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 (P1), and a planetary gear set (P2). Furthermore, the motor vehicle transmission is provided, at least functionally, with a first shifting element (A), a second shifting element (B), and a third shifting element (C).

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 fourth element of the stepped planetary gearset is connected to the drive 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 drive 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.From document DE 10 2022 209 071 A1 a drive device for a vehicle is known, which comprises an electric machine, which is connected via a transmission input shaft to a shiftable planetary transmission, wherein the planetary transmission has at least 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 with a sun gear shaft, a ring gear shaft fixed to a housing and a carrier shaft receiving several planetary gears. The stepped planetary gearset comprises a sun gear shaft connected to the transmission input shaft in a rotationally fixed manner, a first ring gear shaft connectable to the housing in a rotationally fixed manner by means of the first shift element, a second ring gear shaft connectable to the carrier shaft of the minus planetary gearset in a rotationally fixed manner by means of the second shift element, and a carrier shaft receiving a plurality of stepped planetary gears and connected to the sun gear shaft of the minus planetary gearset in a rotationally fixed manner, wherein the carrier shaft of the minus planetary gearset is connected to a transmission output shaft 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 and a high transmission spread 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 claim 9 or 10. In addition, claim 11 relates to an electrically drivable motor vehicle drive axle for an at least partially electrically driven motor vehicle, while claim 12 relates to a hybrid or electric vehicle. Finally, claim 13 also relates to 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 drive 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 in each case with the sun gear, with the ring gear and also 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 in a rotationally fixed manner to the first element of the stepped planetary gear set, whereas the second element of the planetary gear set is connected in a rotationally fixed manner to the output shaft. In addition, the third element of the planetary gear set is fixed. Furthermore, a third shifting element is provided at least functionally, which, in an actuated state, connects the third element of the stepped planetary gearset and the second element of the planetary gearset to one another in a rotationally fixed manner.In the motor vehicle transmission according to the invention, the fourth element of the stepped planetary gearset is therefore permanently connected to the drive shaft in a rotationally fixed manner, so that the drive shaft and the fourth element of the stepped planetary gearset always rotate together. Furthermore, there is a rotationally fixed connection between the second element of the planetary gear set and the output shaft, as a result of which the output shaft and the second 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 by the first element of the planetary gear set being continuously rotationally fixedly connected to the first element of the stepped planetary gear set, such that the first element of the planetary gear set and the first element of the stepped planetary gear set permanently rotate together. Furthermore, the third element of the planetary gear set is permanently fixed and thus permanently prevented from rotating.The motor vehicle transmission according to the invention has at least functionally a first shift element, a second shift element and a third shift 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. When an actuated state of the at least functionally provided third shift element is represented, the third element of the stepped planetary gearset is connected to the second element of the planetary gearset in a rotationally fixed manner, so that the third element of the stepped planetary gearset and the second element of the planetary gearset, and thus also the output shaft, rotate together in the sequence.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 with a high transmission spread and at the same time with a compact installation space, so that overall a motor vehicle transmission with a compact construction and high transmission ratios and high spread 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. A third gear shift between the input shaft and the output shaft is performed by representing an operated state of the third 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 three 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 present case, the third element of the 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 planetary gear set with the stationary component would also be conceivable.In the context of the invention, a fixing 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 component in question is not permanently fixed or the components are not permanently coupled to one another, but a fixing 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.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 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 the invention, the first switching element, the second switching element and the third 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, in a second shift position and in a third 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. In the third shift position, the coupling element functionally depicts an actuated state of the third shift element and connects the third element of the stepped planetary gearset and the second element of the planetary gearset to one another in a rotationally fixed manner. As a result, the function of the first shift element, of the second shift element and of the third 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 adjacent shift positions or in each case in an intermediate neutral position in which neither an actuated state of the first shift element nor an actuated state of the second or third shift element is respectively shown. Within the scope of the invention, a "shift position" or a "neutral position" can also be 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 configured such that the coupling element in the first shifting position and in the second shifting position as well as in an axial displacement between the first shifting position and the second shifting position is rotationally fixedly guided on a first toothing which is fixed, and in the first shifting position encloses a second toothing which is rotationally fixedly connected to the second element of the stepped planetary gearset, whereas in the second shifting position the coupling element encloses a third toothing which is rotationally fixedly connected to the third element of the stepped planetary gearset. In the event of an axial displacement between the second shift position and the third shift position and in the third shift position, the coupling element is then guided on the third toothing in a rotationally fixed manner and, in the third shift position, engages in a fourth toothing which is connected in a rotationally fixed manner to the second element of the 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 or on the third tooth arrangement and / or the respective embedding in the second, third and fourth 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, the first shifting element, the second shifting element and the third shifting element could also be present as individual shifting elements, wherein the shifting elements in this case are designed in particular 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, of the three switching elements, only two switching elements could also be combined to form one switching device, while the switching element still remaining is then present as an individual switching element.In a further development of the invention, the coupling element of the shifting device is coupled to an adjusting actuator, by means of which five positions can be set successively. This allows a suitable actuation of the switching device to be realized. In this case, the actuating actuator positions the coupling element in its first shift position in a first position, so that the actuated state of the first shift element is illustrated and the first gear is thus shifted. In a second position, the actuating actuator positions the coupling element in a first neutral position, as a result of which no gear is shifted. In this case, in this first neutral position, the gear to be shifted in each case in the following can then be synchronized, in particular via the drive machine designed as an electric machine.In a third position, the actuating actuator positions the coupling element in its second shift position, so that the actuated state of the second shift element is realized and thus the second gear is shifted. A further neutral shift of the motor vehicle transmission can be achieved by the actuating actuator positioning the coupling element in a second neutral position in a fourth position. Here too, it is then possible to synchronize the gear to be shifted in each case in the following. Finally, in a fifth position, the actuating actuator positions the coupling element in its third switching position. This then represents the actuated state of the third shift element, whereby the third gear is shifted.It is a further embodiment of the invention that a parking lock element is additionally provided, which in an actuated state fixes the output shaft directly or indirectly. In an advantageous manner, a parking lock function can thereby be realized in the motor vehicle transmission according to the invention by actuating the parking lock element. In this case, the output shaft is fixed when the parking lock function is activated, as a result of which rolling away of a motor vehicle having the motor vehicle transmission according to the invention can be reliably prevented.Within the scope of the invention, the parking lock element can connect the output shaft directly to a permanently fixed component in a rotationally fixed manner when actuated. Particularly preferably, however, the parking lock element is connected in a rotationally fixed manner to the first element of the stepped planetary gearset and, in an actuated state, connects the first element of the stepped planetary gearset in a rotationally fixed manner to a permanently fixed component. This has the advantage that with this arrangement of the parking lock element, the parking lock element can be dimensioned smaller, since a lower torque is present on the first element of the stepped planetary gearset in comparison with the output shaft. The reason for this is the coupling of the first element multi-step planetary gearset with the output shaft via the intermediate planetary gearset.The parking lock element is in particular a further shifting element which, however, is not provided for realizing a transmission ratio between the drive shaft and the output shaft, but rather serves for the direct or indirect fixing of the output shaft. The parking lock element is preferably present here as a form-locking shifting element and in this case in particular as a claw shifting element, wherein the parking lock element could, however, just as well be embodied as a force-locking shifting element. In particular, the parking lock element is arranged axially on a side of the stepped planetary gear set facing away from the planetary gear set.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.Preferably, the stepped planetary gear set of the motor vehicle transmission is placed axially between the at least one electric machine and the planetary gear set of the motor vehicle transmission. This allows a suitable construction of a drive unit.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 stepped planetary gearset P 1 and a planetary gearset P 2. The stepped planetary gear set P 1 includes a first element E 11, a second element E 21, a third element E 31, and a fourth element E 41. While the first element E 11 of the stepped planetary gearset P 1 is present as a planetary carrier 8, the second element E 21 and the third element E 31 are each a ring gear 9 or 10, respectively.As can be seen in FIG. 1, at least one stepped planetary gear 12 is rotatably mounted in the planetary carrier 8 of the stepped planetary gear set P 1, which planetary gear has two axially adjacent tooth arrangements 13 and 14. While tooth meshings with the sun gear 11 and the ring gear 10 are produced on the toothing 13, the at least one stepped planetary gear 12 meshes with the ring gear 9 on the toothing 14.The planetary gear set P 2 has a first element E 12, a second element E 22 and a third element E 32, of which the first element E 12 of the planetary gear set P 2 is a sun gear 15 of the planetary gear set P 1, the second element E 22 of the planetary gear set P 2 is a planet carrier 16 of the planetary gear set P 2 and the third element E 32 of the planetary gear set P 2 is a ring gear 17 of the planetary gear set P 2. In the planetary carrier 16, at least one planetary gear 18 is rotatably mounted, which is in mesh with both the sun gear 15 and the ring gear 17. In this respect, the planetary gear set P 2 is designed as a minus planetary gear set in the present case.In the present case, the sun wheel 11 of the stepped planetary gearset P 1 is connected in a rotationally fixed manner to the drive shaft 6, which is also connected in a rotationally fixed manner to the rotor 5 of the electric machine 2. In this respect, the sun wheel 11 of the stepped planetary gearset P1 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 11 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 11 of the stepped planetary gearset P 1.The planet carrier 8 of the stepped planetary gearset P 1 is permanently connected in a rotationally fixed manner to the sun gear 15 of the planetary gearset P 2, so that the planet carrier 8 and the sun gear 15 also continuously run at the same speed. This connection is produced via a shaft 19, wherein the shaft 19 could be embodied in one piece with the planet carrier 8 of the stepped planetary gearset P 1 and / or with the sun gear 15 of the planetary gearset P 2.In addition, the ring gear 17 of the planetary gear set P 2 is permanently connected in a rotationally fixed manner to a permanently fixed component 20, which 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. In this respect, the ring gear 17 of the planetary gear set P 2 is permanently fixed, wherein the ring gear 17 could also be formed integrally with the permanently fixed component 20. The planet carrier 16 of the planetary gear set P 2 is also continuously connected in a rotationally fixed manner to the output shaft 7. The planet carrier 12 could be configured in one piece with the output shaft 7.In addition to the planet carrier 16 of the planetary gear set 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 gear set 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, by means of which the function of three shifting elements A, B and C is depicted, and in which a coupling element 26 in the form of a sliding sleeve is provided. The coupling element 26 is connected to an adjusting actuator 27, which is only schematically indicated in the present case and by means of which the coupling element 26 of the shifting device 25 can be axially displaced. In this case, the coupling element 26 can be moved axially via the actuating actuator 27 into three different switching positions, each of which is assigned an actuated state of one of the switching elements A, B and C. Between two adjacent shift positions, the coupling element 26 can also be positioned via the actuating actuator 27 in an intermediate neutral position. Accordingly, five different positions can be set successively via the adjusting actuator 27.FIG. 1 shows the shifting device 25 in a first position of the actuator 27 in which a first shifting position of the coupling element 26 is realized, which position represents the actuated state of the shifting element A. The coupling element 26 is in meshing engagement on a first coupling toothing 28 with a toothing 29 which is connected in a rotationally fixed manner to the permanently fixed component 20. On the other hand, the coupling element 26 is still almost inserted at a second clutch toothing 30 into a toothing 31 which is connected in a rotationally fixed manner to the ring gear 9 of the stepped planetary gearset P 1. As a result, in the first switching position of the coupling element 26, the ring gear 9 of the stepped planetary gearset P 1 is connected via the coupling element 26 in a rotationally fixed manner to the permanently fixed component 20 and is thus fixed.From the first shift position, the coupling element 26 can be displaced axially into a first neutral position via the actuating actuator 27 by moving to a second position via the actuating actuator 27. In this case, the coupling element 26 is guided on its clutch toothing 28 via the toothing 29 during this displacement, wherein, when the first neutral position is reached, the tooth engagement between the clutch toothing 30 and the toothing 31 is canceled. As a result, in the first neutral position, no coupling is then brought about via the coupling element 26. In addition to a return to the first switching position by setting the first position, the coupling element 26 can be moved via the actuating actuator 27 further into a second switching position which is assigned to an actuated state of the switching element B and is achieved by setting a third position of the actuating actuator 27. In this case, a displacement of the coupling element 26 from the first neutral position into the second shift position likewise takes place while guiding the coupling element 26 on its coupling toothing 28 via the toothing 29.When the second shift position is reached, the coupling element 26 then engages at its clutch toothing 30 into a toothing 32 which is connected in a rotationally fixed manner to the ring gear 10 of the stepped planetary gearset P 1. Since a tooth engagement into the toothing 29 is still carried out on the clutch toothing 28 of the coupling element 26 in the second switching position, a rotationally fixed connection of the ring gear 10 to the permanently fixed component 20 is produced via the coupling element 26 in the second switching position and the ring gear 10 is thus fixed. The coupling element 26 can be moved from the second shift position back into the first neutral position, on the one hand, wherein a displacement into a second neutral position can be realized, on the other hand, by a fourth position being set via the actuating actuator 27. When transferred into the second neutral position, the toothed engagement of the clutch toothing 28 into the toothing 29 is canceled, as a result of which the coupling element 26 is only still coupled at its clutch toothing 30 to the toothing 32 when the second neutral position is reached. This has the consequence that no coupling via the coupling element 26 is realized even in the second neutral position.From the fourth position, the third position can be approached, on the one hand, and a fifth position can be approached, on the other hand, by means of the actuator 27, wherein this takes place in each case by guiding the coupling element 26 on its coupling toothing 30 via the toothing 32. In the fifth position, the third switching position of the coupling element 26 is realized, to which an actuated state of the switching element C is assigned. In the third shift position, the coupling element 26 then engages at its clutch toothing 28 into a toothing 33, which is connected in a rotationally fixed manner to the planet carrier 16 of the planetary gear set P 2 and thus also to the output shaft 7. Because of the existing tooth engagement of the coupling element 26 on the clutch toothing 30 in the toothing 32, the ring gear 10 of the stepped planetary gearset P 1 and the planetary carrier 16 of the planetary gearset P 2 and the output shaft 7 are connected to one another in a rotationally fixed manner. From the fifth position of the adjusting actuator 27, only the fourth position and thus the second neutral position of the coupling element 26 can then be adjusted.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 stepped planetary gearset P 1 and the planetary gearset P 2, the output shaft 7, the output shafts 23 and 24, the shaft 19 and the differential gearset 22 are arranged coaxially with one another. In this case, the stepped planetary gearset P 1 is arranged axially between the electric machine 2 and the planetary gearset P 2, the differential gearset 22 being arranged axially overlapping with the stepped planetary gearset P 1. Specifically, the differential gearset 22 is located axially overlapping with and radially inward of the tooth meshing of the stepped planetary gear 12 with the ring gear 9, thereby achieving a nested arrangement of the stepped planetary gearset P 1 and the differential gearset 22. The shifting device 25 is arranged radially surrounding the stepped planetary gearset P 1 and the planetary gearset P 2, wherein the shifting device 25 is placed axially substantially covering both the stepped planetary gearset P 1 and the planetary gearset P 2. While the output shafts 23 and 24 are designed as solid shafts, the drive shaft 6, the output shaft 7 and the shaft 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, a parking lock element P is now additionally provided, in the actuated state of which the output shaft 7 is indirectly fixed. The parking lock element P is connected to the shaft 19 and thus to the planet carrier 8 of the stepped planetary gearset P 1 and is specifically designed as a positive-locking shifting element in the form of a claw shifting element. In the actuated state of the parking lock element P, the planet carrier 8 of the stepped planetary gearset P 1 is fixed on the permanently fixed component 20 via the parking lock element P, which also results in the shaft 19 and thus also the sun gear 15 of the planetary gearset P 2 being fixed. Since the ring gear 17 of the planetary gear set P 2 is permanently fixed, the fixing of the sun gear 15 also entails fixing of the planetary carrier 16 of the planetary gear set P 2 and thus of the output shaft 7. The parking lock element P is arranged axially between the electric machine 2 and the stepped planetary gearset P 1. 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 35 from FIGS. 1 and 2 in tabular form. As can be seen, a total of three gears G 1, G 2 and G 3 can be realized between the input shaft 6 and the output shaft 7, wherein in the columns of the shift pattern, X is respectively used to identify which actuated states of the shift elements A, B and C formed by the shift device 25 are to be represented in the individual gear. In each of the gears G 1 to G 3, an actuated state is to be represented in each case in one of the shift elements A, B and C.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. Finally, the third gear G 3 is shifted by representing the actuated state of the shift element C 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, wherein this is carried out in the course of the illustration of one of the two neutral positions of the shifting device 25.Finally, FIG. 4 shows a schematic view of an electric vehicle 36, which can be, in particular, an electric utility vehicle, such as a transporter. In addition to a steerable, non-driven vehicle axle 37, the electric vehicle 36 also has a motor vehicle drive axle 38 with drive wheels 39 and 40. The drive wheel 39 is connected in a rotationally fixed manner to the output shaft 23 of the drive unit 41, while the drive wheel 40 is connected in a rotationally fixed manner to the output shaft 24 of the drive unit 41.While the vehicle axle 37 is a front axle of the electric vehicle 36, the motor vehicle drive axle 38 is a rear axle of the electric vehicle 36.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 Planet carrier 9 Ring gear 10 Ring gear 11 Sun gear 12 Stepped planet gear 13 Toothing 14 Toothing 15 Sun gear 16 Planet carrier 17 Ring gear 18 Planet gear 19 Shaft 20 Fixed component 21 Input element 22 Differential gearset 23 Output shaft 24 Output shaft 25 Switching device 26 Coupling element 27 Actuator 28 Clutch toothing 29 Toothing 30 Clutch toothing 31 Toothing 32 Toothing 33 Toothing 34 Drive unit 35 Motor vehicle transmission 36 Electric vehicle 37 Vehicle axle 38 Motor vehicle drive axle 39 Drive wheel 40 Drive wheel 41 Drive unit P 1 Stepped planet gearset P 2 Planetary gearset E 11 First element Stepped planet gearset E 21 Second element Stepped planet gearset E 31 Third element Stepped planet gearset E 41 Fourth element Stepped planetary gearset E 12 First element planetary gearset E 22 Second element planetary gearset E 32 Third element planetary gearset A Shift element B Shift element C Shift element P Park lock element G 1 First gear G 2 Second gear G 3 Third gear

Claims

Motor vehicle transmission (3; 35) 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 engine, preferably at least one electric machine (2), an output shaft (7) and a stepped planetary gearset (P1) which has a first element (E11) in the form of a planet carrier (8), a second element (E21) in the form of a ring gear (9), a third element (E31) in the form of a further ring gear (10) and a fourth element (E41) in the form of a sun gear (11), wherein the planet carrier (8) of the stepped planetary gearset (P1) rotatably supports at least one stepped planetary gearset (12) which is in toothed engagement with the sun gear (11), the ring gear (9) and the further ring gear (10), respectively, wherein the fourth element (E41) of the stepped planetary gearset (P1) is connected to the drive shaft (6) 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 (E21) of the stepped planetary gearset (P1) in an actuated state, whereas the at least functionally provided second shifting element (B) fixes the third element (E31) of the stepped planetary gearset (P1) in an actuated state, characterized - in that a planetary gearset (P2) is also provided, which fixes a first element (E12), a second element (E22) and a third element (E32) in the form of a sun wheel (15), a ring gear (17) and a planet carrier (16), - the first element (E12) of the planetary gear set (P2) is connected in a rotationally fixed manner to the first element (E11) of the stepped planetary gear set (P1), - the second element (E22) of the planetary gear set (P2) is connected in a rotationally fixed manner to the output shaft, - the third element (E32) of the planetary gear set (P2) is fixed, - and a third shifting element (C) is additionally provided at least functionally, which, in an actuated state, connects the third element (E31) of the stepped planetary gear set (P1) and the second element (E22) of the planetary gear set (P2) in a rotationally fixed manner to one another, - wherein the first shifting element (A) is provided, the second shifting element (B) and the third shifting element (C) are formed by a common shifting device (25), which has a coupling element (26), wherein the coupling element (26) can be positioned in each case in a first shifting position, in a second shifting position and in a third shifting position, wherein the coupling element (26) in the first shifting position functionally depicts an actuated state of the first shifting element (A) and fixes the second element (E21) of the stepped planetary gearset (P1), wherein the coupling element (26) in the second shifting position functionally depicts an actuated state of the second shifting element (B) and fixes the third element (E31) of the stepped planetary gearset (P1), and wherein the coupling element (26) in the third shift position functionally depicts an actuated state of the third shift element (C) and connects the third element (E31) of the stepped planetary gearset (P1) and the second element (E22) of the planetary gearset (P2) to one another in a rotationally fixed manner.Motor vehicle transmission (3; 35) according to Claim 1, characterized in that the at least one stepped planet wheel (12) of the stepped planetary gearset (P1) meshes on a respective first toothing (13) with the sun wheel (11) of the stepped planetary gearset (P1) and the further ring wheel (10) of the stepped planetary gearset (P1), the at least one stepped planet wheel (12) of the stepped planetary gearset (P1) also meshing on a respective second toothing (14) with the ring wheel (9) of the stepped planetary gearset (P1).Motor vehicle transmission (3; 35) according to one of Claims 1 to 2, characterized in that the output shaft (7) is coupled to an input element (21) of a differential gearset (22) which operatively connects the output shaft (7) to two output shafts (23, 24).Motor vehicle transmission (3; 35) according to Claim 3 and according to Claim 2, characterized in that the differential gearset (22) is located axially overlapping with the ring gear (9) of the stepped planetary gearset (P1) and radially on the inside of the tooth engagement of the at least one stepped planet gear (12) of the stepped planetary gearset (P1) with the ring gear (9) of the stepped planetary gearset (P1).Motor vehicle transmission (3; 35) according to Claim 1, characterized in that, in the first shift position and in the second shift position and in the event of an axial displacement between the first shift position and the second shift position, the coupling element (26) is guided in a rotationally fixed manner on a first toothing (29), which is fixed, and additionally encloses, in the first shift position, a second toothing (31), which is connected in a rotationally fixed manner to the second element (E21) of the stepped planetary gearset (P1), whereas, in the second shift position, the coupling element (26) encloses a third toothing (32), which is connected in a rotationally fixed manner to the third element (E31) of the stepped planetary gearset (P1), and wherein the coupling element (26) is then guided on the third toothing (32) in a rotationally fixed manner during an axial displacement between the second shift position and the third shift position and in the third shift position encloses a fourth toothing (33) in the third shift position, which is connected in a rotationally fixed manner to the second element (E22) of the planetary gear set (P2).Motor vehicle transmission (3; 35) according to one of the preceding claims, characterized in that the coupling element (26) of the shifting device (25) is coupled to an actuating actuator (27), by means of which five positions can be set successively, wherein the actuating actuator (27) - positions the coupling element (26) in its first shift position in a first position, - positions the coupling element (26) in a first neutral position in a second position, - positions the coupling element (26) in its second shift position in a third position, - positions the coupling element (26) in a second neutral position in a fourth position, - and positions the coupling element (26) in its third shift position in a fifth position.Motor vehicle transmission (35) according to one of the preceding claims, characterized in that a parking lock element (P) is additionally provided, which in an actuated state fixes the output shaft (7) directly or indirectly.Motor vehicle transmission (35) according to Claim 7, characterized in that the parking lock element (P) is connected in a rotationally fixed manner to the first element (E11) of the stepped planetary gearset (P1) and, in an actuated state, connects the first element (E11) of the stepped planetary gearset (P1) in a rotationally fixed manner to a permanently fixed component (20).Drive unit (1; 34; 41) for an at least partially electrically driven motor vehicle, comprising at least one electric machine (2) and a motor vehicle transmission (3; 35) according to one or more of claims 1 to 8, 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; 35).Drive unit (1; 34; 41) according to claim 9, characterized in that the stepped planetary gearset (P1) of the motor vehicle transmission (3; 35) is placed axially between the at least one electric machine (2) and the planetary gearset (P2) of the motor vehicle transmission (3; 35).Electrically drivable motor vehicle drive axle (38) for an at least partially electrically driven motor vehicle, comprising a drive unit (1; 34; 41) according to claim 9 or 10.Hybrid or electric vehicle (36) comprising a drive unit (1; 34; 41) according to claim 9 or 10 or a motor vehicle drive axle (38) according to claim 11.Method for operating a motor vehicle transmission (3; 35) according to one or more of Claims 1 to 8, 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), - 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), - and a third gear (G3) is shifted between the drive shaft (6) and the output shaft (7) by representing an actuated state of the third shift element (C).

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