Compact hybrid transmission

Abstract

Hybrid transmission (18) for a motor vehicle powertrain (12) of a motor vehicle (10), comprising: a first transmission input shaft (24) for connecting the hybrid transmission (18) with an internal combustion engine (16) of the motor vehicle (10); a second transmission input shaft (26) for connecting the hybrid transmission (18) with a first electric drive motor (14) of the motor vehicle (10); a first intermediate shaft (30) which is connected to the first transmission input shaft (24) in a drive-effective manner; a second intermediate wave (32), an output shaft (28) for connecting the hybrid transmission (18) with an output (38); a first planetary gear set (RS1) which is connected to the second intermediate shaft (32), the second transmission input shaft (26) and the output shaft (28); a countershaft (34); Spur gear pairs (ST1, ST2, ST3) arranged in several gear set planes to form gear steps; and several gearshift devices with shifting elements (A, B, C, D, E) for engaging gear stages, wherein the spur gear pairs (ST1, ST2, ST3) each have a fixed gear arranged on the countershaft (34); at least two pairs of spur gears (ST1, ST2, ST3) are arranged directly axially adjacent to each other to form the gear steps; a differential of the output (38) comprises a differential shaft which is designed as a solid shaft and is at least partially surrounded by the first intermediate shaft (30), the second intermediate shaft (32), the second transmission input shaft (26) and the output shaft (28); and an axial length of the differential shaft is greater than an axial length of the output shaft (28) and the differential shaft completely penetrates the output shaft (28).

Description

[0001] The present invention relates to a hybrid transmission, a motor vehicle drive train with such a hybrid transmission, a motor vehicle with such a motor vehicle drive train and a method for operating such a motor vehicle drive train.

[0002] Vehicles are increasingly being equipped with hybrid drives, i.e. with at least two different drive sources. Hybrid drives can help reduce fuel consumption and pollutant emissions. Drivetrains with an internal combustion engine and one or more electric motors as parallel hybrids or mixed hybrids have largely become established. Such hybrid drives feature an essentially parallel arrangement of the internal combustion engine and the electric drive in the power flow. This allows both a superposition of the drive torques and control with purely internal combustion engine drive or purely electric motor drive. Since the drive torques of the electric drive and the internal combustion engine can be added together depending on the control, a comparatively smaller design of the internal combustion engine and / or its temporary shutdown is possible.This allows for a significant reduction in CO2 emissions without any significant loss of performance or comfort. The possibilities and advantages of an electric drive can thus be combined with the range, performance, and cost advantages of internal combustion engines.

[0003] A disadvantage of the aforementioned hybrid drives is their generally more complex design, as both drive sources typically transmit power to a single drive shaft via a single transmission. This makes such transmissions complex and costly to produce. Reducing the complexity of a hybrid transmission's design usually results in a loss of variability.

[0004] This disadvantage can be at least partially overcome by dedicated hybrid transmissions (DHTs), in which an electric motor is integrated into the transmission to provide the full range of functions. For example, the mechanical transmission part of the transmission can be simplified, for example by eliminating the reverse gear and using at least one electric motor instead.

[0005] Dedicated hybrid transmissions can be derived from familiar transmission concepts, such as dual-clutch transmissions, torque converter planetary transmissions, continuously variable transmissions (CVTs), or automated manual transmissions. The electric motor is preferably integrated into the transmission.

[0006] The published patent application DE 10 2011 005 562 A1 relates to a manual transmission of a hybrid drive for a motor vehicle, with two input shafts and a common output shaft. The first input shaft can be connected to the drive shaft of an internal combustion engine via a controllable separating clutch and can be brought into drive connection with the output shaft via a first group of selectively switchable gear sets. The second input shaft is in drive connection with the rotor of an electric machine operable as a motor and as a generator, as well as with the first input shaft, via a superposition gear designed as a planetary gear, and can be brought into drive connection with the output shaft via a second group of selectively switchable gear sets. Both input shafts can be brought into drive connection with one another via a switchable coupling device.For cost-effective production, the manual transmission is derived from a dual-clutch transmission with two coaxial input shafts, the first input shaft of which is arranged centrally, the second input shaft of which is designed as a hollow shaft and arranged coaxially above the first input shaft, and the coupling device of which comprises a gear stage and / or a switchable clutch, which are provided instead of the gear set and its associated gear clutch which, in the underlying dual-clutch transmission, is assigned to the first input shaft and is arranged axially adjacent to the transmission-side end of the second input shaft. The published patent application DE 10 2020 104 791 A1 relates to a transmission assembly comprising a first transmission input shaft and a second transmission input shaft. The first transmission input shaft and the second transmission input shaft are coupled to a first planetary gear in a torque-conducting manner.Furthermore, a transmission output shaft of the transmission assembly is coupled to a second planetary gear in a torque-conducting manner. A first spur gear is arranged between the first planetary gear and the second planetary gear in the power flow. Furthermore, a drive unit for driving a first vehicle axle is presented, which has such a transmission assembly.

[0007] The published patent application DE 10 2017 221 775 A1 relates to a hybrid drive train for a vehicle having at least one internal combustion engine with a VM drive shaft, in particular a crankshaft, and at least one first electric machine with a first EM drive shaft, wherein the internal combustion engine and the first electric machine are designed to transmit a torque to at least one drive axle, and further having a transmission having a transmission input shaft and a transmission output shaft which is operatively connected to a first drive axle drivable by the internal combustion engine, wherein the transmission input shaft of the transmission is connected at least to the VM drive shaft of the internal combustion engine in order to transmit a torque from the internal combustion engine to the transmission input shaft and further to the first drive axle, wherein the transmission input shaft and the VM drive shaft of the internal combustion engine are arranged parallel to one another.

[0008] Against this background, a person skilled in the art is faced with the task of creating a compact hybrid transmission with a simple mechanical design. Furthermore, a drivetrain configuration should preferably be implemented in which the hybrid transmission is positioned coaxially to the output shafts and the combustion engine and / or the electric drive motor can be arranged axially parallel to it. In particular, a transmission is to be created that enables charging-to-neutral, electrodynamic starting (EDA), and electrodynamic shifting (EDS).

[0009] This task is solved by a hybrid transmission for a motor vehicle drive train of a motor vehicle, with: a first transmission input shaft for operatively connecting the hybrid transmission to an internal combustion engine of the motor vehicle; a second transmission input shaft for operatively connecting the hybrid transmission to a first electric drive motor of the motor vehicle; a first intermediate shaft drivingly connected to the first transmission input shaft; a second intermediate shaft; an output shaft for operatively connecting the hybrid transmission to an output; a first planetary gear set connected to the second intermediate shaft, the second transmission input shaft and the output shaft; a countershaft; spur gear pairs arranged in several gear set levels to form gear steps; and several gearshift devices with switching elements for engaging gear steps, whereby the spur gear pairs each have a fixed gear arranged on the countershaft; and at least two pairs of spur gears are arranged directly axially adjacent to one another to form the gear stages.

[0010] The above object is further achieved by a motor vehicle drive train for a motor vehicle, comprising: a hybrid transmission as previously defined; an internal combustion engine connectable to the first transmission input shaft; and a first electric drive motor which is drivingly connected to the second transmission input shaft.

[0011] The above object is also achieved by a method for operating a motor vehicle drive train as previously defined.

[0012] The above task is finally solved by a motor vehicle with: a motor vehicle powertrain as previously defined; and an energy storage device for storing energy to supply the first electric drive machine and / or a second electric drive machine.

[0013] Preferred embodiments of the invention are described in the dependent claims. It is understood that the features mentioned above and those to be explained below can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the present invention. In particular, the motor vehicle drive train, the motor vehicle, and the method can be designed according to the embodiments described for the hybrid transmission in the dependent claims.

[0014] By providing a first transmission input shaft for operatively connecting the hybrid transmission to an internal combustion engine and a second transmission input shaft for operatively connecting the hybrid transmission to a first electric drive motor, a compact hybrid transmission can be created in a technically simple manner. An operative connection can be designed to be either switchable or non-switchable. In particular, a hybrid transmission can be created that is arranged around one of the vehicle shafts on the front axle, with the internal combustion engine and the first electric drive motor arranged axially parallel to it. Directly adjacent means, in particular, that no switching element is arranged between the two spur gear pairs.The advantageous connection of the planetary gear set, the shifting elements, and the shafts allows for a total of three hybrid gear stages, one purely electric gear stage, two electrodynamic overlay states, and a charging-in-neutral state. The hybrid transmission, in particular, makes it possible to use a shifting-element-free countershaft, which is cost-effective to manufacture. A compact hybrid transmission with low transmission losses and good gearing efficiency can be created, both for combustion engine and purely electric operation. The hybrid transmission features an advantageous gear ratio range and is suitable for performing electrodynamic shifts and electrodynamic starting.

[0015] A differential of the output comprises a differential shaft, which is designed as a solid shaft and is at least partially surrounded by the first intermediate shaft, the second intermediate shaft, the second transmission input shaft, and the output shaft. An axial length of the differential shaft is greater than an axial length of the output shaft, with the differential shaft completely penetrating the output shaft. This allows the hybrid transmission to advantageously be arranged around the differential shaft. The compactness of the drive train can be improved. It is understood that an axially parallel connection of the internal combustion engine and an axially parallel connection of the first electric drive motor can preferably be provided. The hybrid transmission is particularly preferably designed to be arranged around a front axle of a motor vehicle.

[0016] In an advantageous embodiment, the hybrid transmission comprises a second planetary gear set, which is drive-connected to the first planetary gear set and a differential of the output. Preferably, a ring gear is fixed in the second planetary gear set, a planetary gear carrier is connected to the differential of the output, and a sun gear is drive-connected to a planetary gear carrier of the first planetary gear set via the output shaft. A second planetary gear set makes it technically simple to achieve an output ratio of the power transmitted from the hybrid transmission to the differential shaft. In particular, a second planetary gear set, like the hybrid transmission, can advantageously be arranged around the differential shaft, thus enabling a compact design of a hybrid drive train. It is understood that, instead of the planetary gear set, a spur gear stage can also be used as the output gear set.In particular, it is conceivable to provide a hollow output shaft which is operatively connected to the first planetary gear set and the differential of the output via two meshing spur gear pairs, wherein the hollow output shaft is preferably rotatably mounted on the countershaft.

[0017] In a further advantageous embodiment, the hybrid transmission comprises exactly three spur gear pairs to form the gear stages. Preferably, from a connection side of the output to the transmission, the first spur gear stage is arranged first, followed by the second spur gear stage, and finally the third spur gear stage in the hybrid transmission. By using exactly three spur gear pairs, a compact hybrid transmission with minimal meshing can be created, enabling three hybrid gear stages and one purely electric gear stage.

[0018] In a further advantageous embodiment, the hybrid transmission has exactly five shift elements. By using only five shift elements, the countershaft, in particular, can be designed without any shift elements. Furthermore, a compact, easy-to-control hybrid transmission can be created.

[0019] In a further advantageous embodiment, the sun gear of the first planetary gear set is drive-connected to the second intermediate shaft, and the ring gear of the first planetary gear set is drive-connected to the second transmission input shaft. Alternatively, the ring gear of the first planetary gear set is drive-connected to the second intermediate shaft, and the sun gear of the first planetary gear set is drive-connected to the second transmission input shaft. Due to the two alternative connections mentioned above, the first electric drive motor can either be operated at a low compensating speed during electrodynamic starting or electrodynamic gearshifts, or it can only generate a low support torque during electrodynamic starting and electrodynamic gearshifts. Furthermore, the two alternative connections can increase or decrease the duration of generator operation during electrodynamic starting.

[0020] In a further advantageous embodiment, the second transmission input shaft, the first intermediate shaft, the second intermediate shaft, and the output shaft are arranged coaxially with one another. In addition, the first transmission input shaft, the second transmission input shaft, the first intermediate shaft, the second intermediate shaft, and the output shaft are designed as hollow shafts. Furthermore, the first intermediate shaft, the second intermediate shaft, and the second transmission input shaft surround the output shaft at least in sections. By designing the aforementioned shafts as hollow shafts and arranging some of the aforementioned shafts coaxially, the compactness of the hybrid transmission can be further improved. In particular, the advantageous coaxial arrangement and the design of the shafts as hollow shafts enable the hybrid transmission to be arranged around the differential shaft, with the hybrid transmission and the differential shaft being arranged coaxially with one another.

[0021] In a further advantageous embodiment, the first transmission input shaft comprises an internal combustion engine clutch for releasably and driveably connecting the first transmission input shaft to the internal combustion engine. It is understood that the internal combustion engine clutch can be designed as a dog-type shift element or as a friction shift element. An internal combustion engine clutch can decouple the internal combustion engine from the hybrid transmission, thus enabling a highly efficient, purely electric driving mode using the hybrid transmission. A friction clutch also enables a so-called momentum start of the internal combustion engine and can serve as a starting element for the internal combustion engine. An internal combustion engine clutch can increase the variability and efficiency of the hybrid transmission. Furthermore, an internal combustion engine clutch can be used in a hybrid transmission for functional safety reasons.

[0022] In a further advantageous embodiment, a first shifting element is designed to drive-effectively connect the first intermediate shaft to the first planetary gear set by means of the second spur gear pair and the third spur gear pair. Additionally or alternatively, a second shifting element is designed to drive-effectively connect the second transmission input shaft to the first intermediate shaft by means of the first spur gear pair and the second spur gear pair. Additionally or alternatively, a third shifting element is designed to drive-effectively connect the first intermediate shaft to the first planetary gear set. Further additionally, a fourth shifting element is designed to drive-effectively connect the first intermediate shaft to the output shaft by means of the second spur gear pair and the third spur gear pair. Finally, further additionally or alternatively, a fifth shifting element is designed to block the first planetary gear set.This advantageous arrangement of the shift elements allows the hybrid transmission to provide three hybrid gear ratios, sometimes with multiple variants, two electrodynamic overlay states, one electric gear ratio, and a charge-to-neutral mode. A variable and compact hybrid transmission can be created that enables electrodynamic starting and electrodynamic gearshifts.

[0023] In a further advantageous embodiment, the shifting elements are designed as positive-locking shifting elements. Additionally or alternatively, at least two of the shifting elements, preferably four shifting elements, are designed as double-locking shifting elements and can be actuated by a double-acting actuator. Positive-locking shifting elements enable a highly efficient and cost-effective hybrid transmission. The technical design and operation of the hybrid transmission can be further simplified by a double-locking element. In particular, a double-locking element can be switched using a single actuator.

[0024] In a further advantageous embodiment, the motor vehicle drive train preferably comprises a further electric machine that is drivingly connected to the first transmission input shaft. The first electric drive machine and / or preferably the further electric machine can be controlled as a starter generator for starting the internal combustion engine. Additionally or alternatively, the first electric drive machine and / or preferably the further electric machine can be controlled as a charging generator for charging an energy storage device. The further electric machine is preferably designed as a high-voltage starter generator. This makes it possible to create an efficient motor vehicle drive train. In particular, fuel consumption can be reduced.It goes without saying that an additional starter for the combustion engine is not necessary, since the first electric drive motor and / or the high-voltage starter generator can tow the combustion engine.

[0025] In a further advantageous embodiment, an output of the hybrid transmission can be drive-connected to a first motor vehicle axle, wherein a second motor vehicle axle comprises an electric axle with a second electric drive motor. This makes it technically simple to create a hybrid drive train with all-wheel drive. Furthermore, the motor vehicle drive train can easily enable shifting without interruption in tractive force, since the electric axle can maintain tractive force during shifts in the hybrid transmission. Furthermore, a fail-safe drive train for a motor vehicle can be created, since a so-called serial driving mode can be set up in the event of a depleted energy storage device for the second electric drive motor.In the serial driving mode, the electric drive motor is preferably operated as a generator by the internal combustion engine, and the energy thus generated is made available to the second electric drive motor. Preferably, the first electric drive motor and / or the additional electric machine can be controlled as a generator to supply the second electric drive motor in order to establish a serial driving mode. This makes it possible to create a highly variable motor vehicle drive train in which driving and, in particular, starting can be carried out electrically, even when the energy storage device is empty.

[0026] Locking an element of a planetary gear set is understood in particular as blocking the element's rotation about its axis of rotation. Preferably, the element is connected in a rotationally fixed manner to a static component such as a frame and / or a transmission housing by means of a switching element. It is also conceivable to brake the element to a standstill.

[0027] Interlocking a planetary gear set involves connecting two gears and / or the planetary gear carrier and a gear of the planetary gear set in a drive-effective manner, so that they rotate together at the same speed around the same point, preferably the center of the planetary gear set. When interlocking two gears and / or a planetary gear carrier and a gear of the planetary gear set, the planetary gear set preferably acts like a shaft; in particular, no gear ratio is transmitted within the planetary gear set.

[0028] In this context, "drive-effectively connected" refers in particular to a non-switchable connection between two components intended for the permanent transmission of a rotational speed, torque, and / or drive power. The connection can be made either directly or via a fixed transmission ratio. The connection can be made, for example, via a fixed shaft, a gearing, in particular a spur gearing, and / or a belt drive, in particular a traction drive.

[0029] In this context, "drive-connectable," "can be connected to a drive," or "is designed for a drive-connected connection" refers, in particular, to a switchable connection between two components, which, in a closed state, is intended for the temporary transmission of a rotational speed, a torque, and / or a drive power. In an open state, the switchable connection preferably temporarily transmits essentially no rotational speed, no torque, and / or no drive power.

[0030] Stand-by charging or charging-in-neutral means, in particular, operating the electric drive motor as a generator, preferably when stationary with the combustion engine running, in order to fill an energy storage unit and / or to supply on-board electronics.

[0031] In this context, an actuator is, in particular, a component that converts an electrical signal into a mechanical movement. Actuators used with dual switching elements preferably perform movements in two opposite directions, switching one switching element of the dual switching element in the first direction and switching the other switching element in the second direction.

[0032] A gear change, particularly a serial shift, occurs in particular by disengaging a shifting element and / or a clutch and simultaneously engaging the shifting element and / or the clutch for the next higher or lower gear. The second shifting element and / or the second clutch thus gradually takes over the torque from the first shifting element and / or the first clutch until, at the end of the gear change, the entire torque is taken over by the second shifting element and / or the second clutch. With prior synchronization, a gear change can occur more quickly; positive-locking shifting elements can preferably be used.

[0033] An internal combustion engine can be any machine that can generate a rotary motion by burning a fuel such as gasoline, diesel, kerosene, ethanol, liquefied petroleum gas, LPG, etc. An internal combustion engine can be, for example, a gasoline engine, a diesel engine, a rotary engine, or a two-stroke engine.

[0034] In serial driving or crawling, an electric drive motor of a motor vehicle is powered by a combustion engine of the motor vehicle. The energy thus generated is then made available to another electric drive motor of the motor vehicle to provide drive power.

[0035] An electric vehicle axle, or simply an electric axle, is preferably a non-main drive axle of a motor vehicle, in which drive power can be transferred to the wheels of the motor vehicle by means of an electric drive motor. It is understood that the electric drive motor can also be connected via a transmission. Traction can be fully or partially maintained by means of an electric axle when a gear change occurs in the transmission for a main drive axle. Furthermore, all-wheel drive functionality can be implemented at least partially by means of an electric axle.

[0036] An electrodynamic starting element (EDA) ensures that the speed of the combustion engine and the electric drive motor is superimposed via one or more planetary gear sets, enabling a motor vehicle to start from a standstill with the combustion engine running, preferably without a friction clutch. The electric drive motor supports a torque. Preferably, the combustion engine can no longer be separated from the transmission by a starting clutch or the like. By using an EDA, the starter, generator, and starting clutch or hydrodynamic converter can be eliminated. In particular, an EDA is so compact that all components fit into the standard clutch housing without extending the transmission.The electrodynamic starting element can, for example, be firmly connected to an internal combustion engine, and in particular to a flywheel of an internal combustion engine, via a softly tuned torsional damper. This allows the electric drive motor and the internal combustion engine to be operated either simultaneously or alternatively. When the vehicle stops, the electric drive motor and the internal combustion engine can be switched off. Due to the good controllability of the electric drive motor, a very high starting quality is achieved, which can be equivalent to that of a drive with a torque converter clutch.

[0037] In an electrodynamic shift (EDS), as with EDA starting, the speed of the combustion engine and the electric drive motor is superimposed via one or more planetary gear sets. At the start of the shift, the torques of the electric drive motor and the combustion engine are adjusted so that the shift element to be disengaged is load-free. After this shift element is opened, the speed is adjusted while maintaining the tractive force, so that the shift element to be engaged becomes synchronous. After the shift element is closed, the load is distributed between the combustion engine and the electric drive motor as desired, depending on the hybrid operating strategy.The electrodynamic shifting system has the advantage that the shift element of the target gear to be engaged is synchronized through the interaction of the electric drive motor and the combustion engine, with the electric drive motor preferably being precisely controllable. A further advantage of the EDL shifting system is that high tractive effort can be achieved, since the torques of the combustion engine and the electric motor are combined in the hybrid transmission.

[0038] The invention is described and explained in more detail below using selected embodiments in conjunction with the accompanying drawings. They show: Fig. 1 a schematic plan view of a motor vehicle with a motor vehicle drive train according to the invention; Fig. 2 a schematic representation of the hybrid transmission according to the invention; and Fig. 3 schematically shows the switching states of the hybrid transmission according to the Fig. 2.

[0039] In Fig. 1 schematically shows a motor vehicle 10 with a motor vehicle drive train 12. The motor vehicle drive train 12 has a first electric drive motor 14 and an internal combustion engine 16, which are connected to a front axle of the motor vehicle 10 by means of a hybrid transmission 18. In the example shown, the motor vehicle drive train 12 further comprises an optional electric axle with a second electric drive motor 20, which is connected to a rear axle of the motor vehicle 10. It is understood that a reverse connection can also be made, so that the hybrid transmission 18 is connected to the rear axle of the motor vehicle 10 and the front axle of the motor vehicle 10 comprises the electric axle.By means of the motor vehicle drive train 12, drive power of the first electric drive motor 14, the internal combustion engine 16, and / or the optional second electric drive motor 20 is supplied to the wheels of the motor vehicle 10. The motor vehicle 10 further comprises an energy storage device 22 for storing energy that serves to supply the first electric drive motor 14 and / or the second electric drive motor 20.

[0040] Fig. 2 shows a variant of a hybrid transmission 18 according to the invention. The hybrid transmission 18 has a first transmission input shaft 24 and a second transmission input shaft 26, which are designed to transmit drive power from the drive machines 14, 16 to the hybrid transmission 18.

[0041] The hybrid transmission 18 has an output shaft 28, a first intermediate shaft 30, and a second intermediate shaft 32. The aforementioned transmission shafts 24, 26, 28, 30, and 32 are designed as hollow shafts. The hybrid transmission 18 has a first planetary gear set RS1 and a second planetary gear set RS2. A total of three spur gear pairs, designated ST1 to ST3, are arranged in the hybrid transmission 18.

[0042] The hybrid transmission has five shift elements A to E.

[0043] The first transmission input shaft 24 has a torsional vibration damper and is drivingly connected to a crankshaft 36 of the internal combustion engine 16 (not shown) via the torsional vibration damper. It is understood that instead of the torsional vibration damper, another element for torsional vibration decoupling can also be used.

[0044] Not shown, but conceivable, is that an internal combustion engine clutch is arranged on the first transmission input shaft 24, which clutch is designed to decouple the hybrid transmission 18 from the internal combustion engine 16 (not shown) or to drive-connect the hybrid transmission 18 to the internal combustion engine 16 (not shown). The internal combustion engine clutch can be designed as a positive-locking or friction-locking shifting element and can be used in particular for reasons of functional reliability.

[0045] The first transmission input shaft 24 is drive-connected, preferably by means of a chain, to a fixed gear arranged on the first intermediate shaft 30.

[0046] A sun gear of the first planetary gear set RS1 is connected to the second transmission input shaft 26. A planetary gear carrier of the first planetary gear set RS1 is drive-connected to the output shaft 28. A ring gear of the first planetary gear set RS1 is drive-connected to the second intermediate shaft 32.

[0047] The first electric drive machine 14 is connected in a drive-effective manner, for example via a chain or a gear chain or by direct engagement, to a fixed gear arranged on the second transmission input shaft 26.

[0048] The output shaft 28 is drive-connected to a sun gear of the second planetary gear set RS2. A planetary gear carrier of the second planetary gear set RS2 is drive-connected to a differential of the output 38. Furthermore, the ring gear in the second planetary gear set RS2 is fixed, i.e., drive-connected to a component fixed to the housing or non-rotatably connected.

[0049] By connecting the second transmission input shaft 26 to the output shaft 28, the first planetary gear set RS1 can be locked. The gear shifting occurs via a feedthrough through the connecting gear for the first electric drive motor 14 to the second transmission input shaft 26. This is represented by a dashed line in the figure. Consequently, the connection between the second transmission input shaft 26 and the output shaft 28 is located to the left of the connecting gear of the first electric drive motor 14 in the drawing.

[0050] The first spur gear pair ST1 has a fixed gear arranged on the countershaft 34, which is in engagement with an idler gear, wherein the idler gear can be drive-connected to the second transmission input shaft 26.

[0051] The second spur gear pair ST2 is arranged axially adjacent to the first spur gear pair ST1. The second spur gear pair ST2 comprises a fixed gear arranged on the countershaft 34, which meshes with a fixed gear arranged on the first intermediate shaft 30. A fixed gear for connecting the first transmission input shaft 24 is also arranged on the first intermediate shaft 30. The first intermediate shaft 30 can be drive-connected to the second intermediate shaft 32.

[0052] The third spur gear pair ST3 comprises a fixed gear arranged on the countershaft 34, which is in engagement with an idler gear, wherein the idler gear can be drive-connected to the second intermediate shaft 32 or to the output shaft 28.

[0053] The hybrid transmission comprises a first planetary gear set RS1 for implementing an EDA mode, several spur gear pairs ST1 to ST3 for establishing three gear ratios for the internal combustion engine, and a downstream fixed ratio in the form of the second planetary gear set RS2. Furthermore, the hybrid transmission 18 comprises a differential for summing the two drives from the internal combustion engine 16 and the first electric drive motor 14 to produce an output torque. In the example shown, the first electric drive motor 14 is connected to the hybrid transmission 18 in a parallel-axis manner.

[0054] When closed, the first switching element A connects the winding of the second spur gear pair ST2 and the third spur gear pair ST3 with the ring gear of the first planetary gear set RS1.

[0055] When closed, the second shift element B connects the first electric drive motor 14 to the combustion engine 16. This enables charging to neutral. The power flow from the first electric drive motor 14 runs via the second transmission input shaft 26, the shift element B, the first spur gear pair ST1, the second spur gear pair ST2, the first intermediate shaft 30, and finally the connection between the first intermediate shaft 30 and the first transmission input shaft 24 to the crankshaft 36 of the combustion engine 16.

[0056] In the closed state, the third switching element C connects the first intermediate shaft 30 in a drive-effective manner with the ring gear of the first planetary gear set RS1.

[0057] In the closed state, the fourth switching element D connects the first intermediate shaft 30 via the winding of the second spur gear pair ST2 and the third spur gear pair ST3 to the output of the first planetary gear set RS1 or to the output shaft 28.

[0058] When closed, the fifth shift element E locks the first planetary gear set RS1 by connecting two of the three planetary gear set elements of the first planetary gear set RS1. The first planetary gear set RS1 functions as a differential for two electrodynamic superposition states ECVT1, ECVT2.

[0059] In addition to ball differentials, spur gear differentials or other types of differentials known in the state of the art are also possible as differentials.

[0060] The switching elements A to E are preferably designed as positive-locking switching elements, in particular as claw switching elements.

[0061] The third switching element C is combined with the first switching element A and the fifth switching element E is combined with the second switching element B to form a double switching element.

[0062] In Fig. 3, a shift matrix 40 shows, in a first column, the hybrid gear stages H1 to H3, an electric gear stage E1, two electrodynamic superposition states ECVT1, ECVT2, and a charge-in-neutral state (LiN). The second to sixth columns show the shift states of the shift elements A to E, where an "X" means that the respective shift element is closed, i.e., connects the associated transmission components to one another in a drive-effective manner. If no entry is present, it can be assumed that the corresponding shift element is open, i.e., is not transmitting any drive power.

[0063] A first hybrid gear stage H1 can be established by engaging the first shift element A and the fourth shift element D.

[0064] A further variant of the first hybrid gear stage H1.1 can be set up by engaging the third shift element C and the fourth shift element D.

[0065] Engaging the second shift element B and the third shift element C establishes a second hybrid gear stage H2.

[0066] A third hybrid gear stage H3 can be set up by engaging the third shift element C and the fifth shift element E.

[0067] An electric gear stage E1 can be set by engaging the fifth switching element E.

[0068] A first electrodynamic superposition state ECVT1 can be established by inserting the first switching element A.

[0069] Engaging the third switching element C establishes a second electrodynamic superposition state ECVT2.

[0070] A charge-in-neutral, LiN, state can be established by engaging the second switching element B.

[0071] For internal combustion engine or hybrid driving, three mechanical main gears are available for the internal combustion engine 16. The first hybrid gear stage H1 is generated via the winding of the second spur gear pair ST2 and the third spur gear pair ST3. Winding refers in particular to the fact that, through the rotationally fixed connection of the two spur gear pairs ST2, ST3, the gears of the spur gear pairs that are not rotationally fixed can be supplied with drive power, thus allowing drive power to be increased or decreased.

[0072] The second hybrid gear stage H2 is formed by various couplings of the sun gear and ring gear on the first planetary gear set RS1. The third hybrid gear stage runs directly to the output 38 via the interlocked first planetary gear set RS1. In this respect, the third hybrid gear stage H3 can be considered a direct gear stage.

[0073] In the electric gear stage E1, the fifth shift element E is engaged. The first planetary gear set RS1 is consequently locked. The drive power of the first electric drive motor 14 can then be transmitted to the output 38 via the transmission ratio of the first electric drive motor 14, i.e., the connection to the second transmission input shaft 26, and by means of the transmission ratio of the second planetary gear set RS2. It is understood that the term "transmission ratio" encompasses both a transmission ratio and a reduction ratio of the drive power.

[0074] If the first switching element A is closed, a first electrodynamic superposition state ECVT1 is created on the first planetary gear set RS1. The internal combustion engine 16 is then connected to the ring gear of the first planetary gear set RS1 via the winding of the second spur gear pair ST2 and the third spur gear pair ST3. The first electric drive motor 14 supports the torque of the internal combustion engine 16 on the sun gear of the first planetary gear set RS1. The planetary gear carrier of the first planetary gear set RS1 is connected to the output 38 via the second planetary gear set RS2. In this state, forward EDA starting is possible.

[0075] The first hybrid gear stage H1 is formed by interlocking the first planetary gear set RS1. From the first hybrid gear stage H1, shifting can be performed to the second electrodynamic superposition state ECVT2. From the second electrodynamic superposition state ECVT2, all gear stages can be shifted, with the third hybrid gear stage H3 again being formed by interlocking the first planetary gear set RS1.

[0076] With the disclosed hybrid transmission 18, electrodynamic load shifts, so-called EDL shifts, are possible. A shift from the first gear to the second gear can be carried out electrodynamically by the first electric drive motor 14, for example, as follows. In the first hybrid gear H1, the first electric drive motor 14 is initially connected to the differential by switching the first shift element A to the third shift element C. This changes to the further variant of the first hybrid gear H1.1. In this context, shifting means that the first shift element A is disengaged and the third shift element C is engaged. During this aforementioned pre-select shift from the first electrodynamic superposition state ECVT1 to the second electrodynamic superposition state ECVT2, the load orthe drive torque of the internal combustion engine 16 is received via the fourth shifting element D. The load is then transferred to the differential by a support load of the first electric drive motor 14 in the second electrodynamic superposition state ECVT2. The connecting speed of the internal combustion engine 16 is then adjusted in the second electrodynamic superposition state ECVT2 by compensation using the first electric drive motor 14. A load-free switching of the fourth shifting element D and the second shifting element B can then take place, with the fourth shifting element D being disengaged and the second shifting element B being engaged. As soon as a gear is engaged, the internal combustion engine 16 can deliver the full load or the full drive torque via this path.

[0077] Shifting from the second gear to the third gear also occurs electrodynamically by the first electric drive motor in a manner analogous to shifting from the first gear to the second gear. Consequently, the second electrodynamic superposition state ECVT2 is also used for a powershift from the second hybrid gear H2 to the third hybrid gear H3.

[0078] An exemplary shift from the second hybrid gear stage H2 to the third hybrid gear stage H3 can proceed as follows. In the second electrodynamic superposition state ECVT2, the first electric drive motor 14 and the combustion engine 16 are connected via a differential, in particular the first planetary gear set RS1. A reduction in the input speed of the combustion engine 16 can be compensated for by increasing the speed of the first electric drive motor 14. This preferably takes place with load balancing of both drives, i.e. both drive motors 14, 16. At a corresponding connecting speed, an upshift can be executed. In the engaged gear stage, both drives are coupled. The required support power or the required torque of the first electric drive motor 14 must be taken into account during the load shift.

[0079] Downshifts are carried out in the same way as upshifts, only in reverse order.

[0080] In so-called overrun shifts, the first electric drive motor 14 provides support in a generator or braking capacity. These overrun shifts are preferably limited due to the lower drag torque of the internal combustion engine 16 compared to the drive torque. In particular, an engine brake or a service brake can be used here.

[0081] If only the second switching element B is closed, the first electric drive motor 14 can be connected to the internal combustion engine 16 independently of the output 38. The first electric drive motor 14 and the internal combustion engine 16 then rotate in a fixed relationship to one another. This allows, on the one hand, the internal combustion engine 16 to be started by means of the first electric drive motor 14. On the other hand, the first electric drive motor 14 can be operated by the internal combustion engine 16 as a generator, in the so-called charge-in-neutral (LiN) state, and in particular charge the electrical energy storage device 22 or supply electrical consumers. A consumer can also be a second electric drive motor 20, for example, for an electric rear axle, as in Fig. 1 shown.

[0082] A transition from the charge-to-neutral (LiN) state is possible to the first hybrid gear stage H1, the second hybrid gear stage H2, and the third hybrid gear stage H3. This can occur with the second shift element B closed. It is also possible to shift directly to the first electrodynamic superposition state ECVT1 or the second electrodynamic superposition state ECVT2. Shifting to the second electrodynamic superposition state ECVT2 is particularly advantageous, as this should occur before gear changes anyway.

[0083] Is, as for example in Fig.1, an electric rear axle is present, an all-wheel drive system can be created using this combination. For example, a DHT transmission, i.e., a Dedicated Hybrid Transmission, with the combustion engine 16 and the first electric drive motor 14, can be designed as a pure front-wheel drive, with additional rear-axle drive being provided by the separate second electric drive motor 20.

[0084] The electrodynamic superposition states ECVT1 and ECVT2 are power-split driving ranges for the internal combustion engine 16. The first electrodynamic superposition state ECVT1 is used as the driving range when starting electrodynamically. In this case, the first electric drive motor 14 preferably always functions as a generator at the starting point and transitions to motor operation as the vehicle speed increases. The first hybrid gear stage H1 is then coupled, usually in block circulation, to the differential, i.e., the first planetary gear set RS1.

[0085] The second electrodynamic superposition state, ECVT2, is used for powershift gear changes. In this case, the downforce changes only insignificantly, depending on the vehicle's inertia. Instead, the internal combustion engine 16 can be accelerated to a connecting speed for the gear to be coupled, preferably with the goal of accelerating the vehicle gear by gear using the internal combustion engine 16.

[0086] Serial driving is possible by switching the hybrid transmission 18 to the charging-in-neutral (LiN) state, i.e., closing the second switching element B. In this case, the first electric drive motor 14 can be operated as a generator by the combustion engine 16 and thus generate power for the second electric drive motor 20.

[0087] Furthermore, tractive force support can be provided by means of the second electric drive motor 20. The second electric drive motor 20 can support the tractive force while, for example, certain functions are being carried out in front-wheel drive, during which the output 38 of the hybrid transmission 18 is load-free. An example of such transitions is when the vehicle is initially driven with the second electric drive motor 20 and then the combustion engine 16 is to be started in neutral using the first electric drive motor 14. Another example of this is so-called serial shifting. With a closed second shift element B, a load-free change can take place, preferably on the front-wheel drive, between the first hybrid gear H1, the second hybrid gear H2 and / or the third hybrid gear H3.It is particularly advantageous that the first electric drive machine 14 can operate as a generator without interruption and can thus supply both the on-board network and the second electric drive machine 20 with electrical power.

[0088] Not shown in the figures, an alternative connection of the first planetary gear set RS1 is also conceivable. In the alternative connection, the connections to the sun gear and ring gear are swapped. The output 38 remains connected to the planet gear carrier of the first planetary gear set RS1. The combustion engine 16 is connected to the ring gear of the first planetary gear set RS1 and the first electric drive motor 14 is connected to the sun gear of the first planetary gear set RS1. This allows a smaller first electric drive motor 14 to be used because a lower support torque needs to be applied by the first electric drive motor 14 during electrodynamic starting and electrodynamic gear shifts. In particular, during electrodynamic starting, the first electric drive motor 14 can be operated in generator mode for longer because the generator mode is exited later as the driving speed increases.

[0089] It is understood that a further electric machine, in particular in the form of a high-voltage starter generator, can be arranged on the first transmission input shaft 24. The high-voltage starter generator can preferably be drive-connected to the first transmission input shaft 24 via a gear chain.

[0090] The invention has been comprehensively described and explained with reference to the drawings and the description. The description and explanation are to be understood as exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other embodiments or variations will become apparent to those skilled in the art upon use of the present invention and upon careful analysis of the drawings, the disclosure, and the following claims.

[0091] In the patent claims, the words "comprising" and "having" do not exclude the presence of further elements or steps. The undefined article "a" or "an" does not exclude the presence of a plurality. A single element or a single unit can perform the functions of several of the units recited in the patent claims. The mere mention of some measures in several different dependent patent claims should not be understood to mean that a combination of these measures cannot also be used advantageously. Reference symbols in the patent claims are not to be understood as limiting. A method for operating a motor vehicle drivetrain 12 can, for example, be implemented in the form of a computer program that is executed on a control unit for the motor vehicle drivetrain 12.A computer program may be stored / distributed on a non-volatile storage medium, such as optical storage or a solid-state drive (SSD). A computer program may be distributed together with hardware and / or as part of hardware, such as via the Internet or via wired or wireless communication systems. Reference symbol 10 motor vehicle 12 Automotive powertrain 14 first electric drive machine 16 Combustion engine 18 hybrid transmissions 20 second electric drive motor 22 energy storage units 24 first transmission input shaft 26 second transmission input shaft 28 Output shaft 30 first intermediate shaft 32 second intermediate shaft 34 Countershaft 36 Crankshaft 38 downforce 40 switching matrix AE switching elements RS1 first planetary gear set RS2 second planetary gear set ST1-ST3 spur gear pairs

Claims

[1] Hybrid transmission (18) for a motor vehicle drive train (12) of a motor vehicle (10), comprising: a first transmission input shaft (24) for operatively connecting the hybrid transmission (18) to an internal combustion engine (16) of the motor vehicle (10); a second transmission input shaft (26) for operatively connecting the hybrid transmission (18) to a first electric drive motor (14) of the motor vehicle (10); a first intermediate shaft (30) which is drivingly connected to the first transmission input shaft (24); a second intermediate shaft (32), an output shaft (28) for operatively connecting the hybrid transmission (18) to an output (38); a first planetary gear set (RS1) connected to the second intermediate shaft (32), the second transmission input shaft (26) and the output shaft (28); a countershaft (34); spur gear pairs (ST1, ST2, ST3) arranged in several gear set levels to form gear steps; and several gearshift devices with shift elements (A, B, C, D, E) for engaging gear steps, wherein the spur gear pairs (ST1, ST2, ST3) each have a fixed gear arranged on the countershaft (34); at least two spur gear pairs (ST1, ST2, ST3) are arranged directly axially adjacent to one another to form the gear stages; a differential of the output (38) comprises a differential shaft which is designed as a solid shaft and is surrounded at least in sections by the first intermediate shaft (30), the second intermediate shaft (32), the second transmission input shaft (26) and the output shaft (28); and an axial length of the differential shaft is greater than an axial length of the output shaft (28) and the differential shaft completely penetrates the output shaft (28). [2] Hybrid transmission (18) according to one of the preceding claims, wherein the hybrid transmission (18) comprises a second planetary gear set (RS2) which is drivingly connected to the first planetary gear set (RS1) and a differential of the output (38); and preferably a ring gear is fixed in the second planetary gear set (RS2), a planet gear carrier is connected to the differential of the output (38) and a sun gear is drivingly connected to a planet gear carrier of the first planetary gear set (RS1) by means of the output shaft (28). [3] Hybrid transmission (18) according to one of the preceding claims, wherein the hybrid transmission (18) has exactly three spur gear pairs (ST1, ST2, ST3) for forming the gear stages. [4] Hybrid transmission (18) according to one of the preceding claims, wherein the hybrid transmission (18) has exactly five shift elements (A, B, C, D, E). [5] Hybrid transmission (18) according to one of the preceding claims, wherein the sun gear of the first planetary gear set (RS1) is drive-connected to the second intermediate shaft (32) and the ring gear of the first planetary gear set (RS1) is drive-connected to the second transmission input shaft (26); or the ring gear of the first planetary gear set (RS1) is drive-effectively connected to the second intermediate shaft (32) and the sun gear of the first planetary gear set (RS1) is drive-effectively connected to the second transmission input shaft (26). [6] Hybrid transmission (18) according to one of the preceding claims, wherein the second transmission input shaft (26), the first intermediate shaft (30), the second intermediate shaft (32) and the output shaft (28) are arranged coaxially to one another; the first transmission input shaft (24), the second transmission input shaft (26), the first intermediate shaft (30), the second intermediate shaft (32) and the output shaft (28) are designed as hollow shafts; and the first intermediate shaft (30), the second intermediate shaft (32) and the second transmission input shaft (26) surround the output shaft (28) at least in sections. [7] Hybrid transmission (18) according to one of the preceding claims, wherein the first transmission input shaft (24) comprises an internal combustion engine clutch for releasably drivingly connecting the first transmission input shaft (24) to the internal combustion engine (16). [8] Hybrid transmission (18) according to one of the preceding claims, wherein a first shifting element (A) is designed to drive-effectively connect the first intermediate shaft (30) to the first planetary gear set (RS1) by means of the second spur gear pair (ST2) and the third spur gear pair (ST3); a second shift element (B) is designed to drive-effectively connect the second transmission input shaft (26) to the first intermediate shaft (30) by means of the first spur gear pair (ST1) and the second spur gear pair (ST2); a third shifting element (C) is designed to drive-effectively connect the first intermediate shaft (30) to the first planetary gear set (RS1); a fourth shift element (D) is designed to drive-effectively connect the first intermediate shaft (30) to the output shaft (28) by means of the second spur gear pair (ST2) and the third spur gear pair (ST3); and / or a fifth shifting element (E) is designed to block the first planetary gear set (RS1). [9] Hybrid transmission (18) according to one of the preceding claims, wherein the switching elements (A, B, C, D, E) are designed as positive-locking switching elements; and / or at least two of the switching elements (A, B, C, D, E), preferably four switching elements (A, B, C, D, E), are designed as double switching elements and can be actuated by a double-acting actuator. [10] Motor vehicle drive train (12) for a motor vehicle (10), comprising: a hybrid transmission (18) according to one of the preceding claims; an internal combustion engine (16) connectable to the first transmission input shaft (24); and a first electric drive motor (14) which is drivingly connected to the second transmission input shaft (26). [11] Motor vehicle drive train (12) according to claim 10, wherein the motor vehicle drive train (12) preferably comprises a further electric machine which is drivingly connected to the first transmission input shaft (24) and the first electric drive machine (14) and / or preferably the further electric machine can be controlled as a starter generator for starting the internal combustion engine (16); and / or can be controlled as a charging generator for charging an energy storage device (22). [12] Motor vehicle drive train (12) according to claim 10 or 11, wherein an output (38) of the hybrid transmission (18) is driveably connectable to a first motor vehicle axle and a second motor vehicle axle comprises an electric axle with a second electric drive motor (20); and preferably the first electric drive machine (14) and / or the further electric machine can be controlled as a generator for supplying the second electric drive machine (20) in order to establish a serial driving mode. [13] Method for operating a motor vehicle drive train (12) according to one of claims 10 to 12. [14] Motor vehicle (10) with: a motor vehicle drive train (12) according to one of claims 10 to 12; and an energy storage device (22) for storing energy to supply the first electric drive machine (14) and / or the second electric drive machine (20).

Images