DE102013223673B4 - Automotive powertrain - Google Patents

Abstract

Motor vehicle drive train (10) comprising
a brushless electrical machine (12) with a stator (16) and a rotatable rotor (14), the rotor (14) being permanently electrically conductively connected to the stator (16) via a contact element (60), the contact element (60 ) is arranged radially on the outside of a rotor shaft (20) and is electrically conductively connected to a contact element receiving area (58), characterized in that the contact element (60) is circular and has teeth (62) which are evenly distributed radially on the outside in the circumferential direction, wherein the teeth (62) engage with play in the circumferential direction (Su) in receptacles (56), the contact element (60) having a play (S2) between the contact element receiving area (58) and the contact element (60), as well as a play (S1 ) between the rotor shaft (20) and the contact element (60).

Description

The invention relates to a drive train for a motor vehicle according to the preamble of claim 1.

In the DE 196 18 865 C2 a drive train is shown, including an internal combustion engine, an electric machine, a clutch and a transmission.

In the electrical machine of such a motor vehicle drive train, shaft voltages occur between the rotor and the stator. Such shaft voltages are caused on the one hand by induction of a voltage in a conductor loop (rotor shaft, bearing, end shield and stator housing) through magnetic asymmetries in the electrical machine, on the other hand they are generated by steep voltage flanks of a converter. If the shaft voltages occurring between the rotor and stator exceed a certain value, they are discharged, for example through arcing. Such flashovers occur particularly frequently at the bearing points of the motor vehicle drive train, which, due to the lubrication, produce tribological electrical insulation between the rotor and the stator. Bearing points within the electrical machine are just as affected as bearing points outside the electrical machine, for example bearing points within a transmission. The discharges mainly occur on the bearings, damage their surface and change their structure, whereby the changes in structure influence the material properties. This additional load on the bearings leads to increased wear and tear and premature failure.

The generic JP 2000 - 244 180 A as well as the JP 200-310 296 A describe contact devices that provide a conductive connection between a shaft and a housing of an electrical machine in a drive train, for example via pretensioned contact pins, electrically conductive seals or contact via liquids.

It is therefore the task of providing a further possibility to reduce the shaft stresses harmlessly and in a defined manner within a motor vehicle drive train.

This above object is achieved by means of the motor vehicle drive train according to the independent patent claim. Advantageous configurations and developments of the invention are specified in the dependent claims.

According to the invention, a drive train is proposed in which the rotor is permanently electrically conductively connected to the stator via a contact element.

Accordingly, a motor vehicle drive train is proposed, comprising a brushless electrical machine with a stator and a rotatable rotor, the rotor being permanently electrically conductively connected to the stator via a contact element, the contact element being arranged radially on the outside on a rotor shaft and electrically conductively connected to a contact element receiving area The contact element is circular and has teeth that are evenly distributed radially on the outside in the circumferential direction, the teeth engaging with a play in the circumferential direction in receptacles, the contact element having a play between the contact element receiving area and the contact element and a play between the rotor shaft and the contact element.

The electrical potential differences that cause the shaft voltages build up between the rotor and stator during operation of the electrical machine and discharge as soon as the shaft voltage is sufficiently high for a sparkover. Such a spark usually occurs at the bearing points between the stator and rotor. The mounting of the rotor on the stator within an electrical machine can be implemented by different types of bearings, all bearing types having a lubricant which tribologically isolate the components of the bearing that run into one another from one another. A permanent conductive contact between the rotor and the stator through an additional contact element enables permanent equipotential bonding and therefore ensures an immediate and harmless reduction of any shaft voltages that occur. A potential difference threshold that triggers a sparkover is not exceeded.

In order to reliably prevent tribological electrical insulation of the contact element, the contact element is preferably designed to be free of lubricant, in particular free of viscous or liquid lubricant. As a possible alternative, as long as the conductive contact is maintained, solid lubricants, among other things, can be used. The contact element is therefore preferably designed to be free of fluid and / or viscous lubricant. Furthermore, it is advantageous to design the contact element with low friction in order to keep wear to a minimum.

It is also proposed to arrange the contact element within a lubricant-free space. A contact element which is arranged, for example, in an oil-lubricated transmission of a motor vehicle drive train, would be wetted by an oil film, whereby the conductive contact between rotor and stator is interrupted.

In the case of a drive train, it is usually the case that the housings of the individual assemblies are conductively connected to one another, the housing of the electrical machine being normally connected to the stator in an electrically conductive manner. In addition, one of the housings, usually that of a drive motor, is grounded or grounded. Furthermore, the rotating elements of the motor vehicle drive train are also conductively connected to one another, for example the rotor shaft and a transmission input shaft and a clutch disc. The further explanations on shafts or other rotating components of the motor vehicle drive train can also be transferred to other elements that are connected to the rotor in an electrically conductive manner, for example also a clutch disc, the same also applying vice versa. Since a conductive connection between rotor and stator is sufficient to reduce the shaft voltages, it is proposed to functionally arrange the contact element between an element connected in an electrically conductive manner to the stator and an element connected in an electrically conductive manner to the rotor. These elements can include a housing of the motor vehicle train and a shaft of the motor vehicle drive train or a clutch disc, but in particular the rotor shaft of the electrical machine. The contact element can therefore be arranged at any point within the motor vehicle drive train.

According to an advantageous embodiment, it is extremely useful if the contact element is arranged on a contact element receiving area. A contact element receiving area can be formed, for example, on an element that is in conductive contact with the stator or on an element that is in conductive contact with the rotor, in particular on a housing of the motor vehicle drive train or on a shaft, in particular the rotor shaft. This contact element receiving area can be designed as a separate component or integrated within an existing component, in particular on a housing. A contact element receiving area is characterized, inter alia, in that the contact element is arranged captively within the contact element receiving area. The mobility of the contact element is therefore restricted to such an extent that it can only move freely within a predetermined range. This free movable area can be selected to be relatively large or relatively small relative to the size of the contact element, depending on the embodiment.

It is also advantageous if there is play between the contact element and the element in electrical contact with the stator, and between the contact element and the element in electrical contact with the rotor. Such play, for example between the shaft and the contact element and between the contact element receiving area and the contact element, is preferably to be designed in such a way that there is permanent contact between the rotor and the stator. If the contact element is designed, for example, in the shape of a circular ring, then the radial play between the contact element and the shaft should be designed to be smaller than the radial play between the contact element and the contact element receiving area. Due to vibrations and gravity, the contact element cannot remain within a non-contact position. Furthermore, the contact element with play experiences a preferred contact position due to the force of gravity, the contact element nestling against the shaft. A contact element with play can therefore also follow the movements of the shaft, e.g. wobbling movements. There is always electrical and physical contact between the shaft and the contact element.

It is particularly advantageous for the contact element to be designed so that it is essentially non-rotatable, but with little play, with respect to the contact element receiving area. In one embodiment, the contact element has at least one tooth and the contact element receiving area has at least one recess. In the following, advantages and possible embodiments on a tooth and a recess are explained, which, however, can be transferred to other teeth. A tooth is assigned to a recess and engages in it. In one possible variant, the tooth is arranged radially outside on the contact element and engages in the recess with play in the circumferential direction. The play in the circumferential direction enables the contact element to be slightly rotated relative to the contact element receiving area, with a rotation optionally being able to cause a stroke movement in the radial direction towards the axis of rotation of the shaft. Such play allows the contact element to follow the movements of the shaft with permanent electrical contact. The rotation of the shaft entrains the contact element and results in at least one tooth of the contact element making an electrically conductive contact on at least one receptacle in the contact element receiving area. The contact element thus produces a continuous contact between the rotor and the stator. Since the contact element only rests freely, there is little wear. The arrangement of the teeth on the contact element and the receptacle on the contact element receiving area can also be reversed. Other designs that have a similar or using the same functionality are also conceivable. In this case, the functionality of the contact element is independent of the direction of rotation of the shaft.

It was already mentioned above that it is extremely favorable if the radial play between the shaft and contact element is smaller than the radial play between the contact element receiving area and the contact element. In the event that the radial play between the contact element receiving area and the contact element is greater than the radial play between the shaft and the contact element, the contact element rests against the contact element receiving area, but in this case there would still be play between the shaft and the contact element. This means that no electrical contact is made between the shaft and the contact element. In other words, the contact element must rest on the shaft, the outer diameter of the contact element being free and the teeth making conductive contact with the housing. The play is preferably designed in such a way that failure of the contact element due to wear can be ruled out over the entire at least a fixed part of the service life.

In a further development, the teeth of the contact element are evenly distributed over the circumference.

A contact element with no play wears out much faster than the contact element with play, since it cannot follow the movements of the shaft and therefore not only rests on it, but is also subjected to force. Furthermore, a contact element without play has a higher drag torque and, above a certain degree of wear, is no longer able to establish electrical contact between the rotor and the stator due to the wear. Such wear is compensated for by a contact element with play, at least in the embodiment variant explained above, by the specified play. The specified play is designed so that the contact element retains its functionality even with wear and tear on the contact surface facing the shaft. The main wear surface is therefore the contact surface between the contact element and the shaft.

The contact element is preferably made of a hard and resistant material with a low coefficient of friction. This enables a long service life with little wear and tear and low drag torque. The contact element can be designed, for example, as a steel component, in particular made of ZF7B, or as a plastic component.

In addition to the electric machine, a motor vehicle drive train also has a transmission, a clutch device and a drive motor. If the shaft voltages that arise within the electrical machine are not reduced and the bearings of the electrical machine are merely insulated, it is the case that the shaft voltages are reduced within other assemblies of the motor vehicle drive train. This can be the case, among other things, due to arcing within the clutch device, the drive motor or within the transmission. Isolating bearings therefore only move the shaft stress problem to another location in a different assembly in the drive train.

As already mentioned above, the contact element can be integrated within any assembly of the motor vehicle drive train due to the contacting of the individual assembly housings. In principle, the contact element can be arranged at any point within the motor vehicle drive train, as long as the rotor and the stator are connected to one another in an electrically conductive manner via the contact element.

In a further embodiment, the contact element is arranged within the coupling device with a coupling disc, a pressure plate and a flywheel between the clutch disc and the pressure plate or the flywheel. In one embodiment variant, the contact element is formed on a driver disk of the clutch disk, the contact element being arranged within a recess of a friction lining. When the clutch is open, ie the friction lining and the pressure plate or the flywheel are at a distance from one another, the contact element is shaped so that it spatially bridges the gap between the friction lining and the flywheel or the pressure plate and creates an electrical contact between the drive plate and pressure plate or pressure plate. Manufactures flywheel. The contact element is designed to be elastic in such a way that it can be compressed at least by the clearance space when the clutch is closed. In the closed state of the coupling device, a contact surface of the contact element is essentially in a plane with a friction surface of the friction lining. Permanent contact by bridging the gap between the friction lining and the pressure plate or the flywheel can also be produced by a spring element, which the contact element on the one hand rests against the pressure plate or flywheel and on the other hand is compressible to bridge the gap.

Another possibility is to arrange the contact element laterally on a bearing of the shaft. The contact element creates a conductive contact between an outer bearing shell of the bearing and an inner bearing shell of the bearing. This conductive contact can be produced, inter alia, by a conductive plate which is in physical contact with the inner bearing shell and the outer bearing shell. Furthermore, the contact element can be formed completely or only over part of the bearing. In this case, the contact element is advantageously acted upon by a force in the direction of the bearing, the contact element only being in continuous contact with the inner and outer bearing shells. The acting force that the contact element applies to the bearing can be generated, among other things, by a spring element or also by gravity. In an advantageous embodiment variant, the contact element also has a wear reservoir, which ensures a long service life and can be achieved, for example, by means of a thickened material area.
In a further variant, the contact element can produce a contact between a contact element receiving area and a contact flange of the shaft. The contact flange can, among other things, be pressed onto the shaft or formed directly from the shaft. According to an advantageous embodiment, the contact element is mounted on the one hand on the housing, or on a component or element that is in conductive contact with the housing, at least one conductive connection to the stator being required, on the other hand, the contact element is in contact with the shaft or the contact flange. The contact element can, inter alia, be placed laterally, in particular by applying a force, to the bearing and to the housing. In a further development, the contact element is in particular rotatably mounted on the housing and, in a rotary movement, is applied to the contact flange or to the shaft in conductive contact. In an advantageous embodiment, this contact element also has a wear reservoir.

The contact element is expediently designed in such a way that an electrically conductive contact between the stator and rotor is ensured independently of the movements of the shaft.

The various design variants can be advantageously combined with one another as desired.

The invention is explained below by way of example with reference to the accompanying figures.

• 1 einen schematischen Aufbau eines Kraftfahrzeugantriebsstrangs;
• 2 eine Ausführungsvariante eines Kontaktelements des Kraftfahrzeugantriebsstrangs aus 1;
• 3 eine Kupplungsvorrichtung des Kraftfahrzeugantriebsstrangs mit Kontaktelement;
• 4 a, b das Kontaktelement der Kupplungsvorrichtung aus 3;
• 5 eine beispielhafte schematische Darstellung eines Kontaktelements, das an einem Lager angeordnet ist;
• 6 eine weitere beispielhafte schematische Darstellung eines Kontaktelements, das an einem Kontaktflansch angeordnet ist;
• 7 eine alternative Ausführung des Kontaktelements aus 6;

Show it:

• 1 a schematic structure of a motor vehicle drive train;
• 2 an embodiment variant of a contact element of the motor vehicle drive train 1 ;
• 3 a coupling device of the motor vehicle drive train with a contact element;
• 4 a, b the contact element of the coupling device 3 ;
• 5 an exemplary schematic representation of a contact element which is arranged on a bearing;
• 6th a further exemplary schematic representation of a contact element which is arranged on a contact flange;
• 7th an alternative embodiment of the contact element 6th ;

In 1 Figure 3 is a schematic structure of an automotive powertrain 10 with an electric machine 12th shown. The electric machine 12th has a rotor 14th , a stator 16 and a housing, in the following EM housing 18th called, on. The permanently excited rotor 14th is radially inside the stator 16 arranged and with a rotor shaft 20th opposite the stator 16 and the EM housing 18th freely rotatable over a bearing 22nd , in this case two bearings 22nd , on the EM housing 18th stored. A lubricant or a layer of lubricant within the bearing 22nd ensures tribologically based electrical insulation between the rotor 14th and stator 16 .

The stator 16 includes a stator core 24 and on the stator core 24 arranged stator coils 26th , with the stator coils 26th from a converter 28 , especially a frequency converter 28 , are driven. The EM housing 18th is electrically conductively connected to the laminated stator core, in particular via fastening points 19th (shown schematically) of the stator 16 on the EM housing 18th , for example by screwing, riveting, pressing or other known connecting means. Among other things, there are also housings 9, 18 of individual assemblies 8th of the motor vehicle drive train 10 via attachment points 19th (also shown schematically) connected to each other. In principle, the type of connection or the fastening of the housings to one another is irrelevant as long as equipotential bonding is guaranteed or an electrically conductive connection is present between the components. The conductive connections between the various components are in 1 clarified again.

As already described above, occur between the rotor 14th and stator 16 Shaft voltages. In order to reduce these shaft tensions, the drive train 10 a contact element 60 on, which on a contact element receiving area 58 , especially on the EM housing 18th , is arranged. The contact element receiving area 58 is here axially to the side of the bearing 22nd arranged and provides an electrically conductive connection between the housing 18th and the stator 16 here. Radially within the contact element receiving area 58 is the contact element 60 arranged and set substantially in the axial direction. The contact element 60 is radially outside on the rotor shaft 20th arranged and electrically conductive with the contact element receiving area 58 tied together. Furthermore, the contact element represents 60 an electrical contact between the rotor 14th and stator 16 and short-circuit it. Shaft tensions between rotor 14th and stator 16 occur, are therefore degraded immediately. A flashover within the camp 22nd therefore does not take place.

In 2 is a variant of the contact element 60 and the contact element receiving area 58 shown in more detail in the axial direction of view B. The contact element 60 is circular and has teeth 62 which are evenly distributed radially on the outside in the circumferential direction. The teeth 62 grip with a play in the circumferential direction Su (Circumferential play) in recordings 56 a. The contact element 60 is up to the circumference game Su essentially non-rotatably with respect to the contact element receiving area 58 , to the EM housing 18th and the stator 16 arranged. In addition to the scope game Su has the contact element 60 among other things a game S2 between the contact element receiving area 58 and the contact element 60 , as well as a game S1 between the rotor shaft 20th and the contact element 60 on. The game S1 , the game S2 and the scope game Su enable the contact element 60 Continuous electrical contact between the stator with little wear 16 and rotor 14th to manufacture. In this variant is the game S2 executed larger than the game S1 , this depending on the form of the contact element 60 is and can in principle also be solved differently. The contact element 60 stands due to the smaller training of the game S1 compared to the game S2 always in contact with the rotor shaft 20th . A freewheeling of the rotor shaft 20th , that is, a state of the rotor shaft 20th without contact with the contact element 60 , is due to the vibrations in the automotive powertrain 10 as well as not possible due to gravity. Due to the rotation of the rotor shaft 20th becomes the contact element 60 rotated, with at least one tooth 62 electrical contact with a boundary surface 54 one of the recordings 56 records. The electrically conductive contact between the contact element 60 and contact element receiving area 58 or stator 16 is thereby guaranteed. The contact element receiving area 58 can be designed, inter alia, in such a way that the torque or the force in the circumferential direction acting on the tooth 62 acts in a radial direction to the rotor shaft 20th directed force is implemented. This creates a contact between the contact element 60 and rotor shaft 20th , as well as between contact element 60 and contact element receiving area 58 secured by a low application of force. Basically, the contact element is only in contact.

The game S1 , the game S2 and the scope game Su , and a small amount of play in the axial direction are necessary so that the contact element can move freely and, depending on the operating state, can form a necessary minimum of contact points.

The powertrain 10 points next to the electrical machine 12th even more assemblies 8th on, for example a clutch device, a drive motor or a gearbox, which are only indicated schematically here and in the active flow before or after the electrical machine 12th can be arranged. As the housing of the various structural units 8th via connector means 19th are fixed to each other, is an electrical contact between the structural units 8th present, which is connected to ground or grounded, for example, via a contact on the drive motor. It is therefore the case that the contact element 60 in any structural unit 8th in the drive train 10 can be arranged. Basically it is only necessary that the rotor 14th and the stator 16 at any freely selectable position of the motor vehicle drive train 10 are electrically connected to each other.

A coupling device 100 of a motor vehicle drive train 10 that have a contact element 600 is in 3 shown. The coupling device 10 has, among other things, a flywheel 102 , a printing plate 104 and a clutch disc 106 on. The clutch disk further comprises a lining carrier 108 and a friction lining 110 on. Other components of the coupling device 100 and the clutch disc 106 themselves are not discussed here because they are irrelevant for the function. On the one hand is the clutch disc 106 conductive with the rotor 14th (In 3 not shown), on the other hand is the flywheel 102 or the pressure plate 104 conductive with the stator 16 (in 3 not shown) connected. An electrical contact between the rotor 14th and stator 16 is through a contact element 600 manufactured. The contact element 600 is axially on the side of the brake disk 108 the clutch disc 106 within a recess of the friction lining 110 set. In the closed state of the coupling device 100 is the contact element 600 with flywheel 102 and lining carrier 108 and with it the rotor 14th and the stator 16 conductively connected to each other. In the open Condition of the coupling device 100 the contact element relaxes 600 such that the resulting air gap between the friction lining 110 and flywheel 102 is bridged, the electrical contact between the flywheel 102 and contact element 600 does not tear off.

The resulting air gap when the coupling device is open 100 , as well as the elasticity and the wear resistance of the contact element 600 are to be adapted to each other. In order to optimize the service life and elasticity, the contact element should 600 have as advantageous a shape as possible. One possible form of training is in 3 already shown and in 4a, b shown again in more detail. The circular contact element 600 has a base 602 , as well as a pot-shaped bowl 604 on, which is seen in the axial direction to the flywheel 102 expands radially outward. The shell 604 is also through four grooves 606 broken open the shell 604 split up. The number of grooves 606 is basically arbitrary. As a result of the breaking open and the special widening pot or shell shape, the contact element has 600 a significantly improved compressibility or, when the clutch is disengaged, can relax over a large path difference with linear expansion. Such a contact element 600 can for example on the lining carrier 108 be riveted. In principle, it is also possible to integrate a spring element.

In the following, three further contact elements are shown schematically as an example 5 until 7th explained, with only the functionality of the contact element 60 is executed. Since only the basic mode of operation is explained here, the structure of such contact elements 60 differ from the one shown here. Usually only the differences between the different versions are explained, whereby the different variants can also be combined with one another. The same components are given the same reference numbers.

In 5 is a wave 20th , a housing 18th and a warehouse 22nd shown. The wave 20th is on the housing 18th about a warehouse 22nd arranged freely rotatable, the bearing 22nd the housing opposite the shaft 20th tribologically isolated. Axially to the side of the bearing 22nd is a contact element 60 arranged, which is within a contact element receiving area 58 going through the case 18th is formed, is arranged. The contact element 60 is arranged and guided within a type of receptacle, as well as with a force, in this case by a spring element 80 , towards the camp 22nd applied. The contact element is still on an inner running shell 22a and an outer running shell 22b of a warehouse. The contact element creates a conductive contact between the housing 18th and the wave 20th or the rotor 14th and the stator 16 (in 5 - 7th not shown). The contact element is via the application of force to the spring element 80 only to the bearing shells 22a and 22b created.

An alternative variant is shown in 6th shown. The contact element 60 is here, compared with 5 , not at a warehouse 22nd arranged, but on a contact flange 20a the wave 20th as well as on the housing 18th . The contact element 60 is again in a contact element receiving area 58 arranged and guided and is subject to an application of force, again by a spring element 80 . The contact element, which is designed as a plate, is at the same time on contact areas 82 of the housing 18th , as well as a contact area 82 of the contact flange 20a at. The contact area 18a of the housing can in principle be designed as an independent component, with only a direct or indirect contact to the housing or to the stator having to be present. The contact flange 20a can also be placed anywhere on the shaft 20th be designed, for example as a wave ring 20a the one on the wave 20th is pressed.

In 7th is an alternative variant with a contact flange 20a shown. The contact element 60 is here, however, on a contact element receiving area 58 rotatably mounted and subjected to a force on one side. The application of force by the spring element 80 places the contact element 60 only to the contact area 82 of the contact flange 20a the wave 20th on, the contact of the contact element 60 with the case 18th via the contact element receptacle 58 given is. The contact element 60 can also be designed here in such a way that gravity touches the contact element 60 by its own weight on the contact flange 20a applies. Furthermore, the contact element is in one area 84 that the contact flange 20a or facing the shaft, is made correspondingly reinforced or wider. This allows a long service life, as there is a correspondingly large wear reservoir 84 is available.

List of reference symbols

8th

module

9

casing

10

Automotive powertrain

12th

Electric machine

14th

rotor

16

stator

18th

EM housing

19th

Connector means

20th

Rotor shaft / shaft

20a

Contact flange / shaft ring

22nd

camp

22a

Inner barrel shell

22b

Outer barrel shell

24

Stator laminated core

26th

Stator coil

28

Inverter / frequency converter

54

Boundary surface

56

recording

58

Contact element receiving area

60

Contact element

62

tooth

80

Spring element

82

Contact area

84

Wear reservoir

100

Coupling device

102

flywheel

104

printing plate

106

Clutch disc

108

Lining carrier

110

Friction lining

600

Contact element

602

base

604

peel

606

Groove

S1

game

S2

game

Su

Circumferential play

F.

force

Claims (11)

Motor vehicle drive train (10) comprising a brushless electrical machine (12) with a stator (16) and a rotatable rotor (14), the rotor (14) being permanently electrically conductively connected to the stator (16) via a contact element (60), wherein the contact element (60) is arranged radially on the outside on a rotor shaft (20) and is connected in an electrically conductive manner to a contact element receiving area (58), characterized in that the contact element (60) is circular and has teeth (62) which are radially outward in Are evenly distributed in the circumferential direction, the teeth (62) engaging with play in the circumferential direction (Su) in receptacles (56), the contact element (60) having a play (S2) between the contact element receiving area (58) and the contact element (60), as well as a play (S1) between the rotor shaft (20) and the contact element (60). Motor vehicle drive train (10) according to Claim 1 , characterized in that the contact element (60) is free of fluid lubricant. Motor vehicle drive train (10) according to Claim 1 or 2 , characterized in that the contact element (60) is arranged within a fluid-lubricant-free space. Motor vehicle drive train (10) according to one of the Claims 1 until 3 , characterized in that the contact element (60) functionally between an element electrically conductively connected to the stator (16), in particular the housing (9, 18) of an assembly (8) of the motor vehicle drive train (10), and one with the rotor (14 ) electrically conductively connected element, in particular a shaft (20) of one of the assemblies (8) of the motor vehicle drive train (10), is arranged. Motor vehicle drive train (10) according to one of the Claims 1 until 4th , characterized in that the contact element (60) is arranged on the element that is in conductive contact with the stator (16) or on the element that is in conductive contact with the rotor (14), on a contact element receiving area (58) is. Motor vehicle drive train (10) according to one of the Claims 1 until 5 , characterized in that a play is formed between the contact element (60) and the element in electrical contact with the stator (16) and between the contact element (60) and the element in electrical contact with the rotor (14). Motor vehicle drive train (10) according to Claim 5 or 6th , characterized in that the contact element (60) is designed to be essentially non-rotatable with respect to the contact element receiving area (58). Motor vehicle drive train (10) according to one of the Claims 1 until 7th , characterized in that the contact element (60) is circular and at least partially encloses the element which is in electrically conductive contact with the rotor (14). Motor vehicle drive train (10) according to one of the Claims 1 until 8th , characterized in that the motor vehicle drive train (10) further comprises a coupling device (100), the contact element (600) being arranged within the coupling device (100). Motor vehicle drive train (10) according to one of the Claims 1 until 9 , characterized in that the contact element (60) is designed to be elastically deformable. Motor vehicle drive train (10) according to one of the Claims 1 until 10 , characterized in that the contact element (10) on the side of a bearing (22) or on the side of a contact flange (20a), which is connected to the element conductively connected to the rotor (14), in particular on the shaft (20) of the motor vehicle drive train (10) , is arranged.

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