13 in the rotor carrier 3 are shown in detail. Due to the centrifugal force, the oil collects in the groove 13. Through the cutout 14, the oil flowing through can bypass the grounding device by gravity without contaminating the contact elements, namely the friction contact 10, and cool and lubricate the bearing 7.

[0089] The cross section or diameter of the recess 14 is designed so that the amount of oil required for bearing lubrication / cooling can reach the bearing 7 without backflow. The number of recesses 14 is also designed in this regard. This again depends on the required and available amount of oil.

[0090] Furthermore, holes 15 are provided, through which oil which flows through the recess 14 and subsequently collects in the groove 13 is carried away.

[0091] The groove bottom diameter is larger than the contact portion diameter. Therefore, the sliding contact portion 10 will not be contaminated by the backflowing oil.

[0092] This ensures that excess oil is thrown off and does not impair the conductive contact between the grounding device and the rotor carrier 3 .

[0093] With such a device 1 according to the invention, the friction contacts 10 (i.e., bristles, for example) do not point radially inwards, as is common in the prior art, but rather point radially outwards, where they directly or indirectly (e.g., via an electrically conductive sleeve) contact the rotor carrier 3 to produce an electrically conductive connection. The grounding device is thus permanently connected to the grounded housing 5 on its inner side (the surface pointing radially inwards) and contacts the rotating rotor carrier / bearing carrier 3 on its outer side.

[0094] With such an apparatus 1 , the rotor carrier 3 has an uninterrupted cylindrical contact surface for producing a permanent electrically conductive connection, thereby ensuring that the current is permanently discharged.

[0095] Reference numerals list

[0096] 1 device

[0097] 2 Motor

[0098] 3 Rotor carrier

[0099] 4 stacking groups

[0100] 5 Shell

[0101] 6 Shell Arm

[0102] 7 Bearings

[0103] 8 Load-bearing elements

[0104] 9 central recess

[0105] 10 Sliding contact part

[0106] 11 inner diameter

[0107] 12 outer diameter

[0108] 13 slots

[0109] 14 blank space

[0110] 15 holes

[0111] 16 slot bottom

[0112] A Axial direction

[0113] R radial direction

Claims

1. A device (1) for grounding a rotor carrier (3), the device (1) comprising a grounded housing (5) and a rotor carrier (3) arranged in the grounded housing (5) and rotatable and extending in an axial direction (A), the device further comprising a grounding device and at least one bearing (7), in, The rotor carrier (3) is supported relative to the housing (5) via the at least one bearing (7), It is characterized in that The housing (5) has a housing arm (6), wherein the grounding device is arranged on the housing arm (6) on the circumference next to the bearing (7). The grounding device comprises an electrically conductive annular support element (8) with a central recess (9), wherein the support element (8) is connected to the housing arm (6) by means of the central recess (9) in order to form a permanent electrically conductive connection with the housing arm (6) on the inner side of the support element (8), and A conductive friction contact portion (10) is arranged on the support element (8) pointing outward in a radial direction (R) to form a conductive connection with the rotor carrier (3) on the outer side of the friction contact portion (10), thereby establishing an electrical connection between the rotor carrier (3) and the housing (5) via the friction contact portion (10) and the support element (8).

2. The device (1) according to claim 1, characterized in that The housing arm (6) is designed as an internal housing arm (6) that at least partially protrudes into the rotor carrier (3), so that the sliding contact portion (10) can be brought into contact with the rotor carrier (3).

3. The device (1) according to claim 1 or 2, characterized in that The central recess (9) is arranged on the housing arm (6) by means of a non-positive connection.

4. The device (1) according to any one of the preceding claims, characterized in that The rotor carrier (3) has a circumferential groove (13) between the bearing (7) and the grounding device.

5. The device (1) according to claim 4, characterized in that The sliding contact portion (10) has a sliding contact portion diameter extending in the axial direction (A), and the surrounding groove (13) has a groove bottom (16) and a groove bottom diameter extending in the axial direction (A), and wherein the groove bottom diameter is greater than or equal to the sliding contact portion diameter.

6. Device (1) according to any one of the preceding claims 4 or 5, characterized in that The groove (13) has a groove bottom (16), wherein a radial aperture is provided in the groove bottom (16) in the rotor carrier (3).

7. Device (1) according to any of the preceding claims, characterized in that The connection point between the grounding device and the housing arm (6) has at least one continuous recess in the axial direction (A) for establishing a fluid connection with the at least one bearing (7).

8. The device (1) according to claim 7, characterized in that The at least one continuous recess is arranged in the carrier element (8).

9. The device (1) according to claim 8, characterized in that At least one continuous recess in the support element (8) is arranged to point toward a continuous recess (14) of the housing arm (6).

10. The device (1) according to claim 7, characterized in that At least one continuous recess in the housing arm (6) is arranged so as to point toward the support element (8).

11. The device (1) according to claim 10, characterized in that At least one continuous recess in the housing arm (6) is arranged below the support element (8) as a continuous recess (14), so that a fluid can flow through below the support element (8).

12. The device (1) according to claim 11, characterized in that A plurality of recesses (14) are arranged in the housing arm (6) at equidistant intervals.

13. Device (1) according to any one of the preceding claims 11 to 12, characterized in that The at least one recess (14) is designed such that a fluid flowing through it in a defined manner flows without backflow.

14. Device (1) according to any of the preceding claims, characterized in that The grounding device is arranged on the housing arm (6) on the side of the bearing (7) facing away from the rotor.

15. A transmission device for a motor vehicle, characterized in that A device (1) for grounding a rotor carrier (3) mounted in a housing (5) of a transmission is provided according to any one of claims 1 to 14.

16. An electric machine (2) having a stator which is fixed against relative rotation and a rotor which can rotate, wherein: The rotor is coupled to a rotor carrier (3), wherein the rotor carrier (3) is mounted in a housing (5) of the electric machine (2), characterized by having a device (1) for grounding a rotor according to any one of claims 1 to 14.

Images