Transmission for a vehicle's drivetrain

Abstract

Transmission for a drive train (1) of a vehicle (100), comprising • a first transmission input shaft (W1) for connecting an internal combustion engine (VM), • a second gearbox input shaft (W2) for connecting a first electric machine (EM1), • a third gearbox input shaft (W3) for connecting a second electric machine (EM2), • a differential (2) with a differential input shaft (3) and two differential output shafts (4, 5), • a transmission output shaft (W4) which is at least indirectly connected to the differential input shaft (3) and the second transmission input shaft (W2), • a single switching element (A) for decoupling the first and third transmission input shafts (W1, W3) from the transmission output shaft (W4), wherein the first transmission input shaft (W1) and the third transmission input shaft (W3) are at least indirectly connected, wherein the transmission output shaft (W4) can be connected to the first and third transmission input shafts (W1, W3) by means of the switching element (A) via a first spur gear stage (ST1), consisting of a fixed gear (F1) and a loose gear (L1), characterized in that either • the first and third transmission input shafts (W1, W3) are arranged coaxially to each other and are connected to each other in a rotationally fixed manner, or • the first and third transmission input shafts (W1, W3) are arranged parallel to each other, wherein the first and third transmission input shafts (W1, W3) are connected via a fourth spur gear stage (ST4) consisting of a first fixed gear (F41), a second fixed gear (F42) and an intermediate gear (Z) arranged between them, wherein the first fixed gear (F41) of the fourth spur gear stage (ST4) is rotationally fixed to the third transmission input shaft (W3), and the second fixed gear (F42) of the fourth spur gear stage (ST2) is rotationally fixed to the first transmission input shaft (W1).

Description

[0001] The invention relates to a transmission for a drive train of a vehicle and to a drive train comprising an internal combustion engine, two electric motors, and such a transmission. Thus, the transmission is designed as a hybrid transmission. Furthermore, the invention relates to a vehicle, in particular a motor vehicle, comprising such a drive train.

[0002] For example, DE 11 2018 007 598 T5 discloses a hybrid transmission for a motor vehicle. The hybrid transmission comprises a first electric machine, a second electric machine, a transmission input shaft, and a transmission output shaft. The transmission input shaft is connected to an internal combustion engine via a clutch. The first electric machine transmits the torque to the transmission input shaft, and the second electric machine transmits the torque to the transmission output shaft. A first gear, a third gear, and a fifth gear, as well as a first synchronizer, are loosely arranged on the transmission input shaft. The third gear is rotationally fixed to the fifth gear, and the first synchronizer can rotationally fixedly connect the transmission input shaft to either the first gear or the fifth gear.Furthermore, a second gear is arranged on the transmission output shaft in a rotationally fixed manner, and a fourth gear and a sixth gear are loosely arranged, as well as a second synchronizer. The second synchronizer can selectively connect the transmission output shaft to the fourth gear or the sixth gear in a rotationally fixed manner, with the first gear and the second gear meshing, the third gear and the fourth gear meshing, the fifth gear and the sixth gear meshing, and the second electric machine being connected to the fourth gear in a rotationally fixed manner.

[0003] Furthermore, DE 10 2019 203 485 A1 discloses a hybrid transmission device comprising a drive device, a transmission with a first transmission input shaft, and a second transmission input shaft mounted on the first transmission input shaft. At least two gear wheels are arranged on the second transmission input shaft.

[0004] The gear wheel of the highest gear stage is arranged on the second transmission input shaft in the axial direction towards the outside.

[0005] Furthermore, DE 10 2019 212 141 A1 discloses a hybrid drive train for a motor vehicle, comprising a drive shaft to which an internal combustion engine can be connected, a first input shaft which is connected to the drive shaft or which can be connected to the drive shaft via a clutch, an output shaft arrangement, a transmission arrangement with at least one switchable gear set via which the first input shaft and the output shaft arrangement can be connected to one another, an electric machine which has a rotor, and a switchable planetary gear set arrangement via which the rotor can be connected to the output shaft arrangement.

[0006] DE 10 2016 200 583 A1 discloses a hybrid transmission with a drive shaft that can be connected to a drive motor of a vehicle and to an electric machine. The drive shaft can be connected to a first main shaft and a second main shaft via a first spur gear stage and a second spur gear stage. Shifting elements are assigned to the spur gear stages. Furthermore, a planetary gear set is provided so that at least four gear ratios can be realized. The electric machine is connected to a first element of the planetary gear set, wherein a second element of the planetary gear set can be connected to the drive shaft, and wherein a third element of the planetary gear set is fixed.

[0007] The object of the present invention is to provide an alternative transmission for a vehicle. In particular, the transmission should be compact and efficient. This object is achieved by a transmission having the features of patent claim 1. Advantageous embodiments are the subject of the dependent claims, the following description, and the figures.

[0008] A transmission according to the invention for a drive train of a vehicle comprises a first transmission input shaft for connecting an internal combustion engine, a second transmission input shaft for connecting a first electric machine, a third transmission input shaft for connecting a second electric machine, a differential with a differential input shaft and two differential output shafts, a transmission output shaft which is at least indirectly connected to the differential input shaft and the second transmission input shaft, a single shifting element for decoupling the first and third transmission input shafts from the transmission output shaft, wherein the first transmission input shaft and the third transmission input shaft are at least indirectly connected, wherein the transmission output shaft can be connected to the first and third transmission input shafts by means of the shifting element via a first spur gear stage consisting of a fixed gear and an idler gear.

[0009] The transmission is therefore designed as a hybrid transmission and is intended to connect an internal combustion engine and two electric motors to the differential, which distributes the drive power fed through it to two drive wheels of a drive axle. The internal combustion engine can be connected coaxially or axially parallel to the first transmission input shaft. The first electric motor can be connected coaxially or axially parallel to the second transmission input shaft. The second electric motor can be connected coaxially or axially parallel to the third transmission input shaft.

[0010] The transmission has a particularly simple and efficient design, featuring only a single shifting element and no planetary gear set. The transmission output shaft is at least indirectly connected to the first transmission input shaft and the combustion engine, as well as to the third transmission input shaft and the second electric motor, and can thus also be decoupled from them via the shifting element. Furthermore, the transmission output shaft is at least indirectly connected to the second transmission input shaft and the first electric motor, as well as to the differential input, and thus cannot be decoupled from them.

[0011] An “at least indirect connection” means that two shafts are connected to one another either immediately, i.e. directly, or via further shafts and / or gears. A “shaft” in the sense of the invention is a rotatable component of the transmission, via which associated components of the transmission are connected to one another in a rotationally fixed manner or via which such a connection can be established upon actuation of the switching element. The respective shaft can connect the components axially or radially, or even both axially and radially. The respective shaft can also be in the form of an intermediate piece, via which a respective component is connected radially, for example. The term “shaft” does not exclude the possibility that the components to be connected can be designed as a single piece. In particular, two shafts connected to one another in a rotationally fixed manner can be designed as a single piece.

[0012] A “shifting element” is understood to be a device that, at least in a closed shift position, connects two shafts or gears to one another in a rotationally fixed manner, and in an open shift position decouples the shafts or gears from one another so that they can rotate relative to one another. The shifting element is preferably designed as a positive-locking shifting element, for example as a dog clutch. Alternatively, the shifting element can be designed as a frictional-locking shifting element, for example as a multi-disk friction clutch. A positive-locking shifting element is more compact and efficient than a frictional-locking shifting element. The shifting element is preferably actuated by an actuator. The idler gear of the first spur gear stage can be shifted by means of the shifting element. The idler gear and the fixed gear of the first spur gear stage are in meshing engagement with one another.

[0013] According to a preferred embodiment, the fixed gear of the first spur gear stage is rotationally fixedly connected to the first transmission input shaft, wherein the idler gear of the first spur gear stage is rotatably arranged on the transmission output shaft, wherein the shifting element, in a closed state, rotationally fixedly connects the idler gear of the first spur gear stage to the transmission output shaft. In particular, the shifting element is arranged coaxially to the idler gear and thus to the transmission output shaft. The first spur gear stage realizes an axial offset between a rotational axis of the first transmission input shaft and a rotational axis of the transmission output shaft. The amount of the axial offset can be adjusted via the toothing diameter of the first spur gear stage, wherein the first transmission input shaft can be freely positioned in the tangential direction around the transmission output shaft.

[0014] When the shift element is open, the transmission output shaft is decoupled from the first transmission input shaft and the third transmission input shaft, which is at least indirectly connected to it, so that drive power can only be fed into the differential via the first electric motor, enabling electric drive of the vehicle. When the shift element is closed, all three transmission input shafts are connected to the transmission output shaft, enabling hybrid drive of the vehicle with the combustion engine and the two electric motors.

[0015] According to a preferred embodiment, the fixed gear of the first spur gear stage is rotationally fixedly connected to the transmission output shaft, while the idler gear of the first spur gear stage is rotatably mounted on the first transmission input shaft. In a closed state, the shifting element rotationally fixedly connects the idler gear of the first spur gear stage to the first transmission input shaft. In particular, the shifting element is arranged coaxially with the idler gear and thus with the first transmission input shaft.

[0016] According to a preferred embodiment, a damping device is arranged on the first transmission input shaft. The damping device can comprise a torsional damper and / or a mass damper and / or a slip clutch. The torsional damper can be designed as a dual-mass flywheel. The mass damper can be designed as a speed-adaptive mass damper. In particular, the internal combustion engine is connected to the first transmission input shaft via the damping device.

[0017] According to a preferred embodiment, the transmission output shaft is connected to the second transmission input shaft via a second spur gear stage consisting of a first fixed gear and a second fixed gear, wherein the first fixed gear of the second spur gear stage is rotationally fixedly connected to the second transmission input shaft, wherein the second fixed gear of the second spur gear stage is rotationally fixedly connected to the transmission output shaft. The first and second fixed gears of the second spur gear stage are in tooth engagement with one another. The second spur gear stage realizes an axial offset between a rotational axis of the second transmission input shaft and a rotational axis of the transmission output shaft. The amount of the axial offset can be adjusted via the tooth diameter of the second spur gear stage, wherein the second transmission input shaft can be freely positioned in the tangential direction around the transmission output shaft.Alternatively, a traction drive can be provided to connect the transmission output shaft to the second transmission input shaft.

[0018] According to a preferred embodiment, the transmission output shaft is connected to the differential via a third spur gear stage consisting of a first fixed gear and a second fixed gear, wherein the first fixed gear of the third spur gear stage is rotationally fixedly connected to the differential input shaft, wherein the second fixed gear of the third spur gear stage is rotationally fixedly connected to the transmission output shaft. In particular, the differential input shaft is designed as a differential carrier, wherein the first fixed gear of the third spur gear stage is designed as a toothing on the differential carrier. The first and second fixed gears of the third spur gear stage are in tooth engagement with one another. The third spur gear stage realizes an axial offset between a rotational axis of the differential and a rotational axis of the transmission output shaft.The amount of the axle offset can be adjusted via the tooth diameter of the third spur gear stage, whereby the differential can be freely positioned in the tangential direction around the transmission output shaft.

[0019] According to a first aspect of the invention, the first and third transmission input shafts are arranged coaxially with one another and connected to one another in a rotationally fixed manner. In particular, the second electric motor is arranged coaxially with the first and third transmission input shafts. Preferably, the first and third transmission input shafts are formed as a single piece.

[0020] According to a second aspect of the invention, the first and third transmission input shafts are arranged axially parallel to one another, wherein the first and third transmission input shafts are connected via a fourth spur gear stage consisting of a first fixed gear, a second fixed gear, and an intermediate gear arranged therebetween, wherein the first fixed gear of the fourth spur gear stage is rotationally fixedly connected to the third transmission input shaft, wherein the second fixed gear of the fourth spur gear stage is rotationally fixedly connected to the first transmission input shaft. The first and second fixed gears of the fourth spur gear stage are in tooth engagement with the intermediate gear of the fourth spur gear stage. The fourth spur gear stage realizes an axial offset between a rotational axis of the first transmission input shaft and a rotational axis of the third transmission input shaft.The amount of axial offset can be adjusted via the tooth diameter of the fourth spur gear stage, with the third transmission input shaft being freely positioned tangentially around the first transmission input shaft. For example, the second fixed gear of the fourth spur gear stage and the fixed gear of the first spur gear stage are one component. In other words, the first spur gear stage and the fourth spur gear stage share a single common fixed gear, which is non-rotatably mounted on the first transmission input shaft.

[0021] For example, the first and third transmission input shafts are arranged axially parallel to one another, wherein the third transmission input shaft and the transmission output shaft are connected via a fourth spur gear stage consisting of a fixed gear and an idler gear, wherein the fixed gear of the fourth spur gear stage is rotationally fixedly connected to the third transmission input shaft, wherein the idler gear of the fourth spur gear stage is rotatably mounted on the transmission output shaft and can be rotationally fixedly connected to the transmission output shaft by means of the shifting element. The fixed gear and the idler gear of the fourth spur gear stage are in meshing engagement with one another. The fourth spur gear stage realizes an axial offset between a rotational axis of the transmission output shaft and a rotational axis of the third transmission input shaft.The amount of axial offset can be adjusted via the tooth diameter of the fourth spur gear stage, with the third transmission input shaft being freely positioned tangentially around the transmission output shaft. For example, the idler gear of the fourth spur gear stage and the idler gear of the first spur gear stage are one component. In other words, the first spur gear stage and the fourth spur gear stage share a single common idler gear, which is rotatably mounted on the transmission output shaft.

[0022] According to a preferred embodiment, the second transmission input shaft is designed as a hollow shaft and arranged coaxially with the differential, with one of the two differential output shafts extending axially through the second transmission input shaft. Preferably, the first electric motor is either directly adjacent to the differential or the second spur gear stage is arranged axially between the differential and the first electric motor. This makes the transmission more compact.

[0023] According to a preferred embodiment, the differential is designed as a bevel gear differential. A differential designed as a bevel gear differential has two wheel-side output elements, in particular a first output gear and a second output gear. The two output gears each mesh with a compensating element. The compensating elements are mounted in a differential carrier so as to be rotatable about their own axis. The respective output gear is connected in a rotationally fixed manner to a respective sideshaft. The differential is driven via the differential carrier. The drive power fed into the differential gear, i.e. a speed and a torque, is distributed between the sideshafts and transmitted to the drive wheels of the axle. The sideshafts are designed to be operatively connected to the drive wheels of the vehicle. The respective sideshaft can be directly or immediately or indirectly or.be indirectly connected to the associated drive wheel via a joint, a cardan shaft and / or a wheel hub.

[0024] According to a preferred embodiment, the first transmission input shaft is arranged on a first rotational axis, the second transmission input shaft is arranged on a second rotational axis, and the transmission output shaft is arranged on a third rotational axis. The three rotational axes are arranged axially parallel to one another. Preferably, the internal combustion engine is arranged on the first rotational axis, and the first electric motor and the differential are arranged on the second rotational axis.

[0025] A drive train according to the invention comprises an internal combustion engine, a first electric machine, at least one second electric machine, and a transmission according to the invention, wherein the internal combustion engine and the first electric machine are arranged axially parallel to one another. The drive train preferably has a third electric machine for driving a further drive axle of the vehicle. A vehicle according to the invention has a drive train according to the invention, i.e., a drive train with a transmission according to the invention. The above definitions as well as statements regarding technical effects, advantages, and advantageous embodiments of the transmission according to the invention also apply mutatis mutandis to the drive train according to the invention and to the vehicle according to the invention.

[0026] Advantageous embodiments of the invention, which are explained below, are illustrated in the drawings. They show: Fig. 1 is a highly abstracted schematic view of a vehicle with a drive train comprising a transmission according to the invention according to a first embodiment; Fig. 2 a highly abstracted schematic view of the drive train with the transmission according to the invention according to Fig. 1; Fig. 3 a highly abstracted schematic view of a drive train with a transmission according to the invention according to a second embodiment; Fig. 4 a highly abstracted schematic view of a drive train with a transmission according to the invention according to a third embodiment; Fig. 5 a highly abstracted schematic view of a drive train with a transmission according to the invention according to a fourth embodiment; and Fig. 6 a highly abstracted schematic view of a drive train with a transmission not according to the invention.

[0027] Fig. 1 shows the vehicle 100 with a first drive axle 101 with two wheels R1, R2 and a second drive axle 102 with two wheels R3, R4. In the present case, the first drive axle 101 is designed as the front axle of the vehicle 100 and is equipped with a transmission designed as a hybrid transmission, which driveably connects an internal combustion engine VM, a first electric machine EM1, and a second electric machine EM2 to the wheels R1, R2 of the first drive axle 101. For this purpose, the transmission has a differential 2 and a single shift element A. The internal combustion engine VM and the second electric machine EM2 are designed coaxially with one another. Furthermore, the differential 2 and the first electric machine EM1 are designed coaxially with one another and axially parallel to the internal combustion engine VM and the second electric machine EM2.A third electric motor EM3 is arranged on the second drive axle 102, i.e., the rear axle of the vehicle 100, for the electric motor drive of the rear axle. The third electric motor EM3 on the second drive axle 102 implements an all-wheel drive system. In particular, the third electric motor EM3 is drivingly connected to the wheels R3, R4 of the second drive axle 102 via a differential (not shown in detail) on the second drive axle 102. Alternatively, the drive on the second drive axle 102 of the vehicle 100 can be omitted, thereby saving costs, weight, and installation space. In the present case, the internal combustion engine VM, together with the three electric motors EM1, EM2, EM3, and the transmission, forms the drive train 1 of the vehicle 100. The transmission is arranged transversely to the vehicle's longitudinal direction.

[0028] Fig. 2 shows schematically the drive train 1 according to Fig. 1, where the first drive axle is only partially shown, and the second drive axle with the third electric motor is not shown at all. The focus is on the design of the transmission and the connection of the first and second electric motors EM1, EM2 and the combustion engine VM.

[0029] The transmission comprises a first transmission input shaft W1 for connecting the internal combustion engine VM, wherein a damping device 6 designed as a torsional damper is arranged on the first transmission input shaft W1. In this case, a crankshaft of the internal combustion engine VM is rotationally fixedly connected to an input of the damping device 6, wherein the first transmission input shaft W1 is rotationally fixedly connected to an output of the damping device 6. Drive power from the internal combustion engine VM is introduced into the transmission via the first transmission input shaft W1.

[0030] The transmission further comprises a second transmission input shaft W2 for connecting the first electric machine EM1, a third transmission input shaft W3 for connecting the second electric machine EM2, a transmission output shaft W4, which is indirectly connected to a differential input shaft 3 of the differential 2 and the second transmission input shaft W2, and the shifting element A, by means of which the transmission output shaft W4 can be indirectly connected to the first and third transmission input shafts W1, W3. The differential 2 further has two differential output shafts 4, 5 for connecting the respective wheel of the first drive axle.

[0031] The first transmission input shaft W1 and the third transmission input shaft W3 are arranged coaxially to one another and connected to one another in a rotationally fixed manner. The second transmission input shaft W2 is designed as a hollow shaft and arranged coaxially to the differential 2, with the second differential output shaft 5 extending axially through the second transmission input shaft W2. The first and third transmission input shafts W1, W3, together with the internal combustion engine VM and the second electric machine, are arranged on a first axis of rotation A1. The second transmission input shaft W2 with the first electric machine EM1 and the differential 2 are arranged on a second axis of rotation A2. The transmission output shaft W4 and the shift element A are arranged on a third axis of rotation A3. The three axes of rotation A1, A2, A3 are arranged axially parallel to one another and thus have a radial axis distance.

[0032] The transmission output shaft W4 is connectable to the first and third transmission input shafts W1, W3 via a first spur gear stage ST1, consisting of a fixed gear F1 and an idler gear L1. The fixed gear F1 of the first spur gear stage ST1 is rotationally fixedly connected to the first transmission input shaft W1, with the idler gear L1 of the first spur gear stage ST1 being rotatably mounted on the transmission output shaft W4. The fixed gear F1 of the first spur gear stage ST1 and the idler gear L1 of the first spur gear stage ST1 are in meshing engagement. The shifting element A is arranged coaxially to the transmission output shaft W4 and, when closed, rotationally fixedly connects the idler gear L1 of the first spur gear stage ST1 to the transmission output shaft W4.Furthermore, in an open state, shift element A decouples idler gear L1 of the first spur gear stage ST1 from transmission output shaft W4, so that transmission output shaft W4 and the first and third transmission input shafts W1, W3 are decoupled and can rotate independently of each other. Shift element A is preferably designed as a positive-locking shift element, but can alternatively be designed as a friction-locking shift element. A positive-locking shift element is more compact and efficient than a friction-locking shift element.

[0033] The transmission output shaft W4 is connected to the second transmission input shaft W2 via a second spur gear stage ST2, consisting of a first fixed gear F21 and a second fixed gear F22. The first fixed gear F21 of the second spur gear stage ST2 is rotationally fixedly connected to the second transmission input shaft W2. The second fixed gear F22 of the second spur gear stage ST2 is rotationally fixedly connected to the transmission output shaft W4. The first fixed gear F21 of the second spur gear stage ST2 and the second fixed gear F22 of the second spur gear stage ST2 are meshing.

[0034] Furthermore, the transmission output shaft W4 is connected to the differential 2 via a third spur gear stage ST3, consisting of a first fixed gear F31 and a second fixed gear F32. The first fixed gear F31 of the third spur gear stage ST3 is rotationally fixedly connected to the differential input shaft 3, while the second fixed gear F32 of the third spur gear stage ST3 is rotationally fixedly connected to the transmission output shaft W4. The first fixed gear F31 of the third spur gear stage ST3 and the second fixed gear F32 of the third spur gear stage ST3 are meshing.

[0035] A hybrid drive is realized when switching element A is closed, whereby the combustion engine and both electric machines EM1, EM2 are connected to the differential 2. When switching element A is open, two driving modes are realized: purely electric driving and serial driving. During purely electric driving, the differential 2 is driven only by the first electric machine EM1, with the combustion engine VM and the second electric machine EM2 not participating in the drive and, in particular, are stationary. During serial driving, the combustion engine VM drives the second electric machine EM2, whereby the second electric machine EM2 generates electrical energy in generator mode for the motor operation of the first electric machine EM1, which drives the differential 2. Serial driving is therefore a battery-neutral driving mode.

[0036] Fig. Figure 3 shows a second embodiment of a drive train 1 with a transmission according to the invention. The transmission according to Fig. 3 essentially corresponds to the gearbox according to Fig. 2, the difference between these two embodiments being the connection of the second electric machine EM2. In the present case, the first and third transmission input shafts W1, W3 are not arranged coaxially to one another and connected in a rotationally fixed manner, but are arranged axially parallel to one another and connected via a fourth spur gear stage ST4, consisting of a first fixed gear F41, a second fixed gear F42 and an intermediate gear Z arranged therebetween. Thus, the second electric machine EM2 and the combustion engine VM are also arranged axially parallel to one another. The first fixed gear F41 of the fourth spur gear stage ST4 is connected in a rotationally fixed manner to the third transmission input shaft W3, while the second fixed gear F42 of the fourth spur gear stage ST2 is connected in a rotationally fixed manner to the first transmission input shaft W1. The intermediate gear Z is rotatably mounted and meshes with the two fixed gears F41, F42 of the fourth spur gear stage ST4.Otherwise, the embodiment corresponds to . Fig. 3 the embodiment according to Fig. 2, to which reference is made.

[0037] Fig. Figure 4 shows a third embodiment of a drive train 1 with a transmission according to the invention. The transmission according to Fig. 4 essentially corresponds to the gearbox according to Fig. 3, whereby the difference between these two embodiments lies in the arrangement of the shifting element A and the design of the first spur gear stage ST1. In the present case, the fixed gear F1 of the first spur gear stage ST1 is connected in a rotationally fixed manner to the transmission output shaft W4. Thus, exactly three fixed gears F1, F21, F31 are arranged on the transmission output shaft W4. The idler gear L1 of the first spur gear stage ST1 is rotatably arranged on the first transmission input shaft W1. The shifting element A is arranged coaxially to the first transmission input shaft W1 and, in a closed state, connects the idler gear L1 of the first spur gear stage ST1 in a rotationally fixed manner to the first transmission input shaft W1. Otherwise, the embodiment according to Fig. 4 the embodiment according to Fig. 3, to which reference is made.

[0038] Fig. Figure 5 shows a fourth embodiment of a drive train 1 with a transmission according to the invention. The transmission according to Fig. 5 essentially corresponds to the gearbox according to Fig. 3, whereby the difference between these two embodiments lies in the design of the fourth spur gear stage ST4. In the present case, the second fixed gear F42 of the fourth spur gear stage ST4 and the fixed gear F1 of the first spur gear stage ST1 are one component. In other words, the first spur gear stage ST1 and the fourth spur gear stage ST4 share a single common fixed gear F1, F42, which is arranged in a rotationally fixed manner on the first transmission input shaft W1. Thus, because the second electric machine EM2 is directly connected to the first spur gear stage ST1 via the fourth spur gear stage ST4, Fig. 3 a fixed gear on the first transmission input shaft W1 is saved. Otherwise, the embodiment according to Fig. 5 the embodiment according to Fig. 3, to which reference is made.

[0039] Fig. 6 shows an embodiment of a drive train 1 with a transmission not according to the invention. The transmission according to Fig. 6 essentially corresponds to the gearbox according to Fig. 2, the difference between these two embodiments being the connection of the second electric machine EM2. In the present case, the first and third transmission input shafts W1, W3 are not arranged coaxially to one another and connected in a rotationally fixed manner, but are arranged axially parallel to one another. The third transmission input shaft W3 and the transmission output shaft W4 are connected via a fourth spur gear stage ST4', consisting of a fixed gear F4 and an idler gear L4. The fixed gear F4 of the fourth spur gear stage ST4' is connected in a rotationally fixed manner to the third transmission input shaft W3. The idler gear L4 of the fourth spur gear stage ST4' and the idler gear L1 of the first spur gear stage ST1 are one component. In other words, the first spur gear stage ST1 and the fourth spur gear stage ST4' share a single common idler gear L1, L4, which is rotatably arranged on the transmission output shaft W4.The idler gear L1, L4 meshes with the fixed gear F4 and can be connected in a rotationally fixed manner to the transmission output shaft W4 by means of the shift element A. Thus, since the second electric machine EM2 is directly connected to the first spur gear ST1 via the fourth spur gear stage ST4', one fixed gear and one intermediate gear are eliminated. Otherwise, the embodiment shown in FIG. Fig. 6 the embodiment according to Fig. 2, to which reference is made. Reference symbol 1 drivetrain 2 differentials 3 Differential input shaft 4 Differential output shaft 5 Differential output shaft 6 Damping device 100 vehicles 101 first drive axle 102 second drive axle R1 wheel R2 wheel R3 bike R4 wheel W1 first transmission input shaft W2 second transmission input shaft W3 third transmission input shaft W4 gearbox output shaft VM combustion engine EM1 first electric machine EM2 second electric machine EM3 third electric machine ST1 first spur gear stage F1 fixed gear L1 idler gear ST2 second spur gear stage F21 first fixed gear F22 second fixed gear ST3 third spur gear stage F31 first fixed gear F32 second fixed gear ST4 fourth spur gear stage F41 first fixed gear F42 second fixed gear Z intermediate gear ST4' fourth spur gear stage F4 fixed gear L4 idler gear A switching element A1 first rotation axis A2 second rotation axis A3 third rotation axis

Claims

[1] Transmission for a drive train (1) of a vehicle (100), comprising • a first transmission input shaft (W1) for connecting an internal combustion engine (VM), • a second transmission input shaft (W2) for connecting a first electric machine (EM1), • a third transmission input shaft (W3) for connecting a second electric machine (EM2), • a differential (2) with one differential input shaft (3) and two differential output shafts (4, 5), • a transmission output shaft (W4) which is at least indirectly connected to the differential input shaft (3) and the second transmission input shaft (W2), • a single switching element (A) for decoupling the first and third transmission input shafts (W1, W3) from the transmission output shaft (W4), wherein the first transmission input shaft (W1) and the third transmission input shaft (W3) are at least indirectly connected, wherein the transmission output shaft (W4) can be connected to the first and third transmission input shafts (W1, W3) by means of the switching element (A) via a first spur gear stage (ST1), consisting of a fixed gear (F1) and a loose gear (L1), characterized by that either • the first and third transmission input shafts (W1, W3) are arranged coaxially to one another and are connected to one another in a rotationally fixed manner, or • the first and third transmission input shafts (W1, W3) are arranged axially parallel to one another, wherein the first and third transmission input shafts (W1, W3) are connected via a fourth spur gear stage (ST4), consisting of a first fixed gear (F41), a second fixed gear (F42) and an intermediate gear (Z) arranged therebetween, wherein the first fixed gear (F41) of the fourth spur gear stage (ST4) is connected in a rotationally fixed manner to the third transmission input shaft (W3), wherein the second fixed gear (F42) of the fourth spur gear stage (ST2) is connected in a rotationally fixed manner to the first transmission input shaft (W1). [2] Transmission according to claim 1, wherein the fixed gear (F1) of the first spur gear stage (ST1) is connected in a rotationally fixed manner to the first transmission input shaft (W1), wherein the idler gear (L1) of the first spur gear stage (ST1) is rotatably arranged on the transmission output shaft (W4), wherein the switching element (A) in a closed state connects the idler gear (L1) of the first spur gear stage (ST1) to the transmission output shaft (W4) in a rotationally fixed manner. [3] Transmission according to claim 1, wherein the fixed gear (F1) of the first spur gear stage (ST1) is connected in a rotationally fixed manner to the transmission output shaft (W4), wherein the idler gear (L1) of the first spur gear stage (ST1) is rotatably arranged on the first transmission input shaft (W1), wherein the switching element (A) in a closed state connects the idler gear (L1) of the first spur gear stage (ST1) to the first transmission input shaft (W1) in a rotationally fixed manner. [4] Transmission according to one of the preceding claims, wherein the switching element (A) is designed as a positive switching element. [5] Transmission according to one of claims 1 to 3, wherein the switching element (A) is designed as a frictional switching element. [6] Transmission according to one of the preceding claims, wherein a damping device (6) is arranged on the first transmission input shaft (W1). [7] Transmission according to one of the preceding claims, wherein the transmission output shaft (W4) is connected to the second transmission input shaft (W2) via a second spur gear stage (ST2) consisting of a first fixed gear (F21) and a second fixed gear (F22), wherein the first fixed gear (F21) of the second spur gear stage (ST2) is connected in a rotationally fixed manner to the second transmission input shaft (W2), wherein the second fixed gear (F22) of the second spur gear stage (ST2) is connected in a rotationally fixed manner to the transmission output shaft (W4). [8] Transmission according to one of the preceding claims, wherein the transmission output shaft (W4) is connected to the differential (2) via a third spur gear stage (ST3) consisting of a first fixed gear (F31) and a second fixed gear (F32), wherein the first fixed gear (F31) of the third spur gear stage (ST3) is connected in a rotationally fixed manner to the differential input shaft (3), wherein the second fixed gear (F32) of the third spur gear stage (ST3) is connected in a rotationally fixed manner to the transmission output shaft (W4). [9] Transmission according to one of the preceding claims, wherein the second transmission input shaft (W2) is designed as a hollow shaft and is arranged coaxially to the differential (2), wherein one of the two differential output shafts (4, 5) extends axially through the second transmission input shaft (W2). [10] Transmission according to one of the preceding claims, wherein the first transmission input shaft (W1) is arranged on a first axis of rotation (A1), wherein the second transmission input shaft (W2) is arranged on a second axis of rotation (A2), wherein the transmission output shaft (W4) is arranged on a third axis of rotation (A3), wherein the three axes of rotation (A1, A2, A3) are arranged axially parallel to one another. [11] Drive train (1) comprising an internal combustion engine (VM), a first electric machine (EM1), at least one second electric machine (EM2) and a transmission according to one of claims 1 to 10, wherein the internal combustion engine (VM) and the first electric machine (EM1) are arranged axially parallel to one another. [12] Vehicle (100) with a drive train (1) according to claim 11.

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