Motor vehicle transmission for an at least partially electrically powered motor vehicle

Abstract

The invention relates to a motor vehicle transmission (2), comprising a first input shaft (9), a second input shaft (10), an output shaft (11), and a first planetary gear set (P1), a second planetary gear set (P2), and a third planetary gear set (P3), wherein the input shafts (9, 10) are each provided for coupling to a respective drive motor. Furthermore, at least four shifting elements in the form of a first shifting element (B), a second shifting element (C), a third shifting element (E), and a fourth shifting element (F) are provided, at least functionally. The invention further relates to a drive unit (1), a motor vehicle drive axle, a hybrid or electric vehicle, and a method for operating a motor vehicle transmission.

Description

The invention relates to a motor vehicle transmission for an at least partially electrically driven motor vehicle, comprising a first drive shaft, a second drive shaft, an output shaft and a first planetary gear set and a second planetary gear set, wherein the first drive shaft is provided for coupling to a first drive machine, in particular a first electric machine, and the second drive shaft is provided for coupling to a second drive machine, in particular a second electric machine, wherein the first planetary gear set and the second planetary gear set each have a first element, a second element and a third element in the form of a respective sun wheel, a respective planetary carrier and a respective ring gear, wherein at least functionally a first shift element, a second shift element, a third shift element and a fourth shift element are provided, wherein the first element of the first planetary gear set is connected in a rotationally fixed manner to the first input shaft and the second element of the first planetary gear set is connected in a rotationally fixed manner to the first element of the second planetary gear set, wherein the third element of the second planetary gear set is fixed, wherein the second element of the second planetary gear set is connected in a rotationally fixed manner to the output shaft, wherein the at least functionally provided first shift element is configured to connect the third element of the first planetary gear set in a rotationally fixed manner to the output shaft in an actuated state, and wherein the at least functionally provided second shift element is configured to connect two of the elements of the first planetary gear set in a rotationally fixed manner to one another in an actuated state. The invention furthermore relates to a drive unit for an at least partially electrically driven motor vehicle, a motor vehicle drive axle for a hybrid or electric vehicle, a hybrid or electric vehicle and a method for operating a motor vehicle transmission.In motor vehicles designed as electric and hybrid vehicles, a motor vehicle transmission is partially provided in a respective drive train between at least one electric machine and drive wheels of the respective motor vehicle in order to be able to translate a drive movement of the at least one electric machine, in particular into deceleration with respect to the drive wheels. In addition to single-speed transmissions, motor vehicle transmissions are also used in some cases, in which two or more gears can be shifted.DE 10 2019 216 562 A1 discloses a motor vehicle drive axle of an electric vehicle, wherein in this motor vehicle drive axle a drive unit with a motor vehicle transmission and two electric machines is provided. The rotors of the two electric machines are each connected in a rotationally fixed manner to an associated drive shaft of the motor vehicle transmission. Furthermore, the motor vehicle transmission has two planetary gear sets, which are each formed by a respective sun gear, a respective planetary carrier and a respective ring gear. In addition, in the motor vehicle transmission, five shift elements are formed in terms of function, of which three shift elements are provided for respectively shifting a gear between the first drive shaft and an output shaft of the motor vehicle transmission by selective actuation, and thus respectively engaging the first electric machine connected to the first drive shaft. The two still remaining shifting elements can be brought about by a rotationally fixed connection of the two drive shafts in order to make the gears respectively shifted between the first drive shaft and the output shaft also usable for the electric machine connected to the second drive shaft, while the other still remaining shifting element can be used to engage the second electric machine for supporting the tractive force during shifting operations between the gears.Proceeding from the prior art described above, it is now the object of the present invention to provide a motor vehicle transmission for binding two drive engines, wherein in this case binding of the drive engines independently of one another is to be possible via the motor vehicle transmission.This object is achieved on the basis of the preamble of claim 1 in conjunction with its characterizing features. The dependent claims which follow this represent advantageous further developments of the invention. A drive unit in which a motor vehicle transmission according to the invention is provided is furthermore subject matter of claims 15 to 17. Furthermore, claim 18 relates to a motor vehicle drive axle for a hybrid or electric vehicle, while claim 19 relates to a hybrid or electric vehicle. Finally, claims 20 to 23 each relate to a method for operating a motor vehicle transmission according to the invention.According to the invention, a motor vehicle transmission comprises a first input shaft, a second input shaft, an output shaft as well as a first planetary gear set and a second planetary gear set. In this case, the first drive shaft is provided for coupling to a first drive machine, in particular a first electric machine, and the second drive shaft is provided for coupling to a second drive machine, in particular a second electric machine. The first planetary gear set and the second planetary gear set each have a first element, a second element and a third element in the form of a sun gear, a planetary carrier and a ring gear. Furthermore, at least functionally, a first switching element, a second switching element, a third switching element and a fourth switching element are provided. The first element of the first planetary gear set is connected in a rotationally fixed manner to the first drive shaft, while the second element of the first planetary gear set is connected in a rotationally fixed manner to the first element of the second planetary gear set. In addition, the third element of the second planetary gear set is fixed, whereas the second element of the second planetary gear set is connected to the output shaft in a rotationally fixed manner.The at least functionally provided first shift element is configured to connect the third element of the first planetary gear set to the output shaft in a rotationally fixed manner in an actuated state. Furthermore, the at least functionally provided, second shifting element is configured to connect two of the elements of the first planetary gear set to one another in a rotationally fixed manner in an actuated state.A "shaft", such as the respective drive shaft or the output shaft, is understood in the sense of the invention to mean a rotatable component of the transmission, via which a force flow guidance between components can be carried out, if appropriate with simultaneous actuation of an at least functionally provided shift element.The respective shaft can connect the components to one another axially or radially or also both axially and radially. Thus, the respective shaft can also be present as an intermediate piece, via which a respective component is connected purely radially, for example. Furthermore, depending on the profile and connection to the components or a connectivity to them, the respective shaft can be designed as a solid shaft, as a hollow shaft or partly as a solid shaft and partly as a hollow shaft. Alternatively or additionally, the respective shaft can be embodied in one or more parts.In the sense of the invention, "axially" means an orientation in the direction of a longitudinal central axis of the motor vehicle transmission, parallel to which axes of rotation of shafts of the motor vehicle transmission and of the elements of the planetary gear sets are also oriented. The term "radial" is then to be understood as meaning an orientation in the diameter direction of a respective component of the transmission, in particular of a respective shaft or of a respective element of the planetary gear sets.The motor vehicle transmission according to the invention has a first drive shaft and a second drive shaft, wherein the two drive shafts are in particular coaxial with one another. In addition, the first drive shaft and the second drive shaft in the motor vehicle transmission according to the invention are provided for the purpose of respectively producing a drive-side coupling to a respective drive machine, wherein the respective drive shaft preferably serves for the respective coupling to respectively exactly one drive machine. For this purpose, the respective drive shaft is equipped in particular with a connection point at which a coupling of the respective drive shaft to the associated drive machine can be formed. The connection of the associated drive machine to the respective one connection point of the respective drive shaft is carried out in particular permanently in the installed state of the motor vehicle transmission, preferably when the associated drive machine is designed as an electric machine. Alternatively, however, it is also possible to provide a respective intermediate starting element, such as a hydrodynamic torque converter, a starting clutch, etc., via which the respective drive shaft can be or is coupled at its respective one connection point to the associated, upstream drive machine. This is realized in particular when the associated drive machine is designed as an internal combustion engine.The coupling between the associated drive machine and the respective drive shaft is preferably provided in such a way that, in the installed state of the motor vehicle transmission and when the coupling is established between a rotational speed of the respective drive shaft of the motor vehicle transmission and a rotational speed of the associated drive machine, a fixed rotational speed ratio prevails in each case. Thus, within the scope of the invention, at least one further transmission stage, such as a spur gear stage and / or a planetary stage, can optionally be provided between the respective drive shaft and the associated drive machine, by means of which transmission stage a pretransmission of a rotational movement of the associated drive machine to the respective drive shaft can be provided. Preferably, however, the respective drive shaft serves for a rotationally fixed connection to the associated drive machine.The motor vehicle transmission is in particular a hybrid or electric vehicle transmission which is provided to be connected at the respective drive shaft to a respective drive machine in the form of a respective electric machine. A respective rotor of the respective electric machine can be coupled to the respective drive shaft of the motor vehicle transmission via at least one intermediate transmission stage, as described above. Particularly preferably, however, a respective rotor of the respective electric machine is connected in a rotationally fixed manner to the associated drive shaft in the installed state of the motor vehicle transmission according to the invention.In the motor vehicle transmission according to the invention, the output shaft is provided in particular for the purpose of producing a coupling of the motor vehicle transmission on the output side to components which, in the installed state of the motor vehicle transmission, follow the motor vehicle transmission in the force flow direction to drive wheels of the respective motor vehicle. Accordingly, the motor vehicle transmission according to the invention is in particular a drive transmission, by means of which the drive engines having different transmission ratios can be incorporated and coupled to drive wheels of the respective motor vehicle.In this case, a coupling with a differential gearset can be produced on the output shaft of the motor vehicle transmission according to the invention, which differential gearset is coaxial or offset from the axis of the output shaft and can function as a transverse or longitudinal differential. This coupling can be produced via a transmission stage in the form of a bevel gear transmission. Alternatively, the output shaft can also be connected in a rotationally fixed manner to the downstream differential gearset or can be coupled via an intermediate transmission stage, for example in the form of an additional planetary gearset.The invention now comprises the technical teaching that a third planetary gear set is additionally provided, which has a first element, a second element and a third element in the form of a sun wheel, a planetary carrier and a ring gear and the second element of which is connected in a rotationally fixed manner to the second element of the first planetary gear set and the first element of the second planetary gear set. Furthermore, the first element of the third planetary gear set is connected to the second drive shaft in a rotationally fixed manner. The at least functionally provided, third shifting element is configured to connect the third element of the third planetary gear set to the output shaft in a rotationally fixed manner in an actuated state, whereas the at least functionally provided, fourth shifting element is configured to connect two of the elements of the third planetary gear set to one another in a rotationally fixed manner in an actuated state.In the motor vehicle transmission according to the invention, therefore, a third planetary gear set is also provided in addition to the first planetary gear set and the second planetary gear set. Particularly preferably, the motor vehicle transmission according to the invention has exactly three planetary gear sets in the form of the first planetary gear set, the second planetary gear set and the third planetary gear set.In the present case, the first element of the first planetary gear set and the first drive shaft are permanently connected to one another in a rotationally fixed manner, as a result of which the first drive shaft and the first element of the first planetary gear set continuously rotate jointly. Furthermore, the second element of the first planetary gear set, the first element of the second planetary gear set and the second element of the third planetary gear set are continuously connected to one another in a rotationally fixed manner, which always means a common rotation of the second element of the first planetary gear set, of the first element of the second planetary gear set and of the second element of the third planetary gear set. A permanently rotationally fixed connection also exists between the output shaft and the second element of the second planetary gear set, as a result of which the output shaft and the second element of the second planetary gear set continuously rotate together. Furthermore, the third element of the second planetary gear set is permanently fixed, whereby the third element of the second planetary gear set is constantly prevented from rotating. The first element of the third planetary gear set is permanently connected in a rotationally fixed manner to the second drive shaft, as a result of which the first element of the third planetary gear set rotates permanently together with the second drive shaft.An actuated state of the at least functionally provided, first shift element results in a rotationally fixed connection of the third element of the first planetary gear set with the output shaft, whereupon the output shaft and thus also the second element of the second planetary gear set rotate together with the third element of the first planetary gear set. If, on the other hand, an actuated state of the at least functionally provided second shift element is represented, then two of the elements of the first planetary gear set are connected to one another in a rotationally fixed manner, which results in the first planetary gear set being blocked and thus in its block circulation. In an actuated state of the at least functionally provided, third shift element, a rotationally fixed connection is established between the output shaft and the third element of the third planetary gear set, as a result of which the output shaft and the third element of the third planetary gear set then rotate together. Finally, two of the elements of the third planetary gear set are connected to one another in a rotationally fixed manner when an actuated state of the at least functionally provided fourth shift element is represented, so that a block circulation of the third planetary gear set is then brought about.Such a configuration of a motor vehicle transmission has the advantage that this achieves a structure of the motor vehicle transmission in which different gears between the one drive shaft and output shaft can each be shifted independently of the other drive shaft, so that the drive machine connected to the drive shafts can also be incorporated independently of one another. On the one hand, this allows the tractive force to be supported on the one drive shaft and thus via the drive machine connected thereto when a gear change is carried out with respect to the other drive shaft and the drive machine connected thereto. On the other hand, the drive shafts can also be decoupled from the output shaft in each case independently of one another in order to respectively implement decoupling of the drive machine respectively connected thereto. This can be achieved via the three planetary gear sets with a compact construction and with the representation of suitable transmission ratios.Within the scope of the invention, the motor vehicle transmission according to the invention can be operated in such a way that a first transmission ratio is shifted between the first input shaft and the output shaft by representing an actuated state of the first shift element. In addition, a second transmission ratio between the first input shaft and the output shaft can be shifted by representing an actuated state of the second shift element. In both of the aforementioned cases, the first drive machine connected to the first drive shaft is then respectively incorporated.The second drive machine connected to the second drive shaft can be incorporated with a first transmission ratio by virtue of the first transmission ratio being switched between the second drive shaft and the output shaft. For this purpose, an actuated state of the third shift element is shown. In addition, however, a second transmission ratio can also be represented between the second drive shaft and the output shaft by representing an actuated state of the fourth shift element. In this case, a force flow from the second drive shaft to the output shaft is then respectively realized, as a result of which the second drive machine connected to the second drive shaft is then respectively incorporated.Thus, it is possible by way of the motor vehicle transmission according to the invention to engage the first drive machine by actuation of either the first shift element or the second shift element, while the second drive machine is then decoupled in the absence of actuation of the third or the fourth shift element. Conversely, however, the second drive machine can also be coupled to the output shaft by either realizing an actuated state of the third shift element or of the fourth shift element. If neither the first shifting element nor the second shifting element are then actuated during this engagement, the first drive machine is decoupled. This therefore enables the independent binding of the two drive engines to be realized via the motor vehicle transmission according to the invention.However, this independence of the bindings also allows supporting of the traction force via the one drive engine while a change of the transmission ratio in the motor vehicle transmission is carried out with respect to the other drive engine. For this purpose, during a change from one transmission ratio effective between the one input shaft and the output shaft to another transmission ratio effective between the one input shaft and the output shaft, the tractive force is supported on the other input shaft by a transmission ratio effective between the other input shaft and the output shaft being switched at least during the change.The first planetary gear set, the second planetary gear set and the third planetary gear set are each composed of a first element, a second element and a third element, wherein the elements of the first or second or third planetary gear set are each formed by a sun gear, a planetary carrier and a ring gear. Particularly preferably, the first planetary gear set, the second planetary gear set and the third planetary gear set are present here as minus planetary gear set, in which the respective planetary carrier rotatably guides at least one planetary gear, wherein the at least one planetary gear is in meshing engagement with both the respective sun gear and the respective ring gear. In an embodiment of the first planetary gear set or of the second planetary gear set or of the third planetary gear set as a minus planetary gear set, the first element of the first or second or third planetary gear set is the respective sun gear, the second element of the first or second or third planetary gear set is the respective planetary carrier and the third element of the first or second or third planetary gear set is the respective ring gear.Alternatively, the first planetary gear set and / or the second planetary gear set and / or the third planetary gear set could in principle also be designed as a plus planetary gear set. In this case, at least one pair of planet wheels is rotatably mounted in the respective planet carrier, of which planet wheels a planet wheel meshes with the respective sun wheel and a planet wheel meshes with the respective ring wheel. In addition, the planetary gears of the at least one pair of planetary gears mesh with one another. In contrast to an embodiment as a minus planetary gear set, the first element of the first or second or third planetary gear set is then preferably the sun gear, the second element of the first or second or third planetary gear set is the ring gear and the third element of the first or second or third planetary gear set is the planetary carrier. In comparison with an embodiment as a minus planetary gear set, a stationary transmission ratio of the respective planetary gear set is also to be increased by one. As already described above, however, in the sense of the invention the first planetary gear set, the second planetary gear set and also the third planetary gear set are preferably designed as minus planetary gear sets.The motor vehicle transmission according to the invention has at least functionally a first shifting element, a second shifting element, a third shifting element and a fourth shifting element, by the selective actuation of which different force flow guides can be represented in the motor vehicle transmission according to the invention, namely from the respectively associated drive shaft to the output shaft. In a variant of the invention, in the motor vehicle transmission according to the invention, for shifting different gears between the two drive shafts and the output shaft, at least from the functional point of view, exactly these four shift elements are present, wherein, however, within the scope of the invention, for shifting further gears, optionally also further shift elements, provided at least functionally, can be present. The fact that a respective shift element is provided "at least functionally" means, within the meaning of the invention, that at least the respective function of the respective shift element is depicted in the motor vehicle transmission according to the invention. In this case, the switching elements can actually be physically present in detail as an individual switching element or their function is depicted by another component, such as a switching device, for example. A component which forms the function can then combine the function of two or more switching elements in one device.In the motor vehicle transmission according to the invention, the drive shafts and the output shaft are arranged in particular coaxially to one another, wherein, further preferably, the planetary gear sets are also placed coaxially to the drive shafts and the output shaft. This allows a particularly compact construction of the motor vehicle transmission in the radial direction to be realized.A permanent "rotationally fixed" connection of components of the transmission is to be understood in the sense of the invention as meaning that these components which are connected to one another in a rotationally fixed manner or are connected to one another in a rotationally fixed manner are rigidly connected to one another and therefore always have the same rotational speed. In this case, the components connected to one another in a rotationally fixed manner or connected to one another in a rotationally fixed manner can be present as separate components which are fastened to one another. Alternatively, components connected to one another in a rotationally fixed manner or connected to one another in a rotationally fixed manner can also be embodied in one piece and are thus present together as a component, wherein this is realized in particular when these components are arranged lying spatially close to one another.Within the scope of the invention, a fixed state of a component of the motor vehicle transmission is realized in particular by a rotationally fixed connection to a permanently fixed component, which can be a housing of the motor vehicle transmission, a part of the housing or a component permanently connected thereto in a rotationally fixed manner. In the present case, the third element of the second planetary gear set is then permanently connected to the stationary component in a rotationally fixed manner, wherein here a one-piece design of the third element of the second planetary gear set with the stationary component would also be conceivable.In the sense of the invention, a locking of a component of the motor vehicle transmission via an at least functionally provided shifting element or a rotationally fixed connection between components of the motor vehicle transmission via an at least functionally provided shifting element means that the relevant component is not permanently locked or the components are not permanently coupled to one another, but rather a locking or a rotationally fixed connection is only carried out by representing an actuated state of the at least functionally provided, intermediate shifting element. In this case, an actuated state of the at least functionally provided switching element in the sense of the invention means that the relevant switching element is transferred into a closed state and as a result the rotational movements of the components directly coupled thereto are equalized. If at least the function of a form-locking shift element is depicted, the components directly connected to one another in a rotationally fixed manner via this will run at the same speed, while in the case of a mapping of at least the function of a force-locking shift element, even after the representation of an actuated state, the same speed difference between the components can exist. This wanted or also unwanted state is nevertheless referred to within the scope of the invention as a rotationally fixed connection of the respective components via the at least functionally provided shifting element.According to one embodiment of the invention, the at least functionally provided, second shift element, in the actuated state, connects the third element of the first planetary gear set and the second element of the first planetary gear set to one another in a rotationally fixed manner or connects the third element of the first planetary gear set and the first element of the first planetary gear set to one another in a rotationally fixed manner. This results in a rotationally fixed connection of two elements of the first planetary gear set in each case and thus in the blocking thereof. Within the scope of the invention, the blocking of the first planetary gear set could also be brought about when the second shift element is actuated, however, in that, in the actuated state of the second shift element, the first element of the first planetary gear set and the second element of the first planetary gear set are connected to one another in a rotationally fixed manner.In a development of the aforementioned embodiment, the first switching element and the second switching element are formed by a switching device, the coupling element of which can be positioned in a first switching position and in a second switching position. In the first shift position, the coupling element functionally depicts an actuated state of the first shift element and connects the third element of the first planetary gear set to the output shaft in a rotationally fixed manner. In the second shift position, the coupling element functionally depicts an actuated state of the second shift element and connects the third element of the first planetary gear set in a rotationally fixed manner to either the second element of the first planetary gear set or the first element of the first planetary gear set. The mapping of the functions of the first shift element and of the second shift element by a shift device has the advantage that the respective rotationally fixed connections can thus be realized in a compact manner and with a low number of components. In addition, a common actuator can thereby be used for actuating the first shift element and the second shift element, whereby the manufacturing effort is reduced. Particularly preferably, the coupling element can be positioned between the first and the second shift position in an intermediate neutral position, wherein in this neutral position no coupling is carried out via the coupling element, i.e. an open state of both the first shift element and the second shift element is shown. In this case, a "shift position" or a "neutral position" can be, within the scope of the invention, an axial adjustment range within which the coupling element is to be positioned in order to realize the respective shift position or the respective neutral position.The aforementioned shifting device is in particular designed such that the coupling element is guided in a rotationally fixed and axially displaceable manner on a first toothing in the two shift positions and in the event of an axial displacement between the two shift positions, said toothing being connected in a rotationally fixed manner to the third element of the first planetary gear set. In the first shift position, the coupling element then additionally includes a second toothing which is continuously connected to the output shaft in a rotationally fixed manner, wherein the coupling element includes in the second shift position a third toothing which is connected to the second element of the first planetary gear set or to the first element of the first planetary gear set in a rotationally fixed manner.In one embodiment of the invention, a further shift element is additionally provided at least functionally, which shift element is configured to fix the third element of the first planetary gear set in an actuated state. As a result, a further transmission ratio between the first drive shaft and the output shaft can be represented and therefore also a binding of the first drive machine connected to the first drive shaft with this further transmission ratio can be realized. This further transmission ratio is thus shifted between the first input shaft and the output shaft by representing an actuated state of the further shift element.In a development of the aforementioned embodiment of the invention and in combination with the possible embodiment according to which the first switching element and the second switching element are combined to form a switching device, the switching device forming the first switching element and the second switching element also forms the further switching element. In this case, the coupling element of the shifting device can also be positioned in a third shifting position, in which the coupling element functionally depicts the actuated state of the further shifting element and fixes the third element of the first planetary gear set. This has the advantage that the switching device thus represents the function of three shift elements in the form of the first shift element, the second shift element and the further shift element, whereby a particularly compact design of the motor vehicle transmission is possible. In particular, the coupling element of this shifting device can assume a further, second neutral position between the second shifting position and the third shifting position, in which no rotationally fixed connection of the third element of the first planetary gear set is then carried out.Preferably, the coupling element of the aforementioned switching device engages with a fourth toothing in the third switching position, which toothing is permanently fixed in place in this case.The coupling element of the shifting device is present in particular as a sliding sleeve. The coupling element preferably has one or more clutch tooth arrangements, on which the axial, rotationally fixed guidance takes place on the first tooth arrangement and / or the respective embedding in the second and third and optionally the fourth tooth arrangement can be carried out. The tooth arrangements are preferably designed as claw tooth arrangements, so that the function of unsynchronized claw shift elements is depicted via the shifting device.Alternatively, the first shifting element and the second shifting element and optionally also the further shifting element could also be present as individual shifting elements, wherein the shifting elements in this case are in particular designed as form-locking shifting elements and in this case particularly preferably as unsynchronized claw shifting elements. As a further alternative, however, individual shift elements could also be designed as locking synchronizations or as force-locking shift elements, in particular in the form of multi-disk shift elements. In addition, within the scope of the invention, the first switching element and the further switching element could also be combined to form a switching device, while the second switching element is designed as an individual switching element. Further alternatively, in the context of the invention, it is also possible to combine the second switching element and the further switching element to form a switching device, the first switching element then being present as an individual switching element.According to a further embodiment possibility of the invention, the at least functionally provided fourth shift element, in the actuated state, connects the third element of the third planetary gear set in a rotationally fixed manner to the second element of the third planetary gear set or to the first element of the third planetary gear set. This is because in each case a rotationally fixed connection is established between two elements of the third planetary gear set and thus the blocking thereof is achieved. Alternatively, however, it would equally be conceivable within the scope of the invention for the first element of the third planetary gear set and the second element of the third planetary gear set to be connected to one another in a rotationally fixed manner in the actuated state of the at least functionally provided fourth shift element.In a development of the aforementioned design option, the third switching element and the fourth switching element are formed by a switching device, the coupling element of which can be positioned in each case in a first switching position and in a second switching position. In this case, the coupling element in the first shift position functionally depicts the actuated state of the third shift element and connects the third element of the third planetary gear set to the output shaft in a rotationally fixed manner, wherein the coupling element in the second shift position functionally depicts the actuated state of the fourth shift element and connects the third element of the third planetary gear set to either the second element of the third planetary gear set or the first element of the third planetary gear set in a rotationally fixed manner. A compact construction can thereby be realized by the functions of the third switching element and the fourth switching element being formed by a common switching device. Accordingly, for the purposes of illustrating the actuated states of the two shift elements, it is also necessary to provide only one actuator system by means of which the coupling element can be positioned in the different shift positions. In particular, the coupling element can be positioned between the shift positions or in an intermediate neutral position in which neither an actuated state of the third shift element nor an actuated state of the fourth shift element is shown. Here too, a "shift position" or a "neutral position" can be, within the scope of the invention, an axial adjustment range within which the coupling element is to be positioned in order to realize the respective shift position or the respective neutral position.Preferably, the coupling element of the aforementioned shifting device is guided in the two shifting positions and in an axially displaceable manner on a first toothing on an axial displacement between the two shifting positions, wherein this first toothing is connected in a rotationally fixed manner to the third element of the third planetary gear set. In the first switching position, the coupling element then engages in a second toothing which is continuously connected to the output shaft in a rotationally fixed manner. Upon movement into the second shift position, the coupling element meshes with a third toothing which is permanently connected in a rotationally fixed manner to the second element of the third planetary gear set or to the first element of the third planetary gear set.In particular, a further transmission ratio can be represented between the second drive shaft and the output shaft, for which purpose an additional shifting element is also provided at least functionally. This additional shifting element is configured to fix the third element of the third planetary gear set in an actuated state. In this case, the further transmission ratio is then switched between the second input shaft and the output shaft in that an actuated state of the additional shift element is represented.In the case of a combination of the aforementioned variant of the invention with the embodiment according to which the third switching element and the fourth switching element are combined to form a switching device, the switching device forming the third switching element and the fourth switching element also forms the additional switching element. In this case, the coupling element of this shifting device can also be positioned in a third shifting position, in which the coupling element functionally reproduces the actuated state of the additional shifting element and fixes the third element of the third planetary gear set. The switching device thus represents the function of three shift elements in the form of the third shift element, the fourth shift element and the additional shift element, which enables a compact construction of the motor vehicle transmission. In particular, the coupling element of this shifting device can assume a further, second neutral position between the second shifting position and the third shifting position, in which no rotationally fixed connection of the third element of the third planetary gear set is then carried out. Preferably, the coupling element of the aforementioned switching device engages with a fourth toothing in the third switching position, which toothing is permanently fixed in place in this case.The coupling element is preferably designed as a sliding sleeve. In particular, the coupling element also has one or more clutch tooth arrangements, on which the axial, rotationally fixed guidance takes place on the first tooth arrangement and / or the respective embedding in the second and third and optionally the fourth tooth arrangement can be carried out. The tooth arrangements of the shifting device are preferably designed as claw tooth arrangements, so that the functions of the third shifting element and of the fourth shifting element and, if applicable, of the additional shifting element are depicted as unsynchronized claw shifting elements via the shifting device.Alternatively, the third shifting element and the fourth shifting element as well as optionally the additional shifting element could also be present as individual shifting elements, wherein the shifting elements in this case are in particular designed as form-locking shifting elements and in this case particularly preferably as unsynchronized claw shifting elements. However, an embodiment as locking synchronizations or as force-locking shift elements is also possible, in particular as multi-disk shift elements. Within the scope of the invention, the third switching element and the additional switching element could also be combined to form a switching device, while the fourth switching element is designed as an individual switching element. Further alternatively, in the context of the invention, it is also possible to combine the fourth switching element and the additional switching element to form a switching device, the third switching element then being present as an individual switching element.The motor vehicle transmission according to the invention very particularly preferably has a structure in which a first shifting device and a second shifting device are provided, wherein the first shifting device in this case represents the first shifting element, the second shifting element and optionally the further shifting element, while the functions of the fourth shifting element and of the fifth shifting element and optionally of the additional shifting element are represented by the second shifting device.According to a further possible embodiment of the invention, the planetary gear sets are arranged axially in an order of first planetary gear set, third planetary gear set and second planetary gear set. Particularly preferably, a connection point of the output shaft is provided axially on a side of the second planetary gear set facing away from the third planetary gear set. Within the scope of the invention, however, such a connection point of the output shaft could also lie axially on a side of the first planetary gear set facing away from the third planetary gear set.In a development of the aforementioned design option, the at least functionally provided first shift element and the at least functionally provided second shift element are arranged axially on a side of the first planetary gear set facing away from the third planetary gear set. If the two shift elements are formed by a common shift device, this shift device is then located axially on the side of the first planetary gear set facing away from the third planetary gear set. In particular, the shift elements or the shift device forming these shift elements are arranged radially surrounding the first planetary gear set. If, in addition, the further shift element is provided at least functionally or is configured by a shift device, then this shift element or this shift device is also located axially on the side of the first planetary gear set facing away from the third planetary gear set and preferably radially surrounding the first planetary gear set.Alternatively or additionally thereto, the at least functionally provided third shift element and the at least functionally provided fourth shift element are arranged axially between the third planetary gear set and the second planetary gear set. When the third shift element and the fourth shift element are combined to form a shift device, this shift device is then placed axially between the third planetary gear set and the second planetary gear set. In particular, the third shift element and the fourth shift element or a shift device forming the third shift element and the fourth shift element are located radially around the third planetary gear set and the second planetary gear set. If the motor vehicle transmission according to the invention also has the additional shift element or if the additional shift element is formed by a shift device, the additional shift element or the shift device forming it is likewise arranged axially between the third planetary gear set and the second planetary gear set and is further preferably provided radially surrounding the third planetary gear set and the second planetary gear set.The invention also relates to a drive unit which, in addition to a first electric machine and a second electric machine, has a motor vehicle transmission according to one or more of the variants described above. In this case, a rotor of the first electric machine is coupled to the first drive shaft of the motor vehicle transmission, while a rotor of the second electric machine is coupled to the second drive shaft. Within the scope of the invention, the respective electric machine can be operated in particular on the one hand as a generator and on the other hand as an electric motor. As a result, a drive unit can be created which is suitable for use in a motor vehicle in the form of an electric or hybrid vehicle. In this case, the two electric machines are dimensioned in particular identically in terms of their power, but can also have different powers.Particularly preferably, the first electric machine is arranged coaxially to the first drive shaft and the rotor of the first electric machine is connected to the first drive shaft in a rotationally fixed manner. As a result, the first drive shaft and the rotor of the first electric machine run under the same rotational speed during operation. Alternatively, however, it is also conceivable for the rotor of the first electric machine to be coupled to the first drive shaft via at least one transmission stage.Alternatively, but preferably in addition thereto, in a drive unit according to the invention, the second electric machine is arranged in particular coaxially with respect to the second drive shaft of the motor vehicle transmission, wherein the rotor of the second electric machine is connected to the second drive shaft in a rotationally fixed manner. Accordingly, the rotor of the second electric machine and the second drive shaft of the motor vehicle transmission have the same rotational speed during operation. Alternatively, the rotor of the second electric machine and the second drive shaft could, however, also be coupled to one another via at least one intermediate transmission stage.In a development of the invention, the first planetary gear set of the motor vehicle transmission is arranged axially at least partially covering and radially inside the rotor of the first electric machine. This allows an nested and thus also compact construction of the drive unit to be realized.Alternatively, but preferably additionally thereto, the second planetary gear set and / or the third planetary gear set is arranged in each case axially at least partially overlapping with and radially inward of the rotor of the second electric machine. In an advantageous manner, an axial structural length of the drive unit and thus a compact construction can be realized as a result.A drive unit designed according to one or more of the aforementioned variants is in particular part of a motor vehicle drive axle, which is provided for an electric or hybrid vehicle. The drive unit is preferably arranged in a plane with output shafts, each of which is assigned to at least one drive wheel and is coupled to the output shaft of the motor vehicle transmission. In an advantageous manner, a compact construction of a motor vehicle drive axle with the drive unit can be achieved as a result, wherein the coupling between the output shaft of the motor vehicle transmission and the output shafts of the motor vehicle drive axle is accomplished in particular via a differential transmission.At least one such motor vehicle drive axle is provided in the context of the invention in the case of a hybrid or electric vehicle, which can be a passenger car or a commercial vehicle. A commercial vehicle can be present here as an at least partially electrically driven transporter or a light to medium-weight bus or truck.Advantageous embodiments of the invention, which are explained below, are illustrated in the drawings. It shows: FIG. 1 is a schematic view of a drive unit according to an embodiment of the invention; FIG. 2 shows an exemplary shift pattern of a motor vehicle transmission of the drive unit from FIG. 1 ; FIG. 3 shows a schematic illustration of a drive unit according to a further embodiment of the invention; FIG. 4 shows an exemplary shift pattern of a motor vehicle transmission of the drive unit from FIG. 3 ; FIG. 5 is a schematic view of a drive unit according to another embodiment of the invention; FIG. 6 shows an exemplary shift pattern of a motor vehicle transmission of the drive unit from FIG. 5 ; FIG. 7 shows a schematic illustration of a drive unit according to a further embodiment of the invention; FIG. 8 is an exemplary shift pattern of a motor vehicle transmission of the drive unit from FIG. 7 ; and FIG. 9 is a schematic view of an electric vehicle according to a preferred embodiment of the invention.FIG. 1 shows a schematic view of a drive unit 1, which is designed according to an embodiment of the invention. This drive unit 1 is composed of a motor vehicle transmission 2 and two electric machines 3 and 4, wherein the motor vehicle transmission 2 is designed here in accordance with a first embodiment of the invention. The two electric machines 3 and 4 are each formed in a manner known in principle to the person skilled in the art by a stator 5 or 6 and a rotor 7 or 8, wherein the individual electric machine 3 or 4 can be operated on the one hand as a generator and on the other hand as an electric motor.The motor vehicle transmission 2 comprises a first input shaft 9, a second input shaft 10, an output shaft 11 and three planetary gear sets P 1, P 2 and P 3, each of which is composed of a first element E 11 or E 12 or E 13, a second element E 21 or E 22 or E 23 and a third element E 31 or E 32 or E 33. In this case, the respective first element E 11 or E 12 or E 13 of the respective planetary gear set P 1 or P 2 or P 3 is a respective sun gear 12 or 13 or 14, while the respective second element E 21 or E 22 or E 23 of the respective planetary gear set P 1 or P 2 or P 3 is designed as a respective planetary carrier 15 or 16 or 17. In addition, the respective third element E 31 or E 32 or E 33 of the respective planetary gear set P 1 or P 2 or P 3 is present as a respective ring gear 18 or 19 or 20 of the respective planetary gear set P 1 or P 2 or P 3.In each case at least one planetary gear 21 or 22 or 23 is rotatably mounted in the respective planetary carrier 15 or 16 or 17 of the respective planetary gear set P 1 or P 2 or P 3, which planetary gear meshes both with the respective sun gear 12 or 13 or 14 and with the respective ring gear 18 or 19 or 20 of the respective planetary gear set P 1 or P 2 or P 3. In this respect, the planetary gear sets P 1, P 2 and P 3 are embodied here as minus planetary gear sets.In the present case, the first element E 11 of the first planetary gear set P 1 is connected in a rotationally fixed manner to the first drive shaft 9, which is additionally connected in a rotationally fixed manner to the rotor 7 of the electric machine 3 at a connection point 24. In this respect, the first element E 11 of the first planetary gear set P 1 and the rotor 7 are also connected to one another in a rotationally fixed manner via the first drive shaft 9, as a result of which the first element E 11 and the rotor 9 always rotate at the same rotational speed. Within the scope of the invention, the first drive shaft 9 can be formed integrally with the first element E 11 of the first planetary gear set P 1 and / or with the rotor 7 of the electric machine 3.The second element E 21 of the first planetary gear set P 1, the first element E 12 of the second planetary gear set P 2 and the second element E 23 of the third planetary gear set P 3 are continuously connected to one another in a rotationally fixed manner, wherein this rotationally fixed connection is produced via a shaft 25 which can be configured here as a single piece with one or more of the elements E 21, E 12 and E 23. The third element E 32 of the second planetary gear set P 2 is permanently connected in a rotationally fixed manner to a permanently fixed component 26 which is a transmission housing of the motor vehicle transmission 2, a part of the transmission housing or a component connected thereto in a rotationally fixed manner. In addition to components of the motor vehicle transmission 2, the two electric machines 3 and 4 are preferably also accommodated in the transmission housing of the motor vehicle transmission 2. Due to the permanently rotationally fixed connection to the rotationally fixed component 26, the third element E 32 of the second planetary gear set P 2 is constantly prevented from rotating.As can be seen in FIG. 1, the second drive shaft 10 is connected, on the one hand, in a rotationally fixed manner to the rotor 8 of the electric machine 4 and, on the other hand, in a rotationally fixed manner to the first element E 13 of the third planetary gear set P 3, such that the second drive shaft 10, the rotor 8 and the first element E 13 of the third planetary gear set P 3 always rotate at the same rotational speed. The rotationally fixed connection to the rotor 8 is produced at a connection point 27 of the second drive shaft 10, wherein the second drive shaft 10 could be formed integrally with the rotor 8 of the electric machine 4 and / or with the first element E 13 of the third planetary gear set P 3. The output shaft 11 is connected in a rotationally fixed manner to the second element E 22 of the second planetary gear set P 2, wherein the output shaft 11 is in particular further connected at a connection point 28 to a differential gear set of a differential gear mechanism-not shown here.The motor vehicle transmission 2 further has four shift elements B, C, E and F in terms of its function. While the shift elements B and C are formed by a shifting device 29, the function of the shift elements E and F is depicted by a shifting device 30.The shifting device 29 has a coupling element 31 in the form of a shifting sleeve which can be positioned in a first shifting position and in a second shifting position and in an intermediate neutral position. This positioning is carried out by means of an actuator-not shown in detail here. In this case, the coupling element 31 of the shifting device 29 is guided in a rotationally fixed and axially displaceable manner on a toothing 32 which is connected in a rotationally fixed manner to the third element E 31 of the first planetary gear set P 1.From the neutral position shown in FIG. 1, the coupling element 31 can be shifted into the first switching position, in which the coupling element 31 engages in a toothing 33 when there is tooth engagement with the toothing 32, which toothing is connected to the output shaft 11 in a rotationally fixed manner. This then results in a rotationally fixed connection of the third element E 31 of the first planetary gear set P 1 with the output shaft 11 and thus also with the second element E 22 of the second planetary gear set P 2. In the first switching position of the coupling element 31, the actuated state of the switching element A is illustrated.On the other hand, the coupling element 31 can be moved from the neutral position into the second shift position, in which the coupling element 31 then engages, with still existing tooth engagement with the toothing 32, into a toothing 34, which is connected in a rotationally fixed manner to the shaft 25 and thus also to the second element E 21 of the first planetary gear set P 1, the first element E 12 of the second planetary gear set P 2 and the second element E 23 of the third planetary gear set P 3. Accordingly, in the second shift position of the coupling element 31, a rotationally fixed connection of the third element E 31 of the first planetary gear set P 1 with the second element E 21 of the first planetary gear set P 1 then occurs, which results in a blocking of the first planetary gear set P 1. In the second switching position of the coupling element 31, the actuated state of the switching element C is shown.Also in the shifting device 30, a coupling element 35 in the form of a shifting sleeve is provided, which can be moved, by means of an actuator-not shown in more detail in the present case-besides a neutral position shown in FIG. 1-on the one hand into a first shifting position and on the other hand into a second shifting position. The coupling element 35 is guided in a rotationally fixed and axially displaceable manner on a toothing 36 which is connected in a rotationally fixed manner to the third element E 33 of the third planetary gear set P 3. When the coupling element 35 is positioned in the first switching position, an actuated state of the switching element E is represented, wherein the coupling element 35 then additionally engages in a toothing 37 when there is a tooth engagement with the toothing 36, which toothing is connected to the output shaft 11 in a rotationally fixed manner. As a result, in the first shift position of the coupling element 35, the output shaft 11 is connected in a rotationally fixed manner to the third element E 33 of the third planetary gear set P 3.If, on the other hand, the coupling element 35 is transferred from the neutral position into the second shift position, an actuated state of the shift element F is illustrated via the shift device 30. In this second shift position, the coupling element 35 then additionally engages in a toothing 38 when there is a tooth engagement with the toothing 36, which toothing is connected in a rotationally fixed manner to the shaft 25 and thus also to the second element E 23 of the third planetary gear set P 3. Thus, in the second shift position of the coupling element 35, the third planetary gear set P 3 becomes locked.As can be seen in FIG. 1, the first drive shaft 9, the second drive shaft 10, the output shaft 11 and also the planetary gear sets P 1, P 2 and P 3 are arranged coaxially with respect to one another, wherein, in addition to the shaft 25, the two electric machines 3 and 4 are also arranged coaxially with respect thereto. The planetary gear sets P 1, P 2 and P 3 are in this case placed axially in an order of first planetary gear set P 1, third planetary gear set P 3 and finally second planetary gear set P 2, the latter being in this case located axially adjacent to the connection point 28 of the output shaft 11.In the present case, the third planetary gear set P 3 is arranged completely and the second planetary gear set P 2 is arranged partially axially overlapping with the second electric machine 4, wherein both planetary gear sets P 2 and P 3 are placed radially on the inside of the second electric machine 4. In addition, the first planetary gear set P 1 is placed axially at the height of and radially on the inside of the first electric machine 3.The shifting device 29 is provided axially on a side of the first planetary gear set P 1 facing away from the third planetary gear set P 3, wherein the shifting device 29 is arranged axially overlapping with the first electric machine 3. The shifting device 29 is located radially between the first planetary gear set P 1 and the first electric machine 3.By contrast, the shifting device 30 is arranged axially between the third planetary gear set P 3 and the second planetary gear set P 2 and overlaps axially with the second electric machine 4. radially, the shifting device 30 is placed between the second electric machine 4 on the one hand and the third planetary gear set P 3 and the second planetary gear set P 2 on the other hand.While the output shaft 11 is substantially designed as a solid shaft and extends axially starting from the connection point 28 as far as the opposite end of the motor vehicle transmission 2, the first drive shaft 9, the second drive shaft 10 and the shaft 25 are designed as hollow shafts. In this case, the first drive shaft 9 runs axially adjacent to the first planetary gear set P 1 and extends radially outwards as far as the electric machine 3 starting from the first element E 11 of the first planetary gear set P 1, while the second drive shaft 10 is provided axially in the region of the third planetary gear set P 3 and in this case runs radially outwards as far as the electric machine 4 starting from the first element E 13 of the third planetary gear set P 3. The shaft 25 runs as a hollow shaft radially between the output shaft 11 and the planetary gear sets P 1 to P 3, wherein the shaft 25 here, starting from the second planetary gear set P 2, runs axially on the side of the first planetary gear set P 1 facing away from the third planetary gear set P 3 and is connected there to the second element E 21 of the first planetary gear set.FIG. 2 shows an exemplary shift pattern of the motor vehicle transmission 2 from FIG. 1 in tabular form. As can be seen, in the motor vehicle transmission 2, different transmission ratios E1.1, E1.2, E2.1 and E2.2 can be shifted, wherein in the columns of the shift pattern, X in each case identifies which actuated states of the shift elements B, C, E and F formed by the shift devices 29 and 30 are to be represented in the individual transmission ratio. In each of the transmission ratios E 1.1, E 1.2, E 2.1 and E 2.2, an actuated state is to be represented in each case in one of the shift elements B, C, E and F. In this case, the transmission ratios E1.1 and E1.2 are each effective between the first drive shaft 9 and the output shaft 11 and thus each enable a coupling of the electric machine 3 to the output shaft 11, while the transmission ratios E2.1 and E2.2 are each switched between the second drive shaft 10 and the output shaft 11 and each serve for the integration of the electric machine 4.As can be seen in FIG. 2, the transmission ratio E1.1 is shifted between the first input shaft 9 and the output shaft 11 by representing the actuated state of the shift element B in the shifting device 29. For shifting the transmission ratio E1.2, the shifting device 29 is then to realize the actuated state of the shifting element C. Independently of a shift of one of the transmission ratios E1.1 and E1.2, the second drive shaft 10 can be coupled to the output shaft 11 on the one hand with the transmission ratio E2.1 by representing the actuated state of the shift element E in the shifting device 30. On the other hand, the transmission ratio E2.2 between the second input shaft 10 and the output shaft 11 is realized by representing the actuated state of the shift element F in the shift device 30.The transmission ratios E1.1 and E1.2 can be shifted independently of the transmission ratios E2.1 and E2.2, so that the electric machines 3 and 4 can also be connected or also decoupled independently of one another. Thus, in the drive unit, a drive can be carried out without problems via one electric machine 3 or 4, while the other electric machine 4 or 3 is decoupled. In addition, the traction force can be supported via an electric machine 3 or 4 in one of the assigned transmission ratios E1.1 and E1.2 or E2.1 and E2.2, while a change is carried out between the transmission ratios E2.1 and E2.2 or E1.1 and E1.2 assigned to the other electric machine 4 or 3.FIG. 3 shows a schematic illustration of a drive unit 39, which is designed according to a further embodiment of the invention. This drive unit 39 corresponds to the greatest possible extent to the preceding variant according to FIG. 1, with the difference that in a motor vehicle transmission 40 of the drive unit 39, a shifting device 41 is now provided instead of the shifting device 29, which shifting device in this case additionally also depicts the function of a further shifting element A in addition to the functions of the shifting elements B and C.In accordance with the variant according to FIG. 1, the shifting device 41 comprises a coupling element 31, which is guided on the toothing 32 in a rotationally fixed and axially displaceable manner and represents the actuated state of the shifting element B in the first shifting position by tooth engagement in the toothing 33, and represents the actuated state of the shifting element C in the second shifting position by tooth engagement in the toothing 34.In contrast to the shifting device 29 of the motor vehicle transmission 2 from FIG. 1, however, the coupling element 31 can now be shifted, in addition to an axial shift from the first shifting position (actuated state B) in the direction of the one neutral position, axially opposite into a further neutral position, in which the coupling element 31 likewise does not perform any coupling of the third element E 31 of the first planetary gear set P 1. From this further neutral position, the coupling element 31 can then be transferred axially on the one hand into the first switching position (actuated state B) and on the other hand into a third switching position in which the coupling element 31 engages into a further toothing 42 when there is tooth engagement with the toothing 32. This toothing 42 is connected in a rotationally fixed manner to the permanently fixed component 26 and is therefore likewise permanently fixed, with the result that the coupling element 31 causes the third element E 31 of the first planetary gear set P 1 to be fixed in the third switching position. This represents the actuated state of the further switching element A. The shifting device 41 is again placed axially on a side of the first planetary gear set P 1 facing away from the third planetary gear set P 3 and is arranged radially between the first planetary gear set P 1 and the electric machine 3. Otherwise, the embodiment according to FIG. 3 also corresponds to the variant according to FIG. 1, so that reference is made to the description thereof.FIG. 4 shows an exemplary shift pattern of the motor vehicle transmission 40 from FIG. 3, in the case of the motor vehicle transmission 40, the transmission ratios E1.1', E1.2' and E1.3' for engaging the electric machine 3 can be shifted between the first input shaft 9 and the output shaft 11 and the transmission ratios E2.1 and E2.2 for engaging the electric machine 4 can be represented between the second input shaft 10 and the output shaft 11. The transmission ratio E1.1' is shifted in this case by virtue of the fact that the actuated state of the shift element A is realized in the shift device 41. In contrast, the transmission ratio E1.2' corresponds to the transmission ratio E1.1 from FIG. 2 and the transmission ratio E1.3' corresponds to the transmission ratio E1.2 from FIG. 2, in that the actuated state of the shift element B or the actuated state of the shift element C is represented in the shifting device 41. The transmission ratios E2.1 and E2.2 are represented in a manner analogous to the shift pattern from FIG. 2 via the shifting device 30, so that reference is made in this respect to the description relating to FIG. 2. A support of the tensile force can also be realized in a manner analogous to that described with reference to FIG. 2.Furthermore, FIG. 5 shows a schematic view of a drive unit 43 according to a further possible embodiment of the invention, wherein the drive unit 43 corresponds to the greatest possible extent to the variant according to FIG. 1. It is different from the drive unit 1 from FIG. 1 in this case that a motor vehicle transmission 44 of the drive unit 43 has, instead of the shifting device 30, a shifting device 45 by means of which, in addition to the functions of the shifting elements E and F, the function of a shifting element D is additionally also depicted.As in the variant according to FIG. 1, the shifting device 45 has a coupling element 35 which is guided on the toothing 36 in a rotationally fixed and axially displaceable manner and represents the actuated state of the shifting element E in the first shifting position by tooth engagement in the toothing 37 and represents the actuated state of the shifting element F in the second shifting position by tooth engagement in the toothing 38.In the shifting device 45, however, the coupling element 35 can now be moved from the first shifting position (actuated state E) in an axial direction opposite to the second shifting position and can thereby be transferred into a further neutral position, in which the coupling element 35 again does not undertake any coupling of the third element E 33 of the third planetary gear set P 3. By further axial displacement in this direction, the coupling element 35 is then transferred into a third switching position, in which the coupling element 35 represents the actuated state of the switching element D and in this case engages in a further toothing 46 when there is tooth engagement with the toothing 36. The toothing 46 is continuously connected in a rotationally fixed manner to the permanently fixed component 26, as a result of which the toothing 46 is also permanently fixed and the third element E 33 of the third planetary gear set P 3 is thus fixed when the coupling element 35 is engaged in the toothing 46.In the present case, the shifting device 45 is arranged axially between the third planetary gear set P 3 and the second planetary gear set P 2 and is placed radially between the planetary gear sets P 2 and P 3 on the one hand and the electric machine 4 on the other hand. Otherwise, the embodiment according to FIG. 5 corresponds to the variant according to FIG. 1, so that reference is made to the description thereof.FIG. 6 illustrates an exemplary shift pattern of the motor vehicle transmission 44 from FIG. 5. As can be seen here, the transmission ratios E1.1 and E1.2 for engaging the electric machine 3 can be shifted here on the one hand between the first drive shaft 9 and the output shaft 11, wherein this is realized in this case via the shifting device 29 in a manner analogous to that described with reference to FIG. 2. On the other hand, transmission ratios E2.1', E2.2' and E2.3' can be realized between the second drive shaft 10 and the output shaft 11 in each case for the integration of the electric machine 4. In this case, the transmission ratio E2.1' is shifted in that the actuated state of the shift element D is realized in the shift device 45 of the motor vehicle transmission 44. The transmission ratio E2.2', on the other hand, corresponds to the transmission ratio E2.1 from FIG. 2 and the transmission ratio E2.3' to the transmission ratio E2.2 from FIG. 2. the actuated state of the shift element E is to be represented in the case of the transmission ratio E2.2' in the shifting device 45 and the actuated state of the shift element F in the case of the transmission ratio E2.3', reference being made in this respect to the description relating to FIG. 2. Again, a support of the tensile force can also be realized in a manner analogous to that described with reference to FIG. 2.In addition, FIG. 7 shows a schematic view of a drive unit 47, which is designed according to a further embodiment of the invention. The drive unit 47 represents a combination of the two variants according to FIGS. 3 and 5, in that both the shifting device 41 and the shifting device 45 are now provided in a motor vehicle transmission 48 of the drive unit 47. With regard to the respective structure and the respective arrangement of the shifting devices 41 and 45 and also the further structure of the motor vehicle transmission 48, reference is made to the description relating to FIG. 3 or to FIG. 5. As can be seen in FIG. 8, which shows an exemplary shift pattern of the motor vehicle transmission 48 from FIG. 7, the transmission ratios E1.1', E1.2', E1.3', E2.1', E2.2' and E2.3' in the motor vehicle transmission 48 can now also be shifted as a result.Finally, FIG. 9 shows a schematic view of an electric vehicle 49, which can be, in particular, an electric utility vehicle, such as a transporter. In addition to a steerable, non-driven vehicle axle 50, the electric vehicle 49 also has a motor vehicle drive axle 51 with drive wheels 52 and 53. The drive wheels 52 and 53 are coupled to the output shaft of the drive unit 54 via an intermediate differential gearset-not shown here.While the vehicle axle 50 is a front axle of the electric vehicle 49, the motor vehicle drive axle 51 is a rear axle of the electric vehicle 49, but alternatively or additionally to the motor vehicle drive axle 51, the vehicle axle 50 could also be designed as a driven axle with an optionally analogous structure of a drive unit.By means of the embodiments according to the invention, a motor vehicle transmission is created in each case, by means of which an independent incorporation of two drive engines can be represented.Reference numerals denote reference numerals1 Drive unit 2 Motor vehicle transmission 3 Electric machine 4 Electric machine 5 Stator 6 Stator 7 Rotor 8 Rotor 9 Drive shaft 10 Drive shaft 11 Output shaft 12 Sun wheel 13 Sun wheel 14 Sun wheel 15 Planet carrier 16 Planet carrier 17 Planet carrier 18 Ring wheel 19 Ring wheel 20 Ring wheel 21 Planet wheel 22 Planet wheel 23 Planet wheel 24 Connection point 25 Shaft 26 Permanently fixed component 27 Connection point 28 Connection point 29 Switching device 30 Switching device 31 Coupling element 32 Toothing 33 Toothing 34 Toothing 35 Coupling element 36 Toothing 37 Toothing 38 Toothing 39 Drive unit 40 Motor vehicle transmission 41 Switching device 42 Toothing 43 Drive unit 44 Motor vehicle transmission 45 Switching device 46 Toothing 47 Drive unit 48 Motor vehicle transmission 49 Electric vehicle 50 Vehicle axle 51 Motor vehicle drive axle 52 Drive wheel 53 Drive wheel 54 Drive unit P 1 First planetary gear set P 2 Second planetary gear set P 3 Third E11 First element of first planetary gear set E21 Second element of first planetary gear set E31 Third element of first planetary gear set E12 First element of second planetary gear set E22 Second element of second planetary gear set E32 Third element of second planetary gear set E13 First element of third planetary gear set E23 Second element of third planetary gear set E33 Third element of third planetary gear set A Shift element B Shift element C Shift element D Shift element E Shift element F Shift element E1.1 Transmission ratio E1.2 Transmission ratio E2.1 Transmission ratio E2.2 Transmission ratio E1.1' Transmission ratio E1.2' Transmission ratio E1.3' Transmission ratio E2.1' Transmission ratio E2.3' Transmission ratioReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2019 216 562 A1

[0003]

Claims

Motor vehicle transmission (2; 40; 44; 48) for an at least partially electrically driven motor vehicle, comprising a first drive shaft (9), a second drive shaft (10), an output shaft (11) and a first planetary gear set (P1) and a second planetary gear set (P2), - wherein the first drive shaft (9) is provided for coupling to a first drive machine, in particular a first electric machine (3), and the second drive shaft (10) is provided for coupling to a second drive machine, in particular a second electric machine (4), - wherein the first planetary gear set (P1) and the second planetary gear set (P2) each comprise a first element (E11, E12), a second element (E21, E22) and a third element (E31, E32) each in the form of a sun wheel (12, 13), a planetary carrier (15, respectively, 16 ) and each of a ring gear (18, 19), - wherein at least functionally a first shift element (B), a second shift element (C), a third shift element (E) and a fourth shift element (F) are provided, - wherein the first element (E11) of the first planetary gear set (P1) is connected in a rotationally fixed manner to the first input shaft (9) and the second element (E21) of the first planetary gear set (P1) is connected in a rotationally fixed manner to the first element (E12) of the second planetary gear set (P2), - wherein the third element (E32) of the second planetary gear set (P2) is fixed, wherein the second element (E22) of the second planetary gear set (P2) is connected in a rotationally fixed manner to the output shaft (11), - wherein the at least functionally provided first shift element (B) is configured to operate to shift the first gear set up to shift the first gear set up to shift the first gear set up to shift the first gear set up to shift the first gear set up to shift the first gear set up to shift the first, in an actuated state, the third element (E31) of the first planetary gear set (P1) is connected to the output shaft (11) in a rotationally fixed manner, - and wherein the at least functionally provided second shift element (C) is configured to connect two of the elements (E11, E21, E31) of the first planetary gear set (P1) to one another in an actuated state in a rotationally fixed manner, characterized in that a third planetary gear set (P3) is additionally provided, which third planetary gear set comprises a first element (E13), a second element (E23) and a third element (E33) in the form of a sun wheel (14), a planetary carrier (17) and a ring gear (20), and the second element (E23) of which is connected in a rotationally fixed manner to the second element (E21) of the first planetary gear set (P1) and to the first element (E12) of the second planetary gear set (P2), that the first element (E13) of the third planetary gear set (P3) is connected in a rotationally fixed manner to the second input shaft (10), and that the at least functionally provided third shift element (E) is configured to connect the third element (E33) of the third planetary gear set (P3) (11) in a rotationally fixed manner to the output shaft in an actuated state, whereas the at least functionally provided fourth shift element (F) is configured to connect two of the elements (E13, E23 in an actuated state, E33) of the third planetary gear set (P3) are connected to one another in a rotationally fixed manner.Motor vehicle transmission (2; 40; 44; 48) according to Claim 1, characterized in that the second shift element (C), which is provided at least functionally, connects the third element (E31) of the first planetary gear set (P1) in a rotationally fixed manner to the second element (E21) of the first planetary gear set (P1) or to the first element of the first planetary gear set in the actuated state.Motor vehicle transmission (2; 40; 44; 48) according to one of Claims 2, characterized in that the first shift element (B) and the second shift element (C) are formed by a shift device (29; 41), the coupling element (31) of which can be positioned in each case in a first shift position and in a second shift position, wherein the coupling element (31), in the first shift position, functionally represents an actuated state of the first shift element (B) and connects the third element (E31) of the first planetary gear set (P1) to the output shaft (11) in a rotationally fixed manner, wherein the coupling element (31), in the second shift position, functionally represents an actuated state of the second shift element (C) and connects the third element (E31) of the first planetary gear set (P1) in a rotationally fixed manner to either the second element (E21) of the first planetary gear set (P1) or the first element of the first planetary gear set.Motor vehicle transmission (40; 48) according to one of Claims 1 to 3, characterized in that, in addition, a further shift element (A) is provided at least functionally, which shift element is configured to fix the third element (E31) of the first planetary gear set (P1) in an actuated state.Motor vehicle transmission (40; 48) according to Claim 3 and according to Claim 4, characterized in that the switching device (41) which forms the first switching element (B) and the second switching element (C) additionally also forms the further switching element (A) and the coupling element (31) of the switching device (41) can furthermore also be positioned in a third switching position in which the coupling element (31) functionally reproduces the actuated state of the further switching element (A) and fixes the third element (E31) of the first planetary gear set (P1).Motor vehicle transmission (2; 40; 44; 48) according to one of the preceding claims, characterized in that the at least functionally provided, fourth shift element (F) in the actuated state connects the third element (E33) of the third planetary gear set (P3) in a rotationally fixed manner to the second element (E32) of the third planetary gear set (P3) or to the first element of the third planetary gear set.Motor vehicle transmission (2; 40; 44; 48) according to Claim 6, characterized in that the third shift element (E) and the fourth shift element (F) are formed by a shift device (30; 45), the coupling element (35) of which can be positioned in each case in a first shift position and in a second shift position, wherein the coupling element (35), in the first shift position, functionally reproduces the actuated state of the third shift element (E) and connects the third element (E33) of the third planetary gear set (P3) to the output shaft (11) in a rotationally fixed manner, wherein the coupling element (35), in the second shift position, functionally reproduces the actuated state of the fourth shift element (F) and connects the third element (E33) of the third planetary gear set (P3) in a rotationally fixed manner to either the second element (E32) of the third planetary gear set (P3) or the first element of the third planetary gear set.Motor vehicle transmission (44; 48) according to one of the preceding claims, characterized in that an additional shift element (D) is additionally provided at least functionally, which shift element is configured to fix the third element (E33) of the third planetary gear set (P3) in an actuated state.Motor vehicle transmission (44; 48) according to Claim 7 and according to Claim 8, characterized in that the shifting device (45) forming the third shifting element (E) and the fourth shifting element (F) additionally also forms the additional shifting element (D) and the coupling element (35) of the shifting device (45) can furthermore also be positioned in a third shifting position in which the coupling element (35) functionally reproduces the actuated state of the additional shifting element (D) and fixes the third element (E33) of the third planetary gear set (P3).Motor vehicle transmission (2; 40; 44; 48) according to one of the preceding claims, characterized in that the planetary gear sets (P1, P2, P3) are arranged axially in an order of first planetary gear set (P1), third planetary gear set (P3) and second planetary gear set (P2).Motor vehicle transmission (2; 40; 44; 48) according to Claim 10, characterized in that the at least functionally provided first shift element (B) and the at least functionally provided second shift element (C) are arranged axially on a side of the first planetary gear set (P1) which is remote from the third planetary gear set (P3).Motor vehicle transmission (2; 40; 44; 48) according to Claim 4 and according to one of Claims 10 or 11, characterized in that the at least functionally provided, further shift element (A) is placed axially on a side of the first planetary gear set (P1) which is remote from the third planetary gear set (P3).Motor vehicle transmission (2; 40; 44; 48) according to one of Claims 10 to 12, characterized in that the at least functionally provided third shift element (E) and the at least functionally provided fourth shift element (F) are arranged axially between the third planetary gear set (P3) and the second planetary gear set (P2).Motor vehicle transmission (2; 40; 44; 48) according to Claim 8 and one of Claims 10 to 13, characterized in that the at least functionally provided, additional shift element (D) is placed axially between the third planetary gear set (P3) and the second planetary gear set (P2).Drive unit (1; 39; 43; 47) for an at least partially electrically driven motor vehicle, comprising a first electric machine (3), a second electric machine (4) and a motor vehicle transmission (2; 40; 44; 48) according to one or more of claims 1 to 14, wherein a rotor (7) of the first electric machine (3) is coupled to the first drive shaft (9) of the motor vehicle transmission (2; 40; 44; 48) and a rotor (8) of the second electric machine (4) is coupled to the second drive shaft (10) of the motor vehicle transmission (2; 40; 44; 48).Drive unit (1; 39; 43; 47) according to claim 15, characterised in that the first planetary gear set (P1) of the motor vehicle transmission (2; 40; 44; 48) is arranged axially at least partially covering and radially lying on the inside with respect to the rotor (7) of the first electric machine (3).Drive unit (1; 39; 43; 47) according to claim 15 or 16, characterized in that the third planetary gear set (P3) and / or the second planetary gear set (P2) of the motor vehicle transmission (2; 40; 44; 48) is arranged axially at least partially covering and radially lying inside the rotor (8) of the second electric machine (4).Motor vehicle drive axle (51) for a hybrid or electric vehicle (), comprising a drive unit (54) according to one or more of Claims 15 to 17.Hybrid or electric vehicle (49) comprising at least one motor vehicle drive axle (54) according to claim 18 or at least one drive unit (1; 39; 43; 47) according to one or more of claims 15 to 17.Method for operating a motor vehicle transmission (2; 40; 44; 48) according to one or more of Claims 1 to 14, - wherein a first transmission ratio (E1.1; E1.2') is switched between the first drive shaft (9) and the output shaft (11) by representing an actuated state of the first shift element (B), - wherein a second transmission ratio (E1.2; E1.3') is switched between the first drive shaft (9) and the output shaft (11) by representing an actuated state of the second shift element (C), - wherein a first transmission ratio (E2.1; E2.2') is switched between the second drive shaft (10) and the output shaft (11) by representing an actuated state of the third shift element (E), - and wherein a second transmission ratio (E2.2; E2.3') is switched between the second input shaft (10) and the output shaft (11) by representing an actuated state of the fourth switching element (F).Method according to Claim 20 and for operating a motor vehicle transmission (40; 48) according to Claim 4, characterized in that, in addition, a further transmission ratio (E1.1') is shifted between the first drive shaft (9) and the output shaft (11), in that an actuated state of the further shift element (A) is represented.Method according to Claim 20 or 21 and for operating a motor vehicle transmission (44; 48) according to Claim 8, characterized in that, in addition, a further transmission ratio (E2.1') is shifted between the second drive shaft (10) and the output shaft (11), in that an actuated state of the additional shift element (D) is represented.Method according to one of Claims 20 to 22, characterized in that, in the course of a changeover from one transmission ratio which is effective between the one drive shaft (9; 10) and the output shaft (11) to another transmission ratio (G2) which is effective between the one drive shaft (9; 10) and the output shaft (11), the tractive force is supported on the other drive shaft (10; 9) by virtue of a transmission ratio which is effective between the other drive shaft (10; 9) and the output shaft (11) being switched at least during the changeover.

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