Wheel hub drive for a motor vehicle and motor vehicle

Abstract

The invention relates to a wheel hub drive (10) for a motor vehicle, comprising a wheel carrier (12), a wheel hub (40) rotatably mounted on the wheel carrier (12) via a wheel bearing (14), a vehicle wheel (42) which is connected to the wheel hub (40) in a rotationally fixed manner, an electric machine (24) which has a stator (26) connected to the wheel carrier (12) in a rotationally fixed manner and a rotor (30) which is rotatably mounted on the wheel carrier (12) via a rotor bearing (58) provided in addition to the wheel bearing (14), and a positive coupling device (K) which can be switched between a coupled state, in which the rotor (30) is connected to the wheel hub (40) in a rotationally fixed manner by means of the coupling device (K), and a decoupling state, in which the rotor (30) is rotatably connected relative to the wheel hub (40),wherein the coupling device (K) has a coupling element (72) extending in a radial direction (36) of the wheel hub drive (10) and arranged to be displaceable along the radial direction (36) of the wheel hub drive (10).

Description

The invention relates to a wheel hub drive for a motor vehicle, in particular for a motor vehicle, according to the preamble of patent claim 1.DE 10 2022 000 026 A1 discloses a wheel hub drive for a motor vehicle. DE 10 2022 000 035 A1 and JP 4 868 367 B2 each show a wheel hub drive with a clutch, by means of which a rotor of an electric machine can be coupled to a wheel and decoupled from the latter.It is the object of the present invention to provide a wheel hub drive for a motor vehicle and a motor vehicle having such a wheel hub drive, so that particularly efficient operation and a particularly compact design of the wheel hub drive can be realized.This object is achieved by a wheel hub drive having the features of patent claim 1 and by a motor vehicle having the features of patent claim 10. Advantageous embodiments with expedient developments of the invention are specified in the other claims.A first aspect of the invention relates to a wheel hub drive, also referred to as a wheel hub drive device or wheel hub drive device, for a motor vehicle, also referred to simply as a vehicle, which is preferably designed as a motor vehicle, in particular as a passenger vehicle. This means that the motor vehicle has the wheel hub drive in its completely produced state and can be driven, in particular purely electrically, by means of the wheel hub drive. Thus, the wheel hub drive is preferably an electrical wheel hub drive, by means of which the motor vehicle can be driven, in particular purely electrically. For example, the motor vehicle in its completely manufactured state has at least or exactly two vehicle axles arranged one behind the other in the longitudinal direction of the motor vehicle and thus one after the other and also simply referred to as axles. The respective vehicle axle has at least or exactly two respective vehicle wheels, also referred to simply as wheels, wherein the respective vehicle wheels of the respective vehicle axle are arranged on sides of the motor vehicle opposite one another in the transverse direction of the vehicle. The vehicle wheels are ground contact elements, by means of which the motor vehicle can be or is supported on a ground in the vertical direction of the motor vehicle downwards. If the motor vehicle is driven along the ground while the motor vehicle is supported on the ground via the ground contact elements in the vertical direction of the motor vehicle downwards, the ground contact elements roll off the ground, in particular directly. As will be explained in more detail below, in particular precisely, a first of the vehicle wheels is a component of the wheel hub drive. If the vehicle wheel is referred to above and below, this is to be understood as meaning, unless otherwise stated, the first vehicle wheel of the wheel hub drive. In this case, the vehicle wheel can be driven, in particular purely electrically, by means of the wheel hub drive. The aforementioned wheel hub drive is also referred to as a first wheel hub drive, wherein, if the discussion above and below is about the wheel hub drive, unless otherwise indicated, this is to be understood as the first wheel hub drive. For example, the motor vehicle can have at least one second wheel hub drive provided in addition to the wheel hub drive, which can comprise, for example, in particular exactly, a second, wherein the second vehicle wheel can be driven, in particular purely electrically, by means of the second wheel hub drive. In this case, it is preferably provided that the first vehicle wheel and the second vehicle wheel are the vehicle wheels of the same vehicle axle. The preceding and following explanations regarding the first wheel hub drive and regarding the first vehicle wheel can also be easily transferred to the second wheel hub drive and the second vehicle wheel, and vice versa.The wheel hub drive (first wheel hub drive) has a wheel carrier and a wheel bearing, which has, for example, a first bearing shell connected to the wheel carrier, in particular permanently, in a rotationally fixed manner, and, for example, a second bearing shell arranged coaxially and rotatably with respect to the first bearing shell. This means that the second bearing shell is rotatable about a wheel axis of rotation relative to the first bearing shell and relative to the wheel carrier, wherein the second bearing shell is arranged coaxially with respect to the wheel axis of rotation relative to the first bearing shell. The wheel bearing is preferably a first rolling bearing. It is conceivable that the first bearing shell and the wheel carrier are formed separately from one another and are connected to one another in a rotationally fixed manner, in particular permanently. Furthermore, it would be conceivable for the first bearing shell and the wheel carrier to be formed integrally with one another and thereby, in particular, to be permanently connected to one another in a rotationally fixed manner. The feature that two components, such as the first bearing shell and the wheel carrier, are formed integrally with one another is to be understood to mean that the components formed integrally with one another are formed from a single piece, with the result that the operation is formed integrally or integrally with one another. This means that the components are not formed separately from one another and are connected to one another, but the components are formed from a single piece, that is to say formed by a body which is formed from a single piece and is thus formed integrally, that is to say produced integrally, and is a monoblock.The wheel hub drive also has a wheel hub which is mounted on the wheel carrier in a conceivable manner via the wheel bearing, in particular about the main rotational axis relative to the wheel carrier. For example, the second bearing shell is connected, in particular permanently, in a rotationally fixed manner to the wheel hub. In principle, it is conceivable for the second bearing shell and the wheel hub to be formed separately from one another and, in particular, permanently, to be connected to one another in a rotationally fixed manner. Furthermore, it would be conceivable for the second bearing shell and the wheel hub to be formed integrally with one another, and therefore to be formed from a single piece. The vehicle wheel of the wheel hub drive is connected to the wheel hub in a rotationally fixed manner. In particular, the vehicle wheel is connected to the wheel hub in such a way that it can be released in a non-destructive manner that the vehicle wheel is connected to the wheel hub in a rotationally fixed manner.For example, the wheel bearing has rolling bodies. In this case, for example, the first bearing shell forms at least one first raceway for the rolling bodies, and the second bearing shell forms, for example, a second raceway for the rolling bodies. In particular, when the second bearing shell rotates relative to the first bearing shell about the main axis of rotation, which is also referred to as the wheel axis of rotation, the rolling bodies roll off on the first raceway and on the second raceway, in particular directly, so that, for example, the rolling bodies contact the first raceway and the second raceway, in particular directly.Since the vehicle wheel is connected to the wheel hub in a rotationally fixed manner, the vehicle wheel and the wheel hub are jointly, that is to say simultaneously, rotatable about the main rotational axis relative to the wheel carrier.The wheel hub drive also has an electric machine which has a stator which is connected to the wheel carrier, in particular permanently, in a rotationally fixed manner, and a rotor. The rotor can be driven by means of the stator and can thereby be rotated about a machine rotation axis relative to the stator. It is preferably provided that the electric machine or the rotor is arranged coaxially with the wheel hub and the vehicle wheel and thus with the bearing shells, so that the machine rotational axis preferably coincides with the wheel rotational axis. By driving the rotor, the wheel hub and thus the vehicle wheel can be driven by means of the rotor and can thereby be rotated about the main axis of rotation relative to the wheel carrier.The vehicle wheel has, for example, a rim and a wheel disk. In this case, for example, a tire, which is formed in particular from rubber and is formed separately from the wheel disk and separately from the rim and which can be a component of the vehicle wheel, is mounted on the rim, and is therefore fastened to the rim. In particular when the vehicle wheel rolls, rolls or rolls, in particular directly, on the aforementioned ground, in particular directly, on the ground.The wheel hub drive also has a rotor bearing, which is included in addition to the wheel bearing and is designed, for example, as a second rolling bearing, by means of which the rotor is mounted on the wheel carrier such that it can rotate, in particular about the main rotational axis relative to the wheel carrier.The wheel hub drive also has a form-locking coupling device which can be switched over between a coupling state and a decoupling state. In the coupling state, the rotor is connected to the wheel hub in a rotationally fixed manner, in particular in a positive-locking manner, by means of the coupling device. In the decoupling state, the rotor is rotatable about the main axis of rotation relative to the wheel hub, so that in the decoupling state the coupling device releases the rotor for rotations occurring about the main axis of rotation and relative to the wheel hub, and vice versa. Thus, the rotor can drive the wheel hub in particular via the coupling device, for example, then and in particular only when the coupling device is in the coupling state, and conversely, for example, the wheel hub and thus the vehicle wheel can drive the rotor via the coupling device, for example, then and in particular only when the coupling device is in the coupling state. In the uncoupled state, however, the vehicle wheel and the wheel hub cannot drive the rotor via the coupling device, so that, for example, in a coasting mode of the motor vehicle, the rotating vehicle wheel does not drag along the rotor. As a result, particularly efficient operation can be realized.In order to be able to realize a particularly space-saving, i.e. compact, construction of the wheel hub drive, it is provided according to the invention that the coupling device has a, i.e. displaceable, first coupling element extending in a radial direction of the wheel hub drive, the axial direction of which runs perpendicular to the radial direction of the wheel hub drive, and arranged displaceably along the radial direction of the wheel hub drive relative to the wheel hub and relative to the rotor. The axial direction of the wheel hub drive coincides with the main axis of rotation, and the radial direction of the wheel hub drive runs perpendicular to the axial direction of the wheel hub drive and thus perpendicular to the main axis of rotation. In the context of the present disclosure, the term "radial" refers to the radial direction of the wheel hub drive, and the term "axial" refers to the axial direction of the wheel hub drive. In other words, the term "radial" means the radial direction of the wheel hub drive, wherein the term "axial" means the axial direction of the wheel hub drive. If the radial direction is mentioned above and below, this is to be understood as meaning the radial direction of the wheel hub drive, unless otherwise stated. If the above and in the following discussion is with respect to the axial direction, this is to be understood as meaning the axial direction of the wheel hub drive, unless otherwise specified.For example, the first coupling element can be moved translationally, i.e. displaced, in the radial direction of the wheel hub drive relative to the stator and relative to the wheel hub between at least one coupling position and at least one decoupling position. The coupling position causes the coupling state and the decoupling position causes the decoupling state. This means that the coupling device is in the coupling state when the first coupling element is in the coupling position, and when the first coupling element is in the decoupling position, the coupling device is in the decoupling state. If the coupling element is mentioned above and below, this is to be understood as meaning the first coupling element, unless otherwise stated.In particular, in the coupling position, and therefore in the coupling state, the rotor and the wheel hub are connected to one another in a rotationally fixed manner in a positive-locking manner by means of the coupling element. For this purpose, for example, in the coupling state, the first coupling element cooperates positively with both the wheel hub and the rotor. In the decoupling position, for example, the first coupling element cooperates positively with the wheel hub exclusively with respect to the rotor and the wheel hub, or, for example, in the decoupling state, the first coupling element cooperates neither with the wheel hub nor with the rotor positively, such that, in the decoupling state, the rotor is rotatable about the main rotational axis relative to the wheel hub and vice versa.In order to be able to realize a particularly compact construction of the wheel hub drive, it is provided in an embodiment of the invention that the first coupling element is permanently connected to the wheel hub in a rotationally fixed manner at least with respect to the main rotational axis, which is also simply referred to as the rotational axis and about which the wheel hub is rotatable relative to the wheel carrier, so that relative movements occurring between the first coupling element and the wheel hub at least about the main rotational axis are prevented. This is effected, for example, in such a way that the first coupling element cooperates positively with the wheel hub both in the coupling position and in the decoupling position, and therefore both in the coupling state and in the decoupling state.In order to be able to realize a particularly compact construction of the wheel hub drive, it is provided in a further embodiment of the invention that the rotor bearing is arranged axially overlapping and radially outside the wheel bearing.Within the scope of the present disclosure, the feature "radially overlapping" is to be understood as meaning the following: Two elements, in particular at least substantially rotationally symmetrical, are arranged radially, in particular overlapping one another, in particular with respect to a common axis, for example running in the radial direction of the wheel hub drive, and / or in the radial direction of the wheel hub drive, if they are arranged in each case at least partially in a range of identical radial coordinates, in particular identical angular coordinates.The feature "axially overlapping" is to be understood as meaning the following: two elements are arranged axially overlapping, in particular with respect to a common axis, in particular running in the axial direction of the wheel hub drive, and / or axially overlapping, in particular with respect to one another, in the axial direction of the wheel hub drive, if they are each arranged at least partially in a region of the same axial coordinates.Within the scope of the present disclosure, the feature that a first structural element is arranged radially within a second structural element is to be understood to mean that the first structural element is arranged in a region of smaller radii than the second structural element, in particular with respect to the main axis of rotation, which is also referred to as the axis of rotation or the axis of rotation of the wheel. In addition, the feature that a first component is arranged axially within a second component is to be understood to mean that, in the installed position of the wheel hub drive, which assumes its installed position in the completely produced state of the motor vehicle having the wheel hub drive and, in particular, with respect to straight-ahead travel of the motor vehicle, that is to say, in particular, when a steering system of the motor vehicle is set to bring about straight-ahead travel of the motor vehicle, the first component, which is arranged axially within the second component, is arranged on one side of the second component toward a center of the motor vehicle, which is also referred to as the vehicle center, and therefore the first component is arranged on a side of the second component, which side points toward the center of the motor vehicle, such that the first component is arranged, in particular, further inward, as viewed in the vehicle transverse direction of the motor vehicle, that is to say closer to the center of the motor vehicle than the second component.Within the scope of the present disclosure, the feature that two components are connected to one another in a rotationally fixed manner is understood to mean that the components connected to one another in a rotationally fixed manner are arranged coaxially with respect to one another and, in particular when the components are driven, rotate together or simultaneously about a component rotation axis common to the components, such as, for example, the main rotation axis, at the same angular speed, in particular relative to a reference element, such as, for example, the wheel carrier. In other words, two elements are connected to one another in a rotationally fixed manner if they are arranged coaxially with respect to one another, in particular with respect to their component rotation axis or with respect to a rotation symmetry axis, and if they are connected to one another in such a way that they always rotate at the same angular speed. An element is connected to a housing in a rotationally fixed manner if it cannot be rotated with respect to, that is to say relative to, the housing. Thus, an element is connected to the wheel carrier in a rotationally fixed manner when it cannot be rotated with respect to, i.e. relative to, the wheel carrier.The feature that two components are connected or coupled to one another in a torque-transmitting manner is to be understood to mean that the components are coupled or connected to one another in such a way that torques can be transmitted between the components, wherein, if the components are connected or coupled to one another in a torque-transmitting manner, the components are also connected or coupled to one another in a torque-transmitting manner. Two torque-transmittingly connected components can thus be connected to one another in a rotationally fixed manner. It is furthermore conceivable that two torque-transmittingly connected components are connected to one another via an interposed transmission unit in a torque-transmitting manner, so that torques can be transmitted between the components via the transmission unit, while the components are connected to one another in a torque-transmitting manner, wherein the components can be rotatable relative to one another, however.The feature that two components are permanently connected or coupled to one another in a torque-transmitting manner is to be understood to mean that there is not, for example, a shift element which can be switched between a coupling state which connects or couples the components to one another in a torque-transmitting manner and a decoupling state in which no torques can be transmitted between the components via the shift element, but rather the components are always or always and thus permanently connected or coupled to one another in a torque-transmitting manner, that is to say in such a way that a torque can be transmitted between the components. Thus, for example, one of the components can be driven by the respective other component or vice versa.In particular, the feature that two components are permanently connected or coupled to one another in a rotationally fixed manner is to be understood to mean that a shifting element is not provided, for example, which is switchable between a coupling state which connects or couples the components to one another in a rotationally fixed manner and a decoupling state in which the components are decoupled from one another and are rotatable relative to one another, such that no torques can be transmitted between the components via the shifting element, but rather the components are always or always connected or coupled to one another in a rotationally fixed manner, thus in a rotationally fixed manner. Furthermore, the feature that two components can be connected or coupled to one another in a rotationally fixed manner is to be understood as meaning that a changeover element is assigned to the components, which changeover element can be changed over between at least one coupling state and at least one decoupling state. In the coupled state, the components are connected or coupled to one another in a rotationally fixed manner by means of the changeover element. In the decoupling state, the components are decoupled from one another, so that in the decoupling state the components are rotatable relative to one another about the component rotation axis. The same applies to the feature that two components can be connected or coupled to one another in a torque-transmitting manner. Thus, for example, the feature that two components can be connected or coupled to one another in a torque-transmitting manner is understood to mean that the components are assigned a switching element which can be switched over between at least one connection state and at least one release state. In the connected state, the components are coupled or connected to one another in a torque-transmitting manner by means of the shift element, with the result that torques can be transmitted between the components, in particular via the shift element. In the release state, the components are decoupled from one another, so that in the release state no torque can be transmitted between the components via the shift element.In order to be able to realize a particularly space-saving design of the wheel hub drive, it is provided in a further embodiment of the invention that a second coupling element is provided which is connected at least with respect to the main axis of rotation, in particular permanently, in a rotationally fixed manner to a rotor carrier of the electric machine carrying the rotor and which has a recess which is designed, for example, as a through-opening or else in the manner of a blind hole and is designed to receive the first coupling element in the coupled state. In particular, it is provided that the first coupling element is arranged in the recess in the coupling state and thus in the coupling position, so that in the coupling state the first coupling element cooperates in a positive-locking manner with the rotor carrier and via the latter with the rotor.In particular, it is provided that the rotor is formed separately from the rotor carrier and is connected, in particular permanently, to the rotor carrier in a rotationally fixed manner. In particular, the rotor is or comprises, for example, a laminated core also referred to as a laminated rotor core. Alternatively or additionally, the rotor can comprise at least one or more magnets, in particular permanent magnets, which are held, for example, on the laminated rotor core and are thus supported by the laminated rotor core. Alternatively or additionally, for example, the rotor can have at least one winding, also referred to as a rotor winding, which is held on the rotor laminated core and is thus supported by the rotor laminated core. In particular, the rotor, in particular in contrast to the rotor carrier, is a magnetically active element, by means of which, for example, a magnetic flux is to be carried, which flux is or can be generated by the electric machine, for example, during operation of the electric machine, in particular in order thereby to drive the wheel hub and thus the vehicle wheel.In order to realize a particularly compact construction, it has proven particularly advantageous if the second coupling element is arranged radially overlapping the wheel bearing.It is preferably provided that the rotor bearing and the wheel bearing are arranged axially overlapping one another and radially nested one inside the other, whereby a particularly compact construction of the wheel hub drive can be produced in particular in the axial direction of the wheel hub drive.In a further embodiment of the invention, the vehicle wheel has the wheel disk. It is conceivable that the wheel disk and the rim are formed separately from one another and are connected to one another in a rotationally fixed manner, in particular permanently. It is furthermore conceivable for the rim and the wheel disk to be formed integrally with one another and thus to be formed from a single piece and thus to be connected to one another in a rotationally fixed manner, in particular permanently.In order to be able to keep an axial length of the wheel hub drive running in the axial direction particularly small and thus represent a particularly compact construction of the wheel hub drive, it is provided in a further embodiment of the invention that, with respect to the axial direction of the wheel hub drive, the wheel disk, the first coupling element, the wheel bearing and a wheel carrier section of the wheel carrier are arranged one after the other, i.e. one after the other, in the order named. In other words, it is preferably provided that, viewed in the axial direction of the wheel hub drive, the wheel disk, the first coupling element, the wheel bearing and the wheel carrier section are arranged one after the other, that is to say one after the other, in the following sequence: the wheel disk-the first coupling element-the wheel bearing-the wheel carrier section. Thus, it is preferably provided that in the axial direction of the wheel hub drive, the first coupling element follows the wheel disk, the wheel bearing follows the first coupling element, and the wheel carrier section follows the wheel bearing.Preferably, it is provided that the first bearing shell is fastened to the wheel carrier section and thereby, in particular permanently, connected to the wheel carrier in a rotationally fixed manner.A further embodiment is characterized by a friction brake, also referred to as a brake device, which has a first brake element permanently connected to the wheel hub in a rotationally fixed manner, a second brake element and a friction region. The second brake element is connected, for example, in particular permanently, in a rotationally fixed manner to the wheel carrier. The brake elements are friction elements which can be brought into frictional cooperation in the friction region, in particular directly, in order to brake the wheel hub and thus the vehicle wheel, in particular with regard to rotations occurring about the main axis of rotation and relative to the wheel carrier. For example, the first brake element is designed as a brake disk, so that, for example, the friction brake, also referred to as a wheel brake, is designed as a disk brake. It would furthermore be conceivable for the friction brake to be designed as a drum brake. By means of the friction brake, the wheel hub and thus the vehicle wheel can be braked with respect to their rotations about the main axis of rotation and relative to the wheel carrier, as a result of which the motor vehicle or the vehicle wheel can be braked. The feature that the brake elements can be brought into frictional cooperation is to be understood to mean that the friction elements can be brought into frictional cooperation in order to brake the wheel hub relative to the wheel carrier, in particular with regard to the previously mentioned rotation of the wheel hub and thus of the vehicle wheel about the main axis of rotation and relative to the wheel carrier. Again in other words, by in particular hydraulic actuation of the friction brake, the brake elements can be brought into cooperation in such a way, in particular directly, that the brake elements rub against one another, in particular directly, as a result of which the wheel hub and thus the vehicle wheel can be braked with respect to their respective rotation which takes place about the main axis of rotation and relative to the wheel carrier. As a result, the vehicle wheel and thus the motor vehicle can be braked.The electric machine is preferably a high-voltage component, the electrical voltage of which, in particular an electrical operating and rated voltage, is preferably greater than 50 volts, in particular greater than 60 volts, and is very preferably several hundred volts.In order to be able to keep the installation space requirement of the wheel hub drive particularly low, in particular in the axial direction, it is provided in a further embodiment of the invention that the friction region of the friction brake is arranged axially between the wheel disc and the wheel bearing.A second aspect of the invention relates to a motor vehicle which is also referred to simply as a vehicle and is preferably designed as a motor vehicle, in particular as a passenger vehicle, and which has at least one wheel hub drive according to the first aspect of the invention. Advantages and advantageous configurations of the first aspect of the invention are to be regarded as advantages and advantageous configurations of the second aspect of the invention and vice versa.The electric machine can be designed, for example, as an axial flow machine, which is also referred to as an axial flow motor. For example, the electric machine is designed as an internal rotor, and therefore as an internal rotor machine. This means in particular that the stator is connected to the wheel carrier on its radially outer side. In this case, for example, the rotor carrier section and / or a further rotor carrier section of the rotor carrier is arranged radially within the stator, wherein in particular that rotor carrier section of the rotor carrier which is arranged axially overlapping with the stator is arranged radially within the stator. In particular when the electric machine is designed as an axial flux machine, the rotor is preferably designed in an H shape or in an H design, so that the rotor has an H shape, for example. The electric machine could alternatively be designed as an external rotor, and therefore as an external rotor machine. Preferably, the wheel carrier section is a part of the wheel carrier which is arranged radially overlapping with the wheel bearing.Further advantages, features and details of the invention will become apparent from the following description of a preferred exemplary embodiment and with reference to the drawing. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and / or shown alone in the single figure can be used not only in the respectively specified combination but also in other combinations or alone without departing from the scope of the invention.The drawing shows a schematic longitudinal sectional view of a wheel hub drive for a motor vehicle in a detail in the single FIG. 1.In the figures, identical or functionally identical elements are provided with identical reference symbols.The single FIG. 1 shows a detail in a schematic longitudinal sectional view of a wheel hub drive 10, also referred to as a wheel hub drive device, for a motor vehicle, also referred to simply as a vehicle. The wheel hub drive 10 has a wheel carrier 12 and a wheel bearing 14, which has a first bearing shell 16 which is connected to the wheel carrier 12, in particular permanently and in a rotationally fixed manner. The wheel bearing 14 is designed as a first rolling bearing. In the exemplary embodiment shown in FIG. 1, the wheel carrier 12 and the first bearing shell 16 are formed separately from one another and are connected to one another in a rotationally fixed manner, in particular permanently. For this purpose, at least one or more screws 18 are provided, wherein the bearing shell 16 is screwed to the wheel carrier 12 by means of the screw 18 and is thereby fastened, in particular permanently, to the wheel carrier 12 in a rotationally fixed manner. The wheel bearing 14 has a second bearing shell 20 which is coaxial and rotatably arranged with respect to the first bearing shell 16. This means that the bearing shell 20 is arranged coaxially to the bearing shell 16 and is rotatable about a main axis of rotation 22, also referred to as the wheel axis of rotation or axis of rotation, relative to the bearing shell 16 and relative to the wheel carrier 12.The wheel hub drive 10 also has an electric machine 24, which is designed as an axial flux machine (AFM). The axial flow machine is also referred to as an axial flow motor.In the exemplary embodiment shown in FIG. 1, the electric machine 24 is designed as an internal rotor, and therefore as an internal rotor machine. The electric machine 24 has a stator 26 and, in the present case, a stator carrier 28. The stator 26 is formed separately from the wheel carrier 12 and is connected, in particular permanently, to the wheel carrier 12 in a rotationally fixed manner. For this purpose, the stator 26, which is formed separately from the stator carrier 28, is connected in particular permanently, rotationally fixedly to the stator carrier 28, and the stator carrier 28 is connected, in particular permanently, rotationally fixedly to the wheel carrier 12. In the present case, the stator carrier 28 is formed separately from the wheel carrier 12 and is connected, in particular permanently, to the wheel carrier 12 in a rotationally fixed manner. Alternatively, it would be conceivable for the stator carrier 28 and the wheel carrier 12 to be formed integrally with one another.The electric machine 24 also has a rotor 30, which has rotor elements 32 and 34. The rotor 30 can be driven by means of the stator 26 and can thereby be rotated about the main axis of rotation 22 relative to the stator 26 and relative to the wheel carrier 12. The stator 26 is or comprises, for example, a stator laminated core. It is furthermore conceivable for the stator 26 to have magnets, in particular permanent magnets, which can be held on the stator laminated core and can thereby be supported by the stator laminated core. It is furthermore conceivable for the stator 26 to have at least one winding, also referred to as a stator winding, which can be held on the stator laminated core. The stator 26 is, for example, a magnetically active element, by means of which a magnetic flux is to be or is to be guided, which flux is or is to be generated, for example, by the electric machine 24 during operation of the electric machine 24, in particular in order thereby to drive the rotor 30. It can be seen that the rotor 30 and thus the electric machine 24 and the wheel bearing 14 and thus the bearing shell 16 and 20 are all arranged coaxially with respect to one another.The rotor elements 32 and 34 are spaced apart from one another in the axial direction of the wheel hub drive 10, the radial direction 36 of which runs perpendicular to the axial direction of the wheel hub drive 10 and is illustrated by a double arrow. In the present case, at least one subregion T of the stator 26 is arranged between the rotor elements 32 and 34 in the axial direction of the wheel hub drive 10, in such a way that the rotor element 32 at least partially overlaps, i.e. is covered, by the subregion T when viewed in the axial direction of the wheel hub drive 10 and thus along the main axis of rotation 22 toward the rotor element 34, and that the rotor element 34 at least partially overlaps, i.e. is covered, by the subregion T when viewed along the main axis of rotation and toward the rotor element 32.The electric machine 24 has a rotor carrier 38 by which the rotor 30 is carried. The rotor 30 and the rotor carrier 38 are formed separately from one another and are connected to one another in a rotationally fixed manner, in particular permanently. The rotor 30 is, for example, a magnetically active element by means of which the aforementioned magnetic flux is to be or is to be guided. The rotor elements 32 and 34 are spaced apart from one another in the axial direction of the wheel hub drive 10. The axial direction of the wheel hub drive 10 is at the same time the direction of the main rotational axis 22, and the radial direction 36 of the wheel hub drive 10 runs perpendicular to the main rotational axis 22 and is illustrated by the double arrow.The wheel hub drive 10 also has a wheel hub 40 which is mounted rotatably about the main axis of rotation 22 relative to the wheel carrier 12 via the wheel bearing 14 and thus via the bearing shells 16 and 20 on the wheel carrier 12. The wheel hub 40 is arranged coaxially with the bearing shell 20 and coaxially with the bearing shell 16. In the exemplary embodiment shown in FIG. 1, the wheel hub 40 and the bearing shell 20 are formed integrally with one another and are thereby permanently connected to one another in a rotationally fixed manner. The wheel hub drive 10 also has a vehicle wheel 42 which is connected to the wheel hub 40 in a rotationally fixed manner. The vehicle wheel 42 includes a rim 44 having a rim well 46 and a wheel disk 48. In the exemplary embodiment shown in FIG. 1, the rim 44 and the wheel disk 48 are formed integrally with one another and are thereby permanently connected to one another in a rotationally fixed manner. A tire, not shown in FIG. 1, can be mounted on the rim 44, in particular on the rim well 46, which tire is thus formed separately from the rim 44 and separately from the wheel disk 48 and is fastened to the rim 44. The wheel disk 48 has an in particular central fastening region 50, which has a plurality of through-openings 52, which are designed, for example, as bores. The respective through-opening 52 is penetrated by a respective wheel screw 54. The wheel disk 48 and thus the vehicle wheel 42 are screwed to the wheel hub 40 by means of the wheel bolts 54 and are thus connected to the wheel hub 40 in a rotationally fixed manner. Thus, the vehicle wheel 42 is mounted on the wheel carrier 12 such that it can rotate about the main axis of rotation 22 relative to the wheel carrier 12 via the wheel hub 40 and the wheel bearing 14. It can be seen in particular that the respective wheel screw 54 is screwed into a respective corresponding screw opening 56 of the wheel hub 40, which screw opening is designed as a through-opening, for example.The rotor 30 is rotatably mounted at least indirectly on the wheel carrier 12 via a rotor bearing 58 which is provided in addition to the wheel bearing 14 and is designed as a second rolling bearing. In the present case, the rotor 30 is rotatably mounted on the wheel carrier 12 via the rotor bearing 58, with the intermediary of the wheel hub 40 and the wheel bearing 14.The wheel bearing 14 has first rolling bodies 60 which form a first row of rolling bodies. Furthermore, the wheel bearing 14 has second rolling bodies 62, which form a second row of rolling bodies, wherein the first row of rolling bodies and the second row of rolling bodies are arranged successively in the axial direction of the wheel hub drive 10. The bearing shell 16 forms a first raceway L 1 for the rolling bodies 60 and 62, and the bearing shell 20 forms a second raceway L 2 for the rolling bodies 60 and 62, and when the bearing shell 20 rotates about the main rotation axis 22 relative to the bearing shell 16, the rolling bodies 60 and 62 roll directly on the raceways L 1 and L 2.The rotor bearing 58, which is designed as a second rolling bearing, has third rolling bodies 64 and fourth rolling bodies 66. The rotor bearing has, for example, a third bearing shell 68, which is connected in the present case, in particular permanently, in a rotationally fixed manner to the bearing shell 16. In the present case, the third bearing shell 68 and the first bearing shell 16 are formed integrally with one another and are thereby permanently connected to one another in a rotationally fixed manner. Thus, for example, the bearing shell 16 forms the bearing shell 68 or vice versa. The rotor bearing 58 has a fourth bearing shell 70 which is connected, in particular permanently, in a rotationally fixed manner to the rotor carrier 38.In principle, it would be conceivable for the bearing shell 70 and the rotor carrier 38 to be formed integrally with one another, with the result that, as it were, the rotor carrier 38 forms the bearing shell 70. In the exemplary embodiment shown in FIG. 1, however, the fourth bearing shell 70 is formed separately from the rotor carrier 38 and is connected, in particular permanently, to the rotor carrier 38 in a rotationally fixed manner. The bearing shell 68 forms a third raceway L 3 for the rolling bodies 64 and 66, and the bearing shell 70 forms a fourth raceway L 4 for the rolling bodies 64 and 66, and the rotor 30 and thus the rotor carrier 38 permanently connected to the rotor 30 in a rotationally fixed manner and the bearing shell 70 rotate about the main axis of rotation 22 relative to the bearing shell 68 and thus relative to the bearing shell 16, so that the rolling bodies 64 and 66 each roll directly on the raceways L 3 and L 4. It can be seen that the electric machine 24, and therefore the rotor 30, the wheel hub 40, the bearing shells 16 and 20 and therefore the wheel bearing 14 and the bearing shells 68 and 70 and therefore the rotor bearing 58 are all arranged coaxially with respect to one another.The wheel hub drive 10 furthermore has a coupling device K, which can be switched over between a coupling state and a decoupling state. In the coupled state, the rotor 30 is connected to the wheel hub 40 in a positively fixed manner in a rotationally fixed manner by means of the coupling device K, with the result that the coupling device K is a positively locking coupling device K. In the decoupling state, the rotor 30 is rotatable about the main axis of rotation 22 relative to the wheel hub 40, so that in the decoupling state the coupling device K releases the rotor 30 for a rotation about the main axis of rotation 22 and relative to the wheel hub 40. In particular, in the uncoupled state, no torques can be transmitted between the wheel hub 40 and the rotor 30 and thus between the vehicle wheel 42 and the rotor 30 via the coupling device K, so that, for example, when the motor vehicle is in its coasting mode, the rotating vehicle wheel 42 does not drag along the rotor 30. As a result, particularly efficient operation can be realized.In order to be able to realize a particularly compact and thus space-saving construction of the wheel hub drive 10, the coupling device K has a coupling element 72 which extends in the radial direction 36 of the wheel hub drive 10 and which, as is illustrated by a double arrow 74, is displaceable, i.e. translationally movable, in the radial direction 36 of the wheel hub drive 10 relative to the wheel hub 40 and relative to the rotor 30 and relative to the rotor carrier 38, namely between at least one decoupling position shown in FIG. 1 and causing the decoupling state and at least one coupling position causing the coupling state.The coupling element 72 is permanently connected to the wheel hub 40 in a rotationally fixed manner at least with respect to the main rotational axis 22, also referred to as the rotational axis, about which the wheel hub 40 is rotatable relative to the wheel carrier 12. For example, the coupling element 72 is designed as a pin, which is also referred to as a pin. Thus, for example, the coupling element 72 is formed cylindrically on the outer circumference, namely at least in a length region of the coupling element 72.It can also be seen from FIG. 1 that the rotor bearing 58 is arranged axially overlapping and radially outside the wheel bearing 14, wherein in particular an axial length of the wheel hub drive 10 running in the axial direction of the wheel hub drive 10 can be kept particularly low. It can also be seen that the rolling bodies 64 form a third rolling body row and the rolling bodies 66 form a fourth rolling body row, wherein the third rolling body row and the fourth rolling body row are arranged successively in the axial direction of the wheel hub drive 10. The wheel hub drive 10 has a second coupling element 76, which is connected at least with respect to the main rotational axis 22, in particular permanently, in a rotationally fixed manner to the rotor carrier 38 of the electric machine 24 carrying the rotor 30, and which has a recess 78, which is in the present case embodied as a blind hole or in the manner of a blind hole. Both in the coupling state and in the decoupling state, that is to say both in the coupling position and in the decoupling position, at least a partial region of the coupling element 72 is accommodated in a receptacle 80 of the wheel hub 40 which is designed in the present case as a through-opening, wherein the coupling element 72 at least in the coupling position, and therefore at least in the coupling state, completely penetrates, that is to say penetrates, the receptacle 80 of the wheel hub 40 which is designed as a through-opening. Thus, the coupling element 72 cooperates positively with the wheel hub 40 both in the coupling position and in the decoupling position, and therefore both in the coupling state and in the decoupling state. In the decoupling position, i.e. in the decoupling state, the coupling element 72 is arranged completely outside the recess 78, also referred to as a receptacle. In the coupling position, i.e. in the coupling state, the coupling element 72 engages in the recess 78, so that in the decoupling state, and therefore in the decoupling position, the coupling element 72 is accommodated in the recess 78. As a result, in the coupling state, the coupling element 72 cooperates in a positive-locking manner with the coupling element 76 and thus with the rotor carrier 38 and via the latter with the rotor 30. In the exemplary embodiment shown in FIG. 1, the coupling element 76 and the rotor carrier 38 are formed integrally with one another and are thereby permanently connected to one another in a rotationally fixed manner. It can be seen in FIG. 1 that the second coupling element 76 is arranged radially overlapping with the wheel bearing 14. In addition, the coupling element 76 and in particular the recess 78 are arranged axially offset both with respect to the wheel bearing 14 and with respect to the rotor bearing 58.In the axial direction of the wheel hub drive 10, the wheel disk 48, the first coupling element 72, the wheel bearing 14 and a wheel carrier section A of the wheel carrier 12 are arranged one after the other, i.e. one after the other, in the order named in their numbering. In other words, with regard to the axial direction of the wheel hub drive 10, the wheel disk 48, the first coupling element 72, the wheel bearing 14 and the wheel carrier section A of the wheel carrier 12 are arranged one after the other, that is to say one after the other, in the following sequence: the wheel disk 48-the first coupling element 72-the wheel bearing 14-the wheel carrier section A. In this case, the first bearing shell 16 of the wheel bearing 14 formed separately from the wheel carrier 12 is fastened to the wheel carrier section A and is thereby connected to the wheel carrier section A in a rotationally fixed manner.The coupling element 72 can be moved back and forth between the coupling position and the decoupling position in the radial direction 36 of the wheel hub drive 10 in the following manner: the coupling device K has an actuating element 82, which is, for example, a disengaging device or is referred to as a disengaging device. As is illustrated by a double arrow 84, the actuating element 82 can be displaced, that is to say pushed back and forth, along the main axis of rotation 22 and thus in the axial direction of the wheel hub drive 10 relative to the coupling element 72. For this purpose, the coupling device K has an actuator 86, by means of which the actuating element 82 can be pushed, for example, in the direction of the coupling element 72 and can also be pushed, for example, away from the coupling element 72, namely in the axial direction of the wheel hub drive 10. The actuating surfaces run in a respective plane, wherein the respective plane runs obliquely to the radial direction 36 and obliquely to the axial direction of the wheel hub drive 10. The planes coincide, for example, or the planes run parallel to one another. If the actuating element 82 is moved in the axial direction of the wheel hub drive 10 in the direction of the coupling element 72, i.e. is pushed in the present case, and therefore moved in a translatory manner, the actuating surfaces slide off one another, in particular directly. As a result, the translatory movement of the actuating element 82 running in the axial direction of the wheel hub drive 10 is converted into a displacement running in the radial direction 36 of the wheel hub drive 10, and therefore into a translatory movement of the coupling element 72, in such a way that, as a result of the actuating element 82 being pushed in the axial direction of the wheel hub drive 10 in the direction of the coupling element 72, the coupling element 72 is pushed from the decoupling position into the coupling position.A restoring element 88 of the coupling device K is assigned to the actuating element 82, and in the exemplary embodiment shown in FIG. 1, the restoring element 88 is a spring which is designed in the present case as a solid body and thus as a mechanical spring. By moving the coupling element 72 from the decoupling position into the coupling position, the restoring element 88, that is to say in the present case the spring, is or is to be tensioned or tensioned, as a result of which the restoring element 88 provides a restoring force which in the present case is designed as a spring force. By means of the restoring force, the coupling element 72 can be moved in the radial direction 36 back from the coupling position into the decoupling position. In this case, for example, the actuating surfaces slide (again) against one another, as a result of which, for example, the actuating element 82 is moved away from the coupling element 72 in the axial direction of the wheel hub drive 10 or is displaced in a direction pointing away from the coupling element 72.The actuator 86 is, for example, an electric actuator, and therefore an electrically operable actuator. For example, the actuator 86 can be an electric servomotor, which can move, in particular move back and forth, the actuating element 82 axially and translationally, for example via a worm or a worm gear, namely in particular in the direction of the coupling element 72 and away from the coupling element 72, for example. The restoring element 88 can then, for example, move the first coupling element 72 or thereby from the coupling position into the decoupling position when or in that the actuating element 82 is moved away from the first coupling element 72 or in the aforementioned direction by means of the actuator 86 in the axial direction of the wheel hub drive 10. This allows the spring to be relaxed, as a result of which the spring can move the coupling element 72 from the coupling position into the decoupling position.For example, a seal, for example designed as an O-ring and formed for example from a rubber, is provided for the coupling element 72, by means of which seal, for example, the first coupling element 72 is sealed off from the wheel hub 40, and, for example, the seal is arranged in the receptacle 80. For example, the coupling element 72 is lubricated by means of a lubricant, in particular by means of a liquid lubricant, wherein, for example, the seal can prevent the lubricant from flowing excessively away from the coupling element 72.The wheel hub drive 10 furthermore has a braking device designed as a friction brake 90, which has a first braking element 92 permanently connected to the wheel hub 40 in a rotationally fixed manner and a second braking element 94 permanently connected to the wheel carrier 12 in a rotationally fixed manner. In the exemplary embodiment shown in FIG. 1, the friction brake 90 is designed as a disc brake, so that the brake element 92 is designed as a brake disc. The friction brake 90 has a friction region B in which the brake elements 92 and 94 can be brought into frictional cooperation, in particular in a direct manner, in order thereby to brake the vehicle wheel 42. It can be seen that the friction region B of the friction brake 90 is arranged axially between the wheel disc 48 and the wheel bearing 14.The wheel hub drive 10 furthermore has a bearing 96, which is designed, for example, as a plain bearing and by means of which the actuating element 82 is mounted displaceably on the wheel hub 40. For this purpose, the bearing 96 comprises, for example, a first bearing half connected to the wheel hub 40, which is connected to the wheel hub 40, for example, in such a way that relative movements between the wheel hub 40 and the first bearing half are prevented. Furthermore, for example, the bearing 96 comprises a second bearing half connected to the actuating element 82, which is connected to the actuating element 82, for example, in such a way that relative movements between the actuating element 82 and the second bearing half are prevented. The bearing halves of the bearing 96 are displaceable relative to one another, for example, along the main axis of rotation 22. It can also be seen that the first bearing shell 16 is a radially outer bearing ring of the wheel bearing 14 fixed to the wheel carrier, wherein the second bearing shell 20 is a radially inner bearing ring of the wheel bearing 14, wherein the rim 44 or the vehicle wheel 42 is at least indirectly screwed to the second bearing ring.List of reference characters10 Wheel hub drive 12 Wheel carrier 14 Wheel bearing 16 First bearing shell 18 Screw 20 Second bearing shell 22 Main rotational axis 24 Electric machine 26 Stator 28 Stator carrier 30 Rotor 32 Rotor element 34 Rotor element 36 Radial direction 38 Rotor carrier 40 Wheel hub 42 Vehicle wheel 44 Rim 46 Rim bed 48 Wheel disk 50 Fastening region 52 Passage opening 54 Wheel screw 56 Screw opening 58 Rotor bearing 60 First rolling body 62 Second rolling body 64 Third rolling body 66 Fourth rolling body 68 Third bearing shell 70 Fourth bearing shell 72 First coupling element 74 Double arrow 76 Second coupling element 78 Recess 80 Receptacle 82 Actuating element 84 Double arrow 86 Actuator 88 Restoring element 90 Friction brake 92 First braking element 94 Second braking element 96 Bearing A Wheel carrier portion B Brake region L 1 First raceway L 2 Second raceway L 3 Third raceway L 4 Fourth Track k Coupling device T Partial region

Claims

Wheel hub drive (10) for a motor vehicle, having a wheel carrier (12), having a wheel hub (40) which is mounted rotatably on the wheel carrier (12) via a wheel bearing (14), having a vehicle wheel (42) which is connected rotationally fixedly to the wheel hub (40), having an electric machine (24) which has a stator (26) which is connected rotationally fixedly to the wheel carrier (12) and a rotor (30) which can be driven by means of the stator (26) and is thus rotatable relative to the stator (26) and is mounted rotatably on the wheel carrier (12) via a rotor bearing (58) which is additionally included in the wheel bearing (14), and having a positive-locking coupling device (K) which can be switched over between a coupling state in which the rotor (30) is connected rotationally fixedly to the wheel hub (40) by means of the coupling device (K) and a decoupling state, in which the rotor (30) is rotatable relative to the wheel hub (40), characterized in that the coupling device (K) has a first coupling element (72) which extends in a radial direction (36) of the wheel hub drive (10) and is arranged displaceably along the radial direction (36) of the wheel hub drive (10) relative to the wheel hub (40) and relative to the rotor (30).Wheel hub drive (10) according to Claim 1, characterized in that the first coupling element (72) is permanently connected to the wheel hub (40) in a rotationally fixed manner at least with respect to a rotational axis (22) about which the wheel hub (40) is rotatable relative to the wheel carrier (12).Wheel hub drive (10) according to Claim 1 or 2, characterized in that the rotor bearing (58) is arranged axially overlapping and radially outside the wheel bearing (14).Wheel hub drive (10) according to one of the preceding claims, characterized bya second coupling element (76), which is connected in a rotationally fixed manner at least with respect to an axis of rotation (22) about which the wheel hub (40) is rotatable relative to the wheel carrier (12), to a rotor carrier (38) of the electric machine (24) which carries the rotor (30) and has a recess (78) which is designed to receive the first coupling element (72) in the coupled state.Wheel hub drive (10) according to Claim 4, characterized in that the second coupling element (76) is arranged so as to overlap the wheel bearing (14) radially.Wheel hub drive (10) according to one of the preceding claims, characterized in that the vehicle wheel (42) has a wheel disc (48).Wheel hub drive (10) according to Claim 6, characterized in that, with respect to an axial direction of the wheel hub drive (10), the wheel disc (48), the first coupling element (72), the wheel bearing (14) and a wheel carrier section (A) of the wheel carrier (12) are arranged one after the other in the following sequence: the wheel disc (48) - the first coupling element (72) - the wheel bearing (14) - the wheel carrier section (A).Wheel hub drive (10) according to Claim 6 or 7, characterized bya friction brake (90) which has a first brake element (92) which is permanently connected to the wheel hub (40) in a rotationally fixed manner, a second brake element (94) and a friction region (B) in which the brake elements (92, 94) can be brought into frictional cooperation in order thereby to brake the vehicle wheel (42).Wheel hub drive (10) according to Claims 7 and 8 or according to Claims 6 and 8, characterized in that the friction region (B) of the friction brake (90) is arranged axially between the wheel disc (48) and the wheel bearing (14).Motor vehicle, having at least one wheel hub drive (10) according to one of the preceding claims.

Images