Spur gear differential with two differential gears designed as stepped planetary gears

Abstract

Transmission device (10) for a motor vehicle, with a spur gear differential (12), which has: - a first sun gear (14) which is designed as a first output of the spur gear differential (12) and as a first spur gear and has a first pitch circle diameter; - a second sun gear (16) arranged coaxially with the first sun gear (14), which is designed as a second output of the spur gear differential (12) and as a second spur gear and has a second pitch circle diameter different from the first pitch circle diameter; and - at least one planetary gear set (26) by means of which the sun gears (14, 16) are coupled to one another in such a way that the sun gears (14, 16) are rotatable in opposite directions, the planetary gear set (26) comprising: ◯ a planet carrier (28); ◯ at least one first differential planetary gear (30) which engages with the first sun gear (14), has a third pitch circle diameter and is held on the planetary carrier (28) so as to be rotatable about a first planetary axis of rotation (32) relative to the planetary carrier (28); ◯ at least one second differential planetary gear (36) which engages with the second sun gear (16) and is held on the planetary carrier (28) so as to be rotatable about a second planetary axis of rotation (40) running parallel to the first planetary axis of rotation (32) and spaced apart from the first planetary axis of rotation (32) relative to the planetary carrier (28); and ◯ at least one coupling planetary gear (44) arranged coaxially to the first differential planetary gear (30), connected in a rotationally fixed manner to the first differential planetary gear (30) and engaging in the second differential planetary gear (36) and thereby coupling the differential planetary gears (30, 36) to one another, which coupling planetary gear (44) has a fourth pitch circle diameter different from the third pitch circle diameter and forms, with the first differential planetary gear (30), a differential stage planetary gear (46) which is held on the planetary carrier (28) so as to be rotatable about the first planetary axis of rotation (32) relative to the planetary carrier (28) and has the first differential planetary gear (30) as the first stage planetary gear and the coupling planetary gear (44) as the second stage planetary gear; where a first ratio between the first pitch circle diameter and the second pitch circle diameter and a second ratio between the third pitch circle diameter and the fourth pitch circle diameter are equal, and where the transmission device (10) comprises a planetary gear (62) which comprises: ◯ at least one stepped planetary gear (64) provided in addition to the differential step planetary gear (46) and rotatably held on the planet carrier (28), which has a first planetary gear (66) as the third step planet and a second planetary gear (68) as the fourth step planet, which is connected in a rotationally fixed manner to the third step planet, ◯ a third sun gear (70) provided in addition to the first sun gear (14) and in addition to the second sun gear (16) as a drive sun gear, with which one of the planet gears (66, 68) is in engagement; and ◯ a ring gear (72) which is or can be connected in a rotationally fixed manner to a housing (18) of the transmission device (10), with which the other planet gear (68, 66) of the stepped planet gear (64) is in engagement, wherein ◯ the second differential planetary gear (36) is connected in a direction (76) running in the axial direction of the second differential planetary gear (36) to the ring gear (72), to which one planetary gear (66) and to the other planetary gear (68) of the planetary gear train (62) are connected, the ring gear (72) and the other planetary gear (68) of which are connected in the direction (76) to the one planetary gear (66) of the planetary gear train (62), as a result of which the ring gear (72) and the other planetary gear (68) are arranged between the second differential planetary gear (36) of the spur gear differential (12) and the one planetary gear (66) of the planetary gear train (62) as viewed in the axial direction of the second differential planetary gear (36).

Description

The invention relates to a transmission device for a motor vehicle according to the preamble of claim 1.In US 2016 / 0 252 171 A1, a drive module is disclosed that comprises an electric motor, an input pinion driven by the electric motor, a transmission driven by the input pinion, a planetary differential assembly, and a first and a second axle shaft.DE 10 2004 01 5 278 A1 discloses a differential gear, in particular for motor vehicles of the Go-Cart type, in which, for driving two coaxial rotatable shafts, the gear housing of the differential gear, which is in turn coaxial with the shafts, is driven in rotation via a toothed belt. The differential includes two spur gear paths.DE 811 650 B describes a spur-gear differential gear whose differential shaft spur gears are arranged next to one another with the smallest spacing and, like their planetary gears, are designed with correspondingly identical numbers of teeth, but different tooth modules, the smaller differential shaft spur gear being in engagement with the smaller planetary gears by an intermediate gear, and the immediately adjacent planetary gears designed with different modules each forming an entire double gear.In EP 3 181 950 A1, a planetary gear differential with parallel axes is disclosed, which comprises a first sun gear coupled to a first output drive shaft and a second sun gear with a diameter that is larger than the diameter of the first sun gear, wherein the second sun gear is coupled to a second output drive shaft.WO 2020 / 187 868 A1 describes a spur gear differential having a drive wheel and having at least two output shafts for driving a vehicle, wherein the drive wheel is designed as a planetary gear carrier.DE 10 2014 203 522 A1 discloses a spur gear differential gear mechanism as known. Furthermore, DE 10 2015 214 035 B4 discloses an electronic drive unit for a motor vehicle. Furthermore, DE 10 2018 128 836 B3 discloses a transmission device for a motor vehicle.It is the object of the present invention to provide a transmission device for a motor vehicle and a motor vehicle having such a transmission device, so that a particularly compact and weight-saving design and a particularly high torque density of the transmission device can be realized.This object is achieved by a transmission device having the features of claim 1. Advantageous embodiments with expedient developments of the invention are specified in the other claims.A first aspect of the invention relates to a transmission device for a motor vehicle, also referred to simply as a vehicle, which is preferably designed as a motor vehicle, in particular as a passenger vehicle. This means that the motor vehicle has the transmission device in its completely produced state and can be driven via the transmission device, in particular by means of a drive motor of the motor vehicle. In particular, vehicle wheels of the motor vehicle, which are also referred to simply as wheels, in particular the same vehicle axle of the motor vehicle, which is also referred to simply as an axle, can be driven, for example, via the transmission device, in order thereby to drive the motor vehicle overall.The transmission device has a spur gear differential, which is also referred to as a spur gear differential. The spur gear differential is thus a differential gear, also referred to simply as a differential, which is designed as a spur gear differential. For example, the vehicle wheels mentioned can be driven via the spur gear differential, in particular by a drive shaft of the motor vehicle. In this case, for example, the spur gear differential has the function sufficiently known from the prior art of distributing and transmitting a drive torque, which is provided or can be provided by the drive shaft, to the vehicle wheels, in particular to side shafts, via which the vehicle wheels can be driven. Furthermore, for example, the spur wheel differential has the function of allowing different rotational speeds of the vehicle wheels and thus of the side shafts when the motor vehicle is cornering, in such a way that the vehicle wheel on the outside of the curve can rotate or rotates at a greater rotational speed than the vehicle wheel on the inside of the curve, in particular while the vehicle wheels can be driven or are driven by the drive shaft via the spur wheel differential. The side shafts mentioned can be part of the spur gear differential, for example. A first of the vehicle wheels can be driven by a first of the side shafts, for example, and a second of the vehicle wheels can be driven by a second of the side shafts. In particular, the side shafts can be arranged coaxially with respect to one another. In particular, the vehicle wheels are arranged on mutually opposite sides of the vehicle in the transverse direction of the vehicle, which is also referred to simply as a vehicle.The spur gear differential has a first sun gear, which is designed as a first output of the spur gear differential and as a first spur gear. The first sun gear has a first pitch circle diameter. In particular, the first sun gear has a first pitch circle diameter. For example, the first sun gear is connected, in particular permanently, rotationally fixedly to the first side shaft, so that, for example, the first side shaft can be driven by the first sun gear and so that, for example, the first vehicle wheel can be driven by the first sun gear via the first side shaft. The spur gear differential also has a second sun gear, which is designed as a second output of the spur gear differential and as a second spur gear. For example, the second sun gear is connected, in particular permanently, rotationally fixedly to the second side shaft, so that the second side shaft can be driven by the second sun gear. Thus, the second vehicle wheel is drivable by the second sun gear via the second side shaft. The sun gears are arranged coaxially with each other. In other words, for example, the second sun gear is arranged coaxially with a circumferential axis of the first sun gear. In other words again: the first sun gear is rotatable, for example, in particular relative to a housing of the transmission device, about a first sun gear rotational axis. In this case, for example, the first sun gear is arranged at least partially in the housing. The second sun gear is rotatable, for example, about a second sun gear rotation axis relative to the housing in which, for example, the second sun gear is at least partially arranged, wherein, due to the sun gears being arranged coaxially with respect to one another, the sun gear rotation axes coincide. In particular, for example, the first side shaft is arranged coaxially with the first sun gear, and for example, the second side shaft is arranged coaxially with the second sun gear.Within the scope of the present disclosure, the feature that two components are connected to one another in a rotationally fixed manner can be understood to mean that the two components are formed integrally with one another, therefore are formed from a single piece and are thereby connected to one another in a rotationally fixed manner, such that the two components formed integrally with one another are formed as a monoblock, that is to say are formed by a monoblock. In other words again, the structural elements formed integrally with one another are formed by an integral body which is produced integrally and therefore. It is furthermore conceivable for the two components connected to one another in a rotationally fixed manner to be formed separately from one another and to be connected to one another in a rotationally fixed manner, in particular by a joining technique. The components which are connected to one another in a rotationally fixed manner are or are rotated or rotated about a component rotation axis common to the components, in particular relative to the housing, in particular when the components are driven, such that the components can rotate or rotate together or simultaneously at the same angular speed about the component rotation axis, in particular relative to the housing. In addition, relative rotations between the components about the component rotation axis are prevented.The second sun wheel, which is designed as a second spur gear, has a second pitch circle diameter which is different from the first pitch circle diameter. Thus, for example, the first pitch circle diameter is greater than the second pitch circle diameter or vice versa. In particular, the second sun wheel has a second pitch circle diameter which is different from the first pitch circle diameter, so that, for example, the first pitch circle diameter is greater than the second pitch circle diameter or vice versa.The transmission device also has a planetary gear set, which is also referred to as a planetary arrangement or a revolving planetary arrangement. By means of the planetary gear set or via the planetary gear set, the sun gears are coupled to one another in such a way that the sun gears can be rotated in opposite directions. This can be understood to mean, in particular, the following: the vehicle wheels mentioned are ground contact elements of the motor vehicle, also referred to as a vehicle, which is supportable or supported on a ground such as, for example, a roadway in the vertical direction of the motor vehicle downwards via the ground contact elements. If the vehicle wheels and thus the motor vehicle are driven, so that the motor vehicle is driven along the ground, while the motor vehicle is supported on the ground via the ground contact elements (vehicle wheels) in the vertical direction of the vehicle, the vehicle wheels roll off on the ground, in particular directly. If, for example, the motor vehicle is now at least partially lifted in such a way that the vehicle wheels do not touch the ground and so to speak float in the air, and if, for example, the first vehicle wheel and thus the first side shaft and the first sun wheel are then rotated about the first sun wheel rotational axis in a first rotational direction, then, as is sufficiently known from conventional differential transmissions, the second sun wheel and the second side shaft are thereby driven via the planetary gear set and, via the second side shaft, the second vehicle wheel is driven in such a way that the second sun wheel and thus, for example, the second side shaft are rotated about the second sun wheel rotational axis and thus about the first sun wheel rotational axis in a second rotational direction opposite the first rotational direction, thus in the opposite direction to the first sun wheel.The planetary gear set has a planetary carrier which is preferably arranged coaxially with the sun gears. The planet carrier is rotatable relative to the housing, for example about a planet carrier axis of rotation, wherein the planet carrier can be arranged at least partially in the housing. In particular, it is conceivable for the planetary carrier rotation axis to coincide with the sun wheel rotation axes, so that the planetary carrier is preferably arranged coaxially with the sun wheels. The planetary gear set further comprises at least one first differential planetary gear, which meshes with the first sun gear, thus meshes with the first sun gear or is in mesh with the first sun gear. The first differential planetary gear has a third pitch circle diameter. In particular, the first differential planetary gear has a third pitch circle diameter. For example, the planetary gear set has at least one further or more further first differential planetary gears, wherein the preceding and following embodiments relating to the at least one first differential planetary gear can also be easily transferred to the respective further first differential planetary gear and vice versa. If the first differential planetary gear is mentioned above and below, this is to be understood as meaning the at least one first differential planetary gear unless otherwise stated. The first differential planetary gear is rotatably held on the planetary carrier about a first planetary rotational axis relative to the planetary carrier. The first planetary axis of rotation preferably runs parallel to the respective sun wheel axis of rotation and / or parallel to the planet carrier axis of rotation, wherein the first planetary axis of rotation is preferably spaced apart from the respective sun wheel axis of rotation and / or from the planet carrier axis of rotation.The planetary gear set further includes at least one second differential planetary gear. It is conceivable that the planetary gear set has at least one further second or more further second differential planetary gears, wherein the previous and following embodiments for the at least one second differential planetary gear can also be easily transferred to the respective further second differential planetary gear and vice versa. If the second differential planetary gear is mentioned above and below, this is to be understood as meaning the at least one second differential planetary gear unless otherwise stated. The second differential planetary gear meshes with the second sun gear. It is therefore provided that the second differential planetary gear meshes with the second sun gear or is in mesh with the second sun gear. The second differential planetary gear is rotatably held on the planetary carrier relative to the planetary carrier about a second planetary rotational axis extending parallel to the first planetary rotational axis and spaced apart from the first planetary rotational axis. For example, the second planetary axis of rotation extends parallel to the respective sun wheel axis of rotation and / or parallel to the planet carrier axis of rotation, wherein it is preferably provided that the second planetary axis of rotation is spaced apart from the respective sun wheel axis of rotation and / or from the planet carrier axis of rotation.The planetary gear set also has at least one coupling planetary gear, which is arranged coaxially to the first differential planetary gear and is connected in a rotationally fixed manner to the first differential planetary gear and engages in the second differential planetary gear, is therefore in engagement with the second differential planetary gear or meshes with the second differential planetary gear and thereby couples the differential planetary gears to one another, and has a fourth rolling circle diameter different from the third rolling circle diameter. In particular, the coupling planetary gear has a fourth pitch circle diameter different from the third pitch circle diameter. The first differential planetary gear and the second differential planetary gear form, for example, a differential planetary gear group, wherein it is conceivable that the spur gear differential has at least one further or more further differential planetary gear groups, wherein the preceding and following embodiments relating to the first differential planetary gear group can also be easily transferred to the respective further differential planetary gear group and vice versa.The coupling planetary gear and the first differential planetary gear form a differential stage planetary gear which is held on the planetary carrier such that it can rotate about the first planetary rotational axis relative to the planetary carrier. The differential planetary gears and the coupling planetary gear are further spur gears of the spur gear differential. The first differential stepped planetary gear has the first differential planetary gear as a first stepped planetary gear and the coupling planetary gear as a second stepped planetary gear. In other words, the first differential planetary gear is also referred to as a first stepped planet, and the coupling planetary gear is also referred to as a second stepped planet. It is conceivable that the spur gear differential has at least one further or more further differential stage planet gears, wherein the preceding and following embodiments relating to the first differential stage planet gear can also be easily transferred to the respective further differential stage planet gear and vice versa.The differential stage planetary gear and the second differential planetary gear are arranged on different axles. This means in particular that the first planetary axis of rotation and the second planetary axis of rotation run parallel to one another and are spaced apart from one another, in particular in the radial direction of the planetary gear set and / or in the circumferential direction of the planetary gear set running about the axial direction of the planetary gear set.In order to be able to realize a particularly compact, therefore space-saving and particularly weight-saving design and a particularly high torque density of the transmission device, it is provided according to the invention that a first ratio between the first pitch circle diameter and the second pitch circle diameter and a second ratio between the third pitch circle diameter and the fourth pitch circle diameter are the same. For example, the first ratio is a first quotient which has the first pitch circle diameter in its first denominator and the second pitch circle diameter in its first denominator. It is very preferably provided that the second ratio is a second quotient which has the third pitch circle diameter in its second denominator and the fourth pitch circle diameter in its second denominator. Thus, according to the invention, it is provided that the quotients are the same. The preceding and following explanations concerning the pitch circle diameters can also be transferred to the pitch circle diameters and vice versa.When the sun gears are mentioned above and below, unless otherwise stated, these are to be understood as meaning the first sun gear and the second sun gear. Collectively, the first sun gear and the second sun gear are also referred to as output sun gears, wherein the first sun gear is a first of the output sun gears and the second sun gear is a second of the output sun gears.The invention makes it possible to divide the aforementioned drive torque into equal parts, i.e. half, among the output sun gears and thus transmit it, and thus to be able to realize a so-called 50:50 torque distribution. For this purpose, the driven sun gears are configured slightly different in terms of their pitch circle diameters, i.e. differently large. In this case, however, unfavourable, extreme profile displacements and disadvantageous effects resulting therefrom on the load-bearing behavior of toothings of the spur gear differential can be avoided. As a result, the transmission device can be designed to be particularly light-weight and space-saving, and a high torque density can be realized.In order to be able to realize a particularly compact construction, it is provided in one embodiment of the invention that the first differential planetary gear has a first toothing with a first number of teeth and a first toothing module, wherein the first toothing engages in the first sun gear. The first toothing has first teeth with a respective first tooth height, wherein the first tooth heights are preferably the same. The coupling planetary gear has a second toothing with a second number of teeth and a second toothing module, wherein the second toothing engages in the second differential planetary gear. The second toothing has second teeth with a respective second tooth height, wherein the second tooth heights are preferably the same.Preferably, it is provided that the first differential planetary gear meshes with the first sun gear, but preferably the first differential planetary gear does not mesh with the coupling planetary gear, does not mesh with the second sun gear and does not mesh with the second differential planetary gear. Furthermore, it is preferably provided that the coupling planetary gear meshes with the second differential planetary gear, but preferably the coupling planetary gear does not mesh with the first differential planetary gear and does not mesh with the first sun gear, and preferably the coupling planetary gear does not mesh with the second sun gear. Furthermore, it is preferably provided that the second differential planetary gear meshes with the second sun gear and with the coupling planetary gear, wherein preferably the second differential planetary gear does not mesh with the first sun gear and not with the first differential planetary gear.A further embodiment of the invention is characterized in that the first number of teeth and the second number of teeth are identical, wherein the first toothed module and the second toothed module differ from one another, and wherein the respective first tooth height and the respective second tooth height differ from one another. As a result, the installation space requirement can be kept particularly low.In order to be able to realize a particularly compact construction, it is provided in a further embodiment of the invention that the first toothing and the second toothing are rotationally oriented with respect to one another, in particular viewed about the first planetary axis of rotation, in such a way that a respective gap, also referred to as a tooth gap, of the first toothing is aligned with a respective gap, also referred to as a tooth gap, of the second toothing of the coupling planetary gear. In other words, it is preferably provided that the or all tooth gaps of the first toothing are aligned with the or all tooth gaps of the second toothing, in particular viewed in the axial direction of the differential stage planetary gear and thus along the first planetary rotational axis.In a further, particularly advantageous embodiment of the invention, it is provided that the first step planet and the second step planet are formed integrally with one another, and are therefore formed from a single piece. In other words, it is preferably provided that the first step planet and the second step planet are not formed as components which are formed separately from one another and are connected to one another, but rather the first step planet and the second step planet are preferably formed integrally with one another, such that the first step planet and the second step planet are formed as a monoblock or are formed by a monoblock. In other words, it is preferably provided that the first step planet and the second step planet are formed by a one-piece and thus integrally manufactured body which is formed from a single piece. As a result, the installation space requirement, the weight and the costs can be kept within a particularly small scope.A further embodiment of the invention is distinguished in that, viewed in the axial direction of the first stepped planet and the second stepped planet and thus along the first planetary axis of rotation, a transition region is provided, formed or arranged between the first stepped planet, which has a first width running in the axial direction of the first stepped planet, and the second stepped planet, which has a second width running in the axial direction of the second stepped planet and thus along the first planetary axis of rotation, also referred to as coupling width, wherein the transition region has a third width, also referred to as transition width. In principle, it is conceivable for the first width and the second width to be the same. It is furthermore conceivable for the first width and the second width to differ from one another. Further, the first width and the third width may be the same, or the third width and the first width may be different from each other. It is further conceivable that the second width and the third width are the same, or the third width and the second width differ from one another. In particular, it is conceivable that the transition region is free of a toothing, or a toothing, also referred to as a transition toothing, is provided in the transition region, which toothing can be formed, for example, integrally with the first toothing and / or integrally with the second toothing.For example, in the transition region, there is a tool outlet of a toothed tool for producing the first toothing of the first differential planetary gear and / or for producing the second toothing of the coupling planetary gear. Furthermore, it is preferably provided that a radial outer contour of the differential planetary gear, in particular a radial outer contour and thus an outer contour of the differential planetary gear pointing outward in the radial direction of the differential planetary gear, does not fall below a first tip circle diameter of the second toothing of the coupling planetary gear in the transition region, but instead increases or increases from the first tip circle diameter of the second toothing of the coupling planetary gear, in particular continuously, to a second tip circle diameter of the first toothing of the first differential planetary gear. Thus, for example, the second tip diameter is greater than the first tip diameter. The respective width mentioned above runs in the axial direction of the first stepped planetary gear and the second stepped planetary gear, thus in the axial direction of the differential stepped planetary gear and thus along the first planetary rotational axis. As a result, a particularly compact construction can be ensured, in particular when viewed in the axial direction of the differential stage planetary gear and thus of the transmission device as a whole.In order to be able to realize a particularly compact construction in particular in the axial direction of the transmission device, it is provided in a further embodiment of the invention that the third width of the transition region is, in particular significantly, smaller than the first width of the first stepped planetary gear, in particular of the first toothing, and, in particular significantly, smaller than the second width of the second stepped planetary gear, in particular of the second toothing. Preferably, the first width is a first tooth width of the first toothing, and preferably the second width is a second tooth width of the second toothing. The feature that the third width is significantly smaller than the first width and significantly smaller than the second width is to be understood in particular to mean that, for example, the third width is at most 90 percent, in particular at most 80 percent, very particularly at most 70 percent and very particularly at most 60 percent, of the first width and of the second width if the first width and the second width are the same, and that the third width is, for example, at most 90 percent, in particular at most 80 percent, very particularly at most 70 percent and very particularly at most 60 percent, of the smaller of the first width and of the second width if the first width and the second width are different. In particular, for example, the third width is less than 50 percent, in particular less than 40 percent, very particularly less than 30 percent, of the first width and the second width or of the smaller of the first width and the second width.A further embodiment of the invention is characterized in that the first differential planetary gear and the coupling planetary gear are formed separately from one another and are connected to one another, in particular in a rotationally fixed manner, wherein that of the first and second stepped planets whose pitch circle diameter or pitch circle diameter is smaller than the pitch circle diameter or pitch circle diameter of the other of the first and second stepped planets has a projection, which is formed for example as a journal and is also referred to as an extension and on which the other of the first and second stepped planets is arranged and fastened. In other words, if the third pitch circle diameter is greater than the fourth pitch circle diameter, the first step planet is a large planet and the second step planet is a small planet. If the third pitch circle diameter is smaller than the fourth pitch circle diameter, the first step planet is a small planet and the second step planet is a large planet. It is provided here that the small tarpaulin has the projection, which is designed for example as a pin and is also referred to as an extension, on which the large tarpaulin is arranged and fastened.For example, the large planet has a hub in which, for example, at least one longitudinal region of the projection of the small planet is arranged, so that the large planet is arranged via its hub on the longitudinal region of the projection of the small planet. In particular, the large planet is fixed on the projection in a rotationally fixed manner via the hub and is therefore connected to the small planet in a rotationally fixed manner. This allows a particularly space-saving and cost-effective construction to be produced.In order to be able to keep the installation space requirement of the transmission device particularly low, in particular in the axial direction of the transmission device, it is provided in a further embodiment of the invention that the first stepped planet and the second stepped planet directly or directly adjoin one another when viewed in the axial direction of the first stepped planet and the second stepped planet and thus along the first planetary axis of rotation.In a further embodiment of the invention, the first sun gear has a third toothing with a third number of teeth and a third toothing module, wherein the third toothing engages in the first differential planetary gear, in particular in the first toothing thereof. The third toothing has third teeth with a respective third tooth height, wherein it is preferably provided that the third tooth heights are the same. The second sun gear has a fourth toothing with a fourth number of teeth and a fourth toothing module, wherein the fourth toothing engages in the second differential planetary gear, in particular in the fifth toothing thereof. The fourth toothing has fourth teeth with a respective fourth tooth height, wherein the fourth tooth heights are preferably the same. To realize a construction which is particularly advantageous in terms of installation space and weight, it has proven advantageous if the third number of teeth and the fourth number of teeth differ from one another if the third toothed module and the fourth toothed module are identical, and if the respective third tooth height and the respective fourth tooth height are identical.Within the scope of the present disclosure, ordinal words referred to as ordinals, such as "first", "first", "second", "second", etc., are also not necessarily used to indicate or imply a number or set of elements to which the ordinal words relate, but rather to be able to unambiguously reference elements or terms to which the ordinal words are assigned or to which the ordinal words relate.In order to be able to keep the installation space requirement, the costs and the weight particularly low, it is provided in a further embodiment of the invention that all the tooth arrangements of the spur gear differential are straight-toothed, and therefore are formed or designed to be straight-toothed.In order to be able to realize a particularly high torque density in a manner which is particularly advantageous in terms of installation space, it is provided in a further embodiment of the invention that the transmission device has a planetary gear which is provided in particular in addition to the spur gear differential and has at least one stepped planetary gear which is provided in addition to the differential stepped planetary gear and in particular also in addition to the second differential planetary gear and preferably also in addition to the sun gears and is held rotatably on the planetary carrier, in particular about the second planetary rotational axis relative to the planetary carrier and has a first planetary gear and a second planetary gear. The second planetary gear is also referred to as a third step planet, and the second planetary gear is also referred to as a fourth step planet. The third step planet and the fourth step planet are preferably spur gears. The third stage planet and the fourth stage planet are connected to one another in a rotationally fixed manner. It is conceivable that the third step planet and the fourth step planet are formed integrally with one another, thus are formed from a single piece, or the third step planet and the fourth step planet are formed separately from one another and are connected to one another in a rotationally fixed manner.The planetary gear also has a third sun gear, which is provided in addition to the first sun gear and in addition to the second sun gear and preferably also in addition to the differential stepped planetary gear and in addition to the second differential planetary gear and also preferably in addition to the stepped planetary gear and is a drive sun gear or is also referred to as a drive sun gear. The third sun gear is preferably a spur gear. One of the planet gears of the stepped planet gear of the planetary gear set is in engagement, thus meshes with the drive sun gear. Preferably, it is provided that the first planetary gear and the second planetary gear, thus the third step planet and the fourth step planet are of different sizes, in particular have mutually different pitch circle diameters and / or mutually different pitch circle diameters, so that for example the first planetary gear has a fifth pitch circle diameter and / or a fifth pitch circle diameter, and so that for example the second planetary gear has a sixth pitch circle diameter and / or a sixth pitch circle diameter. It is conceivable that the fifth pitch circle diameter and the sixth pitch circle diameter differ from each other. In particular, it is conceivable that the fifth pitch circle diameter and the sixth pitch circle diameter differ from one another. Thus, for example, the fifth pitch circle diameter or the fifth pitch circle diameter is greater than the sixth pitch circle diameter or the sixth pitch circle diameter. For example, the one planetary gear has the fifth pitch circle diameter or the fifth pitch circle diameter, so that, for example, the other planetary gear of the stepped planetary gear of the planetary gear has the sixth pitch circle diameter or sixth pitch circle diameter. Thus, preferably, the one planetary gear is larger than the other planetary gear. In other words, preferably, the one planetary gear is the larger of the planetary gears, so that the other planetary gear is the smaller of the planetary gears. Most preferably, the first planet wheel is the one planet wheel, most preferably the other planet wheel is the second planet wheel. Thus, it is preferably provided that the larger planetary gear of the stepped planetary gear of the planetary gear set is in engagement with the drive sun gear.The planetary gear also has a ring gear which is connected or connectable to the aforementioned housing in a rotationally fixed manner. In particular, the ring gear can be permanently connected to the housing in a rotationally fixed manner. In particular, the ring gear is arranged at least partially in the housing. The other planetary gear, in particular the smaller planetary gear, is in engagement with the ring gear, thus engaging the ring gear or meshing with the ring gear. In particular, it is conceivable that the stepped planetary gear of the planetary gear set is connected, in particular permanently, rotationally fixedly to the second differential planetary gear, or the stepped planetary gear of the planetary gear set, in particular the second planetary rotational axis, is rotatable relative to the second differential planetary gear. In particular, the stepped planetary gear of the planetary gear is arranged coaxially with the second differential planetary gear. The stepped planetary gear is thus preferably held on the planetary carrier such that it can rotate about the second planetary rotational axis relative to the planetary carrier.In order to realize a particularly compact and weight-saving construction, it has proven particularly advantageous if the second differential planetary gear adjoins the ring gear, which is adjoined by one planetary gear and the other planetary gear of the planetary gear, which engages in the ring gear, in a direction running in the axial direction of the second differential planetary gear and thus running parallel to the second planetary rotational axis or coinciding with the second planetary rotational axis, wherein the ring gear and the other planetary gear of the planetary gear adjoin, in the same direction, the one planetary gear of the planetary gear, which engages in the drive sun gear, whereby the ring gear and the other planetary gear of the planetary gear adjoin, in the axial direction of the second differential planetary gear and thus viewed along the second planetary rotational axis, between the second differential planetary gear of the spur gear differential and the planetary gear, which engages in the drive sun gear, a planetary gear of the planetary gear mechanism is arranged. As a result, a particularly compact construction can be represented, in particular in the axial direction of the transmission device.A further embodiment of the invention is characterized in that the first pitch circle diameter of the first sun gear is greater than the second pitch circle diameter of the second sun gear, which is connected to the first sun gear in an arrangement direction running in the axial direction of the sun gears, wherein the first sun gear is connected to the third sun gear in the same arrangement direction. As a result, the first sun gear is arranged between the second sun gear and the third sun gear, as viewed in the axial direction of the sun gears and thus, as viewed along the respective sun gear rotational axis, whereby the transmission device can be of a particularly compact design, in particular in the axial direction.In order to be able to keep the installation space requirement particularly low, it is provided in a further embodiment of the invention that planet carrier walls of the planet carrier, on the planet carrier walls of which bolts are fastened, in particular in a rotationally fixed manner, on which bolts the differential stepped planet gear of the spur gear differential, the second differential planet gear of the spur gear differential and preferably the stepped planet gear of the planetary gear are rotatably held, lie exclusively on the outside when viewed in the axial direction of the planetary gear and of the spur gear differential and thus, when viewed along the respective sun gear rotational axis, and therefore connect on both sides to the ring gear, the second differential planet gear of the spur gear differential, the differential stepped planet gear of the spur gear differential and the sun gears of the spur gear differential and preferably to the stepped planet gear of the planetary gear, such that the planet carrier walls, which are opposite one another in particular in the axial direction of the planet carrier, are arranged outside the planetary gear mechanism and outside the spur gear differential, viewed in the axial direction of the transmission device and thus along the respective sun gear rotational axis.It has furthermore been found to be particularly advantageous if the first differential planetary gear is arranged in phase with the stepped planetary gear.In order to be able to keep the axial installation space requirement particularly low, it is provided in a further embodiment of the invention that the smaller planetary gear of the planetary gear is arranged between the larger planetary gear of the planetary gear and the second differential planetary gear of the spur gear differential when viewed in the axial direction of the second differential planetary gear of the spur gear differential and thus the larger planetary gear of the planetary gear is arranged between the smaller planetary gear of the planetary gear and the second differential planetary gear of the spur gear differential when viewed in the axial direction of the second differential planetary gear of the spur gear differential and thus viewed along the second planetary rotational axis.A second aspect of the invention relates to a motor vehicle, also referred to simply as a vehicle, which is preferably designed as a motor vehicle, in particular as a passenger vehicle. The motor vehicle according to the second aspect of the invention has a transmission device according to the first aspect of the invention. Advantages and advantageous configurations of the first aspect of the invention are to be regarded as advantages and advantageous configurations of the second aspect of the invention and vice versa.Further advantages, features and details of the invention are evident from the following description of preferred exemplary embodiments and with reference to the drawing. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively specified combination but also in other combinations or alone without departing from the scope of the invention.The drawing shows in: FIG. 1 is a schematic front view of a first embodiment of a transmission device for a motor vehicle; FIG. 2 is a schematic side view of the first embodiment of the transmission device; FIG. 3 shows a schematic side view of a second embodiment of the transmission device; FIG. 4 is a schematic front view of a first embodiment of a differential stage planetary gear of a spur gear differential of the transmission device; FIG. 5 shows a second embodiment of the differential stage planetary gear; FIG. 6 is a schematic front view of a third embodiment of the transmission device; FIG. 7 is a schematic side view of the third embodiment of the transmission device; FIG. 8 is a schematic front view of a fourth embodiment of the transmission device; FIG. 9 is a schematic side view of the fourth embodiment of the transmission device; FIG. 10 shows a schematic longitudinal sectional view of a third embodiment of the differential stage planetary gear; FIG. 11 shows a schematic longitudinal sectional view of a fourth embodiment of the differential stage planetary gear; and FIG. 12 shows a schematic longitudinal sectional view of a fifth embodiment of the differential stage planetary gear.In the figures, identical or functionally identical elements are provided with identical reference symbols.FIGS. 1 and 2 show, in a schematic front view or in a schematic and sectioned side view, a first embodiment of a transmission device 10 for a motor vehicle preferably designed as a motor vehicle, in particular as a passenger vehicle, and also referred to simply as a vehicle. The motor vehicle has, in its completely produced state, for example, at least or exactly two vehicle axles arranged one behind the other in the longitudinal direction of the vehicle and also simply referred to as axles. The respective vehicle axle has at least or exactly two vehicle wheels, which are also simply referred to as wheels. The respective vehicle wheels of the respective vehicle axle are arranged on sides opposite one another in the vehicle transverse direction of the motor vehicle. The vehicle wheels are ground contact elements, by means of which the motor vehicle can be or is supported on a ground in the vertical direction of the motor vehicle downwards. For example, the motor vehicle has at least one drive motor, by means of which the vehicle wheels can be driven at least or exactly one of the vehicle axles via the transmission device 10, as a result of which the motor vehicle can be driven overall. In particular, the drive motor can be an internal combustion engine or an electric machine, so that the motor vehicle is designed, for example, as a hybrid vehicle or as an electric vehicle, in particular as a battery-electric vehicle (BEV). The vehicle wheels that can be driven via the transmission device 10 are also referred to as drive wheels. In the following, when the wheels or the vehicle wheels are mentioned, unless otherwise stated, these are understood to mean the drive wheels of the motor vehicle.The transmission device 10 has a spur gear differential 12, which is also referred to as a spur gear differential. The spur gear differential 12 is a differential gear, also referred to simply as a differential, which is designed as a spur gear differential gear. In particular, the spur gear differential 12 is designed as a planetary differential. The spur gear differential 12 has a first sun gear 14, which is also referred to as the first sun. The first sun gear 14 is designed as a first output of the spur gear differential 12. In addition, the first sun gear 14 is formed as a first spur gear. In other words, the sun gear 14 is a first gearwheel which is designed as a spur gear. The first sun gear 14 has a first pitch circle diameter. The spur gear differential 12 also has a second sun gear 16, which is designed as a second output of the spur gear differential 12. The second sun gear 16 is designed as a second spur gear. In other words, the second sun gear 16 is a second gearwheel which is designed as a spur gear. It can be seen particularly well from FIGS. 1 and 2 that the sun gears 14 and 16 are arranged coaxially with respect to one another. The transmission device 10 has a housing 18 which is illustrated particularly schematically in FIG. 1, wherein the spur gear differential 12 is arranged at least partially in the housing 18. The sun gears 14 and 16 are rotatable relative to the housing 18 about a sun gear axis of rotation common to the sun gears 14 and 16. The sun gear rotational axis 20 is also simply referred to as rotational axis, wherein the rotational axis extends in the axial direction of the transmission device 10 and thus of the spur gear differential 12, in particular coincides with the axial direction of the transmission device 10 and thus of the spur gear differential 12. Specifically, the axial direction of the transmission device 10 coincides with the axial direction of the spur gear differential 12 whose radial direction coincides with the radial direction of the transmission device 10. The second sun gear 16 is designed as a second output of the spur gear differential 12. The spur gear differential 12 can provide output torques via its outputs, and therefore via the sun gears 4 and 16, by means of which the drive wheels can be driven. In particular, the respective output torque provided or provided by the respective sun gear 14, 16 results from a drive torque which can be introduced or is introduced into the spur gear differential 12. For example, the drive torque can be provided by the drive motor or the drive torque results from a further torque which can be provided by the drive motor. In particular, the drive torque can be divided and distributed to the vehicle wheels, in particular in half, by means of the spur gear differential 12. It can be seen from FIG. 2 that a first shaft embodied as a first side shaft 22 can be driven by the first sun gear 14 and a second shaft embodied as a second side shaft 24 can be driven by the sun gear 16, wherein a first of the drive wheels can be driven by the side shaft 22 and a second of the drive wheels can be driven by the side shaft 24. In particular, it is provided in the present case that the first sun gear 14 is provided, in particular permanently, in a rotationally fixed manner with the first side shaft 22, and alternatively or additionally the second sun gear 16 is connected, in particular permanently, in a rotationally fixed manner with the second side shaft 24. The second sun gear 16 has a second pitch circle diameter that is different from the first pitch circle diameter, wherein in the present case the second pitch circle diameter is smaller than the first pitch circle diameter. The second sun gear 16 is also referred to as a second sun, a small sun, or a smaller sun, and the sun gear 14 is also referred to as a first sun, a larger sun, or a large sun.The spur gear differential 12 furthermore has a planetary gear set 26, by means of which the sun gears 14 and 16 are coupled to one another in such a way that the sun gears 14 and 26 can be rotated in opposite directions relative to the housing 18, in particular about the axis of rotation. The planetary gear set 26 has a planetary carrier 28, which is also referred to as a carrier and is arranged here coaxially with the sun gears 14 and 16. The planet carrier 28 is rotatable about the axis of rotation (sun gear axis of rotation 20) relative to the housing 18. The planetary gear set 26 also has a first differential planetary gear 30. In particular, the planetary gear set 26 has at least one further or more further first differential planetary gears, wherein the following and previous embodiments for the first differential planetary gear 30 can also be easily transferred to the respective further first differential planetary gear and vice versa. The first differential planetary gear 30 meshes with the first sun gear 14, thus meshes with the first sun gear 14 or meshes with the first sun gear 14. In addition, the first differential planetary gear 30 is rotatably held on the planetary carrier 28 about a first planetary rotational axis 32 relative to the planetary carrier 28. Moreover, the first differential planetary gear 30 has a third pitch circle diameter. In the first embodiment, a first bolt 34 is assigned to the first differential planetary gear 30, which is also referred to as a first planetary bolt. In particular, the first differential planetary gear 30 is arranged, in particular mounted, rotatably about the first planetary rotational axis 32 relative to the bolt 34 and relative to the planetary carrier 28 on, in particular on, the bolt 34, wherein, for example, the bolt 34 is in turn, in particular fixed in a rotationally fixed manner, fastened to the planetary carrier 28.The planetary gear set 26 also includes at least one second differential planetary gear 36. In particular, it is conceivable for the planetary gear set 26 to have at least one further or more, further second differential planet gears, wherein the preceding and following embodiments with respect to the second differential planet gear 36 can also be easily transferred to the further second differential planet gear and vice versa. The second differential planetary gear 36 meshes with the second sun gear 16, which is illustrated in FIG. 2 by a dashed arrow 38. In other words, the second differential planetary gear 36 meshes with the sun gear 16 or the second differential planetary gear 36 meshes with the second sun gear 16. Thus, dashed arrow 38 means "meshes with.". The second differential planetary gear 36 is rotatably held on the planetary carrier 28 about a second planetary rotational axis 40 relative to the planetary carrier 28. It can be seen from FIG. 2 that the second planetary axis of rotation 40 runs parallel to the first planetary axis of rotation 32 and is spaced apart from the planetary axis of rotation 32. In addition, the planetary rotation axes 32 and 40 are parallel to the rotation axis (sun gear rotation axis 20), and the planetary rotation axes 32 and 40 are each spaced from the rotation axis. In the first embodiment, a second bolt 42 is assigned to the second differential planetary gear 36, which is also referred to as a second planetary bolt. In this case, the second differential planetary gear 36 is arranged, in particular mounted, rotatably about the second planetary rotational axis 40 relative to the bolt 42 and relative to the planetary carrier 28 on, in particular on, the second bolt 42, wherein, for example, the second bolt 42 is in turn, in particular fixed in a rotationally fixed manner, fastened to the planetary carrier 28.The planetary gear set 26 also includes at least one coupling planetary gear 44. In particular, the planetary gear set 26, in particular each first differential planetary gear, has a respective coupling planetary gear like the coupling planetary gear 44. The first differential planetary gear 30, the second differential planetary gear 36 and the coupling planetary gear 44 are designed as spur gears, and consequently as gearwheels which are designed as spur gears. The coupling planetary gear 44 is arranged coaxially to the first differential planetary gear 30 and is connected, in particular permanently, rotationally fixedly to the first differential planetary gear 30. The coupling planetary gear 44 engages in the second differential planetary gear 36, whereby the differential planetary gears 30 and 36 are coupled to one another via the coupling planetary gear 44, in particular in a torque-transmitting manner. The coupling planetary gear 44 has a fourth rolling circle diameter that is different from the third rolling circle diameter of the first differential planetary gear 30. Furthermore, the first differential planetary gear 30 and the coupling planetary gear 44 assigned to it form a differential stage planetary gear 46, which is also referred to as a differential stage planet. Thus, the planetary gear set 26 includes the differential stage planetary gear 46. In particular, for example, the planetary gear set 26 has at least one further or more further differential stage planet gears, wherein the preceding and following embodiments relating to the differential stage planet gear 46 can also be easily transferred to the respective further differential stage planet gear and vice versa. The differential stage planetary gear 46 is rotatably held on the planetary carrier 28 about the first planetary rotational axis 32 relative to the planetary carrier 28. This is realized in the present case in that the differential stepped planetary gear 46 is arranged, in particular mounted, rotatably on, in particular on, the bolt 34 about the first planetary rotational axis 32 relative to the bolt 34 and relative to the planetary carrier 28, so that the coupling planetary gear 44 is also arranged, in particular mounted, rotatably on, in particular on, the bolt 34 about the first planetary rotational axis 32 relative to the bolt 34 and relative to the planetary carrier 28. The first differential planetary gear 30 is a first stepped planet of the differential stepped planetary gear 46 or is also referred to as a first stepped planet of the differential stepped planetary gear 46. Accordingly, the coupling planetary gear 44 is a second stepped planet of the differential stepped planetary gear 46, or the coupling planetary gear 44 is also referred to as a second stepped planet of the differential stepped planetary gear 46. In the first embodiment, the fourth pitch circle diameter of the coupling planetary gear 44 is smaller than the third pitch circle diameter of the first differential stepped planetary gear 46, so that the coupling planetary gear 44 is also referred to as a small stepped planet or a smaller stepped planet or a small planet, and so that the first differential planetary gear 30 is also referred to as a large stepped planet or a larger stepped planet or a large planet.In order to be able to realize a particularly compact and weight-favorable construction of the transmission device 10 and a particularly high torque density, it is provided that a first ratio between the first pitch circle diameter and the second pitch circle diameter and a second ratio between the third pitch circle diameter and the fourth pitch circle diameter are the same. In this case, for example, the first differential planetary gear 30 has a first toothing which has a first number of teeth and a first toothing module and which engages with the first sun gear 14 and has first teeth with a respective first tooth height. The coupling planetary gear 44 has, for example, a second toothing having a second number of teeth and a second toothing module, which engages into the second differential planetary gear 36 and has second teeth with a respective second tooth height. In this case, it is furthermore preferably provided that the first number of teeth and the second number of teeth are the same, and that the first toothed module and the second toothed module differ from one another, such that the respective first relationship and the respective second relationship differ from one another.FIG. 4 shows a schematic front view of a first embodiment of the differential step planetary gear 46, and in FIG. 4 the first toothing of the first differential planetary gear 30 is denoted by 48, the first teeth of which are denoted by 50. The second toothing of the coupling planetary gear 44 is denoted by 52 in FIG. 4, the second teeth of which are denoted by 54. It can be seen that the first toothing 48 also has first gaps 56, which are also referred to as first tooth gaps. In the circumferential direction of the toothing 48 and thus of the differential planetary gear 30 running about the planetary axis of rotation 32, a respective one of the gaps 56 is arranged between each two directly adjacent teeth 50. The toothing 52 has second gaps 58, which are also referred to as second tooth gaps. In the circumferential direction of the coupling planetary gear 44 and the toothing 52, which extends about the planetary axis of rotation 32, one of the second gaps 58 is arranged between two teeth 54 which are respectively directly adjacent. The respective gap 56 is also referred to as a first tooth gap, and the respective gap 58 is also referred to as a second tooth gap. In the first embodiment of the differential stage planetary gear 46 shown in FIG. 4, the tooth arrangements 48 and 52, viewed about the planetary axis of rotation 32, are oriented rotationally from one another in such a way that the respective first gaps 56 are aligned with the respective second gaps 58 viewed in the axial direction of the differential stage planetary gear 46 and thus viewed along the first planetary axis of rotation 32.In the first embodiment of the transmission device 10 shown in FIGS. 1 and 2, the first differential planetary gear 30 and the coupling planetary gear 44 are formed separately from one another and are connected to one another. In this case, the first differential planetary gear 30 and the coupling planetary gear 44 directly adjoin, in particular abut, one another when viewed in the axial direction of the differential stage planetary gear 46 and thus along the first planetary rotational axis 32, so that, for example, the first differential planetary gear 30 and the coupling planetary gear 44 directly contact one another in the axial direction of the differential stage planetary gear 46. FIG. 3 shows a schematic and sectional side view of a second embodiment of the transmission device 10. In contrast to the first embodiment, however, viewed in the axial direction of the differential stepped planetary gear 46 and thus along the first planetary rotational axis 32, an intermediate region 60 is arranged between the first differential planetary gear 30 and the associated coupling planetary gear 44, which intermediate region can also be referred to as a transition region or can be formed as a transition region. For example, the first differential planetary gear 30, in particular its toothing 48, has a first width running in the axial direction of the differential stepped planetary gear 46, via which width, for example, the toothing 48 engages in the sun gear 14. For example, the coupling planetary gear 44, in particular its toothing 52, has a second width, in particular a second toothing width, which runs in the axial direction of the differential stepped planetary gear 46 and via which, for example, the toothing 52 engages in the differential planetary gear 36. The first width is also referred to as b1, for example, and the second width is also referred to as b2, for example. It is furthermore conceivable for the intermediate region 60 to have a third width which runs in the axial direction of the differential stage planetary gear 46 and is also designated by b3.FIG. 5 shows a schematic front view of a second embodiment of the differential planetary gear 46. in the second embodiment, the toothings 48 and 52 are rotationally oriented with respect to one another when viewed in the circumferential direction of the differential planetary gear 46 extending about the first planetary rotational axis 32, such that the first gaps 56 of the first toothing 48 of the first differential planetary gear 30 are aligned with the second teeth 54 of the second toothing 52 of the coupling planetary gear 44 when viewed in the axial direction of the differential planetary gear 46, and that the first teeth 50 of the first toothing 48 of the first differential planetary gear 30 are aligned with the second gaps 58 of the second toothing 52 of the coupling planetary gear 44 when viewed in the axial direction of the differential planetary gear 46. Alternatively, it is conceivable that, while in the first embodiment of the differential stage planetary gear 46 shown in FIG. 4 the tooth arrangements 48 and 52 are exactly aligned in the axial direction of the differential stage planetary gear 46, thus the teeth 50 are exactly aligned with the teeth 54 and the gaps 56 are exactly aligned with the gaps 58 in the axial direction of the differential stage planetary gear 46, in the second embodiment of the differential stage planetary gear 46 shown in FIG. 5 the tooth arrangements 48 and 52 are not aligned, but are offset or rotated relative to one another by an offset angle V in the circumferential direction of the differential stage planetary gear 46 extending about the first planetary axis of rotation 32, such that, for example, at least respective partial regions of the teeth 50 and of the gaps 58 and at least respective partial regions of the gaps 56 and of the teeth 54 are arranged at the same height or in the same rotational position, as viewed about the circumferential direction of the differential planetary gear 46.In the second embodiment of the transmission device 10 shown in FIG. 3, it is preferably provided that the third width b 3 of the intermediate region 60 is smaller than the first width b 1 of the first stepped planetary gear and smaller than the second width b 2 of the second stepped planetary gear. It is conceivable that the first width and the second width are the same or the first width and the second width may be different from each other.It is preferably provided that the first sun gear 14 has a third number of teeth and a third toothing module, has third toothing which engages into the first differential planetary gear 30, in particular into the first toothing 48 thereof, and has third teeth with a respective third tooth height. The second sun gear 16 has, for example, a fourth toothing having a fourth number of teeth and a fourth toothing module, which engages into the second differential planetary gear 36, in particular into the fifth toothing thereof, and has fourth teeth with a respective fourth tooth height. In this case, it is preferably provided that the third number of teeth and the fourth number of teeth differ from one another, wherein the third toothed module and the fourth toothed module are preferably the same, so that the respective third tooth height and the respective fourth tooth height are preferably the same. Therefore, it is preferably provided that all the tooth arrangements of the spur gear differential 12 are straight-toothed.FIGS. 6 and 7 show a schematic front view and a schematic and sectional side view, respectively, of a third embodiment of the transmission device 10. The planetary gear 62 has at least one stepped planetary gear 64 provided in addition to the differential stepped planetary gear 46 or in addition to the differential stepped planetary gears 46, which is held on the planetary carrier 28 such that it can rotate about the second planetary rotational axis 40 relative to the planetary carrier 28. In the third embodiment, the stepped planetary gear 64 is arranged, in particular mounted, rotatably about the planetary axis of rotation 40 relative to the bolt 42 and relative to the planetary carrier 28 on, in particular on, the second bolt 42. Thus, in the third embodiment, the stepped planetary gear 64 is disposed coaxially with the second differential planetary gear 36. In particular, the second differential planetary gear 36 and the stepped planetary gear 64 are rotatable relative to one another about the second planetary rotational axis 40. For example, the planetary gear 62 can have at least one further or more stepped planet gears, wherein the preceding and following embodiments relating to the stepped planet gear 64 can be easily transferred to the respective further stepped planet gear and vice versa. In particular, a respective stepped planetary gear 64 is provided for each second differential planetary gear 36.The stepped planetary gear 64 has a first planetary gear 66 and a second planetary gear 68, wherein the planetary gears 66 and 68 are connected to one another in a rotationally fixed manner, in particular permanently. The planet gears 66 and 68 are spur gears. The planetary gears 66 and 68 are therefore gears which are designed as spur gears. Preferably, the planet gears 66 and 68 are also straight-toothed. The planet gear 66 is also referred to as a third step planet, and the planet gear 68 is also referred to as a fourth step planet. It can be seen that the planetary gears 66 and 68 are of different sizes, thus have different pitch circle diameters and / or different pitch circle diameters, in the present case in such a way that the planetary gear 66 has a fifth pitch circle diameter and the planetary gear 68 has a sixth pitch circle diameter which is smaller than the fifth pitch circle diameter. Thus, the planetary gear 66 is also referred to as a large planetary gear or larger planetary gear, and the planetary gear 68 is also referred to as a small planetary gear or smaller planetary gear.The planetary gear 62 also has a third sun gear 70, which is provided in addition to the first sun gear 14 and in addition to the second sun gear 16 and is also referred to as a drive sun gear or drive sun gear. Preferably, the third sun gear 70 is also a spur gear and preferably straight-toothed. It can be seen that the large planetary gear, and therefore in the present case the planetary gear 66, engages into the third sun gear 70. In other words, the large pinion gear is meshed with the third sun gear 70. The planetary gear 62 furthermore has a ring gear 72, which in the third embodiment is connected, in particular permanently, to the housing 18 in a rotationally fixed manner. In an alternative embodiment, it would be conceivable for a switching element to be provided, which can be switched over between a coupling state and a decoupling state. In the coupled state, for example, the ring gear 72 is connected to the housing 18 in a rotationally fixed manner by means of the shift element. In the decoupling state, for example, the shift element releases the ring gear 72 for rotations about the axis of rotation (sun gear axis of rotation 20) relative to the housing 18, so that the ring gear 72 can rotate about the axis of rotation relative to the housing 18 in the decoupling state. Thus, in the third embodiment, the planetary gear 62 is disposed coaxially with the spur gear differential 12. The sun gear 70 is arranged coaxially with the sun gears 14 and 16 and is thus rotatable about the sun gear axis of rotation 20 relative to the housing 18. It can also be seen that the planet carrier 28 is a planet carrier common to the spur gear differential 12 and the planetary gear 62, on which the stepped planet gear 64 is also held rotatably about the second planetary axis of rotation 40. It can be seen that the small planetary gear, and therefore in the present case the planetary gear 68, is in engagement with the ring gear 72.For example, the sun gear 70 can be driven by the drive motor, so that the aforementioned drive torque can be provided, for example, via the planetary gear 62 and can be introduced into the spur gear differential 12 via the planetary gear 62, in order thereby to drive the planetary carrier 28 and thus the spur gear differential 12. Thus, the planet carrier 28 is preferably designed as a drive of the spur gear differential 12, via whose drive the aforementioned drive torque of the spur gear differential 12 can be introduced.In FIG. 3, a dashed arrow 74 means "meshes with", so that the dashed arrow 74 illustrates that the sun gear 70 meshes with the large planetary gear (planetary gear 66), and is therefore in mesh with the large planetary gear.In order to be able to realize a particularly compact construction, in particular as viewed in the axial direction of the transmission device 10 and thus along the sun gear rotational axis 20, it is provided in the third embodiment that the second differential planetary gear 36 adjoins the ring gear 72 and the planetary gear 68 engaged with the ring gear 72 in a direction running in the axial direction of the second differential planetary gear 36 and thus running parallel to the second planetary rotational axis 40 or coinciding with the second planetary rotational axis 40 and illustrated in FIG. 7 by an arrow 76, wherein the ring gear 72 and the planetary gear 68 engaged therewith adjoin the planetary gear 66 in the direction illustrated by the arrow 76, whereby the ring gear 72 and the planetary gear 68 are arranged between the second differential planetary gear 36 and the planetary gear 66, viewed in the axial direction of the second differential planetary gear 36 and in the present case also in the axial direction of the stepped planetary gear 64 and thus along the second planetary rotational axis 40.As in the first embodiment and the second embodiment of the transmission device 10, the first pitch circle diameter of the first sun gear 14 is also greater than the second pitch circle diameter of the second sun gear 16 in the third embodiment of the transmission device 10, In the second embodiment, the second sun gear 16 adjoins the sun gear 14 in an arrangement direction which runs in the axial direction of the sun gears 14 and 16 and thus runs parallel to the sun gear rotational axis 20 or coincides with the sun gear rotational axis 20 and is illustrated by an arrow 78 in FIG. 3, wherein in the present case the arrangement direction illustrated by the arrow 78 corresponds to the direction illustrated by the arrow 76. The first sun gear 14 connects to the third sun gear 70 in the arrangement direction (arrow 78), whereby the first sun gear 14 is arranged between the second sun gear 16 and the third sun gear 70 as viewed in the axial direction of the sun gears 14, 16 and 70 and thus along the sun gear rotational axis 20.Furthermore, it is provided that planet carrier walls 80 and 82 of planet carrier 28, on whose planet carrier walls 80 and 82 bolts 34 and 42 are fastened, in particular in a rotationally fixed manner, are situated exclusively on the outside in the axial direction of planetary gear 62 and spur gear differential 12 and thus, as viewed along sun gear axis of rotation 20, and therefore connect on both sides to ring gear 72, stepped planetary gear 64, second differential planetary gear 36, differential stepped planetary gear 46 and sun gears 14, 16 and 70, and are thus situated outside both planetary gear 62 and spur gear differential 12.FIGS. 8 and 9 show, in a schematic front view and in a schematic and sectional side view, respectively, a fourth embodiment of the transmission device 10. In the fourth embodiment, however, it is provided that, as viewed in the axial direction of the second differential planetary gear 36 and the stepped planetary gear 64, the large planetary gear (planetary gear 66) is arranged between the second differential planetary gear 36 and the small planetary gear (planetary gear 68), so that the planetary gear 66 is arranged between the second differential planetary gear 36 and the ring gear 72 as viewed in the axial direction of the stepped planetary gear 64 and the second differential planetary gear 36.FIG. 10 shows a third embodiment of the differential stepped planetary gear 46, In the third embodiment, the differential planetary gear 30 and the associated coupling planetary gear 44 are formed separately from one another and are connected to one another in a rotationally fixed manner. Here, the coupling planetary gear 44 has a projection 84 which is formed in the present case as a collar of the coupling planetary gear 44 or by a collar of the coupling planetary gear 44. The differential planetary gear 30 is arranged on the projection 84 and is connected, in particular permanently, rotationally fixedly to the projection 84, as a result of which the differential planetary gear 30 is connected, in particular permanently, rotationally fixedly to the coupling planetary gear 44. In the present case, the differential planetary gear 30 has a hub 86 in which the projection 84 is arranged. Thus, the differential planetary gear 30 is connected via its hub 86, in particular permanently, in a rotationally fixed manner to the projection 84 and thus to the coupling planetary gear 44.FIG. 11 shows a fourth embodiment of the differential stage planetary gear 46, In the fourth embodiment of the differential stage planetary gear 46, the first differential planetary gear 30 and the associated coupling planetary gear 44 are formed integrally with one another and are thereby connected to one another in a rotationally fixed manner, in particular permanently. In FIG. 11, a region is denoted by B. As can be seen from FIG. 11, a radial outer contour 88 of the differential stepped planetary gear 46 does not fall below a first tip circle diameter k 1 of the second toothing 52 in the transition region (intermediate region 60), but instead increases from the first tip circle diameter k 1 to a second tip circle diameter k 2 of the first toothing 48, in particular at least substantially continuously. In particular, for example, in the region B, machining, in particular production, of the toothing 52 and / or of the toothing 48, in particular by means of a toothing tool, takes place, such that the region B is, for example, a tool outlet region.FIG. 12 shows a fifth embodiment of the differential stage planetary gear 46. it can be seen from FIG. 12 that in the fifth embodiment the intermediate region 60 (transition region) is free of a toothing.It can be seen that the spur gear differential 12 comprises the planet carrier 28, which is driven or drivable in particular as well as the two sun gears 14 and 16 of different sizes, which simultaneously represent the two outputs of the spur gear differential 12, which are also designated as outputs. Furthermore, the spur gear differential 12 comprises the differential stage planetary gear 46 or preferably a group of respectively identical differential stage planetary gears 46, wherein the group comprises respectively at least or more than two identical differential stage planetary gears 46. The differential step planet gears 46 are preferably arranged uniformly distributed in the circumferential direction of the spur gear differential 12 running about the sun gear rotational axis 20, in particular over a respective circumference of the respective sun gear 14, 16. Furthermore, the spur gear differential 12 comprises the second differential planet gear 36 or preferably a group of identical differential planet gears 36, wherein the plurality of differential planet gears 36 are preferably arranged uniformly distributed in the circumferential direction of the spur gear differential 12 running about the sun gear rotational axis 20. In particular, a respective second differential planetary gear 36 is provided for each differential stage planetary gear 46. The differential stage planet gears 46 and the second differential planet gears 36 are rotatably mounted on, in particular on, their respective associated bolts 34 and 42. For this purpose, for example, rolling and / or sliding bearings can be used. The bolts 34 and 42 are fastened, in particular in a rotationally fixed manner, to the planet carrier 28, in particular. The planet carrier 28 can be embodied in one or more parts, and therefore in one piece or in multiple parts. The planet carrier 28 is mounted, for example, directly or indirectly, in particular rotatably, relative to the one- or multi-part housing 18, which is formed, for example, as a transmission housing or as a drive housing. For example, a direct bearing is provided between the planet carrier 28 and the housing via at least or exactly two bearings, which are designed, for example, as slide bearings or roller bearings, in particular in such a way that the planet carrier 28 is rotatably mounted on the housing 18 via the bearings mentioned, in particular in such a way that the planet carrier 28 is rotatable about the axis of rotation relative to the housing 18. The second differential planetary gear 36 meshes with the second, smaller sun gear 16 and with the coupling planetary gear 44 which is smaller than the first differential planetary gear 30, in particular directly in each case, and preferably not otherwise with any other, further gear. The first differential planetary gear 30 meshes, for example, exclusively with the first, larger sun gear 14. In order that identical torques are present on the two sun gears 14 and 16, and therefore the drive torque can be divided or is divided vigorously and therefore to equal parts between the sun gears 14 and 26 and thus the side shafts 22, 24, the ratios between the pitch circle diameters of the sun gears 14 and 16 and those of the stepped planets (differential planetary gear 30 and coupling planetary gear 44) of the differential stepped planetary gear 46 are identical, and so the following applies:Here, WS 1 denotes the first pitch circle diameter of the first sun gear 14, WS 2 denotes the second pitch circle diameter of the second sun gear 16, WSP 1 denotes the third pitch circle diameter of the first differential planetary gear 30, and WSP 2 denotes the fourth pitch circle diameter of the coupling planetary gear 44.All the tooth arrangements of the spur gears can be straight-toothed or helical-toothed. Spur gearing is preferred. If, as is shown in FIG. 4, the toothings 48 and 52 are oriented rotationally with respect to one another in such a way that the teeth 50 are exactly aligned with the teeth 54, so that therefore exactly gap 56 stands on gap 58 and exactly tooth 50 stands on tooth 54, then a tool outlet for a toothing tool for producing the smaller toothing 52 can project, for example, into the gaps of the larger toothing 48 to a certain extent without removing material in the region of the larger toothing 48. 90 denotes a collar, by means of which a particularly wide bearing base of the stepped planetary gear 64 can be represented.In this way, the unusable intermediate region 60 between the toothings 48 and 50 can be kept small or short in the axial direction of the differential stepped planetary gear 46. The smaller the difference between the third pitch circle diameter and the fourth pitch circle diameter, the smaller or shorter advantageously also becomes the intermediate region 60 that cannot be used for a toothing.If the differential planetary gear 30 and the associated coupling planetary gear 44 are formed separately from one another and are connected to one another in a rotationally fixed manner, the rotationally fixed connection between the differential planetary gear 30 and the associated coupling planetary gear 44 can be formed via a press fit, via a spline, a weld seam, a combination of these connections or in another manner. An advantage here is that the differential planetary gear 30 and the associated coupling planetary gear 44 can be designed axially directly adjacent, i.e. without the intermediate region 60, as a result of which a particularly short axial construction can be produced.Preferably, however, the intermediate region 60 with the width B 3 is provided between the differential planetary gear 30 and the coupling planetary gear 44, and therefore between the toothings 48 and 52. The gear tool, which is also simply referred to as a tool, for example, even runs into the region of the toothing 48 of the differential planetary gear 30, but only into the gaps 56 of the toothing 48, so that the toothing 48 is not damaged, machined or otherwise impaired by the gear tool by means of which the toothing 52 is produced, for example, in the intermediate region 60 of the gear tool for producing the toothing 52. In the intermediate region 60, the teeth 54 of the toothing 52 grow to a certain extent from the second pitch circle diameter or from the tip circle diameter k 1 to the first pitch circle diameter or to the tip circle diameter k 2. The radial outer contour 88 of the differential planetary gear 46 therefore does not fall below the tip circle diameter k 1 of the coupling planetary gear 44 smaller than the first differential planetary gear 30 in the intermediate region 60. Preferably, the difference between the first pitch circle diameter of the differential planetary gear 30 and the second pitch circle diameter of the coupling planetary gear 44 is selected to be as small as possible, since as a result the width b 3 of the intermediate region 60 can be kept small. Advantages of this embodiment are in particular:The differential stepped planetary gear 46 can be embodied in one piece or in one piece, whereby the costs can be kept particularly low.By dipping the gear tool for producing the gear 52 into the gear 48, the width b3, which represents a distance running in the axial direction of the differential planetary gear 46 between the differential planetary gear 30 and the coupling planetary gear 44, can be kept small.Tooth root strength higher than in offset teeth.Finally, as is shown in FIG. 12, it is conceivable in the fifth embodiment that the intermediate region 60 with the width b 3 exists between the two toothings 48 and 52 or between the differential planetary gear 30 and the associated coupling planetary gear 44, as viewed in the axial direction of the differential stepped planetary gear 46, wherein in the fifth embodiment shown in FIG. 12 the outer diameter of the differential stepped planetary gear 46 is significantly smaller within the intermediate region 60 than the tip circle diameter k 1 of the teeth 54 or of the toothing 52 that is smaller than the tip circle diameter k 2 of the teeth 50 or of the toothing 48. The outer diameter is designated a in FIG. 12. The outer diameter a can even be made equal to or smaller than a root circle diameter of the toothing 52 in this intermediate region 60. It is conceivable that, for example, the gear cutting tool for producing the toothing 52 does not enter the region or the gaps 56 of the toothing 48. In this case it is advantageous not to make the teeth 50 and 54 of the toothings 48 and 52 axially aligned, but rather, as shown in FIG. 5, to rotate the toothings 48 and 52 relative to one another about the planetary rotational axis 32. This rotational alignment or rotation of the toothings 48 and 52 can be selected at least freely, but should be of the same size in all differential step planet gears 46, so that an advantageous assembly capability of the spur gear differential 12 can be represented. In this specific embodiment, therefore, the tooth arrangements 52 and 48 should not necessarily have the same number of teeth. As a disadvantage of this, a large width b 3 may result between the serrations 48 and 52, which, however, may be classified as acceptable. Advantages resulting therefrom can be:one-piece or one-piece embodimentsimple manufacturing processIt is conceivable that the number of teeth in the toothings 48 and 52 are identical, wherein, for example, as is provided in the first embodiment shown in FIG. 4, the teeth 50 and 54 of the two toothings 48 and 52 are aligned in the axial direction of the differential stepped planetary gear 46. Alternatively, it is conceivable that, as is shown in FIG. 5, the toothings 48 and 52 are arranged rotated with respect to one another, as viewed in the circumferential direction of the differential step planetary gear 46, in contrast to the alignment aligned with one another.In particular, the following advantages can be realized by the transmission device 10:In classic bevel gear differentials, high axial spreading forces arise during the transmission of torque between the bevel gears, which must be absorbed via massive housings, frequently made of grey cast iron. In the transmission device 10, no significant axial forces are advantageously produced in the housing 18, wherein the installation space requirement in the axial direction can be kept particularly low, and the planet carrier 28 can be designed to be significantly lighter than a grey cast iron housing of a conical differential.In conventional solutions, there may be a disadvantage in that there must be a significant axial space between the two sun gears 14 and 26, in which space the two wide planetary gears mesh with one another without being in meshing engagement with one of the two sun gears in this region. In contrast, in the transmission device 10, the axial installation space requirement can be kept particularly low, and the weight and the material costs can be kept particularly low.The problem described above can be solved, for example, by using at least partially toothings with extreme profile displacements, which can be disadvantageous for the operational stability and the specific load capacity of the affected profile-shifted gearwheels and must be compensated for by a significant widening of the profile-shifted toothings. Furthermore, the extreme profile displacement has a disadvantageous effect on the rolling behavior and thus on the noise radiation of the profile-shifted tooth arrangements. These disadvantages and problems can be avoided in the transmission device 10. Thus, a smaller axial installation space requirement, a smaller weight and a smaller material cost can be realized. In addition, a lower mechanical excitation (noise radiation) within the toothing can be represented at a relative rotational speed.

Claims

Transmission device (10) for a motor vehicle, having a spur gear differential (12), which has: - a first sun gear (14), which is designed as a first output of the spur gear differential (12) and as a first spur gear and has a first pitch circle diameter; - a second sun gear (16), which is arranged coaxially with the first sun gear (14) and is designed as a second output of the spur gear differential (12) and as a second spur gear and has a second pitch circle diameter different from the first pitch circle diameter; and - at least one planetary gear set (26), by means of which the sun gears (14, 16) are coupled to one another in such a way that the sun gears (14, 16) are rotatable in opposite directions, wherein the planetary gear set (26) has: ◯ a planetary carrier (28); ◯ at least one first differential planetary gear (30), which meshes with the first sun gear (14), has a third pitch circle diameter and is held on the planetary carrier (28) such that it can rotate about a first planetary axis of rotation (32) relative to the planetary carrier (28); ◯ at least one second differential planetary gear (36), which meshes with the second sun gear (16) and is held on the planetary carrier (28) such that it can rotate about a second planetary axis of rotation (40), which runs parallel to the first planetary axis of rotation (32) and is spaced apart from the first planetary axis of rotation (32), relative to the planetary carrier (28); and ◯ at least one coupling planet wheel (44), which is arranged coaxially with the first differential planet wheel (30) and is connected in a rotationally fixed manner to the first differential planet wheel (30) and engages in the second differential planet wheel (36) and thereby couples the differential planet wheels (30, 36) to one another, and which has a fourth rolling circle diameter different from the third rolling circle diameter and forms with the first differential planet wheel (30) a differential stepped planet wheel (46), which is held on the planet carrier (28) rotatably about the first planetary axis of rotation (32) relative to the planet carrier (28) and which has the first differential planet wheel (30) as a first stepped planet and the coupling planet wheel (44) as a second stepped planet; wherein a first ratio between the first pitch circle diameter and the second pitch circle diameter and a second ratio between the third pitch circle diameter and the fourth pitch circle diameter are the same, and wherein the transmission device (10) has a planetary gear (62) which has: ◯ at least one stepped planetary gear (64), which is provided in addition to the differential stepped planetary gear (46) and is rotatably held on the planetary carrier (28), and has a first planetary gear (66) as a third stepped planetary gear and a second planetary gear (68), which is connected in a rotationally fixed manner to the third stepped planetary gear, as a fourth stepped planetary gear, ◯ a third sun gear (70), which is provided in addition to the first sun gear (14) and in addition to the second sun gear (16), as a driving sun gear, with which one of the planetary gears (66, 68) is engaged; ◯ a ring gear (72) which is connected or can be connected in a rotationally fixed manner to a housing (18) of the transmission device (10) and to which the other planetary gear (68, 66) of the stepped planetary gear (64) is in engagement, wherein ◯ the second differential planetary gear (36) adjoins the ring gear (72), to which one planetary gear (66) and the other planetary gear (68) of the planetary gear (62), whose ring gear (72) and the other planetary gear (68) adjoin the one planetary gear (66) of the planetary gear (62) in the direction (76), whereby the ring gear (72) and the other planetary gear (68) are arranged between the second differential planetary gear (36) of the spur gear differential (12) and the one planetary gear (66) of the planetary gear (62), as viewed in the axial direction of the second differential planetary gear (36).Transmission device (10) according to Claim 1, characterized in that: - the first differential planetary gear (30) has a first toothing (48), which has a first number of teeth and a first toothing module and engages with the first sun gear (14) and has first teeth (50) with a respective first tooth height; and - the coupling planetary gear (44) has a second toothing (52), which has a second number of teeth and a second toothing module and engages with the second differential planetary gear (36) and has second teeth (54) with a respective second tooth height.Transmission device (10) according to claim 2, characterized in that: - the first number of teeth and the second number of teeth are equal; - the first toothed module and the second toothed module differ from each other; and - the respective first tooth height and the respective second tooth height differ from each other.Transmission device (10) according to Claim 2 or 3, characterized in that the first toothing (48) and the second toothing (52) are rotationally oriented with respect to one another in such a way that a respective gap (56) of the first toothing (48) of the first differential planetary gear (30) is aligned with a respective gap (58) of the second toothing (52) of the coupling planetary gear (44).Transmission device (10) according to one of the preceding claims, characterized in that the stepped planets are formed integrally with one another.Transmission device (10) according to Claim 5 and one of Claims 2 to 4, characterized in that a transition region (60) having a third width (b3) is provided in the axial direction of the respective stepped planet between the first stepped planet having a first width (b1) and the second stepped planet having a second width (b2), wherein a radial outer contour (88) of the differential stepped planet wheel (46) does not fall below a first tip circle diameter (k1) of the second toothing (52) in the transition region (60), but instead rises from the first tip circle diameter (k1) to a second tip circle diameter (k2) of the first toothing (48).Transmission device (10) according to Claim 6, characterized in that the third width (b3) of the transition region (60) is smaller than the first width (b1) of the first stepped planet and smaller than the second width (b2) of the second stepped planet.Transmission device (10) according to one of Claims 1 to 4, characterized in that the first differential planetary gear (30) and the coupling planetary gear (44) are formed separately from one another and are connected to one another, wherein that of the first and second stepped planets whose pitch circle diameter is smaller than the pitch circle diameter of the other of the first and second stepped planets has a projection (84) on which the other stepped planet is fastened.Transmission device (10) according to Claim 8, characterized in that the stepped planets directly adjoin one another in the axial direction of the respective stepped planet.Transmission device (10) according to one of the preceding claims, characterized in that: - the first sun wheel (14) has a third toothing which has a third number of teeth and a third toothing module and which engages into the first differential planetary wheel (30) and has third teeth with a respective third tooth height; - the second sun wheel (16) has a fourth toothing which has a fourth number of teeth and a fourth toothing module and which engages into the second differential planetary wheel (36) and has fourth teeth with a respective fourth tooth height; - the third number of teeth and the fourth number of teeth differ from one another; - the third toothing module and the fourth toothing module are identical; and - the respective third tooth height and the respective fourth tooth height are identical.Transmission device (10) according to one of the preceding claims, characterized in that all the tooth arrangements of the spur gear differential (12) are straight-toothed.Transmission device (10) according to one of the preceding claims, characterized in that the first pitch circle diameter of the first sun wheel (14) is greater than the second pitch circle diameter of the second sun wheel (16), which adjoins the first sun wheel (14) in an arrangement direction (78) running in the axial direction of the first sun wheel (14) and of the second sun wheel (16), which adjoins the third sun wheel (70) in the arrangement direction (78), as a result of which the first sun wheel (14) is arranged between the second sun wheel (16) and the third sun wheel (70) as viewed in the axial direction of the first sun wheel (14) and of the second sun wheel (16).

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