Hybrid transmission for a motor vehicle powertrain

Abstract

Hybrid transmission (14) for a motor vehicle powertrain (10), with - a first shaft (20) for connection to an internal combustion engine (12); - a second shaft (22) which can be connected to the first shaft (20) via at least one gear set (24;30) which can be switched by means of a switching element (C;A), wherein the second shaft (22) is connected to an output (17); - a third shaft (40) which can be connected to a first electric machine (EM1) by means of at least one switching element (E;F), wherein the first electric machine (EM1) is arranged coaxially to the third shaft (40) and wherein the third shaft (40) is connected to the second shaft (22) via a coupling gear set (42); wherein the third shaft (40) is arranged parallel offset to the first shaft (20), so that the first electric machine (EM1) is arranged axially offset from the first shaft (20), wherein the coupling gear set (42) comprises a fixed gear (44) fixed to the third shaft (40) and a fixed gear (46) fixed to the second shaft (22), which are connected via an intermediate gear (48), wherein the intermediate gear (48) is rotatably mounted on the first shaft (20), and where the intermediate gear (48 IV ) is a double gear which engages in a first gear set plane (R1) with the fixed gear (44) fixed to the third shaft (40) and engages in an axially offset second gear set plane (R2) with the fixed gear fixed to the second shaft (46).

Description

[0001] The present invention relates to a hybrid transmission for a motor vehicle powertrain, comprising a first shaft for connection to an internal combustion engine, a second shaft which can be connected to the first shaft via at least one gear set switchable by means of a switching element, wherein the second shaft is connected to an output, and a third shaft which can be connected to a first electric machine by means of at least one switching element.

[0002] Hybrid powertrains for motor vehicles generally feature an internal combustion engine that can provide drive power to propel the vehicle, as well as an electric machine that, depending on the operating mode, can provide drive power for the vehicle alternatively or additionally to the internal combustion engine.

[0003] Hybrid powertrains utilize a variety of different concepts, each employing a different approach to connecting the electric motor to the transmission within the hybrid powertrain. In dual-clutch transmissions, a typical variant involves arranging the electric motor concentrically to an input element of the dual-clutch assembly. It is also known to assign an electric motor to one of the two sub-transmissions in dual-clutch transmissions.

[0004] Furthermore, it is known to arrange an electric machine concentrically to a first input shaft, wherein a rotor of the electric machine is connected to a hollow shaft that is arranged around the input shaft.

[0005] Document DE 10 2013 215 114 A1 discloses a hybrid drive for a motor vehicle in which an electric motor can be connected to an output shaft of a hybrid transmission via a spur gear set. Furthermore, this document discloses arranging an electric motor coaxially to a transmission output shaft, axially offset from a planetary gear set designed as a superimposed transmission for electric motor drive power and for internal combustion engine drive power.

[0006] Hybrid transmissions are preferably designed as powershift transmissions. The axial length of the hybrid transmission is particularly important when installed transversely to the direction of travel in a vehicle (front-transverse or rear-transverse). Furthermore, when installed transversely to the direction of travel, the surrounding installation environment often needs to be considered. Potential bottlenecks include a joint between side shafts, a transmission mount, and / or a lower longitudinal member of the vehicle.

[0007] Generally, it is preferable for an electric motor that provides drive power for a hybrid powertrain to have a large outer diameter. Such electric motors often have a short axial design, but due to their large outer diameter, they frequently fit poorly into installation space. This is especially true when the electric motor is located on the side facing away from the combustion engine, towards a wheel of the vehicle.

[0008] Hybrid transmissions are known from documents WO 2018 / 028 747 A1, US 2017 / 0 274 ​​757 A1, DE 10 2013 221 461 A1, DE 10 2013 221 061 A1, DE 10 2016 012 811 A1 and WO 2020 / 035 558 A1.

[0009] Against this background, it is an object of the present invention to provide an improved hybrid transmission for a motor vehicle powertrain.

[0010] The above problem is solved by a hybrid transmission for a motor vehicle powertrain according to claim 1, comprising a first shaft for connection to an internal combustion engine, a second shaft which can be connected to the first shaft via at least one gear set switchable by means of a switching element, wherein the second shaft is connected to an output, and a third shaft which can be connected to a first electric machine by means of at least one switching element, wherein the first electric machine is arranged coaxially to the third shaft and wherein the third shaft is connected to the second shaft via a coupling gear set, wherein the third shaft is arranged parallel offset to the first shaft, so that the first electric machine is arranged axially offset from the first shaft.

[0011] The hybrid transmission includes a first electric motor for providing drive power. Furthermore, the hybrid transmission includes a first shaft for connection to an internal combustion engine. The first shaft is preferably a transmission input shaft and is preferably connected coaxially to the internal combustion engine. The hybrid transmission is designed to perform purely internal combustion engine operation, whereby internal combustion engine drive power can be transmitted to the output via the first shaft, the at least one switchable gear set, and the second shaft.

[0012] The output shaft can include a power distribution device such as a differential.

[0013] Furthermore, the electromotive drive power of the first electric machine can be directed to the third shaft via the at least one switching element, and from there via the coupling gear set to the second shaft, which is connected to the output.

[0014] The coupling gear set is a spur gear set by means of which a transmission ratio is established between the first electric motor and the second shaft. Internal combustion engine power and electric motor power can be summed in the second shaft. The hybrid transmission can include a planetary gear set for establishing a further pre-reduction ratio between the first electric motor and the second shaft, the planetary gear set preferably being arranged coaxially with the third shaft.

[0015] The third shaft is arranged parallel to and offset from the first shaft, such that the first electric machine is arranged axially offset from the first shaft.

[0016] This measure allows an axis offset to be essentially established between the first shaft, which is preferably arranged coaxially to an internal combustion engine drive shaft, and the first electric machine, which is arranged coaxially to the third shaft.

[0017] Furthermore, the first electric motor is preferably arranged in the region of an axial end of the hybrid transmission. The first electric motor preferably has a relatively large outer diameter. Due to the axial offset between the first and third shafts, it is nevertheless possible to accommodate such a large electric motor in a front-transverse installation space within a motor vehicle, thereby avoiding or preventing installation by constraints such as a joint of a side shaft, a transmission mount, and / or a lower longitudinal member of the vehicle. In other words, despite these constraints, a comparatively large first electric motor with a large diameter can be used in the hybrid transmission.

[0018] The hybrid transmission preferably includes at least two and preferably a maximum of six forward gears for combustion engine operation. It is particularly preferred that the number of forward gears for purely combustion engine operation is four. This allows combustion engine operation to be achieved over a wide speed range.

[0019] For electric-powered driving, the hybrid transmission is designed so that this can be implemented either in a single gear, but preferably in two different gears. Consequently, electric-powered driving can also be achieved over a relatively wide speed range.

[0020] Preferably, electric motor drive power and combustion engine drive power can be summed in the second shaft and then jointly directed to the output.

[0021] Preferably, the hybrid transmission does not have a mechanical reverse gear. Reversing is preferably carried out exclusively by means of the first electric motor (and / or by means of an optionally provided second electric motor).

[0022] The first electric motor can also be used to support traction during gear changes in purely combustion engine driving mode.

[0023] Because the third shaft can be connected to the first electric machine by means of at least one switching element, the first electric machine can be decoupled in purely combustion engine driving mode, thus avoiding drag losses.

[0024] The following terms can be understood in the context of this disclosure in particular as follows: A gear pair comprises exactly two gears that mesh with each other. Two meshing gears are to be understood in particular as two gears whose teeth mesh. The gears preferably each have spur teeth, are preferably arranged in a radial plane, and are preferably each assigned to a different shaft. The gears of the gear pair can be two fixed gears (so-called constant gear set). In a switchable gear pair, the two gears can be a fixed gear and a loose gear (su), which preferably together define a gear stage (su).

[0025] A gear set comprises at least two meshing (especially mating) gears and can include one or more gear pairs, preferably located in a common radial gear set plane. If a gear set has a fixed gear meshing with two different loose gears, the gear set can define two gear ratios; this is also referred to as dual use of the fixed gear. Generally, a gear set can also be a planetary gear set.

[0026] A loose gear is a gear rotatably mounted on a shaft, which can be connected to or disconnected from the shaft by means of a switching element. A fixed gear is a gear that is fixed to a shaft and cannot rotate.

[0027] A switching element serves to connect or disconnect links, such as a gear and a shaft, and is in this case formed in particular by a switching clutch, especially a positive-locking switching clutch, such as a jaw clutch. However, the switching clutch can also be a synchronous switching clutch.

[0028] A double switching element comprises two switching elements, preferably assigned to different loose gears on a shaft, which can be switched alternatively by means of a single actuating device to connect one of the loose gears to the shaft at a time. Furthermore, the double switching element includes a neutral position in which neither of the loose gears is connected to the shaft.

[0029] Two elements that can rotate relative to each other are connected if they necessarily rotate at a proportional speed. The term "connected" is synonymous with "functionally connected." A "rotationally fixed connection" means that the two elements rotate at the same speed. Two elements can be connected if they can either be engaged or disengaged from each other. Preferably, the elements can be connected by means of a switching element such as a clutch or a brake.

[0030] Two elements are axially aligned if they overlap at least partially in the axial direction and / or if they lie in a common radial plane.

[0031] The task is completely solved.

[0032] According to the hybrid transmission, the coupling gear set has a fixed gear fixed to the third shaft and a fixed gear fixed to the second shaft, which are connected via an intermediate gear.

[0033] The coupling gear set is preferably located axially in a region between the at least one switchable gear set and the first electric machine.

[0034] In the hybrid transmission, the intermediate gear is rotatably mounted on the first shaft. This allows for a defined and relatively large axial offset between the third and first shafts. Furthermore, a separate shaft for the intermediate gear can be eliminated.

[0035] According to the hybrid transmission, the intermediate gear is a double gear that engages with the fixed gear on the third shaft in a first gear set plane and engages with the fixed gear on the second shaft in an axially offset second gear set plane.

[0036] In this context, a double gear is understood to be a device comprising two axially offset gears on a single base body, which in particular have different diameters and / or different numbers of teeth. In this way, the double gear can be used to adjust the gear ratio between the rotational speed of the fixed gear on the third shaft and the rotational speed of the fixed gear on the second shaft over an even wider range.

[0037] Furthermore, this measure may make it possible to vary the relative position of the first electric motor with respect to the first shaft to an even greater extent, thus enabling the accommodation of a radially large first electric motor in a narrow front-transverse or rear-transverse installation space. These advantages can compensate for any potential disadvantage of a slightly greater axial length.

[0038] Overall, it is also advantageous if the hybrid transmission has a fourth shaft which can be connected to the first shaft via at least one gear set switchable by means of a switching element, wherein the fourth shaft is connected to the output.

[0039] In this embodiment, the second and fourth shafts form an output shaft arrangement. A driven gear is preferably attached to each shaft, with the two driven gears of the second and fourth shafts respectively meshing with an input element of a power distribution device such as a differential. The driven gears are preferably arranged between the gear sets and an input of the hybrid transmission, i.e., in particular between the gear sets and an internal combustion engine.

[0040] It is preferred if the second shaft can be connected to the first shaft via two switchable gear sets and / or if the fourth shaft can be connected to the first shaft via two switchable gear sets.

[0041] It is particularly advantageous if there are exactly two switchable gear sets in each case. The resulting four switchable gear sets thus allow for four different forward gear ratios to be set up for combustion engine operation.

[0042] According to a further preferred embodiment, at least one switchable gear set for connecting the first shaft to the second shaft and at least one switchable gear set for connecting the first shaft to the fourth shaft share a fixed gear fixed to the first shaft.

[0043] It is particularly advantageous if the second shaft and the fourth shaft can each be connected to the first shaft via two switchable gear sets, and if both switchable gear sets for connecting the first shaft to the second shaft and both switchable gear sets for connecting the first shaft to the fourth shaft each share a fixed gear fixed to the first shaft.

[0044] In this case, preferably exactly two fixed gears are fixed to the first shaft, each of which engages with two loose gears that are rotatably mounted on the second shaft and the fourth shaft, respectively.

[0045] Overall, this results in a particularly compact axial design. This further contributes to the fact that the hybrid transmission according to the invention can be easily installed in a front-transverse or a rear-transverse mounting space.

[0046] According to a generally preferred embodiment, the first electric machine can be connected to the third shaft via at least one planetary gear set.

[0047] The planetary gear set is preferably a switchable planetary gear set. It is particularly advantageous if two of the three elements of the planetary gear set are connectable to each other and / or if one element of the planetary gear set is connectable to a housing. Furthermore, it is preferred if at least one element of the planetary gear set is connected to a rotor of the first electric machine.

[0048] Furthermore, it is advantageous if a first element of the planetary gear set is connected to the third shaft and / or if a second element of the planetary gear set can be connected to a housing and / or if a third element of the planetary gear set is connected to a rotor of the first electric machine.

[0049] The first member of the planetary gear set is preferably a sun gear. The second member of the planetary gear set is preferably a ring gear. The third member of the planetary gear set is preferably a planet carrier (bridge) of the planetary gear set.

[0050] Furthermore, it is advantageous if the second element of the planetary gear set can be connected to the housing by means of a switching element. It is also preferred if the second element can be connected to the first element by means of another switching element. It is further advantageous if the two switching elements are integrated into a double switching element, by means of which a neutral position can also be established, so that neither switching element is engaged and consequently the first electric motor is decoupled from the third shaft. This reduces drag losses during purely combustion engine operation.

[0051] According to a further preferred embodiment, the planetary gear set is arranged at least partially radially within a rotor of the first electric machine and / or is arranged at least partially axially overlapping with the rotor of the first electric machine.

[0052] This allows for a saving of axial installation space when using a first electric motor with a relatively large diameter. Consequently, the hybrid gearbox can be built with a compact axial design.

[0053] Overall, it is also advantageous if a second electric machine is connected to the first shaft via another coupling gear set.

[0054] The second electric motor is preferably arranged such that it is connected to the first shaft via a spur gear connection. Preferably, the second electric motor is therefore arranged parallel and offset from the first shaft. The second electric motor is preferably arranged such that it is axially overlapping with at least one gear set of the hybrid transmission and is preferably radially and / or axially spaced from the first electric motor.

[0055] The additional coupling gear set preferably includes a pinion that is rotationally fixed to the drive shaft of the second electric machine, and further includes a fixed gear fixed to the first shaft. The fixed gear can be a fixed gear from a gear set. Alternatively, the pinion can also be connected to or meshed with a loose gear from one of the gear sets.

[0056] The second electric motor can cover, for example, the following functions: - a combustion engine start from a purely electric driving mode using the first electric motor; - an on-board power supply; - a serial creep mode in which the second electric machine is driven by the internal combustion engine to charge a battery without any internal combustion engine drive power being applied to the output shaft, and in which a creep mode is established by means of the first electric machine, using energy from the vehicle battery which is supplied by generator operation of the second electric machine; - driving forwards and backwards, whereby all gear stages of the gear sets can be used that can also be used for combustion engine driving operation; - Support for speed control of the internal combustion engine during coupling and gear changes; in this way, the internal combustion engine can preferably be coupled in all forward gear stages from a purely electric driving mode using the first electric machine; - Load shifting can be performed during combustion engine operation, even if the shift elements assigned to the switchable gear sets are designed as dog clutches; in this case, a load reduction can occur at a source shift element and a simultaneous load build-up can occur at the first electric machine (for which the first electric machine must be connected to the third shaft); the load reduction can then take place by the combustion engine and / or the second electric machine reducing the torque; subsequently, the source shift element can be opened for a low output gear stage; then the speeds of the combustion engine or the electric motor are reduced.The second electric machine is lowered so that a target switching element becomes synchronized; for this purpose, for example, the second electric machine can operate as a generator (preferred), or the combustion engine can enter overrun mode; finally, the target switching element can be engaged for a higher gear stage. - The speed of the first electric machine can be reduced in hybrid operation, whereby gear changes can be made in the background without load, thereby reducing its speed, for example; this switching can take place while the combustion engine (and / or the second electric machine) maintains traction in one of the combustion engine forward gear stages; - In hybrid mode, the first electric motor can be decoupled, allowing for efficient combustion engine driving.

[0057] Furthermore, it is generally advantageous if the hybrid transmission has a disconnect clutch to connect the first shaft to an internal combustion engine. The disconnect clutch can be a positive-locking switching element, but it can also be a friction clutch.

[0058] When the disconnect clutch is open, electric motor operation is possible using the first electric motor and the second electric motor.

[0059] In combustion engine or hybrid mode, the disconnect clutch remains closed at all times. This ensures that the combustion engine is always connected to the second electric motor.

[0060] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0061] An embodiment of the invention is shown in the drawings and is explained in more detail in the following description. The drawings show: Fig. 1 a schematic representation of an embodiment of a motor vehicle powertrain with a hybrid transmission; Fig. 2 a shift table for the hybrid transmission of the Fig. 1; Fig. 3 a schematic representation of another embodiment of a hybrid transmission; Fig. 4 a schematic representation of another embodiment of a hybrid transmission; Fig. 5 a schematic representation of another embodiment of a hybrid transmission; Fig. 6 a schematic representation of another embodiment of a hybrid transmission.

[0062] In Fig. Figure 1 schematically depicts a motor vehicle powertrain, generally designated by 10. The motor vehicle powertrain 10 comprises an internal combustion engine 12 and a hybrid transmission 14. The hybrid transmission 14 includes an output shaft 17 with a power distribution unit 16. The power distribution unit 16 is designed to distribute drive power to driven wheels 18L and 18R. The motor vehicle powertrain 10 is specifically designed for transverse installation in a motor vehicle, either front-transverse or rear-transverse.

[0063] The hybrid transmission 14 comprises a first shaft 20 and a second shaft 22. The second shaft 22 is connected to the first shaft 20 via a first gear set 24. The first gear set 24 includes a fixed gear 26, which is rotationally fixed to the first shaft, and a loose gear 28, which is rotatably mounted on the second shaft 22. The loose gear 28 can be connected to the second shaft 22 by means of a shift element C to engage a gear.

[0064] The second shaft 22 can also be connected to the first shaft 20 via a second gear set 30. The second gear set 30 comprises a fixed gear 32, which is fixed to the first shaft 20, and a loose gear 34, which is rotatably mounted on the second shaft 22. The loose gear 34 can be connected to the second shaft 22 by means of a switching element A to establish an additional gear stage.

[0065] The second shaft 22 is rigidly connected to an output wheel 36, which engages with an input element of the power distribution device 16.

[0066] The first shaft 20 is preferably arranged coaxially with a drive shaft of the internal combustion engine 12. Preferably, the first shaft is connected to the output element of a disconnect coupling K0, the input element of which can be connected to the internal combustion engine 12. The disconnect coupling K0 can be a positive-locking coupling, such as a jaw coupling, as shown, but can also be a friction coupling. Alternatively, the first shaft 20 can also be rotationally fixed to a drive shaft of the internal combustion engine 12.

[0067] With the disconnect clutch K0 closed, internal combustion engine drive power can be transmitted via the first gear set 24 or the second gear set 30 to the second shaft 22 and from there via the output 17 (including the output gear 36) to the power distribution device 16 in order to establish an internal combustion engine driving operation in two different gear stages.

[0068] The hybrid transmission 14 further includes a third shaft 40. The third shaft 40 is connected to the second shaft 22 via a connecting gear set 42. The connecting gear set 42 is preferably a spur gear set. Alternatively or additionally, it is preferred that the connecting gear set is a constant-ratio gear set.

[0069] The coupling gear set 42 comprises a fixed gear 44, which is fixed to the third shaft 40, and a fixed gear 46, which is fixed to the second shaft 22. In one possible embodiment, the fixed gears 44 and 46 are directly engaged with each other.

[0070] In the present case, however, the coupling gear set 42 also includes an intermediate gear 48, whereby both the fixed gear 44 and the fixed gear 46 are engaged with the intermediate gear 48.

[0071] The intermediate gear 48 can be rotatably mounted on a separate shaft. In the present case, however, the intermediate gear 48 is rotatably mounted on the first shaft 20.

[0072] The coupling gear set 42 is arranged on one side of the gear sets 24, 30 facing away from the disconnect coupling K0, viewed in the axial direction.

[0073] The hybrid transmission includes a first electric motor EM1, which has a relatively large diameter. The first electric motor EM1 is arranged on the side of the gear sets 24, 30 facing away from the disconnect clutch K0 and is preferably arranged at one axial end of the hybrid transmission 14 facing away from the disconnect clutch K0. The first electric motor EM1 is arranged coaxially with the third shaft 40 and can be connected to the third shaft by means of at least one switching element, E, F.

[0074] The hybrid transmission 14 further includes a planetary gear set 50. The planetary gear set is preferably arranged at least partially radially within a rotor 52 of the first electric machine EM1 and / or at least partially axially overlapping with the rotor 52. The first electric machine EM1 further includes a stator 54, which is connected to a housing 56.

[0075] The planetary gear set 50 comprises a first element 58, a second element 60, and a third element 62. The first element 58 is preferably a sun gear and is preferably non-rotatably connected to the third shaft 40. The second element 60 is preferably a ring gear. The third element 62 is preferably a planet carrier. The third element 62 is preferably non-rotatably connected to the rotor 52.

[0076] The second link 60 can be connected to the third shaft 40 or the first link 58 by means of a switching element E. Furthermore, the second link 60 can be connected to the housing 56 by means of another switching element F.

[0077] The switching elements E and F form a double switching element that can also establish a neutral position in which the second element 60 of the planetary gear set 50 is connected neither to the housing 56 nor to the first element 58. In this case, the first electric motor EM1 is decoupled from the output. This neutral position can be set during purely combustion engine operation to reduce drag losses.

[0078] Fig. Figure 1 further shows that a parking lock wheel P can be arranged on the third shaft 40. However, the parking lock wheel P, which is part of a parking lock assembly, can alternatively also be arranged on the second shaft 22 (or on the fourth shaft described below).

[0079] The switching elements E and F are preferably arranged axially between the planetary gear set 50 and the connecting gear set 44. The connecting gear set 44 is preferably axially adjacent to one of the gear sets, in this case axially adjacent to the second switchable gear set 30.

[0080] As it is in Fig. As shown in Figure 4, an axial offset V between the first shaft 20 and the third shaft 40 is established via the coupling gear set 42, more precisely via the gear pairing between the fixed gear 44 and the intermediate gear 48. This allows the use of a first electric motor with a relatively large axial diameter even in difficult installation situations in a front-transverse installation space of a motor vehicle.

[0081] The hybrid transmission 14 further includes a fourth shaft 64. The fourth shaft 64 is non-rotatably connected to an output gear 66, which lies in the same radial plane as the output gear 36 and which is connected to an input element of the power distribution device 16.

[0082] The fourth shaft 64 can be connected to the first shaft 20 via a third gear set 68. The third gear set 68 includes the fixed gear 26 and a loose gear 70, which is rotatably mounted on the fourth shaft 64. The loose gear 70 can be connected to the fourth shaft 64 by means of a switching element D.

[0083] The fourth shaft 64 can also be connected to the first shaft 20 by means of a fourth gear set 72. The fourth gear set 72 includes a fixed gear that is fixed to the first shaft 20, in this case the fixed gear 32 of the second gear set. Furthermore, the fourth gear set 72 has a loose gear 74 that is rotatably mounted on the fourth shaft 64. The loose gear 74 can be connected to the fourth shaft 64 by means of a switching element B.

[0084] The switching elements A and C of the first and second gear sets form a double switching element, by means of which either switching element C or switching element A is switched. However, the double switching element can also establish a neutral position in which neither of the two switching elements C and A is switched.

[0085] Furthermore, the switching element D and the switching element B form a double switching element, so that either the switching element D is switched or the switching element B is switched or a neutral position is set up.

[0086] The double switching elements C, A and D, B are arranged in the axial direction between the first and second gear sets 24, 30 and the third and fourth gear sets 68, 72 respectively.

[0087] Optionally, the hybrid transmission 14 also includes a second electric motor EM2. The second electric motor EM2 has a motor shaft 76 to which a fixed gear (pinion) 78 is attached. The fixed gear 78 engages with one of the gear sets, in this case with the fixed gear 26 of the first gear set 24. Consequently, the second electric motor EM2 is connected to the first shaft 20.

[0088] The first shaft 20 and the optional disconnect clutch K0 are preferably arranged on a first axis A1, on which a drive shaft or crankshaft 80 of the internal combustion engine 12 is also arranged when the latter is connected to the hybrid transmission. The second shaft 22 lies on an axis A2, together with the loose gears 24, 30 and the double shift element C, A. The fourth shaft 64 lies on a fourth axis A4, together with the loose gears 70, 74 and the double shift element D, B.

[0089] The third shaft 40 lies on a third axis A3. The power distribution device 16 lies on an axis A5, and the motor shaft 76 lies on an axis A6. The axes A1 to A6 are preferably offset from each other or parallel to each other.

[0090] The hybrid transmission 14 has multiple radial planes. In a first radial plane, viewed from an input of the hybrid transmission 14, lies the output with the output gears 36, 66. In an axially adjacent plane lie the first gear set 24 and the third gear set 68. In a subsequent radial plane lie the double shift elements C, A and D, B, respectively. In a subsequent radial plane lie the second gear set 30 and the fourth gear set 72. In a subsequent radial plane lies the coupling gear set 42.

[0091] In a subsequent radial plane lies the double switching element E, F, and in a radial plane located at the outermost axial end lie the first electric machine EM1 and the planetary gear set 50.

[0092] The second electric machine EM2 is designed to overlap axially with the radial plane in which the second and fourth gear sets 30, 72 are arranged, and / or preferably to overlap axially with the radial plane in which the coupling gear set 42 is arranged.

[0093] The hybrid transmission 14 allows the following gear ratios to be set, as shown in the shift table of the Fig. 2 is shown.

[0094] The selectable gear ratios comprise four forward combustion engine gear ratios, V1 to V4. In all of these gear ratios, V1 to V4, the disconnect clutch K0 is closed, if one is present. In the first combustion engine gear ratio, V1 (starting gear), the shift element A is closed. In the second combustion engine gear ratio, V2, the shift element B is closed. In the third combustion engine gear ratio, V3, the shift element C is closed. In the fourth combustion engine gear ratio, V4, the shift element D is closed.

[0095] The same switching elements must be closed when hybrid operation is established using the combustion engine 12 and the second electric machine EM2. Furthermore, purely electric driving operation using the second electric machine EM2 can be established using the same switching elements A to D, in which case the disconnect clutch K0 is opened.

[0096] To establish purely electric drive operation using the first electric motor EM1, the disconnect clutch K0 is also opened. Two gear stages, E1 and E2, are then possible. In the first electric motor gear stage E1, the switching element E is closed. In the second electric motor gear stage E2, the switching element F is closed.

[0097] Both forward and reverse operation can be set up in the electric motor gear stages E1 and E2. Furthermore, the electric motor power from the first electric motor EM1 can be summed with the electric motor power from the second electric motor EM2 if, for example, one of the switching elements A to D is closed.

[0098] Serial operation is possible in two gear stages, as shown in Fig. Figure 2 is shown for Ser1 and Ser2. In both cases, the clutch K0 is closed and none of the elements A to D are closed. Consequently, the internal combustion engine can be driven to power the second electric machine EM2, which acts as a generator to produce electrical power for charging a battery (not shown). During this operation, the first electric machine EM1 can provide electromotive drive power, with either the switching element E or the switching element F closed. Electromotive drive power therefore flows from the third shaft 40 via the coupling gear set 42 to the second shaft 22, and from there to the output 17.

[0099] The electrical power drawn from the vehicle battery for this driving mode is compensated for, or "recharged," by the generator operation of the second electric machine EM2. Consequently, purely electric driving mode, especially in a creep mode (i.e., at very low speeds, below a minimum speed for purely combustion-engine operation), can be maintained for a relatively long period, even if the vehicle battery is relatively small.

[0100] In the Fig. Figures 3 to 6 show further embodiments of hybrid transmissions which, in terms of structure and function, are generally similar to hybrid transmission 14. Fig. 1. Furthermore, in all hybrid transmissions, the Fig. 3 to 6 the switching table of the Fig. 2 applicable. The differences are explained in detail below.

[0101] In Fig. Figure 3 shows a hybrid transmission 14' in which the disconnect clutch K0 is not present. In this case, the crankshaft 80 and the first shaft 20 are rotationally fixed to each other. With this variant, which is comparatively inexpensive, purely electric drive operation using the second electric machine EM2 is generally not possible, since the combustion engine 12 would have to be dragged along.

[0102] In Fig. Figure 4 shows a hybrid transmission 14'' in which an alternative planetary gear set 50'' is used. The alternative planetary gear set 50'' includes a first element 58'' in the form of a ring gear, which is non-rotatably connected to the third shaft 40. Furthermore, the alternative planetary gear set 50'' includes a second element 60'', which is formed by the sun gear of the planetary gear set. The second element 60'' can be connected to the housing 56 by means of the switching element F or to the third element 62'' by means of the switching element E. The third element 62'' (planet carrier) of the alternative planetary gear set 50'' is non-rotatably connected to the rotor 52 of the first electric machine EM1.

[0103] The alternative planetary gear set 50'' can be used in place of the planetary gear set 50 in all embodiments. Likewise, the planetary gear set 50 can be used in all embodiments. Fig. 1 can be used.

[0104] Fig. Figure 5 shows a hybrid transmission 14''' with an alternative realization of a coupling gear set 42'''.

[0105] The coupling gear set 42''' includes the fixed gears 44, 46, which are connected to the third shaft 40 and the second shaft 22 respectively, and an intermediate gear 48'''. Unlike the previous embodiments, the intermediate gear 48''' is not rotatably mounted on the first shaft 20. Instead, the intermediate gear 48''' is non-rotatably connected to a fifth shaft 84, which is rotatably mounted on a housing, on an axis A7 that differs from the axis A1 of the first shaft 20 and preferably does not coincide with any of the other axes A2 to A6.

[0106] By arranging the intermediate gear 48''' on a separate fifth shaft 84, greater freedom is achieved in the arrangement of the first electric machine EM1 in the installation space.

[0107] In Fig. 6 is another hybrid transmission 14 IVshown, which is also an alternative embodiment of a coupling gear set 42 IV Includes the coupling gear set 42. IV The first radial plane R1 includes the fixed gear 44, which is fixed to the third shaft 40. Furthermore, the coupling gear set 40 includes IV The fixed gear 46 is fixed to the second shaft 22. The fixed gear 46 lies in a second axially adjacent radial plane R2.

[0108] An intermediate gear 48 IV is designed as a double gear, with two gears non-rotatably connected to each other, one of which lies in the first radial plane R1 and the other of which lies in the second radial plane R2. One gear of the double gear meshes with the fixed gear 44. The other gear of the double gear meshes with the fixed gear 46. The intermediate gear 48 is designed as a double gear. IVIn this case, it is rotatably mounted on the first shaft 20, but it can also be mounted on a fifth shaft 84, similar to the embodiment of the Fig. 5.

[0109] Through the double gear 48 IV and the additional spur gear pair thus realized can provide an additional gear ratio for the first electric machine EM1. Reference sign 10 Automotive powertrain 12 Internal combustion engine 14 hybrid transmissions 17 Drive 16. Service distribution system 18L / R driven wheels 20 first wave 22 second wave 24 first gear set 26" fixed wheel 28 Loose wheel 30 second gear set 32 Fixed wheel 34 Loose wheel 36 Output gear 40 third wave 42 coupling wheel set 44 Fixed wheel 46 Fixed wheel 48 Intermediate wheel 50 planetary gear set 52 Rotor EM1 54 Stator EM1 56 cases 58 first item 60 second item 62 third item 64 fourth wave 66 Output gear 68 third gear set 70 Loose wheel 72 fourth gear set 74 Loose wheel 76 Motor shaft EM2 78 Fixed wheel 80 Crankshaft 84 fifth wave K0 disconnect coupling EM1 first electric machine V-axis offset EM2 second electric machine P Parking lock wheel A1-A7 axles C first switching element A second switching element The third switching element B fourth shell element E fifth switching element F sixth switching element R1 first radial plane R2 second radial plane

Claims

[1] Hybrid transmission (14) for a motor vehicle powertrain (10), with - a first shaft (20) for connection to an internal combustion engine (12); - a second shaft (22) which can be connected to the first shaft (20) via at least one gear set (24;30) which can be switched by means of a switching element (C;A), wherein the second shaft (22) is connected to an output (17); - a third shaft (40) which can be connected to a first electric machine (EM1) by means of at least one switching element (E;F), wherein the first electric machine (EM1) is arranged coaxially to the third shaft (40) and wherein the third shaft (40) is connected to the second shaft (22) via a coupling gear set (42); wherein the third shaft (40) is arranged parallel offset to the first shaft (20), so that the first electric machine (EM1) is arranged axially offset from the first shaft (20), wherein the coupling gear set (42) comprises a fixed gear (44) fixed to the third shaft (40) and a fixed gear (46) fixed to the second shaft (22), which are connected via an intermediate gear (48), wherein the intermediate gear (48) is rotatably mounted on the first shaft (20), and where the intermediate gear (48 IV ) is a double gear which engages in a first gear set plane (R1) with the fixed gear (44) fixed to the third shaft (40) and engages in an axially offset second gear set plane (R2) with the fixed gear fixed to the second shaft (46). [2] Hybrid transmission according to claim 1, with a fourth shaft (64) which can be connected to the first shaft (20) via at least one gear set (68; 72) which can be switched by means of a switching element (D; B), wherein the fourth shaft (64) is connected to the output (17). [3] Hybrid transmission according to claim 2, wherein the second shaft (22) can be connected to the first shaft (20) via two switchable gear sets (24, 30) and / or wherein the fourth shaft (64) can be connected to the first shaft (20) via two switchable gear sets (24, 30). [4] Hybrid transmission according to claim 2 or 3, wherein at least one switchable gear set (24, 30) for connecting the first shaft (20) to the second shaft (22) and at least one switchable gear set (68, 72) for connecting the first shaft (20) to the fourth shaft (64) share a fixed gear (26, 30) fixed to the first shaft (20). [5] Hybrid transmission according to one of claims 1-4, wherein the first electric machine (EM1) can be connected to the third shaft (40) via at least one planetary gear set (50). [6] Hybrid transmission according to claim 5, wherein two (58, 60; 60 II , 62 II) of three links of the planetary gear set (50) are connectable to each other and / or a link (60) of the planetary gear set (50) is connectable to a housing (56). [7] Hybrid transmission according to claim 5 or 6, wherein - a first link (58) of the planetary gear set (50) is connected to the third shaft (40), and / or - a second member (60) of the planetary gear set (50) can be connected to a housing (56), and / or - a third link (62) of the planetary gear set (50) is connected to a rotor (52) of the first electric machine (EM1). [8] Hybrid transmission according to one of claims 5 to 7, wherein the planetary gear set (50) is arranged at least partially radially within a rotor (52) of the first electric machine (EM1) and / or at least partially axially overlapping with the rotor (52) of the first electric machine (EM1). [9] Hybrid transmission according to one of claims 1-8, wherein a second electric machine (EM2) is connected to the first shaft (20) via a further coupling gear set (78, 26). [10] Hybrid transmission according to one of claims 1-9, comprising a disconnect coupling (K0) for connecting the first shaft (20) to an internal combustion engine (12).

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