Motor vehicle transmission for a drive unit of a motor vehicle that is at least partially electrically powered

Abstract

Motor vehicle transmission (6; 23; 35; 37; 51; 56) for a drive unit (4; 22; 34; 36; 50; 55) of an at least partially electrically powered motor vehicle, comprising a drive shaft (11) which is provided for a drive-effective connection with at least one electric machine (5), an output shaft (12) and a stepped planetary gear set (10) which has a first sun gear (15), a second sun gear (14), a ring gear (17) and at least one stepped planetary gear (18) rotatably mounted on a planet carrier (16), wherein the at least one stepped planetary gear (18) is in tooth mesh with the two sun gears (14, 15) and the ring gear (17), wherein at least functionally a first switching element (A; A'), a second switching element (B; B') and a third switching element (C) are provided, of which the third switching element (C) is configured to is to fix a shaft (21) in a closed state, characterized in that - that the drive shaft (11) is connected to the ring gear (17) in a rotationally fixed manner, - that the output shaft (12) is rotationally fixed to the planet carrier (16), - that the first switching element (A; A') is configured to connect the first sun gear (15) to the shaft (21) in a rotationally fixed manner when in a closed state. - and that the second switching element (B; B') is designed to connect the second sun gear (14) to the shaft (21) in a rotationally fixed manner when in a closed state.

Description

[0001] The invention relates to a motor vehicle transmission for a drive unit of an at least partially electrically driven motor vehicle, comprising a drive shaft which is provided for a drive-effective connection to at least one electric machine, an output shaft and a stepped planetary gear set which has a first sun gear, a second sun gear, a ring gear and at least one stepped planetary gear rotatably mounted on a planet carrier, wherein the at least one stepped planetary gear is in tooth engagement with the two sun gears and the ring gear, wherein at least functionally a first shifting element, a second shifting element and a third shifting element are provided, of which the third shifting element is designed to fix a shaft in a closed state.Furthermore, the invention relates to a drive unit for an at least partially electrically driven motor vehicle, a drive axle for a hybrid or electric vehicle, an electric vehicle and a method for operating a motor vehicle transmission.

[0002] In electric and hybrid vehicles, a motor vehicle transmission is sometimes provided in the respective drivetrain between a respective electric motor and the drive wheels of the respective motor vehicle. This transmission enables the drive movement of the electric motor to be translated, particularly at low speed, to the drive wheels. In addition to single-gear transmissions, motor vehicle transmissions that can engage two or more gears are also sometimes used.

[0003] CN 1 05 972 165 A discloses a drive unit for an electric vehicle, comprising a motor vehicle transmission and an electric motor. The motor vehicle transmission has a stepped planetary gear set formed by a first sun gear, a second sun gear, a ring gear, and a planet carrier. Several stepped planetary gears are rotatably mounted in the planet carrier and mesh with the two sun gears and the ring gear, respectively. The ring gear of the stepped planetary gear set is permanently attached to a housing of the motor vehicle transmission, while the planet carrier is connected in a rotationally fixed manner to an output shaft of the motor vehicle transmission.A drive shaft of the motor vehicle transmission is non-rotatably connected to a rotor of the electric motor and can be non-rotatably connected to the first sun gear via a first shifting element and to the second sun gear via a second shifting element. The two shifting elements are designed as friction clutches and together form a double clutch.

[0004] Furthermore, DE 10 2020 211 080 A1 discloses a drive unit for an at least partially electrically powered motor vehicle, wherein the drive unit is composed of an electric motor and a motor vehicle transmission. The motor vehicle transmission is connected to the electric motor via a drive shaft and has a stepped planetary gear set, in which a first sun gear, a second sun gear, a ring gear, and at least one stepped planetary gear rotatably mounted on a planet carrier are provided. The at least one stepped planetary gear meshes with the two sun gears and the ring gear. While the first sun gear is connected to the drive shaft, the second sun gear is connected to an output shaft.Additionally, a first shifting element, a second shifting element, and a third shifting element are provided. When actuated, the first shifting element establishes a rotationally fixed connection between the ring gear and a shaft, which, when the second shifting element is actuated, is also rotationally fixed to the planet carrier. Furthermore, the third shifting element locks the shaft in a closed state.

[0005] Based on the prior art described above, it is now the object of the present invention to provide an alternative embodiment of a motor vehicle transmission for an at least partially electrically driven motor vehicle, wherein a large number of different gears should be switchable in the motor vehicle transmission.

[0006] This object is achieved based on the preamble of claim 1 in conjunction with its characterizing features. The dependent claims that follow thereon each represent advantageous developments of the invention. A drive unit in which a motor vehicle transmission according to the invention is provided is further the subject of claims 8 and 9. Furthermore, claim 10 relates to a drive axle for a hybrid or electric vehicle, while claim 11 relates to a hybrid or electric vehicle with such a drive axle. Finally, claim 12 relates to a method for operating a motor vehicle transmission according to the invention.

[0007] According to the invention, a motor vehicle transmission comprises a drive shaft provided for a drive-active connection to at least one electric motor, an output shaft, and a stepped planetary gear set comprising a first sun gear, a second sun gear, a ring gear, and at least one stepped planetary gear rotatably mounted on a planetary carrier. The at least one stepped planetary gear meshes with the two sun gears and the ring gear.

[0008] For the purposes of the invention, a "shaft" is understood to mean a rotatable component of the motor vehicle transmission, via which a power flow can be guided between components, whereby an associated, at least functionally provided, switching element may be actuated for this purpose. The respective shaft, in particular the drive shaft and / or the output shaft, can connect components axially or radially, or even both axially and radially. Thus, the respective shaft can also be present as an intermediate piece, via which only a radial connection is realized.

[0009] For the purposes of the invention, "axial" refers to an orientation along a longitudinal center axis of the motor vehicle transmission, parallel to which the rotational axes of rotatable components of the transmission, in particular the shafts of the transmission and the elements of the stepped planetary gear set, are arranged. "Radial" then refers to an orientation along the diameter direction of each component of the transmission.

[0010] In the motor vehicle transmission according to the invention, the drive shaft is provided for establishing a drive-effective coupling to at least one electric machine in order to initiate a drive movement of the at least one electric machine into the motor vehicle transmission at the drive shaft. 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 electric machine can be formed. This coupling between the at least one electric machine and the drive shaft is in the form that, in the installed state of the motor vehicle transmission, a fixed speed ratio always prevails between a speed of the drive shaft of the motor vehicle transmission and a speed of the at least one electric machine. Thus, within the scope of the invention, a fixed speed ratio can be established between the drive shaft and the at least one electric machine if necessary.At least one further gear ratio, such as a spur gear stage and / or a planetary gear stage, can be provided, via which a pre-transmission of a rotary movement of the electric motor to the drive shaft can be realized. However, the drive shaft of the motor vehicle transmission according to the invention is particularly preferably provided to establish a rotationally fixed connection to the at least one electric motor, so that the at least one electric motor and the drive shaft run at the same speed during operation. If necessary, the drive shaft and a respective rotor of the at least one electric motor can also be designed as a single piece.

[0011] In the motor vehicle transmission according to the invention, the input shaft and the output shaft are arranged coaxially to one another, with the stepped planetary gear set also preferably being positioned coaxially to the input shaft and the output shaft. This allows for a particularly compact design of the motor vehicle transmission in the radial direction.

[0012] The stepped planetary gear set of the motor vehicle transmission according to the invention is composed of the first sun gear, the second sun gear, the ring gear, and the planet carrier, with at least one stepped planetary gear being rotatably mounted in the planet carrier. The at least one stepped planetary gear meshes with the first sun gear, the second sun gear, and the ring gear. For this purpose, the at least one stepped planetary gear is equipped in particular with two different, axially adjacent toothings, with one toothing engaging with one sun gear and the ring gear, while the other toothing engages with the other sun gear. The toothings are preferably designed with different numbers of teeth on different diameters of the stepped planetary gear.

[0013] Within the scope of the invention, these different toothings can be provided on a one-piece stepped planetary gear, wherein the at least one stepped planetary gear is preferably composed of two coaxial spur gears connected to one another in a rotationally fixed manner, of which one spur gear forms one toothing and meshes with one sun gear and the ring gear, while the other spur gear forms the other toothing and meshes with the other sun gear.

[0014] The invention now encompasses the technical teaching that the drive shaft is connected in a rotationally fixed manner to the ring gear, while the output shaft is connected in a rotationally fixed manner to the planetary carrier. Furthermore, at least functionally, a first shifting element, a second shifting element, and a third shifting element are provided, of which the first shifting element is configured to connect the first sun gear to a shaft in a closed state in a rotationally fixed manner. The second shifting element is configured to connect the second sun gear to the shaft in a closed state in a rotationally fixed manner, whereas the third shifting element is configured to fix the shaft in a closed state.

[0015] In other words, in the motor vehicle transmission according to the invention, there is a permanently rotationally fixed connection between the input shaft and the ring gear of the stepped planetary gear set, so that the input shaft and the ring gear always run at the same speed. Likewise, the output shaft and the planet carrier are permanently rotationally fixed to one another, whereby the planet carrier and the output shaft also always have the same speed. At least in terms of one function, a first shifting element, a second shifting element, and a third shifting element are provided, wherein the first shifting element, in its closed state, brings about a rotationally fixed connection between the first sun gear and a shaft. An actuated state of the second shifting element results in a rotationally fixed connection of the shaft to the second sun gear, whereas the third shifting element, in its actuated state, causes the shaft to become stuck.

[0016] Such a design of a motor vehicle transmission has the advantage that at least three different gears can be shifted between the input shaft and the output shaft via the at least functionally provided three shifting elements. When the motor vehicle transmission according to the invention is used in a drive unit, these gears are accordingly also available for the integration of at least one electric motor. Due to the use of a stepped planetary gear set, a compact design of the motor vehicle transmission with a small number of components is simultaneously possible. Overall, this makes it possible to realize a compact motor vehicle transmission with a high number of shiftable gears.

[0017] Within the meaning of the invention, the individual, permanently rotationally fixed connection is preferably realized via an intermediate shaft, which can be made of one or more parts. Furthermore, within the scope of the invention, a respective configuration is also possible in which the respective shaft is constructed in one piece with one or both components connected thereto in a rotationally fixed manner, the latter being particularly realized when the permanently connected components of the transmission are arranged spatially close to one another.

[0018] The motor vehicle transmission according to the invention has, at least functionally, a first shifting element, a second shifting element, and a third shifting element, the selective actuation of which can, in particular, represent different gears between the drive shaft and the output shaft. Particularly preferably, in terms of function, exactly three shifting elements are provided in the motor vehicle transmission according to the invention, with these shifting elements more preferably then being able to engage exactly three different gears between the drive shaft and the output shaft. In principle, however, one or more further shifting elements could be provided, at least functionally, within the scope of the invention, in addition to the first shifting element, the second shifting element, and the third shifting element.

[0019] The fact that a respective shifting element is provided "at least functionally" means, within the meaning of the invention, that at least the respective function of the respective shifting element is represented in the motor vehicle transmission according to the invention. In this case, the individual shifting elements can actually be physically present as individual shifting elements, or their function can be represented by another component, such as a shifting device. A component representing the function can then combine the function of two or more shifting elements in one device. Particularly preferably, the first shifting element, the second shifting element, and the third shifting element are designed as individual shifting elements.

[0020] When actuated, the three at least functionally provided shifting elements each bring about a connection of the shaft provided in the motor vehicle transmission according to the invention. This shaft, which is in particular coaxial with the drive shaft and the output shaft, can thus be connected in a rotationally fixed manner to the first sun gear of the stepped planetary gear set via the first shifting element, connected in a rotationally fixed manner to the second sun gear of the stepped planetary gear set via the second shifting element, and fixed via the third shifting element. In this context, a common actuating device for the three at least functionally present shifting elements can be provided in the motor vehicle transmission according to the invention, such as actuation via a common shift drum.

[0021] The shaft is secured via the at least functionally provided third shifting element, in particular, by the shaft being connected in a rotationally fixed manner to a permanently secured component. The permanently secured component is preferably a transmission housing of the motor vehicle transmission, a part of the transmission housing, or a component connected thereto in a rotationally fixed manner.

[0022] During operation of the motor vehicle transmission according to the invention, a first gear is preferably engaged between the input shaft and the output shaft by engaging the first shifting element and the third shifting element, with a second gear being engaged between the input shaft and the output shaft by engaging the second shifting element and the third shifting element. Furthermore, a third gear is engaged between the input shaft and the output shaft by engaging the first shifting element and the second shifting element. Advantageously, this allows three different gears with suitable gear ratios to be engaged in the motor vehicle transmission according to the invention.When these gears are successively engaged, only the shifting state of two shifting elements needs to be changed at a time, by opening one of the shifting elements involved in the gear to be disengaged and subsequently closing another shifting element to represent the gear to be engaged. Particularly preferably, in the motor vehicle transmission according to the invention, exactly three different gears can be realized by the precisely three shifting elements that are at least functionally provided.

[0023] According to one embodiment of the invention, the individual shifting element which is at least functionally provided is designed as a positive-locking shifting element, wherein in this case an embodiment is preferably carried out as an unsynchronized claw shifting element. Designing the individual shifting element as a positive-locking shifting element has the advantage that, when the respective shifting element is open, no or only minimal drag losses occur at this shifting element. This can improve the efficiency of the motor vehicle transmission. Alternatively, one or more of the shifting elements can also be designed as positive-locking shifting elements in the form of locking synchronizers. Within the scope of the invention, two or even all three shifting elements can also be formed by a common shifting device, provided that this does not impair the representation of the gears. This can be done if necessary.a particularly compact representation of the function of the three switching elements can be presented.

[0024] Alternatively or in addition to the aforementioned embodiment, the individual, at least functionally provided, switching element is designed as a force-locking switching element, with particular consideration given to a design as a lamella switching element or as a conical switching element. This advantageously allows the respective switching element to be actuated under load.

[0025] In the sense of the invention, of the at least functionally provided three switching elements, all three can be designed as positive-locking switching elements, all three as non-positive switching elements or one or more can be designed as positive-locking switching elements and one or more as non-positive switching elements.

[0026] According to one possible embodiment of the invention, the output shaft is coupled to a differential gear set, which drive-effectively connects the output shaft to two output shafts. As a result, a drive movement translated from the input shaft to the output shaft by selective actuation of the shift elements can then be distributed between two output shafts. Within the scope of the invention, the differential gear set can be provided in a drive train of a motor vehicle for transverse distribution to drive wheels of a drive axle, with the differential gear set then acting as a transverse differential and preferably providing an even distribution. Alternatively, it is also conceivable within the scope of the invention for the differential gear set to be used to longitudinally distribute the movement to several drive axles in a drive train of a motor vehicle.The differential gear set serves as a longitudinal differential, whereby an even or even an uneven distribution would also be conceivable.

[0027] In a further development of the aforementioned design option, the output shaft and the differential gear set are coupled via at least one gear ratio. This at least one gear ratio can provide an additional, fixed gear ratio between the output shaft and the differential gear set, thus potentially increasing the overall gear ratio of the motor vehicle transmission.

[0028] In one variant of the invention, each of the at least one gear ratio stage is designed as a spur gear stage composed of two meshing spur gears, one spur gear being coupled to the output shaft and the other spur gear being coupled to the differential gear set. If a single spur gear stage is provided between the output shaft and the differential gear set, one spur gear is provided in particular in a rotationally fixed manner on the output shaft, while the other spur gear meshing with the one spur gear is rotationally fixedly connected to an input element of the differential gear set, preferably a differential carrier. In this case, the output shaft and the differential gear set are then arranged with their axially offset from one another.

[0029] Alternatively, two spur gear stages can be provided between the output shaft and the differential gear set, with one spur gear of one spur gear stage being non-rotatably connected to the output shaft, while the spur gear of one spur gear stage meshing with this spur gear is non-rotatably connected to a spur gear of the other spur gear stage, preferably via an intermediate shaft. The other spur gear meshing with the one spur gear of the other spur gear stage is then non-rotatably connected to an input element of the differential gear set, preferably a differential carrier. This advantageously allows a two-stage coupling between the output shaft and the differential gear set to be realized.

[0030] Alternatively or in addition to the aforementioned variant, the at least one gear ratio is designed as a planetary stage, each comprising a first element, a second element, and a third element in the form of a sun gear, a planet carrier, and a ring gear, wherein the first element is coupled to the output shaft, the second element is coupled to the differential gear set, and the third element is fixed. This also makes it possible to represent a fixed gear ratio between the output shaft and the differential gear set. In particular, the first element of the planetary stage is connected in a rotationally fixed manner to the output shaft, and the second element is connected in a rotationally fixed manner to an input element of the differential gear set, preferably a differential carrier.

[0031] Preferably, at least one planetary gear is rotatably mounted in the planet carrier of each planetary stage, which planetary gear meshes with both the radially inner sun gear and the radially surrounding ring gear. In this case, each planetary stage is therefore designed as a minus planetary stage, with the first element preferably being the sun gear, the second element preferably being the planet carrier, and the third element preferably being the ring gear. Alternatively, each planetary stage could also be designed as a plus planetary stage, with at least one pair of planetary gears being rotatably mounted in the planet carrier, with one planetary gear meshing with the sun gear and one planetary gear meshing with the ring gear, and the planetary gears meshing with one another.In this variant, the first element would preferably be the sun gear, the second element the ring gear and the third element the planet carrier.

[0032] One embodiment of the invention provides that the differential gear set is designed as a bevel gear differential. In a manner known in principle to those skilled in the art, the differential gear set comprises two bevel gears, each of which is arranged in a rotationally fixed manner on one of the output shafts and meshes with at least one compensating element. The at least one compensating element is preferably also in the form of a bevel gear, which is rotatably mounted in a differential carrier of the bevel gear differential, wherein the differential carrier forms an input element of the differential gear set and is coupled to the output shaft. Alternatively, other designs of the differential gear set are also conceivable within the meaning of the invention, for example as a spur gear differential or planetary differential.

[0033] Alternatively, the differential gear set is formed by a first planetary gear set and a second planetary gear set, each comprising a sun gear, a ring gear, and a planet carrier each rotatably supporting at least one planetary gear. The sun gear of the first planetary gear set is coupled to the output shaft, and the planet carrier of the first planetary gear set is coupled to the first output shaft, whereas the ring gear of the first planetary gear set and the sun gear of the second planetary gear set are connected to one another in a rotationally fixed manner. Furthermore, the planet carrier of the second planetary gear set is fixed, and the ring gear of the second planetary gear set is coupled to the second output shaft. Using such a differential gear set, the drive torque introduced into the differential gear set can be split equally between the output shafts as output torque.In the differential gearset, the sum of both output torques is not applied to any component. Furthermore, at identical output shaft speeds, the differential gearset has no gears rotating in a single unit or rotating without rolling motion. In other words, regardless of the output shaft speeds, there is always a relative movement between the meshing components of the differential gearset. At the same time, the differential gearset performs the function of generating the overall gear ratio and the differential function. In other words, a differential gearset designed in this way increases torque and distributes drive power. This is possible while saving weight.

[0034] In the aforementioned differential gear set, the first planetary gear set and the second planetary gear set are preferably arranged axially at the same height, with the first planetary gear set being positioned radially inward of the second planetary gear set. Alternatively or additionally, the aforementioned differential gear set is arranged, in particular, coaxially with the output shaft and the two output shafts, and more preferably also with the input shaft and the stepped planetary gear set.

[0035] The invention also relates to a drive unit which is intended in particular for use in a drive train of an at least partially electrically powered motor vehicle. This drive unit comprises at least one electric machine and a motor vehicle transmission which is designed 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 particular, exactly one electric machine is connected to the drive shaft of the motor vehicle transmission, although a rotationally fixed connection with several electric machines is also conceivable. In the latter case, decoupling of the individual electric machine via an intermediate separating clutch could also be conceivable.

[0036] The at least one electric machine comprises a stator in addition to the rotor and can be operated in particular as an electric motor and as a generator.

[0037] In a further development of the invention, the stepped planetary gear set and / or the differential gear set of the motor vehicle transmission is arranged at least partially or completely spatially within the respective rotor of the at least one electric motor. This allows for a compact design of the drive unit.

[0038] A drive unit designed according to one or more of the aforementioned variants is, in particular, part of a vehicle drive train, which is provided for a hybrid or electric vehicle. The drive unit is preferably part of a drive axle, wherein the output shaft of the motor vehicle transmission is coupled to output shafts of the drive axle. This advantageously makes it possible to achieve a compact design of a drive axle with the drive unit, wherein the coupling between the output shaft of the motor vehicle transmission of the drive unit and the output shafts of the drive axle is implemented, in particular, via a differential gear set of the motor vehicle transmission. Furthermore, the drive unit is arranged, in particular, above the drive axle.

[0039] Within the scope of the invention, at least one aforementioned drive unit is preferably provided in a hybrid or electric vehicle, which is in particular a commercial vehicle. In this case, the commercial vehicle can in particular be an at least partially electrically powered van.

[0040] For the purposes of the invention, the fact that two components of the motor vehicle transmission are "connected" or "coupled" or "connected to one another" in a rotationally fixed manner means a permanent coupling of these components, so that they cannot rotate independently of one another. Therefore, no shifting element is provided between these components, which can be components of the stepped planetary gear set and / or shafts and / or a rotationally fixed component of the transmission. Instead, the corresponding components are coupled to one another at a fixed speed ratio.

[0041] If, on the other hand, a switching element is provided at least functionally between two components, these components are not permanently coupled to one another in a rotationally fixed manner, but a rotationally fixed coupling is only established by actuating the at least functionally intermediate switching element. Actuation of the switching element within the meaning of the invention means that the switching element in question is transferred to a closed state and subsequently aligns the rotational movements of the components directly coupled to it. If the switching element in question is designed as a form-fitting switching element, the components directly connected to one another in a rotationally fixed manner will run at the same speed, whereas in the case of a force-fitting switching element, speed differences can exist between the components even after the switching element has been actuated.This intended or unwanted state is nevertheless referred to in the context of the invention as a rotationally fixed connection of the respective components via the switching element.

[0042] The invention is not limited to the specified combination of features of the main claim or the dependent claims. Furthermore, possibilities arise for combining individual features with one another, even if they emerge from the claims, the following description of preferred embodiments of the invention, or directly from the drawings. The reference of the claims to the drawings by the use of reference symbols is not intended to limit the scope of protection of the claims.

[0043] Advantageous embodiments of the invention, which are explained below, are illustrated in the drawings. It shows: Fig. 1 is a schematic representation of an electric vehicle according to a preferred embodiment of the invention, Fig. 2 to 7 each show a schematic view of a drive unit according to an embodiment of the invention; and Fig. 8 an exemplary circuit diagram of motor vehicle transmissions of the drive units from the Fig. 2 to 7.

[0044] Fig. Figure 1 shows a schematic view of an electric vehicle 1, which may be an electric commercial vehicle, such as a van. In addition to a steerable, non-driven vehicle axle 2, the electric vehicle 1 also has a drive axle 3, which houses a drive unit 4. While the vehicle axle 2 is a front axle of the electric vehicle 1, the drive axle 3 is a rear axle of the electric vehicle 1. However, as an alternative or in addition to the drive axle 3, the vehicle axle 2 could also be designed as a driven axle.

[0045] Out of Fig. Figure 2 shows a schematic representation of the drive unit 4 designed according to a first embodiment of the invention, which in this case is composed of an electric machine 5 and a motor vehicle transmission 6. The electric machine 5 has a stator 7 and a rotor 8, of which the stator 7 is permanently fixed to a rotationally fixed component 9. The rotationally fixed component 9 can be a transmission housing in which the electric machine 5 and the motor vehicle transmission 6 are jointly accommodated to form the drive unit 4. In this case, the electric machine 5 in the drive unit 4 can be operated on the one hand as an electric motor for driving the drive axle 3 and on the other hand as a generator for braking the drive axle 3.

[0046] The motor vehicle transmission 6 is designed in accordance with a first embodiment of the invention and comprises a stepped planetary gear set 10, a drive shaft 11 designed as a hollow shaft, an output shaft 12 and a - in Fig. 2 only schematically shown - differential gear set 13. The stepped planetary gear set 10 is composed of two sun gears 14 and 15, a planet carrier 16 and a ring gear 17, wherein a plurality of stepped planetary gears 18 are rotatably mounted in the planet carrier 16. In this case, the individual stepped planetary gear 18 is formed by two spur gears 19 and 20 each, which have different diameters and different numbers of teeth and are connected to one another coaxially in a rotationally fixed manner. In the case of the individual stepped planetary gear 18, a tooth engagement with the sun gear 14 and the ring gear 17 is established at the respective toothing of the respective spur gear 19, while a tooth engagement with the sun gear 15 is established at the toothing of the respective spur gear 20.

[0047] Within the drive unit 4, the drive shaft 11 is connected in a rotationally fixed manner to the rotor 8 of the electric machine 5, so that the ring gear 17 is also constantly connected in a rotationally fixed manner to the rotor 8 of the electric machine 5. The rotor 8 and the drive shaft 11 and / or the drive shaft 11 and the ring gear 17 can optionally be formed as a single piece. The planet carrier 16 of the stepped planetary gear set 10 is connected in a rotationally fixed manner to the output shaft 12, via which the planet carrier 16 is connected to the differential gear set 13. The latter is preferably designed as a bevel gear differential, with a rotationally fixed connection to a differential carrier of the differential gear set 13 being established via the output shaft 12. Alternatively, the differential gear set 13 could also be designed as a planetary differential or a spur gear differential.The differential gear set 13 distributes the drive power to output shafts of the drive axle 3 (not shown here).

[0048] As in Fig. 2, the sun gear 15 can be connected in a rotationally fixed manner to a shaft 21 designed as a hollow shaft via a switching element A, wherein this shaft 21 can also be connected in a rotationally fixed manner to the sun gear 14 via a switching element B and can be fixed to the rotationally fixed component 9 by means of a switching element C.

[0049] The shifting elements A, B, and C are designed as force-locking shifting elements, with the individual shifting elements A, B, and C preferably being designed as multi-disk shifting elements. A coupling of the shaft 21 is effected individually via the shifting elements A, B, and C. When actuated, the shifting elements A and B act as clutches, each ensuring a rotationally fixed connection of the shaft 21 to the respective sun gear 15 or 14, while the shifting element C acts as a brake, locking the shaft 21 to the rotationally fixed component 9.

[0050] In the drive unit 4, the electric machine 5, the stepped planetary gear set 10, the drive shaft 11, the output shaft 12, the differential gear set 13, the shaft 21 and the shift elements A to C are arranged coaxially with one another. The stepped planetary gear set 10 is positioned axially at the level of the electric machine 5 and radially inward of it, with the drive shaft 11 correspondingly also running essentially axially at the level of the electric machine 5 and radially inward of the electric machine 5. Axially following the stepped planetary gear set 10 are the shift elements A and B, which are axially directly adjacent to one another and are positioned radially at essentially the same level and also radially inward of the electric machine 5. The shift element A is arranged axially so as to partially overlap the electric machine 5.Radially surrounding the shift elements A and B and essentially radially at the level of the electric machine 5 is the shift element C, which axially also overlaps with the shift element B. Due to this arrangement of the shift elements A, B, and C, a nested structure can be realized, which, in combination with the placement of the stepped planetary gear set 10 within the electric machine 5, enables a compact design of the drive unit 4. The differential gear set 13 is provided axially following the shift elements A, B, and C, lying next to the electric machine 5.

[0051] Fig. Figure 3 shows a schematic view of a drive unit 22, which is designed according to a further embodiment of the invention and is also arranged on the drive axle 3 in Fig. 1 can be applied. This embodiment essentially corresponds to the previous variant according to Fig. 2, in contrast to this, in a motor vehicle transmission 23 of the drive unit 22, the output shaft 12 is now not directly connected to the differential gear set 13, but the output shaft 12 is coupled to the differential gear set 13 via an intermediate gear ratio in the form of a planetary stage 24.

[0052] This planetary stage 24 has a first element 25, a second element 26, and a third element 27. Of these elements 25 to 27, the first element 25 is formed by a sun gear of the planetary stage 24, while the second element 26 is designed as a planet carrier, and the third element 27 is designed as a ring gear. Several planetary gears are rotatably mounted in the planet carrier, each of which meshes with both the sun gear and the ring gear. In this respect, the planetary stage 24 is designed as a minus planetary stage.

[0053] The first element 25 of the planetary stage 24 and thus its sun gear is non-rotatably connected to the output shaft 12, so that the output shaft 12 in this case establishes a non-rotatable connection between the first element 25 of the planetary stage 24 and the planet carrier 16 of the stepped planetary gear set 10. In contrast, the third element 27 of the planetary stage 24 is permanently fixed to the non-rotatable component, while the second element 26 of the planetary stage 24 is non-rotatably connected to a differential carrier 28 of the differential gear set 13, which is designed as a bevel gear differential.

[0054] In the differential gear set 13, several compensating elements 29 in the form of bevel gears are rotatably mounted in the differential carrier 28, with each compensating element 29 meshing with bevel gears 30 and 31, each of which is arranged in a rotationally fixed manner on an output shaft 32 and 33, respectively. When the drive unit 22 is installed, the output shafts 32 and 33 each establish a rotationally fixed connection to a drive wheel of the drive axle 3.

[0055] Another difference compared to the embodiment according to Fig. 2, in the drive unit 22, the differential gear set 13 is placed axially at the level and radially inside of the electric motor 5, with the stepped planetary gear set 10, then the switching elements A, B and C and finally the planetary stage 24 following axially on the electric motor 5. Otherwise, the embodiment according to Fig. 3 of the variant Fig. 2, so that reference is made to what has been described therein.

[0056] Furthermore, Fig. 4 shows a schematic view of a drive unit 34 which is designed according to a further possible embodiment of the invention and which essentially corresponds to the preceding variant Fig. 3. What is different here is that now in a motor vehicle transmission 35 of the drive unit 34 the stepped planetary gear set 10, as in the variant according to Fig. 2, is arranged axially at the level and radially inward of the electric machine 5. Axially, the nested structure formed by the electric machine 5 and the stepped planetary gear set 10 is followed first by the switching elements A, B and C, then the planetary stage 24 and finally the differential gear set 13. Otherwise, the design option according to Fig. 4 of the variant Fig. 3, so that reference is made to what has been described in this regard.

[0057] Fig. 5 shows a schematic representation of a drive unit 36 ​​according to a further embodiment of the invention, wherein this drive unit 36 ​​is also arranged at the drive axle 3 in Fig. 1 can be used. The drive unit 36 ​​essentially corresponds to the variant according to Fig. 2, with the difference that in a motor vehicle transmission 37 of the drive unit 36, a shifting element A', upon actuation of which the sun gear 15 of the stepped planetary gear set 10 is connected in a rotationally fixed manner to the shaft 21, is now designed as a positive-locking shifting element. Specifically, the shifting element A' is in the form of an unsynchronized claw clutch. In addition, a shifting element B' is also designed as a positive-locking shifting element, in the actuated state of which the sun gear 14 of the stepped planetary gear set 10 is connected in a rotationally fixed manner to the shaft 21. The shifting element B' is also designed in particular as an unsynchronized claw clutch.

[0058] As a further difference, the output shaft 12 of the motor vehicle transmission 37 establishes a rotationally fixed connection of the planet carrier 16 to a differential gear set 38, which distributes the power to the output shafts 32 and 33. The differential gear set 38 is formed by a first planetary gear set 39 and a second planetary gear set 40, each of which is composed of a sun gear 41 or 42, a planet carrier 43 or 44, and a ring gear 45 or 46. In the respective planet carrier 43 or 44, a plurality of planet gears 47 or 48 are rotatably mounted, wherein the individual planet gear 47 or 48 in the respective planetary gear set 39 or 40 is in meshing engagement with both the associated sun gear 41 or 42 and the associated ring gear 45 or 46. In this respect, the two planetary gear sets 39 and 40 are designed as minus planetary gear sets.

[0059] The sun gear 41 of the planetary gear set 39 is rotationally fixed to the output shaft 12 and thus also rotationally fixed to the planet carrier 16 of the stepped planetary gear set 10. Furthermore, the planet carrier 43 of the planetary gear set 39 is rotationally fixed to the output shaft 32, while the ring gear 45 of the planetary gear set 39 and the sun gear 42 of the planetary gear set 40 are permanently rotationally fixed to one another. The ring gear 45 and the sun gear 42 can optionally be formed integrally and optionally also integrally with an associated coupling shaft 49. Furthermore, the planet carrier 44 of the planetary gear set 40 is permanently fixed to the rotationally fixed component 9, whereas the ring gear 46 of the planetary gear set 40 is rotationally fixed to the output shaft 33.

[0060] The design differs from the axial arrangement of the components according to Fig. 5 compared to the variant according to Fig. 2 also in that the switching element A' and also the switching element C together with the stepped planetary gear set 10 are placed axially at the same height as well as radially inward of the electric machine 5. Axially following this are the switching element B' and finally the differential gear set 38, in which the planetary gear sets 39 and 40 are arranged axially essentially in one plane and the planetary gear set 39 is provided radially inward of the planetary gear set 40. Otherwise, the embodiment according to Fig. 5 of the variant Fig. 2, so that reference is made to what has been described therein.

[0061] Out of Fig. 6 shows a schematic representation of a drive unit 50 which is designed according to a further embodiment of the invention and is also arranged on the drive axle 3 in Fig. 1 can be used. This drive unit 50 largely corresponds to the drive unit 4 from Fig. 2. However, as with the previous variant, the difference is Fig. 5, in a motor vehicle transmission 51 of the drive unit 50, a shifting element A' is designed as a positive-locking shifting element, upon actuation of which the sun gear 15 of the stepped planetary gear set 10 is connected in a rotationally fixed manner to the shaft 21. In this case, the shifting element A' is present as an unsynchronized claw clutch. Furthermore, a shifting element B' is also designed as a positive-locking shifting element, in the actuated state of which the sun gear 14 of the stepped planetary gear set 10 is connected in a rotationally fixed manner to the shaft 21. The shifting element B' is also designed in particular as an unsynchronized claw clutch.

[0062] As a further difference, the output shaft 12 is now not directly connected to the differential gear set 13, but rather coupled via an intermediate gear stage in the form of a spur gear stage 52. This spur gear stage 52 consists of a spur gear 53 and a spur gear 54, which are permanently meshed with each other. The spur gear 53 is arranged in a rotationally fixed manner on the output shaft 12, while the spur gear 54 is permanently connected in a rotationally fixed manner to a differential carrier 28 of the differential gear set 13. As with the variant according to Fig. 3, compensating elements 29 in the form of bevel gears are rotatably mounted in the differential carrier 28, which mesh with bevel gears 30 and 31, respectively. Bevel gear 30 is non-rotatably mounted on the output shaft 32, and bevel gear 31 is non-rotatably mounted on the output shaft 33.

[0063] As a result of the coupling of the output shaft 12 with the differential gear set 13 via the spur gear stage 52, the differential gear set 13 and the two output shafts 32 and 33 are now arranged axially offset from the electric motor 5 and the stepped planetary gear set 10. Again, in addition to the stepped planetary gear set 10, the shifting element A' is also placed axially at the same height as and radially inside the electric motor 5, followed axially by the shifting element C, then the shifting element B', and finally, essentially in one plane, the spur gear stage 52 and the differential gear set 13. Otherwise, the design option according to Fig. 6 of the variant Fig. 2, so that reference is made to what has been described therein.

[0064] Fig. Fig. 7 shows a schematic view of a drive unit 55 which is designed according to a further embodiment of the invention and alternatively to the drive unit 4 of Fig. 2 at the drive axle 3 in Fig. 1 can be used. This drive unit 55 largely corresponds to the previous variant according to Fig. 6, with the difference that in a motor vehicle transmission 56 of the drive unit 55, a shifting element B is now designed as a non-positive shifting element in the form of a multi-plate clutch, which, when actuated, connects the sun gear 14 to the shaft 21 in a rotationally fixed manner. As a further difference, the coupling of the output shaft 12 to the differential gear set 13 is now carried out via two spur gear stages 57 and 58, each of which consists of two permanently meshing spur gears 59 and 60 or 61 and 62.

[0065] In the spur gear stage 57, the spur gear 59 is arranged in a rotationally fixed manner on the output shaft 12 and is thus permanently connected in a rotationally fixed manner to the planet carrier 16 of the stepped planetary gear set 10, while the spur gear 60 is arranged in a rotationally fixed manner on an intermediate shaft 63. In addition to the spur gear 60, the spur gear 61 of the spur gear stage 58 is also arranged in a rotationally fixed manner on this intermediate shaft 63, whereby the spur gear 62, which meshes with the spur gear 61, is then connected in a rotationally fixed manner to the differential carrier 28 of the differential gear set 13.

[0066] In this respect, the variant according to Fig. 7, a 2-stage coupling of the output shaft 12 with the differential gear set 13 is made. In terms of the arrangement of the components, the drive unit 55 differs from the previous variant according to Fig. 6 in that the switching element B is provided axially between the switching element A' and the switching element C. The two spur gear stages 57 and 58 are arranged essentially in one plane with the differential gear set 13. Otherwise, the embodiment according to Fig. 7 of the variant Fig. 6, so that reference is made to what has been described in this regard.

[0067] Finally, Fig. 8 an exemplary shift diagram of the motor vehicle transmissions 6, 23, 35, 37, 51 and 56 from the Fig. 2 to 7. It can be seen that in the motor vehicle transmissions 6, 23, 35, 37, 51 and 56, a first gear G1, a second gear G2 and a third gear G3 can be engaged, whereby in the table Fig. 8 is marked with an X, which of the switching elements A or A', B or B' and C is to be operated.

[0068] First gear G1 is achieved between input shaft 11 and output shaft 12 by engaging shift elements A or A' and C, respectively, so that sun gear 15 of stepped planetary gear set 10 is locked, while sun gear 16 can rotate freely. Starting from first gear G1, shifting into second gear G2 is possible by opening shift element A or A' and actuating shift element B or B'. As a result, shift element B or B' and shift element C are engaged in second gear G2, locking sun gear 14 of stepped planetary gear set 10 and allowing free rotation of sun gear 15.

[0069] A shift from second gear G2 to third gear G3 is then accomplished by opening shift element C and actuating shift element A or A'. By thus simultaneously actuating shift elements A or A' and B or B' in gear G3, the two sun gears 14 and 15 of the stepped planetary gear set 10 are connected to one another in a rotationally fixed manner.

[0070] By means of the inventive design of a motor vehicle transmission, three different gears for integrating an electric machine can be realized in an advantageous and compact manner. Reference symbol 1 electric vehicle 2 vehicle axles 3 drive axle 4 Drive unit 5 Electric machine 6 Automotive transmissions 7 Stator 8 Rotor 9 non-rotatable component 10 stepped planetary gear set 11 Drive shaft 12 Output shaft 13 Differential gear set 14 Sun gear 15 Sun gear 16 planet carriers 17 Ring gear 18 stepped planetary gears 19 Spur gear 20 spur gear 21 Wave 22 Drive unit 23 Automotive transmissions 24 planetary stage 25 first element 26 second element 27 third element 28 Differential cage 29 compensation elements 30 bevel gear 31 Bevel gear 32 Output shaft 33 Output shaft 34 Drive unit 35 automotive transmissions 36 drive unit 37 automotive transmissions 38 Differential gear set 39 Planetary gear set 40 planetary gear set 41 Sun gear 42 Sun gear 43 planet carrier 44 planet carriers 45 ring gear 46 ring gear 47 planetary gears 48 planetary gears 49 Coupling shaft 50 drive unit 51 automotive transmissions 52 spur gear stage 53 Spur gear 54 Spur gear 55 drive unit 56 automotive transmissions 57 Spur gear stage 58 spur gear stage 59 Spur gear 60 spur gear 61 Spur gear 62 spur gear 63 Intermediate shaft A, A' switching element B, B' switching element C switching element

Claims

[1] Motor vehicle transmission (6; 23; 35; 37; 51; 56) for a drive unit (4; 22; 34; 36; 50; 55) of an at least partially electrically driven motor vehicle, comprising a drive shaft (11) which is provided for a drive-effective connection with at least one electric machine (5), an output shaft (12) and a stepped planetary gear set (10) which has a first sun gear (15), a second sun gear (14), a ring gear (17) and at least one stepped planetary gear (18) rotatably mounted on a planet carrier (16), wherein the at least one stepped planetary gear (18) is in meshing engagement with the two sun gears (14, 15) and the ring gear (17), wherein at least functionally a first shifting element (A; A'), a second shifting element (B; B') and a third shifting element (C) are provided, of which the third shifting element (C) is designed to fix a shaft (21) in a closed state, characterized by , - that the drive shaft (11) is connected to the ring gear (17) in a rotationally fixed manner, - that the output shaft (12) is connected to the planet carrier (16) in a rotationally fixed manner, - that the first switching element (A; A') is designed to connect the first sun gear (15) to the shaft (21) in a closed state in a rotationally fixed manner. - and that the second switching element (B; B') is designed to connect the second sun gear (14) to the shaft (21) in a closed state in a rotationally fixed manner. [2] Motor vehicle transmission (6; 23; 35; 37; 51; 56) according to claim 1, characterized by that the output shaft (12) is coupled to a differential gear set (13; 38) which connects the output shaft (12) in a driving manner to two output shafts (32, 33). [3] Motor vehicle transmission (23; 35; 51; 56) according to claim 2, characterized by that the output shaft (12) and the differential gear set (13) are coupled via at least one gear ratio. [4] Motor vehicle transmission (51; 56) according to claim 3, characterized by that the at least one transmission stage is designed as a spur gear stage (52; 57, 58) which is composed of two spur gears (53, 54; 59, 60, 61, 62) which are in meshing engagement with one another, wherein one spur gear (53; 59; 61) is coupled to the output shaft (12) and the other spur gear (54; 60; 62) is coupled to the differential gear set (13). [5] Motor vehicle transmission (23; 35) according to claim 3 or 4, characterized by that the at least one transmission stage is designed as a planetary stage (24) which has a first element (25), a second element (26) and a third element (27) in the form of a sun gear, a planet carrier and a ring gear, wherein the first element (25) is coupled to the output shaft (12), the second element (26) is coupled to the differential gear set (13) and the third element (27) is fixed. [6] Motor vehicle transmission (23; 35; 51; 56) according to one of claims 2 to 5, characterized by that the differential gear set (13) is designed as a bevel gear differential. [7] Motor vehicle transmission (37) according to one of claims 2 to 5, characterized bythat the differential gear set (38) is formed by a first planetary gear set (39) and a second planetary gear set (40), which are each composed of a sun gear (41, 42), a ring gear (45, 46) and a planet carrier (43, 44) rotatably supporting at least one planetary gear (47, 48), wherein the sun gear (41) of the first planetary gear set (39) is coupled to the output shaft (12) and the planet carrier (43) of the first planetary gear set (39) is coupled to the first output shaft (32), whereas the ring gear (45) of the first planetary gear set (39) and the sun gear (42) of the second planetary gear set (40) are connected to one another in a rotationally fixed manner, and wherein the planet carrier (44) of the second planetary gear set (40) is fixed and the ring gear (46) of the second planetary gear set (40) is connected to the second Output shaft (33) is coupled. [8] Drive unit (4; 22; 34; 36; 50; 55) for an at least partially electrically driven motor vehicle, comprising at least one electric machine (5) and a motor vehicle transmission (6; 23; 35; 37; 51; 56) according to one or more of claims 1 to 7, wherein a respective rotor (8) of the at least one electric machine (5) is coupled to the drive shaft (11) of the motor vehicle transmission (6; 23; 35; 37; 51; 56). [9] Drive unit (4; 22; 34; 36; 50; 55) according to claim 8, characterized by that the stepped planetary gear set (10) and / or the differential gear set (13) of the motor vehicle transmission (6; 23; 35; 37; 51; 56) is arranged at least partially or completely spatially within the respective rotor (8) of the at least one electric machine (5). [10] Drive axle (3) for a hybrid or electric vehicle, comprising a drive unit (4; 22; 34; 36; 50; 55) according to claim 8 or 9. [11] Hybrid or electric vehicle (1) comprising at least one drive unit (4; 22; 34; 36; 50; 55) according to claim 8 or 9. [12] Method for operating a motor vehicle transmission (6; 23; 35; 37; 51; 56) according to one or more of claims 1 to 7, wherein - a first gear (G1) between the drive shaft (11) and the output shaft (12) by closing the first switching element (A; A') and the third switching element (C), - a second gear (G2) between the drive shaft (11) and the output shaft (12) by closing the second switching element (B; B') and the third switching element (C), and - a third gear (G3) is engaged between the drive shaft (11) and the output shaft (12) by closing the first shifting element (A; A') and the second shifting element (B; B').

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