WO2023217504A1

WO2023217504A1 - Electric drive system for a motor vehicle, and method for operating such an electric drive system

Info

Publication number: WO2023217504A1
Application number: PCT/EP2023/060179
Authority: WO
Inventors: Peter Hahn; Carsten Gitt; Tobias Schilder
Original assignee: Mercedes-Benz Group AG
Priority date: 2022-05-09
Filing date: 2023-04-19
Publication date: 2023-11-16
Also published as: DE102022001623A1; DE102022001623B4

Abstract

The invention relates to an electric drive system (10) for a motor vehicle, comprising a first electric machine (18) with a first rotor (22), a second electric machine (25) with a second rotor (28), and a coupler mechanism (30) which has a first output shaft (33) and a second output shaft (35), said output shafts being designed to output output torques from the coupler mechanism (30). A first planetary gear set (32) is provided, having a first element (36), a second element (38) which is rotationally fixed to the second output shaft (35), and a third element (40) which is rotationally fixed to the first output shaft (33), and a second planetary gear set (34) is provided, having a fourth element (42), a fifth element (44) which is rotationally fixed to the second element (38), and a sixth element (46). A first shift element (SE1) is also provided which is designed to couple the first rotor (22) to the fourth element (42).

Description

Electric drive system for a motor vehicle and method for operating such an electric drive system

The invention relates to an electric drive system for a motor vehicle, in particular for a motor vehicle, according to the preamble of patent claim 1. The invention further relates to a method for operating such an electric drive system.

The US 9 494218 B2 is an engine for driving two driven parts as known to drive a vehicle. Furthermore, DE 10 2019 107 538 A1 discloses a torque distribution transmission, with a first drive shaft, which is connected in a rotationally fixed manner to a first sun gear of a spur gear differential.

The object of the present invention is to create an electric drive system and a method for operating such an electric drive system, so that a particularly compact design of the drive system and a particularly advantageous drive can be realized.

This object is achieved by an electric drive system with the features of patent claim 1 and by a method with the features of patent claim 10. Advantageous embodiments with useful developments of the invention are specified in the remaining claims.

A first aspect of the invention relates to an electric drive system, also referred to as an electric drive device or designed as an electric drive device, for a motor vehicle, in particular for a motor vehicle and especially for a passenger car. This means that the motor vehicle in its fully manufactured state has the electric drive system and is driven electrically, in particular purely electrically, by means of the electric drive system can be. For example, in its fully manufactured state, the motor vehicle has at least or exactly two axles, also referred to as vehicle axles, which are arranged one after the other in the longitudinal direction of the vehicle and thus one behind the other. The respective axle of the motor vehicle, also referred to as a vehicle, has at least or exactly two vehicle wheels, also referred to as wheels, with, for example, the vehicle wheels of the respective axle being arranged on sides of the motor vehicle that are opposite one another in the transverse direction of the vehicle. By means of the electric drive system, for example, the vehicle wheels of at least one of the axles or both axles can be driven, whereby the motor vehicle as a whole can be driven. The vehicle wheels are ground contact elements via which the motor vehicle can be supported or supported downwards on a ground in the vertical direction of the vehicle. If the motor vehicle is driven along the ground while the motor vehicle is supported on the ground in the vertical direction of the vehicle downwards via the ground contact elements, the ground contact elements roll, in particular directly, on the ground. The vehicle wheels that can be driven by the electric drive system are also referred to as drivable wheels or driven wheels. When we talk about the vehicle wheels or the wheels below, this refers to the vehicle wheels that can be driven by the electric drive system, unless otherwise stated.

The electric drive system has a first electric machine which has a first rotor. For example, the first electrical machine has a first stator, by means of which, for example, the first rotor can be driven and thereby rotatable about a first machine axis of rotation relative to the first rotor. In particular, the first electric machine can provide first drive torques for driving the vehicle wheels and thus the motor vehicle via the first rotor. The electric drive system also has a second electric machine with a second rotor. In particular, the second electrical machine has a second stator, by means of which, for example, the second rotor can be driven and thereby rotated about a second machine axis of rotation relative to the second stator. In particular, the second electric machine can provide second drive torque via its second rotor, by means of which the vehicle wheels and thus the motor vehicle can be driven. For example, the machine axes of rotation run parallel to one another, and the machine axes of rotation can, for example, be spaced apart from one another. In particular, the machine axes of rotation coincide, so that the electrical machines can, for example, be arranged coaxially with one another. The electric machine also has a coupling gear, which has two output shafts, namely a first output shaft and a second output shaft. The output shafts are designed to transfer output torques from the coupling gear. In other words, the coupling gear can provide the output torque via its output shafts. Thus, for example, the first output shaft is designed to discharge the first of the output torques from the coupling gear, with the second output shaft, for example, being designed to discharge the second of the output torques from the coupling gear. For example, the respective first output torque and/or the respective second output torque result from the respective first drive torque and/or from the respective second drive torque.

The linkage also has a first planetary gear set, which has a first element, a second element and a third element. The second element is, in particular permanently, connected in a rotationally fixed manner to the second output shaft. The third element is, in particular permanently, connected in a rotationally fixed manner to the first output shaft. The linkage also includes a second planetary gear set having a fourth element, a fifth element and a sixth element. The fifth element is, in particular permanently, connected to the second element in a rotationally fixed manner.

The first element, the second element and the third element are gear elements of the first planetary gear set or are also referred to as gear elements of the first planetary gear set. Preferably, a first of the gear elements is designed as a first sun gear, a second of the gear elements as a first planet carrier and a third of the gear elements as a first ring gear of the first planetary gear set. The fourth element, the fifth element and the sixth element are also collectively referred to as components of the second planetary gear set, and preferably a first of the components is a second sun gear, a second of the components is a second planet carrier and a third of the components is a second ring gear of the second planetary gear set . The planet carriers are also known as webs. For example, the drive system has a housing, wherein, for example, the first planetary gear set and/or the second planetary gear set can each be arranged at least partially in the housing. In particular, if the respective gear element is not connected to the housing in a rotationally fixed manner, the respective gear element can, for example, be rotated about a first planetary gear set rotation axis relative to the housing. For example, if the respective Component is not rotatably connected to the housing, the respective component can be rotated about a second planetary gear set rotation axis relative to the housing. It is conceivable that the planetary gear sets are arranged coaxially with one another, so that the planetary gear set rotation axes preferably coincide. The respective planetary gear set rotation axis runs, for example, parallel to the respective machine rotation axis, wherein the respective planetary gear set rotation axis can be spaced, for example, from the respective machine rotation axis. Furthermore, it is conceivable that the respective planetary gear set rotation axis coincides with the respective machine rotation axis, so that the respective planetary gear set can be arranged coaxially to the respective electrical machine.

In the context of the present disclosure, the feature that two components such as the second output shaft and the second element or the first output shaft and the third element are connected to one another in a rotationally fixed manner means that the components connected to one another in a rotationally fixed manner are arranged coaxially to one another and are in particular when the components are driven, rotate together or simultaneously about a component rotation axis common to the components, such as the first planetary gear set rotation axis, with the same angular velocity, in particular relative to the housing. The feature that two components are connected to one another in a torque-transmitting manner is to be understood as meaning that the components are coupled or connected to one another in such a way that torques can be transmitted between the components, whereby when the components are connected to one another in a rotationally fixed manner, the components also transmit torque are connected to each other. The feature that two components are permanently connected to one another in a torque-transmitting manner means that a switching element is not provided which can be switched between a coupling state that connects the components to one another in a torque-transmitting manner and a decoupling state in which no torques can be transmitted between the components , but the components are always or always and therefore permanently torque-transmitting, that is, connected to one another in such a way that torque can be transmitted between the components. Thus, for example, one of the components can be driven by the other component and vice versa. In particular, the feature that two components are permanently connected to one another in a rotationally fixed manner means that a switching element is not provided which is between a coupling state that connects the components to one another in a rotationally fixed manner and a decoupling state is switchable, in which the components are decoupled from one another and can be rotated relative to one another, in particular about the component rotation axis, so that no torques can be transmitted between the components, but rather the components are always connected or coupled to one another in a permanently rotated manner. In other words, the term “rotational test” means that two elements, in particular rotatably mounted, are connected to one another in a rotational manner when they are arranged coaxially to one another and are connected to one another in such a way that they rotate at the same angular velocity, in particular about the component rotation axis. Furthermore, it is possible, for example, for the respective gear element to be connected in a rotationally fixed manner to a respective shaft of the first planetary gear set, in particular permanently, or to also form this shaft. Furthermore, it is conceivable that the respective component is connected to a respective shaft of the second planetary gear set in a rotationally fixed manner, in particular permanently, or that it also forms this respective shaft.

In order to be able to realize a particularly compact design of the electric drive system and a particularly advantageous drive, a first switching element is provided according to the invention, which is designed or intended to couple the first rotor to the fourth element, in particular in a torque-transmitting manner and, in particular, in a rotationally fixed manner that the first drive torques provided or able to be provided by the first electric machine via the first rotor can be introduced to the fourth element or via the fourth element into the coupling gear, and can therefore be initiated. In other words, the first switching element is intended or designed to couple the first rotor to the fourth element, in particular in a torque-transmitting and, in particular, rotationally fixed manner, in such a way that the first drive torques, starting from the first electrical machine or from the first rotor, are transmitted to the fourth element, that is, can be introduced into the coupling gear via the fourth element. For example, the first switching element can be switched between a first coupling state and a first decoupling state. In the first coupling state, the first rotor is coupled, i.e. connected, to the fourth element in a torque-transmitting manner, in particular in a rotationally fixed manner, by means of the first switching element. In the first decoupling state, the first rotor is decoupled from the fourth element, in particular in such a way that no torques can be transmitted between the first rotor and the fourth element via the first switching element, so that in particular, for example, relative rotations between the first rotor occur in particular about the second planetary gear set rotation axis and the fourth element are permitted, and are therefore made possible. For example, the first switching element is movable, in particular relative to the housing and/or translationally, between at least one first coupling position causing the first coupling state and at least one second coupling position bringing about the second coupling state.

According to the invention, a second switching element is also provided, which is designed or intended to couple the first rotor to the sixth element, in particular torque-transmitting and most particularly rotating, in such a way that the first ones provided or able to be provided by the first electrical machine via the first rotor Drive torques on the sixth element, that is to say can be introduced into the coupling gear via the sixth element, and can therefore be initiated. For example, the second switching element can be switched between a second coupling state and a second decoupling state. In the second coupling state, the first rotor is coupled to the sixth element in a torque-transmitting, in particular rotating, manner by means of the second switching element. In the second decoupling state, for example, the first rotor is decoupled from the sixth element, so that no torques can be transmitted between the first rotor and the sixth element via the second switching element, in particular so that the second switching element rotates relative to the first rotor in particular about the second planetary gear set rotation axis and the sixth element allows. For example, the second switching element can be moved, in particular translationally and/or relative to the housing, between at least one second coupling position causing the second coupling state and at least one second decoupling position causing the second decoupling state.

Furthermore, according to the invention, a third switching element is provided, which is designed or intended to couple the second rotor to the first element, in particular in a torque-transmitting manner and in particular in a rotationally fixed manner, in such a way that the switches provided or able to be provided by the second electrical machine via the second rotor second drive torques on the first element, that is to say via the first element into which the coupling gear can be introduced, and can therefore be initiated. For example, the third switching element can be switched between a third coupling state and a third decoupling state. In the third coupling state, the second rotor is coupled to the first element in a torque-transmitting manner, in particular in a rotationally fixed manner, by means of the third switching element, so that torques can be transmitted between the second rotor and the first element via the third switching element. In the third decoupling state is the second rotor is decoupled from the first element, so that no torques can be transmitted between the second rotor and the first element via the third switching element, in particular so that the third switching element allows relative rotations between the second rotor and the first element, in particular about the first planetary gear set rotation axis. For example, the third switching element can be moved, in particular translationally and/or relative to the housing, between at least one third coupling position causing the third coupling state and at least one third decoupling position causing the third decoupling state.

In order to be able to implement a particularly advantageous drive in a particularly space-saving manner, it is provided in one embodiment of the invention that the second element is the first planet carrier and the fifth element is the second planet carrier.

In order to realize a particularly compact design, it has proven to be particularly advantageous if first planet gears and second planet gears are rotatably held on the second element. The first planetary gears permanently mesh with a first toothing of the first element, and the second planetary gears permanently mesh with a third toothing of the third element. Preferably, the first planetary gears do not mesh with the third gearing, and preferably the second planetary gears do not mesh with the first gearing. In addition, for example, one of the first planetary gears meshes, in particular precisely, with a respective one of the second planetary gears. It is preferably provided that third planet gears are rotatably held on the fifth element. The third planet gears mesh permanently with a fourth toothing of the fourth element and permanently with a sixth toothing of the sixth element. Preferably, the third planet gears do not mesh with either the first toothing or the third toothing. In addition, it is provided that in each case, in particular precisely, one of the first planet gears meshes, in particular precisely, with a respective one of the third planet gears.

In a further, particularly advantageous embodiment of the invention, it is provided that first planet gears are rotatably held, that is, arranged, in the second element. Second planet gears and third planet gears are rotatably held on the fifth element, that is, arranged. The first planet gears mesh with a first toothing of the first element and with a third toothing of the third element. The second planetary gears mesh with a fourth Gearing of the fourth element, and the third planet gears mesh with a sixth gearing of the sixth element. It is preferably provided that the second planetary gears do not mesh with the sixth toothing, and preferably the third planetary gears do not mesh with the fourth toothing. Furthermore, it is preferably provided that in each case, in particular precisely, one of the first planet gears meshes, in particular precisely, with a respective one of the second planet gears. Furthermore, it is preferably provided that in each case, in particular precisely, one of the second planet gears meshes, in particular precisely, with a respective one of the third planet gears. This allows a particularly compact design and a particularly advantageous drive to be achieved.

In the context of the present disclosure, ordinal words referred to as ordinals, such as "first", "first", "second", "second", etc., are not necessarily used to indicate or imply a number or set of elements, but rather to uniquely to be able to reference terms to which the ordinal number words are assigned or to which the ordinal number words refer.

In order to be able to realize a particularly advantageous drive and a particularly space-saving design of the drive system, it is provided in a further embodiment of the invention that the electric drive system has a first transmission stage, which, with regard to a first torque flow, is downstream of the first output shaft and downstream of the coupling gear and in particular upstream a first of the vehicle wheels is arranged, wherein, for example, the respective first output torque can be transmitted along the first torque flow from the coupling gear and the first output shaft via the first gear ratio to or on the first vehicle wheel, so that the first gear ratio in the first torque flow and thereby downstream the first output shaft and is arranged upstream of the first vehicle wheel. Furthermore, a second transmission stage is preferably provided, which is arranged with respect to a second torque flow downstream of the second output shaft and downstream of the coupling gear and in particular upstream of the second vehicle wheel, for example along the second torque flow the respective second output torque from the coupling gear and the second output shaft via the second gear ratio can be transferred to the second vehicle wheel. The second transmission stage is thus arranged in the second torque flow and upstream of the second vehicle wheel and downstream of the second output shaft. This can be particularly important A particularly efficient drive of the vehicle wheels and thus the motor vehicle can be represented in a space-saving manner.

The term “torque flow” refers to a torque transmission path originating from the electrical machines and directed to the output shafts.

In order to keep the installation space requirement particularly low and to be able to create a particularly advantageous functionality, it is provided in a further embodiment of the invention that the first element is the first sun gear, the third element is the first ring gear, the fourth element is the second sun gear and the sixth element is second ring gear.

A further embodiment is characterized in that the first switching element is designed to couple the first rotor to the fourth element in a rotationally fixed manner. As a result, the installation space requirement can be kept particularly low.

In order to be able to create a particularly space-saving design of the electric drive system, it is provided in a further embodiment of the invention that the second switching element is designed to couple the first rotor to the sixth element in a rotationally fixed manner.

In a particularly advantageous embodiment of the invention, it is provided that the third switching element is designed or intended to couple the second rotor to the first element in a rotationally fixed manner. As a result, the installation space requirement of the drive system can be kept particularly low, especially when viewed in the radial direction of the coupling gear and thus along a straight line running perpendicular to the respective planetary gear set rotation axis.

A second aspect of the invention relates to a method for operating an electric drive system according to the first aspect of the invention. Advantages and advantageous refinements of the first aspect of the invention are to be viewed as advantages and advantageous refinements of the second aspect of the invention and vice versa.

In order to realize a particularly advantageous drive, it has proven to be advantageous if for a first torque shift operation, also referred to as the first Torque shift operation of the drive system, the first switching element is closed, the second switching element is open and the third switching element is closed.

In order to be able to realize a particularly efficient operation in a particularly space-saving manner, it is provided in a further embodiment of the invention that the first switching element is open, the second switching element is closed and the third switching element is open for efficient operation of the electric drive system.

In order to be able to create a particularly advantageous drive and a particularly extensive functionality of the drive system, it is provided in a further embodiment of the invention that for a second torque shift operation of the drive system, also referred to as a second torque shift operation, the first switching element is open, the second switching element closed and the third switching element is closed.

During or in the respective torque shift operation, for example, both electrical machines, that is to say both rotors, drive the motor vehicle, in particular the vehicle wheels, in particular simultaneously, with a distribution of the drive torques provided or available by the electrical machines via their rotors to the both vehicle wheels depends on a torque ratio and / or speed ratio of the two electric machines to each other. Thus, for example, more torque, i.e. a greater torque, can be transmitted to one of the vehicle wheels than to the other vehicle wheel.

In particular, it is conceivable that during or in the first torque shift operation, based on the electrical machines, only one of the electrical machines, in particular the first electrical machine, drives the vehicle wheels, or the one electrical machine predominantly, that is to say substantially, drives the vehicle wheels stronger than the other electric machine, whereby the drive torque provided by the one electric machine is distributed to the two vehicle wheels by corresponding operation of the other electric machine, in particular the second electric machine, and therefore can be carried out by, in particular, corresponding operation of the others electric machine, a distribution of the drive torque provided by the one electric machine, in particular by the rotor, which is an electric machine, is adjusted to the vehicle wheels, that is, varied. Thus, for example, in the first torque shift operation, the other electric machine does not have a significant torque contribution to drive the motor vehicle. By In the second torque shift operation, for example, both electric machines drive the vehicle wheels, in particular equally strongly, in particular with a 50:50 distribution of the respective drive torques or a total torque resulting from the respective first drive torque and from the respective second drive torque. For example, the second torque shift operation is a boost operation, by means of which the motor vehicle can be accelerated particularly strongly. The efficient operation provides, for example, that the vehicle wheels are driven in relation to the electric machine by means of only one of the electric machines, while the vehicle wheels are not driven by the other electric machine, in particular while the other electric machine is deactivated, in particular one 50:50 distribution of the drive torque provided by the one electric machine to the output shafts and thus the vehicle wheels is provided.

It can be seen that, for example, in the first torque shift operation, such a torque shift or torque distribution can be realized that a distribution or division of the drive torque that can be provided or provided by the one electric machine via the rotor of the one electric machine to the vehicle wheels by operating of the other electrical machine varies, that is, can be adjusted, in particular by the other electrical machine either driving or braking the coupling gear. The coupling transmission has, for example, a basic distribution according to which, for example, a total torque introduced into the coupling transmission is divided or distributed to the output shafts and via these to the vehicle wheels. In particular, the basic distribution is defined, i.e. predetermined, by a mechanical design of the coupling gear. The total torque results, for example, from the respective, first drive torque and/or from the respective, second drive torque, wherein, for example, the total torque can result in particular from the respective, first drive torque and from the respective, second drive torque when the second rotor produces the respective, second Drive torque and, in particular at the same time, the first rotor provides the respective first drive torque and the first drive torque and the second drive torque are introduced into the coupling gear, in particular simultaneously. By operating the other electric machine, that is, by the other electric machine driving the coupling gear, that is, for example, at least one of the gear elements and/or at least one of the components, and/or by the electric machine driving the coupling gear, that is, that at least one gear element and/or the at least one component brakes, the coupling transmission can be influenced in such a way that, for example, the respective drive torque provided by the one electric machine or the total torque is not or not only according to the basic distribution, but according to a distribution to the which is different from the basic distribution Output shafts and divided or distributed via these to the vehicle wheels, for example by varying the operation of the other electrical machine, that is, for example by varying a torque provided by the other electrical machine, in particular by the rotor of the other electrical machine, for driving or braking of the coupling gear, the distribution mentioned can be varied. This makes it possible, for example, to set that the respective first output torque has a first value, in particular a first amount, and the second output torque, in particular at the same time, has a second value that is different from the first value, in particular a second amount that is different from the first amount, having. This torque shift is particularly advantageous when the motor vehicle is cornering, since a greater torque can then be assigned to the vehicle wheel on the outside of the curve than to the vehicle wheel on the inside of the curve, for example in order to advantageously accelerate the motor vehicle out of a curve. This makes it possible to achieve particularly advantageous driving dynamics. The invention thus enables the realization of a particularly high level of performance, particularly with regard to high transverse dynamics, in particular with a high level of efficiency of the drive system at the same time. Furthermore, the invention enables a particularly compact design of the drive system.

Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawing. The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and/or shown in the figures alone can be used not only in the combination specified in each case, but also in other combinations or on their own, without the scope of to abandon invention.

The drawing shows in:

1 shows a schematic representation of a first embodiment of an electric drive system for a motor vehicle; Fig. 2 is a schematic representation of a second embodiment of the drive system;

3 shows a switching table to illustrate different operations of the electric drive system, also referred to as modes or operating modes, and

Fig. 4 is a schematic representation of a third embodiment of the electric drive system.

In the figures, identical or functionally identical elements are provided with the same reference numerals.

Fig. 1 shows a schematic representation of a first embodiment of an electric drive system 10 for a motor vehicle, also simply referred to as a vehicle, which is preferably designed as a motor vehicle, especially as a passenger car. In its fully manufactured state, the motor vehicle has, for example, at least or exactly two vehicle axles, which are arranged one after the other in the longitudinal direction of the vehicle and thus one behind the other, also simply referred to as axles. One of the vehicle axles can be seen in FIG. 1 and is designated 12. The respective vehicle axle has at least or exactly two vehicle wheels, also simply referred to as wheels. The vehicle wheels of the vehicle axle 12 can be seen in FIG. 1 and are designated 14 and 16. It can be seen that the vehicle wheels 14 and 16 are arranged on sides of the motor vehicle that are opposite one another in the transverse direction of the vehicle. By means of the drive system 10, the vehicle wheels 14 and 16 and the motor vehicle as a whole can be driven, in particular purely, electrically. The vehicle wheels 14 and 16 are ground contact elements via which the motor vehicle can be supported or supported downwards on a ground in the vertical direction of the vehicle.

The electric drive system 10 has a first electric machine 18, which has a first stator 20 and a first rotor 22. The rotor 22 can be driven by means of the stator 20 and can therefore be rotated about a machine axis of rotation relative to the stator 20 and relative to a housing 24 of the drive system 10, which is shown particularly schematically in FIG. The electric machine 18 can provide respective first drive torques for driving the vehicle wheels 14 and 16 of the motor vehicle via its first rotor 22. The electric drive system 10 also includes a second electric machine 25, which has a second stator 26 and a second rotor 28 has. By means of the stator 26, the rotor 28 can be driven and thereby rotated about a second machine axis of rotation relative to the stator 26 and relative to the housing 24. The electric machine 25 can provide respective second drive torques via its second rotor 28 for driving the vehicle wheels 14 and 16 and thus the motor vehicle.

From Fig. 1 it can be seen that the respective electrical machine 18, 25 can be designed as an axial flux machine (AFM). Here, the respective rotor 22, 28 has two rotor elements designed, for example, as rotor disks or also referred to as rotor disks, which are spaced apart from one another in the axial direction of the respective electrical machine 18, 25 and thus along the respective machine axis of rotation. The respective stator 20, 26 of the respective electrical machine 18, 25 is arranged in the axial direction of the respective electrical machine 18, 25 between the respective rotor elements of the respective electrical machine 18, 25.

The term “axial direction” thus refers to the axes of rotation of the rotors 22, 28. In these exemplary embodiments, the rotors 22, 28 are each arranged coaxially to one another, so that the axes of rotation of the rotors 22, 28 coincide to form an axis of rotation. Even if terms such as “axial between” or similar are used below, “axial” refers to the axial direction and thus to the axis of rotation of the rotors 22, 28.

The drive system 10 also has a coupling gear 30, which can have a central superposition unit or can be designed as a central superposition unit. The coupling gear 30 has a first output shaft 33 and a second output shaft 35. First output torques can be transferred from the coupling gear 30 via the output shaft 33, so that the coupling gear 30 can provide the first output torques via the first output shaft 33. Second output torques can be transferred from the coupling gear 30 via the second output shaft 35, which can thus provide the second output torques via the second output shaft 35. For example, the respective first output torque results from the respective first drive torque and/or from the respective second drive torque, and the respective second output torque results, for example, from the respective first drive torque and/or from the respective second drive torque. It can be seen that the vehicle wheel 14 is connected to the output shaft 33 and thus via the output shaft 33 to the coupling gear 30 and can be driven via this by the respective electrical machine 18, 25. As a result, the vehicle wheel 16 can be driven by the output shaft 35 and thus via the output shaft 35 by the coupling gear 30 and via this by the respective electric machine 18, 25.

The coupling gear 30, in particular the superposition unit, has a first planetary gear set 32 and a second planetary gear set 34. The planetary gear set 32 has a first element 36, a second element 38 and a third element 40, and the second planetary gear set 34 has a fourth element 42, a fifth element 44 and a sixth element 46. In the embodiments shown in the figures, the element 36 is a first sun gear, the second element 38 is a first planet carrier, which is also referred to as a first web, and the element 40 is a first ring gear. The fourth element 42 is a second sun gear, the fifth element 44 is a second planet carrier, which is also referred to as a second web, and the sixth element 46 is a second ring gear.

It can be seen that the second element 38 is connected, in particular permanently, to the fifth element 44 in a rotationally fixed manner. The second element 38 and thus the fifth element 44 are, in particular permanently, connected in a rotationally fixed manner to the second output shaft 35. In addition, the third element 40 is connected, in particular permanently, to the first output shaft 33 in a rotationally fixed manner.

In order to be able to realize a particularly advantageous drive and a particularly compact design of the electric drive system 10, the drive system 10 has a first switching element SE1, which is designed to couple the first rotor 22 to the fourth element 42 in a torque-transmitting manner, in particular in a rotationally fixed manner , so that the respective first drive torque provided or able to be provided by the first electric machine 18 via the first rotor 22 can be introduced to the fourth element 42 or via the fourth element 42 into the coupling gear 30. A second switching element SE2 is also provided, which is designed to couple the first rotor 22 to the sixth element 46 in a torque-transmitting manner, in particular in a rotationally fixed manner, so that the respective first rotor 22 is provided or can be provided by the first electric machine 18 via the first rotor 22 Drive torque can be introduced at the sixth element 46 or via the sixth element 46 into the coupling gear 30. From Fig. 1 it can be seen that the switching elements SE1 and SE2 are assigned a common first switching part 48, which is designed, for example, as a sliding sleeve. The first switching part 48 is switchable between a first state and a second state. In particular, the first switching part 48 can be moved, in particular relative to the housing 24 and/or translationally, between at least one first position causing the first state and at least one second position causing the second state. The first state is a first coupling state, and the second state is a second coupling state which is accompanied by a first decoupling state, the first coupling state being accompanied by a second decoupling state. In the first embodiment, the following is provided in particular: In the first coupling state, the rotor 22 is connected to the element 42 in a rotationally fixed manner and thus in a torque-transmitting manner by means of the switching element SE1 and by means of the first switching part 48. In the second coupling state, the rotor 22 is connected to the element 46 in a rotationally fixed manner and thus in a torque-transmitting manner by means of the switching element SE2 and by means of the first switching part 48. In the first decoupling state (second state), the rotor 22 is decoupled from the element 42, so that no torques can be transmitted via the switching element SE1 and the first switching part 48 between the rotor 22 and the element 42 and in particular so that the rotor 22 and the element 42 can be rotated relative to one another about a planetary gear set rotation axis common to the planetary gear sets 32 and 34. In the second decoupling state (first state), the rotor 22 is decoupled from the element 46, so that no torques can be transmitted between the rotor 22 and the element 46 via the switching element SE2 and the first switching part 48 and in particular so that the rotor 22 and the element 46 can be rotated relative to one another about the planetary gear set rotation axis.

The electric drive system 10 also includes a third switching element SE3, which is designed to couple the second rotor 28 to the first element 36 in such a way that the respective second drive torque provided or able to be provided by the second electric machine 25 via the second rotor 28 can be introduced into the coupling gear 30 on the first element 36 or via the first element 36. In the first embodiment, the rotor 22 and the element 42 can be connected to one another in a rotationally fixed manner by means of the first switching element SE1, and the rotor 22 and the element 46 can be connected to one another in a rotationally fixed manner by means of the switching element SE2. In addition, in the first embodiment, the second rotor 28 and the element 36 can be coupled to one another in a torque-transmitting manner, in particular in a rotationally fixed manner, by means of the switching element SE3. For this purpose, a second switching part 49 is provided, which can be switched between a third coupling state and a third decoupling state. In particular, the second switching part 49 can, in particular relative to the housing 24 and/or translationally, between at least one of the third coupling states causing the third coupling position and at least one third decoupling position causing the third decoupling state. In the third coupling state, the rotor 28 is rotatably connected to the element 36 by means of the third switching element SE3. In the third decoupling state, the rotor 28 is decoupled from the element 36, so that no torques can be transmitted between the rotor 28 and the element 36 via the switching element SE3 and the second switching part 49 and in particular so that the rotor 28 and the element 36 can be transmitted about the planetary gear set rotation axis can be rotated relative to each other.

In the first embodiment, first planet gears 50 and second planet gears 52 are rotatably held, that is, arranged, on the second element 38. The first planetary gears 50 permanently mesh with a first toothing of the first element 36, and the second planetary gears 52 permanently mesh with a third toothing of the third element 40. Furthermore, it is provided that in each case, in particular precisely, one of the first planetary gears 50 with, in particular exactly, one of the second planet gears 52 meshes. The respective planetary gear 52 does not mesh with the first toothing of the first element 36, and the respective planetary gear 50 does not mesh with the third toothing of the third element 40. Third planetary gears 54 are rotatably held on the fifth element 44, that is to say arranged, preferably the Planet gears 54 do not mesh with either the first toothing or the third toothing. The third planetary gears 54 mesh permanently with a fourth toothing of the fourth element 42 and permanently with a sixth toothing of the sixth element 46. For example, the planetary gears 50 do not mesh with either the fourth toothing or the sixth toothing. Furthermore, for example, the planet gears 52 do not mesh with either the fourth toothing or the sixth toothing. It is provided that in each case, in particular precisely, one of the first planetary gears 50 meshes, in particular precisely, with a respective one of the third planetary gears 54.

The first planetary gears 50 and the third planetary gears 54 can be stepped or unstepped planetary gears. If the two ring gears (third element 40 and sixth element 46) have the same diameter or the same number of teeth, both the first planetary gears 50 and the third planetary gears 54 are unstepped. If the two ring gears (third element 40 and sixth element 46) have unequal diameters or unequal number of teeth, one set of the first and third planetary gears 50, 54 is unstepped and the other set is stepped. The drive system 10 also has a first transmission stage 56, which, with regard to a first torque flow, along which the respective first output torque can be transferred from the first output shaft 33 to the first vehicle wheel 14, downstream of the first output shaft 33 and downstream of the coupling gear 30 and located upstream of the vehicle wheel 14 in the first torque flow. Accordingly, the drive system 10 has a second transmission stage 58, which, with regard to a second torque flow, via which or along which the respective second output torque can be transferred from the output shaft 35 to the second vehicle wheel 16, downstream of the second output shaft 35 and downstream of the coupling gear 30 and is arranged upstream of the second vehicle wheel 16 in the second torque flow. In the present case, the respective transmission stage 56, 58 is designed as a respective third planetary gear set, which has a respective seventh element 60, a respective eighth element 62 and a respective ninth element 64. The elements 60, 62 and 64 are also referred to as transmission parts, with a first of the transmission parts being, for example, a third sun gear, a second of the transmission parts being a third planet carrier and a third of the transmission parts being a third ring gear. In the present case, element 60 is the third sun gear, element 62 is the third planet carrier and element 64 is the third ring gear. Respective additional planet gears 66 of the respective transmission stage 56, 58 are rotatably held on the element 62, the respective planet gear 66 meshing simultaneously with the respective element 60 and the respective element 64. In the present case, the respective output shaft 33, 35 is connected, in particular permanently, in a rotationally fixed manner to the respective element 60 of the respective transmission stage 56, 58, the respective element 62 being a respective output or output from which the respective vehicle wheel 14, 16 can be driven. The respective element 64 is, in particular permanently, connected to the housing 24 in a rotationally fixed manner.

Fig. 2 shows a second embodiment of the electric drive system 10. In the second embodiment, first planet gears 50 are rotatably held on the second element 38. Second planet gears 52 and third planet gears 54 are rotatably held on the fifth element 44. The first planet gears 50 mesh, in particular permanently, with the first toothing and with the third toothing, but preferably neither with the fourth toothing nor with the sixth toothing. The second planet gears 52 mesh with the fourth toothing, but preferably not with the sixth toothing and also not with the first toothing and not with the third toothing. The third planet gears 54 mesh with the sixth toothing and preferably not with the fourth toothing and preferably not with that either first toothing and not with the third toothing. In particular, the planet gears 50 mesh permanently with the first toothing and with the third toothing. In addition, the planetary gears 52 preferably permanently mesh with the fourth gearing, and preferably the planetary gears 54 permanently mesh with the sixth gearing. Furthermore, it is provided that in each case, in particular precisely, one of the first planetary gears 50 meshes, in particular precisely, with a respective one of the second planetary gears 52. In addition, it is preferably provided that in each case, in particular precisely, one of the second planetary gears 52 meshes, in particular precisely, with a respective one of the third planetary gears 54. While in the first embodiment the first planetary gear set 32 is designed as a double planetary gear set or the second element 38 as a double planetary carrier, in the second embodiment the second planetary gear set 34 or the fifth element 44 is designed as a double planetary gear set or as a double planetary carrier. In the first embodiment, the fifth element 44 is designed as a simple planetary carrier, whereas in the second embodiment, the second element 38 is designed as a simple planetary carrier.

In the second embodiment, a connection of the second output shaft 35 to the second element 38 and to the fifth element 44, which is non-rotatably connected to the second element 38, is arranged axially between the two planetary gear sets 32, 34.

3 shows a switching table, based on which three operations A, B and C of the electric drive system 10, also referred to as modes or operating modes, are illustrated. For or in operation A, the first switching element SE1 is closed, the second switching element SE2 is open and the third switching element SE3 is closed. For or in operation B, the first switching element SE1 is open, the second switching element SE2 is closed and the third switching element SE3 is open. For or in operation C, the first switching element SE1 is open, the second switching element SE2 is closed and the third switching element SE3 is closed. For example, operation A is a first torque shift operation, which is also referred to as a first torque shift operation. For example, the second operation B is an efficiency operation of the drive system 10. For example, the operation C is a second torque shift operation, which is also referred to as a second torque shift operation of the drive system 10.

4 shows a schematic representation of a third embodiment of the electric drive system 10. The third embodiment differs from the first embodiment shown in FIG. 1 only in two respects: As an alternative to the arrangement of the transmission stages 56, 58, the transmission stages 56, 58 in the third embodiment are arranged upstream of the coupling gear 30 with regard to a torque flow emanating from the electric machines 18, 25; A fourth switching element SE4 is additionally provided, by means of which the first rotor 22 can be coupled to the second rotor 28, the fourth switching element SE4 being arranged upstream of the coupling gear 30 with regard to the torque flow emanating from the electrical machines 18, 25.

Both differences mentioned can of course also be used in the same way in the second embodiment shown in FIG. Both differences mentioned are advantageous in their own right and can each be applied advantageously to the first or second embodiment.

In the third embodiment, the second rotor 28 is connected in a rotationally fixed manner to the seventh element 60 of the second transmission stage 58. The eighth element 62 of the second transmission stage 58 can be connected in a rotationally fixed manner to the first element 36 by means of the third switching element SE3. The second translation stage 56 is advantageously arranged axially on a side of the second electrical machine 28 facing away from the first electrical machine 18.

In the third embodiment, the third switching element SE3 can alternatively also be arranged between the second electrical machine 28 and the second transmission stage 58 with regard to the torque flow emanating from the second electrical machine 25.

Furthermore, in the third embodiment, the first rotor 22 is connected in a rotationally fixed manner to the seventh element 60 of the first transmission stage 56, wherein the eighth element 62 of the first transmission stage 56 can be connected in a rotationally fixed manner to the fourth element 42 by means of the first switching element SE1 and by means of the second switching element SE2 can be connected in a rotationally fixed manner to the sixth element 46.

By means of the fourth switching element SE4, the first rotor 22 can be connected to the second rotor 28 in a rotationally fixed manner. When the fourth switching element SE4 is closed and the third switching element SE3 is open, both electrical machines can operate at the same time 18, 25 introduce their power into the coupling gear 30 via the fourth element 42 or via the sixth element 46.

In the third exemplary embodiment, a third switching part 67 is assigned to the fourth switching element SE4.

In the case of the third embodiment, the second element 38 is coupled, in particular in a rotationally fixed manner, to the second vehicle wheel 16 without an additional intermediate transmission stage. The third element 40 is coupled, in particular in a rotationally fixed manner, to the first vehicle wheel 14 without an additional intermediate transmission stage.

Reference symbol list

10 electric drive system

12 vehicle axle

14 vehicle wheel

16 vehicle wheel

18 first electric machine

20 first stator

22 first rotor

24 cases

25 second electric machine

26 second stator

28 second rotor

30 coupling gears

32 first planetary gear set

33 first output shaft

34 second planetary gear set

35 second output shaft

36 first element

38 second element

40 third element

42 fourth element

44 fifth element

46 sixth element

48 first switching part

49 second switching part

50 first planetary gear

52 second planetary gear

54 third planetary gear

56 first translation stage

58 second translation stage

60 seventh element

62 eighth element

64 ninth element

66 another planetary gear

67 third switching part

SE1 first switching element SE2 second switching element

SE3 third switching element

SE4 fourth switching element

A first operation

B second operation

C third operation

Claims

Claims Electric drive system (10) for a motor vehicle, with a first electric machine (18) with a first rotor (22), with a second electric machine (25) with a second rotor (28), and with a coupling gear (30), which has:

- a first output shaft (33) and a second output shaft (35), which are designed to transfer output torques from the coupling gear (30),

- a first planetary gear set (32) with a first element (36), a second element (38) connected in a rotationally fixed manner to the second output shaft (35) and a third element (40) connected in a rotationally fixed manner to the first output shaft (33) and

- a second planetary gear set (34) with a fourth element (42), a fifth element (44) connected in a rotationally fixed manner to the second element (38) and a sixth element (46), characterized by:

- a first switching element (SE1), which is designed to couple the first rotor (22) to the fourth element (42) in such a way that first drive torques provided by the first electrical machine (18) via the first rotor (22). can be introduced into the coupling gear (30) on the fourth element (42),

- a second switching element (SE2), which is designed to couple the first rotor (22) to the sixth element (46) in such a way that the first ones provided by the first electrical machine (18) via the first rotor (22). Drive torques on the sixth element (46) can be introduced into the coupling gear (30), and

- A third switching element (SE3), which is designed to couple the second rotor (28) to the first element (36) in such a way that the second Electric machine (25) via the second rotor (28), second drive torques on the first element (36) can be introduced into the coupling gear (30). Electric drive system (10) according to claim 1, characterized in that the second element (38) is designed as a first planet carrier and the fifth element (44) is designed as a second planet carrier. Electric drive system (10) according to claim 2, characterized in that:

- first planet gears (50) and second planet gears (52) are rotatably held on the second element (38),

- the first planet gears (50) permanently mesh with a first toothing of the first element (36),

- the second planet gears (52) permanently mesh with a third toothing of the third element (40),

- one of the first planet gears (50) meshes with a respective one of the second planet gears (52),

- third planet gears (54) are rotatably held on the fifth element (44),

- the third planet gears (54) permanently mesh with a fourth toothing of the fourth element (42) and permanently with a sixth toothing of the sixth element (46) and

- One of the first planet gears (50) meshes with a respective one of the third planet gears (54). Electric drive system (10) according to claim 2, characterized in that:

- first planet gears (50) are rotatably held on the second element (38),

- second planet gears (52) and third planet gears (54) are rotatably held on the fifth element (44),

- the first planet gears (50) mesh with a first toothing of the first element (36) and with a third toothing of the third element (40),

- the second planet gears (52) mesh with a fourth toothing of the fourth element (42), - the third planet gears (54) mesh with a sixth toothing of the sixth element (46),

- one of the first planet gears (50) meshes with a respective one of the second planet gears (52) and

- One of the second planet gears (52) meshes with a respective one of the third planet gears (54). Electric drive system (10) according to one of the preceding claims, characterized by:

- a first transmission stage (56), which is arranged downstream of the first output shaft (33) and downstream of the coupling gear (30) with regard to a torque flow, and

- A second transmission stage (58), which is arranged downstream of the second output shaft (35) and downstream of the coupling gear (30) with regard to a torque flow. Electric drive system (10) according to one of the preceding claims, characterized in that the first element (36) as a first sun gear, the third element (40) as a first ring gear, the fourth element (42) as a second sun gear and the sixth Element (46) is designed as a second ring gear. Electric drive system (10) according to one of the preceding claims, characterized in that the first switching element (SE1) is designed to couple the first rotor (22) to the fourth element (42) in a rotationally fixed manner. Electric drive system (10) according to one of the preceding claims, characterized in that the second switching element (SE2) is designed to couple the first rotor (22) to the sixth element (46) in a rotationally fixed manner. Electric drive system (10) according to one of the preceding claims, characterized in that the third switching element (SE3) is designed to couple the second rotor (28) to the first element (36) in a rotationally fixed manner. Method for operating an electric drive system (10) according to one of

Claims 1 to 9, characterized in that for a first torque shift operation (A) of the drive system (10), the first switching element (SE1) is closed, the second switching element (SE2) is open and the third switching element (SE3) is closed. Method for operating an electric drive system (10) according to one of claims 1 to 9, characterized in that for efficient operation (B) of the drive system (10) the first switching element (SE1) is open, the second switching element (SE2) is closed and the third switching element (SE3) is open. Method for operating an electric drive system (10) according to one of claims 1 to 9, characterized in that for a second torque shift operation (C) of the drive system (10), the first switching element (SE1) is open, the second switching element (SE2 ) is closed and the third switching element (SE3) is closed.