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

Abstract

The invention relates to a motor vehicle transmission (3) comprising a drive shaft (6), an output shaft (7), a stepped planetary gear set (P2), and a planetary gear set (P1). Furthermore, a first shifting element (A) and a second shifting element (B) are provided, at least functionally, in the motor vehicle transmission.

Description

The invention relates to a motor vehicle transmission for an at least partially electrically driven motor vehicle, comprising a drive shaft which is provided for a drive-effective connection to at least one drive machine, preferably at least one electric machine, an output shaft and a stepped planetary gearset which has a first element, a second element, a third element and a fourth element in the form of a sun gear, a planet carrier, a ring gear and a further sun gear or a further ring gear, wherein the planet carrier of the stepped planetary gearset rotatably supports at least one stepped planetary gear which is in toothed engagement with the sun gear, the ring gear and the further sun gear or the further ring gear, wherein the first element of the stepped planetary gearset is connected to the output shaft in a rotationally fixed manner, and wherein at least functionally a first shift element and a second shift element are provided, of which the at least functionally provided shift element is rotatably engaged with the output shaft, In an actuated state, the first shift element fixes the second element of the stepped planetary gearset, whereas the at least functionally provided, second shift element fixes the third element of the stepped planetary gearset in an actuated state. The invention furthermore relates to a drive unit for an at least partially electrically driven motor vehicle, an electrically driven motor vehicle drive axle for an at least partially electrically driven motor 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 11 2011 104 355 T5 discloses a drive train of an electric vehicle. In this drive train, an electric machine is connected in a rotationally fixed manner to a drive shaft of a downstream motor vehicle transmission which, in addition to a differential gearset, has a stepped planetary gearset. The stepped planetary gearset has a planetary carrier which rotatably supports at least one stepped planetary, the at least one stepped planetary meshing at a first toothing with a sun gear and a first ring gear and meshing at a second toothing with a second ring gear. While the sun gear is connected to the drive shaft in a rotationally fixed manner, the planet carrier is connected to an output shaft in a rotationally fixed manner, which is also connected to an input element of the differential gearset in a rotationally fixed manner. In this case, a coupling of the output shaft with two output shafts is produced via the differential gearset. Furthermore, a switching device is provided, by means of which the function of two switching elements is depicted, wherein the switching device fixes the first ring gear in a first switching state and fixes the second ring gear to a transmission housing in a second switching state.The prior publication DE 10 2022 208 154 A1 by the applicant discloses an electric drive device for a vehicle, having a single electric machine which is connected via a transmission input shaft to a shiftable planetary transmission, wherein the planetary transmission has a first shifting element for shifting a first gear, a second shifting element for shifting a second gear, a stepped planetary gearset and a minus planetary gearset. The stepped planetary gearset has a first ring gear shaft that can be connected to a housing in a rotationally fixed manner by means of the second shift element, a second ring gear shaft that can be connected to the housing in a rotationally fixed manner by means of the first shift element, and a carrier shaft that receives a plurality of stepped planetary gears and is connected to the sun gear shaft of the minus planetary gearset in a rotationally fixed manner.Proceeding from the prior art described above, it is now the object of the present invention to provide a motor vehicle transmission which is suitable for the incorporation of a drive engine and here preferably an electric machine and by means of which high transmission ratios can be represented in this incorporation.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 the subject matter of further claims. In addition, an electrically drivable motor vehicle drive axle for an at least partially electrically driven motor vehicle is claimed, as well as a hybrid or electric vehicle and a method for operating a motor vehicle transmission according to the invention.According to the invention, a motor vehicle transmission comprises an input shaft, which is provided for a drive-effective connection to at least one drive machine, preferably at least one electric machine, an output shaft and a stepped planetary gearset, which has a first element, a second element, a third element and a fourth element in the form of a sun gear, a planetary carrier, a ring gear and a further ring gear. The planet carrier of the stepped planetary gearset rotatably supports at least one stepped planet gear which meshes with the sun gear, the ring gear and the further ring gear. In addition, the first element of the stepped planetary gearset is connected to the output shaft in a rotationally fixed manner. In addition, at least functionally a first shifting element and a second shifting element are provided, of which the at least functionally provided first shifting element fixes the second element of the stepped planetary gearset in an actuated state, whereas the at least functionally provided second shifting element fixes the third element of the stepped planetary gearset in an actuated state.A respective "shaft", such as the drive shaft and the output shaft of the motor vehicle transmission according to the invention, is to be understood in the sense of the invention as a rotatable component of the motor vehicle transmission, via which a power flow guidance between components can be carried out. The respective shaft can connect these components to one another axially or radially or also both axially and radially when guiding the force flow. Thus, the respective shaft can also be present as an intermediate piece, by means of which, for example, a purely radial connection is realized. Furthermore, depending on the profile and connection to the components, 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.The motor vehicle transmission according to the invention has a drive shaft which, in the motor vehicle transmission according to the invention, is provided for the purpose of producing a drive-side coupling to at least one drive machine, wherein the drive shaft in this case preferably serves for the coupling to exactly one drive machine. For this purpose, the drive shaft is equipped, in particular, with a connection point at which a coupling of the drive shaft to the at least one drive machine can be formed. The connection of the at least one drive machine to the connection point of the drive shaft is carried out in particular permanently in the installed state of the motor vehicle transmission, preferably when the drive machine is designed as an electric machine. Alternatively, however, an intermediate starting element, such as a hydrodynamic torque converter, a starting clutch, etc., can also be provided, via which the drive shaft can be or is coupled at its connection point to the upstream drive machine. This is realized in particular when the drive engine is designed as an internal combustion engine.The coupling between the at least one drive machine and the 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 drive shaft of the motor vehicle transmission and a rotational speed of the drive machine, a fixed rotational speed ratio prevails at all times. 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 drive shaft and the drive machine, by means of which transmission stage a pretransmission of a rotational movement of the drive machine to the drive shaft can be provided. Preferably, however, the drive shaft serves for a rotationally fixed connection to the at least one drive machine.The motor vehicle transmission is in particular a hybrid or electric vehicle transmission which is provided to be connected at the drive shaft to a drive machine in the form of an electric machine. A rotor of the electric machine can be coupled to the drive shaft of the transmission via at least one intermediate transmission stage, as described above. Particularly preferably, however, a rotor of the electric machine is connected to the drive shaft in a rotationally fixed manner 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 a coupling of the at least one drive machine connected to the drive shaft to drive wheels of the respective motor vehicle can be produced in order to translate a drive movement generated via the drive machine with different transmission ratios in each case to the drive wheels.The stepped planetary gearset of the motor vehicle transmission according to the invention is composed of a sun gear, a ring gear, a further sun gear or a further ring gear and a planet carrier, wherein at least one stepped planetary gear is rotatably mounted in the planet carrier. In the stepped planetary gearset, therefore, four elements are present, namely a sun gear, a ring gear, a planetary carrier as well as a further sun gear or a further ring gear. The at least one stepped planetary gear meshes here both with the sun gear, with the ring gear, and with the further sun gear or the further ring gear. For this purpose, the at least one stepped planetary gear is equipped in particular with two different axially adjacent tooth arrangements, wherein the tooth engagement with the one sun gear and the one ring gear is carried out on the one tooth arrangement, while the tooth engagement with the other sun gear or the other ring gear takes place on the other tooth arrangement. The tooth arrangements are preferably designed on different diameters of the stepped planetary gear with different numbers of teeth.Within the scope of the invention, these different gear sets can be provided on a stepped planetary gear configured in one piece, wherein the at least one stepped planetary gear is, however, preferably composed of two coaxial spur gears connected to one another in a rotationally fixed manner, of which one spur gear is provided on an outer circumference with the one gear set and meshes with the one sun gear and the one ring gear, while the other spur gear has the other gear set on an outer circumference and meshes with the other sun gear or the other ring gear.The invention now comprises the technical teaching that a 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 ring gear and a planetary carrier. In this case, the first element of the planetary gear set is connected to the drive shaft in a rotationally fixed manner, whereas the second element of the planetary gear set is connected to the fourth element of the stepped planetary gear set in a rotationally fixed manner. In addition, the third element of the planetary gear set is also connected in a rotationally fixed manner to the first element of the stepped planetary gear set.In the motor vehicle transmission according to the invention, the first element of the stepped planetary gearset is therefore permanently connected to the output shaft in a rotationally fixed manner, so that the output shaft and the first element of the stepped planetary gearset always rotate together. Furthermore, there is a rotationally fixed connection between the first element of the planetary gear set and the drive shaft, as a result of which the drive shaft and the first element of the planetary gear set also rotate permanently together. The planetary gear set and the stepped planetary gear set are also coupled to one another in that, on the one hand, the second element of the planetary gear set is permanently connected to the fourth element of the stepped planetary gear set in a rotationally fixed manner, so that the second element of the planetary gear set and the fourth element of the stepped planetary gear set permanently rotate together. On the other hand, the third element of the planetary gear set and the first element of the stepped planetary gear set are continuously connected to one another in a rotationally fixed manner and thus also always rotate jointly. Since the first element of the stepped planetary gear set is also continuously connected to the output shaft in a rotationally fixed manner, the third element of the planetary gear set is also thereby permanently connected to the output shaft in a rotationally fixed manner.The motor vehicle transmission according to the invention has at least functionally a first shifting element and a second shifting element. An actuated state of the at least functionally provided first shift element results in a locking of the second element of the stepped planetary gearset, whereby the second element of the stepped planetary gearset is then prevented from rotating. The third element of the stepped planetary gearset can also be fixed and thus prevented from rotating, by realizing the actuated state of the at least functionally provided second shift element.Such a configuration of a motor vehicle transmission has the advantage that high transmission ratios can be realized by the coupling according to the invention of the stepped planetary gear set and the planetary gear set to one another and by selective actuation of the at least functionally provided shift elements, which ratios are suitable in particular for the incorporation of a drive machine in the form of an electric machine. This can be realized simultaneously in a compact installation space, so that overall a motor vehicle transmission of compact construction with high transmission ratios is realized.Thus, a first gear can be shifted between the input shaft and the output shaft by representing an actuated state of the first shift element. In addition, a second gear is represented between the input shaft and the output shaft by realizing an actuated state of the second shift element.In the motor vehicle transmission according to the invention, the drive shaft and the output shaft are arranged in particular coaxially with respect to one another, wherein, further preferably, the stepped planetary gearset and the planetary gearset are also respectively placed coaxially with respect to the drive shaft and the output shaft. This allows a particularly compact construction of the motor vehicle transmission in the radial direction to be realized.In the context 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 stepped planetary gearset and of the planetary gearset 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 stepped planetary gear set or of the planetary gear set.Very particularly preferably, in the motor vehicle transmission according to the invention, exactly two shift elements are provided at least functionally for shifting different gears between the drive shaft and the output shaft, wherein, however, further shift elements provided at least functionally may optionally also be provided within the scope of the invention. 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 respective switching element can actually be physically present in detail as an individual switching element or the function of the respective switching element 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 switching elements in one device.A "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 context of the invention, a locking of a component of the motor vehicle transmission via an at least functionally provided shift element means that the component in question is not permanently locked, but rather a locking is only carried out by illustrating an actuated state of the at least functionally provided, intermediate shift 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.The planetary gear set is composed of a first element, a second element and a third element, wherein of these elements an element is configured as a sun gear, an element as a planetary carrier and an element as a ring gear. The planetary gear set is preferably present here as a minus planetary gear set, in which the planetary carrier guides at least one planetary gear rotatably mounted, wherein the at least one planetary gear is in mesh with both the sun gear of the planetary gear set and the ring gear of the planetary gear set. In an embodiment of the planetary gear set as a minus planetary gear set, the first element of the planetary gear set is then in particular the sun gear, the second element of the planetary gear set is the planetary carrier and the third element of the planetary gear set is the ring gear. In particular, a plurality of planetary gears are rotatably mounted in the planetary carrier.Alternatively, the planetary gear set could also be designed as a plus planetary gear set. In this case, at least one pair of planet wheels is rotatably mounted in the planet carrier of the planetary gear set, of which planet wheels a planet wheel meshes with the sun wheel of the planetary gear set and a planet wheel meshes with the ring wheel of the planetary gear set. 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 planetary gear set is then preferably the sun gear, the second element of the planetary gear set is the ring gear and the third element of the planetary gear set is the planetary carrier. In addition, in comparison with an embodiment as a minus planetary gear set, a stationary transmission ratio of the planetary gear set is to be increased by one. As already described above, however, the planetary gear set is preferably a minus planetary gear set.According to an embodiment of the invention, the first element of the stepped planetary gearset is the planet carrier of the stepped planetary gearset, the second element of the stepped planetary gearset is the ring gear of the stepped planetary gearset, the third element of the stepped planetary gearset is another ring gear of the stepped planetary gearset, and the fourth element of the stepped planetary gearset is the sun gear of the stepped planetary gearset. In this case, the stepped planetary gearset therefore has, in addition to the planetary carrier, exactly one sun wheel and exactly two ring gears. The first element of the stepped planetary gearset is formed by the planetary carrier of the stepped planetary gearset, while the second element of the stepped planetary gearset is formed by one ring gear, the third element of the stepped planetary gearset by the other ring gear, and the fourth element of the stepped planetary gearset by the exactly one sun gear.In a development of this embodiment, the at least one stepped planet gear of the stepped planetary gearset meshes with the sun gear of the stepped planetary gearset and the further ring gear of the stepped planetary gearset on a first toothing each, the at least one stepped planet gear of the stepped planetary gearset also meshing with the ring gear of the stepped planetary gearset on a second toothing each.According to one possible embodiment of the invention, the output shaft is coupled to an input element of a differential gearset, which drive-effectively connects the output shaft to two output shafts. In an advantageous manner, a distribution of a drive torque produced at the output shaft to the two output shafts can thereby be carried out, wherein a rotational speed compensation between the output shafts can also be implemented via the differential gearset. The differential gearset functions in particular as a transverse differential and is preferably designed in the manner of a bevel gear differential. Via the transverse differential thus formed, a distribution of a drive movement transmitted to the output shaft of the motor vehicle transmission is preferably carried out to the output shafts, which are preferably assigned to a motor vehicle drive axle. The differential gearset can, however, also have the function of a longitudinal differential, via which a distribution of a drive power to a plurality of drive axles can be carried out. As an alternative to an embodiment as a bevel gear differential, the differential gearset can also be designed as a planetary gear differential, as a spur gear differential, etc. within the scope of the invention.The input element to which the output shaft is coupled is preferably a differential cage of the differential gearset. When the differential gearset is used as a transverse differential and the motor vehicle transmission is installed transversely to a direction of travel of the associated motor vehicle, the output shaft is then preferably connected to the input element in a rotationally fixed manner. This is also realized in particular when the differential gearset functions as a longitudinal differential and the motor vehicle transmission is oriented in the direction of travel of the motor vehicle. When the motor vehicle transmission is installed in the direction of travel and the differential gearset is used as a transverse differential, in contrast, in particular the output shaft is coupled to the input element via a bevel drive. Such a bevel gear is also preferably used when the differential gearset is used as a longitudinal differential and the motor vehicle transmission is oriented transversely to the direction of travel.In the motor vehicle transmission according to the invention, the design option according to which the output shaft is coupled to an input element of a differential gearset is particularly preferred combined with the variant protruding above. The differential gearset is then located axially overlapping with and radially inward of the tooth meshing of the at least one stepped planetary gear of the stepped planetary gearset with the ring gear of the stepped planetary gearset. This allows an interleaved arrangement of the differential gearset with the stepped planetary gearset, wherein the differential gearset at least partially overlaps axially with the meshing of the at least one stepped planetary gearset with the ring gear. As a result, the axial structural length of the motor vehicle transmission can be further reduced.According to one embodiment of the invention, the first switching element and the second switching element are formed by a common switching device which has a coupling element. The coupling element can be positioned in a first shift position and in a second shift position, respectively, wherein the coupling element in the first shift position functionally depicts an actuated state of the first shift element and fixes the second element of the stepped planetary gearset, whereas in the second shift position the coupling element functionally depicts an actuated state of the second shift element and fixes the third element of the stepped planetary gearset. As a result, the function of the first shift element and of the second shift element can be reproduced by a shift device and thus in a compact manner. For the representation of the actuated states, as a result, furthermore only one common actuating actuator system is necessary, by means of which the coupling element can be positioned in the respectively different switching positions. The coupling element can preferably be positioned between the shift positions or in a neutral position in which neither an actuated state of the first shift element nor an actuated state of the second shift element is represented.The aforementioned switching device is in particular configured such that the coupling element of the switching device is guided in a rotationally fixed and axially displaceable manner on a first toothing in the two switching positions and in the event of an axial displacement between the two switching positions, which toothing is permanently fixed. In this case, the first toothing can be configured on a permanently fixed component, such as a transmission housing, a part of a transmission housing or a component connected thereto in a rotationally fixed manner. In the first shift position, the coupling element then engages in a second toothing which is connected to the second element of the stepped planetary gearset in a rotationally fixed manner. When transferred into the second shift position, the coupling element meshes with a third toothing which is connected in a rotationally fixed manner to the third element of the stepped planetary gear set.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 tooth arrangements 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, however, the first shifting element and the second shifting element could also be present as individual shifting elements, wherein the two 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.The invention also relates to a drive unit which, in addition to at least one electric machine, has a motor vehicle transmission according to one or more of the variants described above. In this case, a respective rotor of the at least one electric machine is coupled to the drive shaft of the motor vehicle transmission. In the context of the invention, the at least one 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. Particularly preferably, in the drive unit, exactly one electric machine is provided in addition to the motor vehicle transmission.The at least one electric machine is preferably each connected in a rotationally fixed manner to the drive shaft of the motor vehicle transmission, wherein the at least one electric machine is then arranged coaxially with respect to the drive shaft. As a result, the drive shaft and the respective rotor of the at least one electric machine run under the same rotational speed during operation. Alternatively, however, it is also conceivable that the respective rotor of the at least one electric machine is connected in a rotationally fixed manner to a respective intermediate shaft of the motor vehicle transmission, which intermediate shaft is coupled to the drive shaft via at least one transmission stage, so that the at least one electric machine is then optionally offset from the drive shaft. Depending on the design of the at least one transmission stage, however, a coaxial arrangement of the at least one electric machine with respect to the drive shaft is also possible.The planetary gear set of the motor vehicle transmission is preferably placed axially covering and radially inside the at least one electric machine. As a result, an nested arrangement of the at least one electric machine and of the planetary gear set can be realized and an axially compact arrangement can thus be achieved.A drive unit designed according to one of the aforementioned variants is in particular part of an electrically drivable motor vehicle drive axle, which is provided for an electric or hybrid vehicle. The motor vehicle transmission preferably has a differential gearset which is coupled to the output shaft and couples the output shaft to output shafts. Each of the output shafts is assigned to a drive wheel of the motor vehicle drive axle.An aforementioned 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 a schematic illustration of a drive unit according to a further possible embodiment of the invention; FIG. 3 shows an exemplary shift pattern of a motor vehicle transmission of the drive unit from FIG. 1 or FIG. 2 ; and FIG. 4 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 a preferred embodiment of the invention. This drive unit 1 is composed of an electric machine 2 and a motor vehicle transmission 3, which is designed according to one possible embodiment of the invention. The electric machine 2 is formed in a manner known in principle to the person skilled in the art by a stator 4 and a rotor 5, wherein the electric machine 2 can be operated on the one hand as a generator and on the other hand as an electric motor.The motor vehicle transmission 3 has, in addition to an input shaft 6 and an output shaft 7, a planetary gear set P 1 and a stepped planetary gear set P 2. The planetary gear set P 1 has a first element E 11, a second element E 21 and a third element E 31, of which the first element E 11 of the planetary gear set P 1 is a sun gear 8 of the planetary gear set P 1, the second element E 21 of the planetary gear set P 1 is a planet carrier 9 of the planetary gear set P 1 and the third element E 31 of the planetary gear set P 1 is a ring gear 10 of the planetary gear set P 1. In the planetary carrier 9 at least one planetary gear 11 is rotatably mounted which meshes with both the sun gear 8 and the ring gear 10. In this respect, the planetary gear set P 1 is designed as a minus planetary gear set in the present case.The stepped planetary gear set P 2 includes a first element E 12, a second element E 22, a third element E 32, and a fourth element E 42. While the first element E 12 of the stepped planetary gearset P 2 is present as a planetary carrier 12, the second element E 22 and the third element E 32 are each a ring gear 13 or 14, respectively.As can be seen in FIG. 1, at least one stepped planetary gear 16 is rotatably mounted in the planetary carrier 12 of the stepped planetary gear set P 2, which planetary gear has two axially adjacent tooth arrangements 17 and 18. While tooth meshings with the sun gear 15 and the ring gear 14 are produced on the toothing 17, the at least one stepped planetary gear 16 meshes with the ring gear 13 on the toothing 18.In the present case, the sun gear 8 of the planetary gear set P 1 is connected in a rotationally fixed manner to the drive shaft 6, which is additionally connected in a rotationally fixed manner to the rotor 5 of the electric machine 2. In this respect, the sun wheel 8 of the planetary gear set P 1 and the rotor 5 are also connected to one another in a rotationally fixed manner via the drive shaft 6, as a result of which the sun wheel 8 and the rotor 5 always rotate at the same rotational speed. Within the scope of the invention, the drive shaft 6 can be configured in one piece with the rotor 5 of the electric machine 2 and / or with the sun gear 8 of the planetary gear set P 1.The planet carrier 9 of the planetary gear set P 1 is permanently connected in a rotationally fixed manner to the sun gear 15 of the stepped planetary gear set P 2, so that the planet carrier 9 and the sun gear 15 also continuously run at the same rotational speed. This connection is produced via a shaft 19, wherein the shaft 19 could be embodied in one piece with the planet carrier 9 of the planetary gear set P 1 and / or with the sun gear 15 of the stepped planetary gear set P 2.In addition, the ring gear 10 of the planetary gear set P 1 and the planet carrier 12 of the stepped planetary gear set P 2 are continuously connected to one another in a rotationally fixed manner and thus always rotate jointly, wherein the rotationally fixed connection is produced via a shaft 20 which could be formed integrally with the ring gear 10 of the planetary gear set P 1 and / or with the planet carrier 12 of the stepped planetary gear set P 2. The planet carrier 12 of the stepped planetary gearset P 2 is also permanently connected to the output shaft 7 in a rotationally fixed manner, so that the ring gear 10 of the planetary gearset P 1 is also permanently connected to the output shaft 7 in a rotationally fixed manner. The planet carrier 12 could be configured in one piece with the output shaft 7, wherein the shaft 20 could then also be configured in one piece therewith and could thus form a section of the output shaft 7.In addition to the planet carrier 12 of the stepped planetary gearset P 2, the output shaft 7 is also permanently connected in a rotationally fixed manner to an input element 21 in the form of a differential cage of a differential gearset 22. This differential gearset 22 is designed as a differential bevel gear, which, in a manner known in principle to the person skilled in the art, distributes a drive torque introduced into the input element 21 via the output shaft 7 to two output shafts 23 and 24. In this case, the differential gearset 22 also makes possible rotational speed differences between the output shafts 23 and 24.The motor vehicle transmission 3 also has a shifting device 25, in which a coupling element 26 in the form of a sliding sleeve is provided. The coupling element 26 is guided in a rotationally fixed and axially displaceable manner on a toothing 27 which is connected in a rotationally fixed manner to a permanently fixed component 28. The fixed component 28 is preferably a transmission housing of the motor vehicle transmission 3, a part of such a transmission housing or a component connected thereto in a rotationally fixed manner. Axial displacements of the coupling element 26 on the toothing 27 can be carried out via an adjusting actuator-not shown in detail here-which is preferably designed as an electromechanical adjusting actuator.The coupling element 26 can be moved via the actuator between two different switching positions in which the coupling element 26 is individually in each case engaged in a respective associated toothing 29 or 30. The toothing 29 is connected in a rotationally fixed manner to the ring gear 13 of the stepped planetary gearset P 2, while the toothing 30 is connected in a rotationally fixed manner to the ring gear 14 of the stepped planetary gearset P 2.The switching device 25 represents the function of two switching elements A and B, the respective actuated state of which the switching device 25 represents in each case one of its switching states. Thus, an actuated state of the shift element A is realized in a first shift position of the coupling element 26, in which the coupling element 26 engages in the toothing 29 and thus fixes the ring gear 13 of the stepped planetary gearset P 2 by a rotationally fixed connection to the permanently fixed component 28. From the first shift position, the coupling element 26 can be moved via the actuator into a neutral position in which no coupling is carried out via the coupling element 26. In addition to a transfer of the coupling element 26 into the first switching position, the coupling element 26 can also be moved from the neutral position into a second switching position, which is shown in FIG. 1 and in which a tooth engagement of the coupling element 26 into the toothing 30 takes place. As a result, the coupling element 26 connects the ring gear 14 of the stepped planetary gearset P 2 to the permanently fixed component 28 in a rotationally fixed manner, which accordingly results in the ring gear 14 being fixed and corresponding to an actuated state of the shift element B.In the present case, the electric machine 2 is placed coaxially with the motor vehicle transmission 3, in which, in addition, the input shaft 6, the planetary gear set P 1 and the stepped planetary gear set P 2, the output shaft 7, the output shafts 23 and 24, the shafts 19 and 20 and the differential gear set 22 are arranged coaxially with respect to one another. In this case, the planetary gear set P 1 is arranged axially between the electric machine 2 and the stepped planetary gear set P 2, wherein the planetary gear set P 1 could, however, also be placed axially covering and radially inside the electric machine 2. The differential gearset 22 is arranged axially overlapping with the stepped planetary gearset P 2. Specifically, the differential gearset 22 is located axially overlapping with and radially inward of the tooth meshing of the stepped planetary gear 16 with the ring gear 13, thereby achieving an interleaved arrangement of the stepped planetary gearset P 2 and the differential gearset 22. The shifting device 25 is arranged radially surrounding the planetary gear set P 1 and the stepped planetary gear set P 2, wherein the shifting device 25 is placed here axially substantially covering both the planetary gear set P 1 and the stepped planetary gear set P 2. While the output shafts 23 and 24 are designed as solid shafts, the drive shaft 6, the output shaft 7 and the shafts 19 and 20 are each present as hollow shafts.Furthermore, FIG. 2 shows a schematic view of a drive unit 31 according to a further possible embodiment of the invention, wherein this possible embodiment corresponds to the greatest possible extent here to the preceding variant according to FIG. 1. In contrast to the embodiment according to FIG. 1, in a motor vehicle transmission 32 of the drive unit 31, the planetary gear set P 1 is arranged axially overlapping with and radially inside the electric machine 2. In addition, the switching device 25 is now placed axially covering the stepped planetary gearset P 2 and the differential gearset 22, wherein the switching device 25 is located radially around the stepped planetary gearset P 2 and the differential gearset 22. Otherwise, the design option according to FIG. 2 corresponds to the variant according to FIG. 1, so that reference is made to the one described for this purpose.FIG. 3 shows an exemplary shift pattern of the motor vehicle transmissions 3 and 32 from FIGS. 1 and 2 in tabular form. As can be seen, a total of two gears G 1 to G 2 can be realized between the drive shaft 6 and the output shaft 7, wherein an X is respectively labeled in the columns of the shift pattern, which actuated states of the shift elements A and B formed by the shift device 25 are to be represented in the individual gear. In each of the gears G 1 and G 2, an actuated state is to be represented in each case in one of the shift elements A and B.As can be seen in FIG. 3, a first gear G 1 is shifted between the input shaft 6 and the output shaft 7 by representing the actuated state of the shift element A in the shifting device 25. For shifting a second gear G 2, the operated state of the shift element B is then to be realized in the shifting device 25. Synchronization of rotational speeds when engaging a respective gear can be at least assisted by a corresponding braking or acceleration of the drive shaft 6 via the electric machine 2.Finally, FIG. 4 shows a schematic view of an electric vehicle 33, which can be, in particular, an electric utility vehicle, such as a transporter. In addition to a steerable, non-driven vehicle axle 34, the electric vehicle 33 also has a motor vehicle drive axle 35 with drive wheels 36 and 37. The drive wheel 36 is connected in a rotationally fixed manner to the output shaft 23 of the drive unit 38, while the drive wheel 37 is connected in a rotationally fixed manner to the output shaft 24 of the drive unit 38.While the vehicle axle 34 is a front axle of the electric vehicle 33, the motor vehicle drive axle 35 is a rear axle of the electric vehicle 33.By means of the configuration according to the invention, a motor vehicle transmission of compact construction can be realized with suitable transmission ratios for the integration of an electric machine.Reference numerals denote reference numerals1 Drive unit 2 Electric machine 3 Motor vehicle transmission 4 Stator 5 Rotor 6 Drive shaft 7 Output shaft 8 Sun wheel 9 Planet carrier 10 Ring gear 11 Planet wheel 12 Planet carrier 13 Ring gear 14 Ring gear 15 Sun wheel 16 Stepped planet wheel 17 Toothing 18 Toothing 19 Shaft 20 Shaft 21 Input element 22 Differential gearset 23 Output shaft 24 Output shaft 25 Switching device 26 Coupling element 27 Toothing 28 Fixed component 29 Toothing 30 Toothing 31 Drive unit 32 Motor vehicle transmission 33 Electric vehicle 34 Vehicle axle 35 Motor vehicle drive axle 36 Drive wheel 37 Drive wheel 38 Drive unit P 1 Planetary gearset P 2 Stepped planetary gearset E 11 First element Planetary gearset E 21 Second element Planetary gearset E 31 Third element Planetary gearset E 12 First element Stepped planetary gearset E 22 Second element Stepped planetary gearset E 32 Third element Stepped planetary gearset E42 Fourth Element Stepped planetary gearset A Shift B Shift G1 First Speed G2 Second Speed

Claims

Motor vehicle transmission (3; 32) for an at least partially electrically driven motor vehicle, comprising a drive shaft (6) which is provided for a drive-effective connection to at least one drive machine, preferably at least one electric machine (2), an output shaft (7) and a stepped planetary gearset (P2) which has a first element (E12) in the form of a planet carrier (12), a second element (E22) in the form of a ring gear (13), a third element (E32) in the form of a further ring gear (14) and a fourth element (E42) in the form of a sun gear (15), wherein the planet carrier (12) of the stepped planetary gearset (P2) rotatably supports at least one stepped planetary gearset (16) which is in toothed engagement with the sun gear (15), the ring gear (13) and the further ring gear (14), respectively, wherein the first element (E12) of the stepped planetary gearset (P2) is connected to the output shaft (7) in a rotationally fixed manner, and wherein at least functionally a first shifting element (A) and a second shifting element (B) are provided, of which the at least functionally provided first shifting element (A) fixes the second element (E22) of the stepped planetary gearset (P2) in an actuated state, whereas the at least functionally provided second shifting element (B) fixes the third element (E32) of the stepped planetary gearset (P2) in an actuated state, characterized - in that a planetary gearset (P1) is also provided, which fixes a first element (E11) in the form of a sun wheel (8), a second element (E21) in the form of a planet carrier (9) and a third element (E31) in the form of a ring gear (10), - the first element (E11) of the planetary gear set (P1) is connected in a rotationally fixed manner to the input shaft (6), - the second element (E21) of the planetary gear set (P1) is connected in a rotationally fixed manner to the fourth element (E42) of the stepped planetary gear set (P2), - and the third element (E31) of the planetary gear set (P1) is connected in a rotationally fixed manner to the first element (E12) of the stepped planetary gear set (P2).Motor vehicle transmission (3; 32) according to Claim 1, characterized in that the at least one stepped planet wheel (16) of the stepped planetary gearset (P2) meshes on a respective first toothing (17) with the sun wheel (15) of the stepped planetary gearset (P2) and the further ring wheel (14) of the stepped planetary gearset (P2), wherein the at least one stepped planet wheel (16) of the stepped planetary gearset (P2) also meshes on a respective second toothing (18) with the ring wheel (13) of the stepped planetary gearset (P2).Motor vehicle transmission (3; 32) according to one of the preceding claims, characterized in that the output shaft (7) is coupled to an input element (21) of a differential gearset (22) which connects the output shaft (7) in a drive-effective manner to two output shafts (23, 24).Motor vehicle transmission (3; 32) according to Claim 3 and according to Claim 2, characterized in that the differential gearset (22) is located axially overlapping with the ring gear (13) of the stepped planetary gearset (P2) and radially on the inside of the tooth engagement of the at least one stepped planet gear (16) of the stepped planetary gearset (P2) with the ring gear (13) of the stepped planetary gearset (P2).Motor vehicle transmission (3; 32) according to one of the preceding claims, characterized in that the first shift element (A) and the second shift element (B) are formed by a common shift device (25) which has a coupling element (26), wherein the coupling element (26) can be positioned in each case in a first shift position and in a second shift position, wherein the coupling element (26) in the first shift position functionally depicts an actuated state of the first shift element (A) and fixes the second element (E22) of the stepped planetary gearset (P2), and wherein the coupling element (26) in the second shift position functionally depicts an actuated state of the second shift element (B) and fixes the third element (E32) of the stepped planetary gearset (P2).Motor vehicle transmission (3; 32) according to Claim 5, characterized in that the coupling element (26) is guided in a rotationally fixed and axially displaceable manner on a first toothing (27) in the two shift positions and during an axial displacement between the two shift positions, said first toothing being fixed, wherein the coupling element (26), in the first shift position, encloses a second toothing (29) which is connected in a rotationally fixed manner to the second element (E22) of the stepped planetary gearset (P2), and wherein, in the second shift position, the coupling element (26) encloses a third toothing (30) which is connected in a rotationally fixed manner to the third element (E32) of the stepped planetary gearset (P2).Drive unit (1; 31; 38) for an at least partially electrically driven motor vehicle, comprising at least one electric machine (2) and a motor vehicle transmission (3; 32) according to one or more of claims 1 to 6, wherein a respective rotor (5) of the at least one electric machine (2) is coupled to the drive shaft (6) of the motor vehicle transmission (3; 32).Drive unit (31; 38) according to Claim 7, characterized in that the planetary gear set (P1) of the motor vehicle transmission (32) is placed axially covering and radially inside the at least one electric machine (2).Electrically drivable motor vehicle drive axle (35) for an at least partially electrically driven motor vehicle, comprising a drive unit (1; 31; 38) according to claim 7 or 8.Hybrid or electric vehicle (33), comprising a drive unit (1; 31; 38) according to claim 7 or 8 or a motor vehicle drive axle (35) according to claim 9.Method for operating a motor vehicle transmission (3; 32) according to one or more of Claims 1 to 6, wherein - a first gear (G1) is shifted between the drive shaft (6) and the output shaft (7) by representing an actuated state of the first shift element (A), - and wherein a second gear (G2) is shifted between the drive shaft (6) and the output shaft (7) by representing an actuated state of the second shift element (B).

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