Transmission for an electric drive system of a motor vehicle, as well as an electric drive system with such a transmission

Abstract

Transmission (G) for an electric drive system of a motor vehicle, comprising a housing (GG) with a central section (MG) as well as a first axial end section (E1) and a second axial end section (E2), wherein the central section (MG) of the housing (GG) is configured to accommodate an electric machine (EM), wherein at least one differential gear (D) is arranged in the region of the second end section (E2) of the housing (GG), which is directly or indirectly operatively connected to the electric machine (EM) on the input side, and which is operatively connected on the output side to a first output shaft (AB1) and to a second output shaft (AB2), wherein the differential gear (D) comprises a sun gear (SR), a ring gear (HR), a first planet carrier (PS1) and a second planet carrier (PS2) different from the first planet carrier (PS1) as well as an intermediate gear (ZR), wherein one of these elements of the differential gear (D) is configured toto introduce drive power from the electric machine (EM) into the differential gear (D), wherein the first planet carrier (PS1) of the differential gear (D) is non-rotatably connected to the first output shaft (AB1), wherein the second planet carrier (PS2) of the differential gear (D) is non-rotatably connected to a non-rotatable component of the transmission (G), and wherein the ring gear (HR) of the differential gear (D) meshes with planet gears rotatably mounted on the second planet carrier (PS2) and is non-rotatably connected to the second output shaft (AB2), wherein the two output shafts (AB1, AB2) are arranged coaxially to each other, and wherein the second output shaft (AB2) is at least partially designed as a hollow shaft and the first output shaft (AB1) projects at least partially into the second output shaft (AB2),wherein a single first bearing (L1) for rotatable support of the second output shaft (AB2) is arranged radially between the second output shaft (AB2) and a rotationally fixed component of the gearbox (G), wherein at least a second bearing (L2) for rotatable support of the two output shafts (AB1, AB2) is arranged radially between the first and second output shafts (AB1, AB2).

Description

[0001] The invention relates to a transmission for an electric drive system of a motor vehicle, comprising at least a first planetary gear set, a differential gear, and a first and second output shaft. The invention further relates to an electric drive system for a motor vehicle with a transmission and an electric machine comprising a stator and a rotor.

[0002] WO 2015 / 082 168 A1 discloses a transmission comprising a transmission input shaft and a transmission output shaft, a main gear set, an auxiliary gear set, and an electric machine with a rotor and a stator. The transmission has at least one power path between the transmission input shaft and the main gear set, the main gear set comprising a first and a second planetary gear set with a total of four shafts designated as first, second, third, and fourth shafts in order of rotational speed. The at least one power path is connectable to at least one of the four shafts of the main gear set via at least one switching element. The third shaft of the main gear set is connected to the transmission output shaft. The auxiliary gear set comprises a planetary gear set with a first, second, and third shaft, the first shaft of the auxiliary gear set being permanently connected to the rotor.The first planetary gear set of the main gear set is configured as a plus gear set, and the second planetary gear set of the main gear set is configured as a minus gear set. A web of the first planetary gear set of the main gear set, a web of the second planetary gear set of the main gear set, and a web of the planetary gear set of the auxiliary gear set are interconnected. Furthermore, a ring gear of the planetary gear set of the auxiliary gear set and a ring gear of the first planetary gear set of the main gear set are interconnected. A sun gear of the planetary gear set of the auxiliary gear set meshes with the outer planet gears of the first planetary gear set of the main gear set. DE 602 24 020 T2, DE 10 2020 204 639 A1, DE 10 2012 101 209 A1, DE 10 2017 212 781 A1, DE 10 2020 117 451 A1 and DE 10 2017 214 908 B4 show further designs of gearboxes.

[0003] The object of the invention is to provide an alternative transmission for an electric drive system of a motor vehicle. Furthermore, an electric drive system for a motor vehicle is also to be provided. This object is achieved by the subject matter of claims 1 and 16. Preferred embodiments are the subject matter of the dependent claims.

[0004] A transmission according to the invention for an electric drive system of a motor vehicle comprises a housing with a central section and a first and second axial end section, wherein the central section of the housing is configured to accommodate an electric machine, wherein at least one differential transmission is arranged in the region of the second end section of the housing, which is operatively connected on the input side to at least a first planetary gear set, and which is operatively connected on the output side to a first and second output shaft, wherein the two output shafts are arranged coaxially to each other, and wherein the second output shaft is at least partially designed as a hollow shaft and the first output shaft projects at least partially into the second output shaft, wherein a single first bearing for rotatably supporting the second output shaft is arranged radially between the second output shaft and a rotationally fixed component of the transmission.wherein at least a second bearing for the rotatable mounting of the two output shafts is arranged radially between the first and second output shafts.

[0005] Thus, the first bearing contacts both an inner circumferential surface of the rotationally fixed component of the gearbox and an outer circumferential surface of the second output shaft. In contrast, the second bearing contacts both an inner circumferential surface of the second output shaft and an outer circumferential surface of the first output shaft.

[0006] For the rotatable mounting of the second output shaft relative to the rotationally fixed component of the gearbox, which is preferably designed as a housing cover, only a single bearing is provided, namely the first bearing. According to a preferred embodiment of the invention, the first bearing is designed as a ball bearing. The ball bearing has at least an inner ring arranged on the second output shaft, an outer ring arranged on the rotationally fixed component of the gearbox, and spherical rolling elements that roll between the inner ring and the outer ring. Optionally, a cage can be provided to guide the rolling elements. In particular, the first bearing is designed as a deep groove ball bearing.

[0007] For the rotatable mounting of the first output shaft relative to the second output shaft, which only exhibit a differential rotational speed in certain cases, for example, when cornering, at least one bearing is provided, namely the second bearing. According to a preferred embodiment of the invention, the second bearing is designed either as a rolling bearing or as a plain bearing. The rolling bearing has at least an inner ring arranged on the first output shaft, an outer ring arranged on the second output shaft, and rolling elements that roll between the inner ring and the outer ring. Optionally, a cage can be provided to guide the rolling elements. In particular, the second bearing is designed as a needle roller bearing or needle roller cage, or as a cylindrical roller bearing, wherein at least one or both raceways for the rolling elements are formed directly on one or both output shafts.By designing the second bearing as a radial plain bearing, space and weight can be saved in particular, although the lubrication of the plain bearing should be adapted compared to the rolling bearing.

[0008] The central section of the housing is arranged axially between the first and second axial end sections of the housing. In particular, a housing cover is arranged at each axial end section of the housing and is rotationally fixed to the housing.

[0009] A functional connection between the differential and at least the first planetary gear set means that the differential is either directly connected to the first planetary gear set or at least indirectly connected to the first planetary gear set via several shafts, in particular via further planetary gear sets. Thus, at least one further planetary gear set can be arranged in the power flow between the differential and the first planetary gear set. Furthermore, a functional connection between the first and second output shafts and the differential means that the respective output shaft is either directly connected to a shaft or element of the differential or is in gear mesh with it, or at least one further shaft or element is arranged between the respective output shaft and the shaft or element of the differential.The respective output shaft is preferably operatively connected to a wheel of a drive axle of the motor vehicle.

[0010] For the purposes of the invention, a shaft is understood to be a rotatable component of the transmission, via which the respective components of the transmission are connected to each other in a rotationally fixed manner, or via which such a connection is established when a corresponding switching element is actuated. The shaft can, for example, be designed as a gear, ring gear, sun gear, or planetary gear.

[0011] The electric machine is designed as an electric motor and comprises a stator and a rotor. The drive power is generated via the rotor and a rotor shaft rigidly connected to it, and is then transmitted to the gearbox or the rotating gearbox components. In particular, the electric machine is part of the gearbox and is arranged in a common housing together with at least the first planetary gear set and the differential gear.

[0012] A second output shaft designed at least partially as a hollow shaft means that the second output shaft is either completely or only partially hollow, i.e., tubular. The first output shaft extends partially into the hollow section of the second output shaft, with the second bearing arranged radially between the first and second output shafts within this hollow section.

[0013] According to a preferred embodiment of the invention, at least one third bearing for rotatably supporting the two output shafts is arranged radially between the first and second output shafts. The first and second output shafts only have a differential rotational speed relative to each other in certain cases, for example, when the vehicle is cornering. According to this embodiment, at least two bearings, in particular exactly two bearings, namely the second and third bearings, are provided for rotatably supporting the two output shafts, with both bearings arranged radially between the first and second output shafts. According to a preferred embodiment of the invention, the third bearing is designed either as a rolling bearing or as a plain bearing. The rolling bearing has at least an inner ring arranged on the first output shaft, an outer ring arranged on the second output shaft, and rolling elements that roll between the inner ring and the outer ring.A cage can optionally be provided to guide the rolling elements. In particular, the second bearing is designed as a needle roller bearing or needle roller cage, or as a cylindrical roller bearing, wherein at least one or both running surfaces for the rolling elements are directly adjacent to one or both output shafts. Designing the third bearing as a radial plain bearing allows for significant savings in installation space and weight, although the lubrication of the plain bearing should be adapted compared to that of the rolling bearing.

[0014] For example, the first bearing is arranged axially within the area occupied by the second and third bearings. In other words, the first bearing is either arranged on a common first axis, perpendicular to the axis of rotation of the two output shafts, with the second bearing; or on a common second axis, perpendicular to the axis of rotation of the two output shafts, with the third bearing; or in any position between the first and second axes. The axial distance between the second and third bearings is the bearing base. The greater the length of the bearing base, the smaller the radial force component acting on the first bearing. Thus, the force distribution across the three bearings can be influenced by adjusting the length of the bearing base.

[0015] According to a further preferred embodiment of the invention, the first output shaft is at least partially designed as a hollow shaft, wherein a bearing journal projects at least partially into the first output shaft and at least partially into the second output shaft, wherein at least a third bearing for rotatably supporting the first output shafts is arranged radially between the first output shaft and the bearing journal, the bearing journal being rotationally fixed to the second output shaft. A first output shaft designed at least partially as a hollow shaft is understood to mean that the first output shaft is either completely or only partially designed as a hollow shaft, i.e., tubular. A bearing journal is understood to be a shaft, in particular a cylindrical element, preferably made of solid material, or alternatively tubular, i.e., as a hollow shaft.

[0016] The bearing journal extends partially into the hollow shaft section of the first output shaft and partially into the hollow shaft section of the second output shaft. The third bearing is arranged radially between the first output shaft and the bearing journal in the hollow shaft section of the first output shaft. Thus, the third bearing contacts both an outer circumferential surface of the bearing journal and an inner circumferential surface of the first output shaft. Because the bearing journal is rotationally fixed to the second output shaft, it always rotates at the same speed as the second output shaft. The bearing journal only rotates at a different speed than the first output shaft in certain situations, for example, when the vehicle is cornering. According to a preferred embodiment of the invention, the third bearing is designed either as a rolling bearing or as a plain bearing.The rolling bearing comprises at least one inner ring arranged on the bearing journal, one outer ring arranged on the first output shaft, and rolling elements that roll between the inner and outer rings. Optionally, a cage may be provided to guide the rolling elements. In particular, the third bearing is designed as a needle roller bearing or needle roller cage, or as a cylindrical roller bearing, wherein at least one or both raceways for the rolling elements are formed directly on the bearing journal and / or the first output shaft. Designing the third bearing as a radial plain bearing allows for significant savings in installation space and weight, although the lubrication of the plain bearing should be adapted to that of the rolling bearing.

[0017] For example, the first and second bearings are arranged radially stacked, with the third bearing located axially outside the first and second bearings in a region of the bearing journal. In other words, the first and second bearings are arranged on a common axis, this axis being orthogonal to a rotational axis of the two output shafts. In contrast, the third bearing is not arranged on this common axis, but axially offset from it. The axial distance between the axis on which the first and second bearings are arranged and the third bearing is the bearing base. The greater the length of the bearing base, the smaller the radial force component acting on the first and second bearings. Thus, the force distribution across the three bearings can be influenced by adjusting the length of the bearing base.

[0018] Preferably, the third bearing is arranged at one end of the bearing journal. This maximizes the bearing base while minimizing the radial force component acting on the first and second bearings. In particular, the third bearing is arranged at the end of the bearing journal in a groove provided for this purpose on the bearing journal.

[0019] According to a preferred embodiment of the invention, the rotationally fixed component of the transmission is designed as a housing cover. The housing cover is rotationally fixed to the transmission housing, in particular by bolting. Preferably, the housing cover extends in the region of the second end section of the housing such that the entire differential transmission is arranged within the housing cover.

[0020] Preferably, the differential gear comprises a sun gear, a ring gear, a first and second planet carrier, and an intermediate gear, wherein the sun gear is configured to transmit drive power from the electric machine to the differential gear, wherein the first planet carrier is non-rotatably connected to the first output shaft, wherein the second planet carrier is non-rotatably connected to a non-rotatable component of the gear, and wherein the ring gear is non-rotatably connected to the second output shaft. In particular, the intermediate gear is designed as a ring-type sun gear and has a first toothed section on an inner circumferential surface that serves as a ring gear for the planet gears on the first planet carrier, and wherein the ring-type sun gear has a second toothed section on an outer circumferential surface that serves as a sun gear for the planet gears on the second planet carrier. Thus, the respective planet gears on the first and second planet carrier mesh with the intermediate gear.with the ring-gear sun gear. In particular, the planet gears on the first planetary spar and the planet gears on the second planetary spar are arranged radially one above the other.

[0021] Preferably, a fourth bearing for rotatably supporting the second output shaft relative to the first planet carrier is arranged axially between the second output shaft and the first planet carrier. Thus, the fourth bearing contacts both the first planet carrier and the second output shaft. According to a preferred embodiment of the invention, the fourth bearing is designed either as a rolling bearing or as a plain bearing. In particular, the fourth bearing is designed as a needle roller bearing or needle roller cage, or as a cylindrical roller bearing, wherein at least one or both running surfaces for the rolling elements are located directly on the second output shaft and / or on the first planet carrier. Designing the fourth bearing as an axial plain bearing allows for significant savings in installation space and weight, although the lubrication of the plain bearing should be adapted to that of the rolling bearing.

[0022] According to a preferred embodiment of the invention, a first and second switching element and at least one first planetary gear set are arranged in the region of the first end section of the housing, the first planetary gear set comprising a first, second, and third element. The elements of the first planetary gear set are, in particular, in the form of a sun gear, planet carrier, and ring gear. In particular, the first planetary gear set is designed as a negative planetary gear set. A negative planetary gear set consists of the elements sun gear, planet carrier, and ring gear, wherein the planet carrier rotatably guides at least one, but preferably several, planet gears, each of which meshes with both the sun gear and the surrounding ring gear. When gears mesh with each other, they are in tooth engagement with one another.

[0023] A switching element is understood to be a device that has at least one open and one closed state, wherein, in the open state, the device cannot transmit torque between two elements interacting with this device or switching element, and wherein, in the closed state, the device can transmit torque between two elements interacting with this device or switching element. A connection between two elements is provided for transmitting torques and forces, or a rotary motion, from one transmission element to the other.

[0024] In particular, the first planetary gear set is configured to be operatively connected to the electric machine in order to introduce a drive power from the electric machine into the gearbox, wherein the first element of the first planetary gear set can be connected in a rotationally fixed manner to a rotationally fixed component of the gearbox via the first switching element, wherein the first element of the first planetary gear set can be connected in a rotationally fixed manner to the third element of the first planetary gear set via the second switching element, and wherein the second element of the first planetary gear set is configured to extract the drive power of the electric machine from the first planetary gear set.

[0025] The first and second switching elements are configured to realize a first and second gear stage, respectively. The first gear stage is realized when the first switching element is closed and the second switching element is open, while the second gear stage is realized when the first switching element is open and the second switching element is closed. Thus, when the first switching element is closed, the first element of the first planetary gear set is fixed to the rotationally rigid component of the transmission, specifically braked against a housing cover. The first switching element acts as a brake. When an element is fixed, i.e., non-rotatably connected to a rotationally rigid component of the transmission, it is prevented from rotating.The rotationally fixed component of the gearbox can preferably be a permanently stationary component, preferably a gearbox housing, a part of such a housing or a housing cover that is rotationally fixed to the gearbox housing.

[0026] In contrast, when the second switching element is closed, the first element of the first planetary gear set is rotationally fixed to the third element of the first planetary gear set. When the second switching element is open, the first and third elements of the first planetary gear set can rotate relative to each other. Thus, the second switching element is designed as a clutch. Preferably, both switching elements are open in the unactuated state. Preferably, each switching element has several inner and outer plates. Thus, each switching element is designed as a friction-fit switching element.

[0027] An electric drive system according to the invention for a motor vehicle comprises a transmission and an electric machine according to the invention. In particular, the electric machine is integrated into the housing such that the transmission and the electric machine together form the drive system of the motor vehicle. The stator of the electric machine is arranged non-rotatably on the housing, with at least the first planetary gear set with the two switching elements arranged towards a first end face of the electric machine, and at least the differential gear being arranged towards a second end face of the electric machine. Thus, the motor vehicle is designed as an electric vehicle and comprises the transmission and the electric machine according to the invention, which together form the electric drive system.

[0028] Two exemplary embodiments of the invention will be explained in more detail below with reference to the drawings. Here, [the following is shown] Fig. 1 a highly simplified diagram of an electric drive system of a motor vehicle, shown only in part, Fig. 2 a schematic sectional view of a section of the electric drive system according to Fig. 1, and Fig. 3 a schematic sectional view of a section of the electric drive system according to a second embodiment.

[0029] According to Fig. Figure 1 comprises an electric drive system according to the invention for a motor vehicle, consisting of a transmission G and an electric machine EM with a stator S and a rotor R, wherein the transmission G and the electric machine EM are arranged in a common housing GG. The transmission G comprises a first planetary gear set P1, a differential gear D operatively connected to the first planetary gear set P1, and a first and second output shaft AB1, AB2 operatively connected to the differential gear D. The two output shafts AB1, AB2 are coaxial with the first planetary gear set P1 and the differential gear D, with the first output shaft AB1 extending axially through the entire transmission G. The housing GG has a central section MG and first and second axial end sections E1, E2.The electric machine EM is arranged in the central section MG of the housing GG, with the stator S being rotationally fixed to the housing GG, and the rotor R being rotatably arranged within the stator S. The differential gear D is arranged in the region of the second end section E2 of the housing GG. Furthermore, the first planetary gear set P1 and a first and second switching element B, K are arranged in the region of the first end section E1 of the housing GG. Thus, the electric machine EM borders the first planetary gear set P1 on one end face and the differential gear D on the other end face. The rotor R is connected to the gear set G via a rotor shaft RW.

[0030] The first planetary gear set P1 is operatively connected to the electric machine EM for drive purposes and to the differential gear D for output purposes. In other words, drive power from the electric machine EM is introduced into the gearbox G via the first planetary gear set P1 and then distributed to the two output shafts AB1 and AB2 via the differential gear D. The first planetary gear set P1 comprises a first, second, and third element E11, E21, and E31, respectively. The first element E11 of the first planetary gear set P1 is non-rotatably connected to a rotationally fixed component of the gearbox G via the first switching element B. In this case, the rotationally fixed component of the gearbox G is designed as a housing cover, which is non-rotatably connected to the housing GG. The first element E11 of the first planetary gear set P1 is non-rotatably connected to the third element E31 of the first planetary gear set P1 via the second switching element K.The second element E21 of the first planetary gear set P1 is designed as a planet carrier and configured for output, with several planet gears rotatably mounted on the second element E21 of the first planetary gear set P1, each meshing with both the first element E11 and the third element E11 of the first planetary gear set P1. The first element E11 of the first planetary gear set P1 is designed as a sun gear, and the third element E31 of the first planetary gear set P1 is designed as a ring gear. In this case, the second element E21 of the first planetary gear set P1 is non-rotatably connected to a sun gear SR of the differential gear D.

[0031] The first and second switching elements B and K are configured to implement a first and second gear stage, respectively. The first gear stage is implemented when the first switching element B, configured as a brake, is closed and the second switching element K, configured as a clutch, is open. The second gear stage is implemented when the first switching element B is open and the second switching element K is closed. In the first gear stage, the third element E31 of the first planetary gear set P1 is configured to transmit the drive power from the electric machine EM to the first planetary gear set P1, with the first element E11 of the first planetary gear set P1 being rotationally fixed to the stationary housing cover via the first switching element B.In contrast, the first and third elements E11, E31 of the first planetary gear set P1 in the second gear stage are rotationally fixed to each other and configured to rotate within the block, so that the drive power from the electric machine EM is introduced into the first planetary gear set P1. The two switching elements B, K are arranged within the first axial end section E1 of the housing GG, with the differential gear D being arranged within the second axial end section E2 of the housing GG.

[0032] The differential gear D comprises, in addition to the sun gear SR, a ring gear HR, first and second planet carriers PS1 and PS2, and an intermediate gear ZR, the intermediate gear ZR being designed as a sun gear ring gear and freely rotatable. Several planet gears are rotatably mounted on the first planet carrier PS1, each meshing with both the sun gear SR and an internal toothing of the surrounding intermediate gear ZR. Several planet gears are rotatably mounted on the second planet carrier PS2, each meshing with both an external toothing of the intermediate gear ZR and the ring gear HR. The first planet carrier PS1 is non-rotatably connected to the first output shaft AB1. The second planet carrier PS2 is non-rotatably connected to the housing GG of the gear unit G. Furthermore, the ring gear HR is non-rotatably connected to the second output shaft AB2.

[0033] Fig. Figure 2 shows an excerpt from Fig. 1 according to a sectional view. According to Fig. 1 and Fig. In Figure 2, the second output shaft AB2 is partially designed as a hollow shaft, with the first output shaft AB1 partially projecting into the second output shaft AB2. A single first bearing L1 is arranged radially between the second output shaft AB2 and a housing cover GD in the region of the second end section E2 of the housing GG for rotatable support of the second output shaft AB2. Furthermore, a second and third bearing L2, L3 are arranged radially between the first and second output shafts AB1, AB2 for rotatable support of the two output shafts AB1, AB2. In this case, the first bearing L1 is arranged axially within the second and third bearings L2, L3. When a radial force acts on the second output shaft AB2, the radial force is distributed due to the arrangement of the three bearings L1, L2, L3 such that a larger radial force component acts on the first bearing L1 than on the second and third bearings L2, L3.

[0034] In the excerpt according to Fig. 2. Several details are recognizable due to the cross-sectional view than in Fig. 1. According to Fig. 2. The housing cover GD is axially screwed to the housing GG. The first bearing L1 is designed as a ball bearing, wherein an outer ring of the first bearing L1 is arranged non-rotatably on the housing cover GD, wherein an inner ring of the first bearing L1 is arranged non-rotatably on the second output shaft AB2, and wherein the rolling elements of the first bearing L1 roll between the outer ring and the inner ring. The first bearing L1 is axially secured by means of two retaining rings and sealed by sealing rings arranged radially between the housing cover GD and the second output shaft AB2. The second and third bearings L2, L3 are each designed as needle roller bearings and bear radially against the first and second output shafts AB1, AB2, respectively, wherein the first output shaft AB1 is non-rotatably connected to the first planet carrier PS1, and wherein the second output shaft AB2 is non-rotatably connected to the ring gear HR.A fourth bearing L4 is arranged axially between the second output shaft AB2 and the first planetary carrier PS1 for the rotatable mounting of the second output shaft AB2 relative to the first planetary carrier PS1. The fourth bearing L4 is designed as a needle roller bearing and bears axially against the first planetary carrier PS1 and the second output shaft AB2.

[0035] In Fig. Figure 3 shows a second embodiment of the invention. Fig.In the third section, the first output shaft AB1 and the second output shaft AB2 are partially designed as hollow shafts. A single first bearing L1 is arranged radially between the second output shaft AB2 and a housing cover GD in the region of the second end section E2 of the housing GG for the rotatable mounting of the second output shaft AB2. Furthermore, a second bearing L2 is arranged radially between the first and second output shafts AB1 and AB2 for the rotatable mounting of both output shafts AB1 and AB2. A bearing journal LZ extends partially into the first output shaft AB1 and partially into the second output shaft AB2. The bearing journal LZ is non-rotatably connected to the second output shaft AB2. A third bearing L3 is arranged radially between the first output shaft AB1 and the bearing journal LZ for the rotatable mounting of the first output shaft AB1 relative to the bearing journal LZ.The first and second bearings L1, L2 are arranged radially stacked, with the third bearing L3 located axially outside the first and second bearings L1, L2 in a region of the bearing journal LZ. In this configuration, the third bearing L3 is located at an end region of the bearing journal LZ, while the second bearing L2 is located at an end region of the first output shaft AB1, thus maximizing the bearing base. When a radial force acts on the second output shaft AB2, the arrangement of the three bearings L1, L2, L3 results in a distribution of the radial force such that a larger radial force component acts on the first and second bearings L1, L2 than on the third bearing L3.

[0036] The first bearing L1 is designed as a ball bearing, wherein an outer ring of the first bearing L1 is fixedly mounted to the housing cover GD, and an inner ring of the first bearing L1 is fixedly mounted to the second output shaft AB2, with the rolling elements of the first bearing L1 rolling between the outer and inner rings. The first bearing L1 is axially secured by two retaining rings and sealed by sealing rings arranged radially between the housing cover GD and the second output shaft AB2. The second and third bearings L2 and L3 are each designed as needle roller bearings. The second bearing L2 bears radially against the first and second output shafts AB1 and AB2, respectively, wherein the first output shaft AB1 is fixedly connected to the first planet carrier PS1, and the second output shaft AB2 is fixedly connected to the ring gear HR.The third bearing, L3, rests radially against the first output shaft AB1 and in a circumferential groove against the bearing journal LZ. A fourth bearing, L4, is arranged axially between the second output shaft AB2 and the first planetary web PS1 for the rotatable support of the second output shaft AB2 relative to the first planetary web PS1. The fourth bearing, L4, is designed as a needle roller bearing and rests axially against the first planetary web PS1 and the second output shaft AB2. Reference sign EM electric machine S Stator R Rotor RW rotor shaft B first switching element K second switching element L1 first camp L2 second camp L3 third camp L4 fourth camp P1 first planetary gear set D Differential gear SR sun wheel HR ring gear PS1 First Planet Bridge PS2 second planetary bridge ZR intermediate gear E11 first element of the first planetary gear set E21 second element of the first planetary gear set E31 third element of the first planetary gear set AB1 first output shaft AB2 second output shaft G gearbox GG housing GD housing cover MG middle section E1 first end section E2 second final section

Claims

[1] Transmission (G) for an electric drive system of a motor vehicle, comprising a housing (GG) with a central section (MG) and a first axial end section (E1) and a second axial end section (E2), wherein the central section (MG) of the housing (GG) is configured to accommodate an electric machine (EM), wherein at least one differential gear (D) is arranged in the region of the second end section (E2) of the housing (GG), which is directly or indirectly operatively connected to the electric machine (EM) on the input side, and which is operatively connected to a first output shaft (AB1) and to a second output shaft (AB2) on the output side, wherein the differential gear (D) comprises a sun gear (SR), a ring gear (HR), a first planet carrier (PS1) and a second planet carrier (PS2) different from the first planet carrier (PS1), and an intermediate gear (ZR), wherein one of these elements of the differential gear (D) is configured toto introduce drive power from the electric machine (EM) into the differential gear (D), wherein the first planet carrier (PS1) of the differential gear (D) is non-rotatably connected to the first output shaft (AB1), wherein the second planet carrier (PS2) of the differential gear (D) is non-rotatably connected to a non-rotatable component of the transmission (G), and wherein the ring gear (HR) of the differential gear (D) meshes with planet gears rotatably mounted on the second planet carrier (PS2) and is non-rotatably connected to the second output shaft (AB2), wherein the two output shafts (AB1, AB2) are arranged coaxially to each other, and wherein the second output shaft (AB2) is at least partially designed as a hollow shaft and the first output shaft (AB1) projects at least partially into the second output shaft (AB2),wherein a single first bearing (L1) for rotatable support of the second output shaft (AB2) is arranged radially between the second output shaft (AB2) and a rotationally fixed component of the gearbox (G), wherein at least a second bearing (L2) for rotatable support of the two output shafts (AB1, AB2) is arranged radially between the first and second output shafts (AB1, AB2). [2] Gearbox (G) according to claim 1, wherein at least a third bearing (L3) for rotatable mounting of the two output shafts (AB1, AB2) is arranged radially between the first and second output shaft (AB1, AB2). [3] Gearbox (G) according to claim 2, wherein the first bearing (L1) is arranged axially within a region inside the second and third bearings (L2, L3). [4] Gearbox (G) according to claim 1, wherein the first output shaft (AB1) is at least partially designed as a hollow shaft, wherein a bearing journal (LZ) projects at least partially into the first output shaft (AB1) and at least partially into the second output shaft (AB2), wherein at least a third bearing (L3) for rotatable mounting of the first output shafts (AB1) relative to the bearing journal (LZ) is arranged radially between the first output shaft (AB1) and the bearing journal (LZ), wherein the bearing journal (LZ) is non-rotatably connected to the second output shaft (AB2). [5] Gearbox (G) according to claim 4, wherein the first and second bearings (L1, L2) are arranged radially stacked, wherein the third bearing (L3) is arranged axially outside the first and second bearings (L1, L2) in a region of the bearing journal (LZ). [6] Gearbox (G) according to claim 4 or 5, wherein the third bearing (L3) is arranged at an end region of the bearing journal (LZ). [7] Gearbox (G) according to one of the preceding claims, wherein the first bearing (L1) is designed as a ball bearing. [8] Gearbox (G) according to one of the preceding claims, wherein the second bearing (L2) is designed as a rolling bearing or a sliding bearing. [9] Gearbox (G) according to any one of claims 2 to 8, wherein the third bearing (L3) is designed as a rolling bearing or a sliding bearing. [10] Gearbox (G) according to one of the preceding claims, wherein the rotationally fixed component of the gearbox (G) is designed as a housing cover (GD). [11] Transmission (G) according to one of the preceding claims, wherein the sun gear (SR) of the differential transmission (D) is configured to introduce a drive power from the electric machine (EM) into the differential transmission (D). [12] Gearbox (G) according to claim 11, wherein a fourth bearing (L4) for rotatable support of the second output shaft (AB2) relative to the first planet carrier (PS1) is arranged axially between the second output shaft (AB2) and the first planet carrier (PS1). [13] Transmission (G) according to one of the preceding claims, wherein the differential transmission (D) is operatively connected to the electric machine (EM) on the drive side via a first planetary gear set (P1). [14] Transmission (G) according to claim 13, wherein a first and second switching element (B, K) and the at least one first planetary gear set (P1) are arranged in the region of the first end section (E1) of the housing (GG), wherein the first planetary gear set (P1) comprises a first element (E11), a second element (E21) and a third element (E31). [15] Transmission (G) according to claim 14, wherein the first planetary gear set (P1) is configured to be operatively connected to the electric machine (EM) in order to introduce a drive power from the electric machine (EM) into the transmission (G), wherein the first element (E11) of the first planetary gear set (P1) can be connected in a rotationally fixed manner to a rotationally fixed component of the transmission (G) via the first switching element (B), wherein the first element (E11) of the first planetary gear set (P1) can be connected in a rotationally fixed manner to the third element (E31) of the first planetary gear set (P1) via the second switching element (K), and wherein the second element (E21) of the first planetary gear set (P1) is configured to output the drive power of the electric machine (EM) from the first planetary gear set (P1). [16] Electric drive system for a motor vehicle comprising a transmission (G) according to any one of claims 1 to 15 and an electric machine (EM).

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