WO2023217513A1

WO2023217513A1 - Electric drive system for a motor vehicle, and method for operating such an electric drive system

Info

Publication number: WO2023217513A1
Application number: PCT/EP2023/060488
Authority: WO
Inventors: Peter Hahn; Carsten Gitt; Tobias Schilder
Original assignee: Mercedes-Benz Group AG
Priority date: 2022-05-09
Filing date: 2023-04-21
Publication date: 2023-11-16
Also published as: DE102022001620A1; DE102022001620B4

Abstract

The invention relates to an electric drive system (10), 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), and a third element (40), 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) which is rotationally fixed to the second output shaft (35). The first rotor (22) is coupled to the second element (38) such that first drive torques provided by the first electric machine (18) via the first rotor (22) can be introduced into the coupler mechanism (30) at the second element (38).

Description

Mercedes-Benz Group AG

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 for a motor vehicle 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 7. 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 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, although it is conceivable that the machine axes of rotation are 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 drive system 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 receive the first of the output torques from the coupling gear to discharge, for example the second output shaft is designed to discharge 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 coupling gear has a first planetary gear set, which has a first element, a second element and a third element. 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 sixth element is, in particular permanently, connected in a rotationally fixed manner to the second output shaft. 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. 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 connected to the housing in a rotationally fixed manner, 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, it being conceivable that the respective planetary gear set rotation axis is spaced from the machine rotation axis. Furthermore, it is conceivable that the respective planetary gear set rotation axes coincide with the respective machine rotation axis, so that, for example, 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 sixth element are connected to one another in a rotationally fixed manner is to be understood to mean 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 or second planetary gear set rotation axis, with the same angular velocity, in particular relative to the housing. The feature that two components are connected or coupled to one another in a torque-transmitting manner is to be understood as meaning that the components are connected or coupled 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 are also connected to each other to transmit torque. 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 can be switched between a coupling state that connects the components to one another in a rotationally fixed manner and a decoupling state in which the components are decoupled from one another and relative to one another are rotatable to each other, in particular about the component rotation axis, so that no torques can be transmitted between the components, but the components are always or always, therefore permanently connected or coupled to one another in a rotationally fixed manner. Expressed again in other words, the term “rotationally fixed” means that two elements are connected to one another in a rotationally fixed manner if 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 axis of rotation. Expressed again in other words, the term “rotatably fixed” means in particular the following: Two rotatably mounted components are connected to one another in a rotationally fixed manner if they are coaxial with one another are arranged and are connected to one another in such a way that they rotate at the same angular speed.

Furthermore, it is provided that the first rotor is coupled to the second element, in particular in a torque-transmitting and most particularly rotating manner, in such a way that the first drive torques provided or able to be provided by the first electric machine via the first rotor are applied to the second element, that is to say can be introduced into the coupling gear via the second element. In other words, the first rotor is coupled to the second element in such a way that the respective first drive torque, starting from the first electric machine and thus starting from the first rotor, can be introduced to the second element or into the coupling gear via the second element .

In order to be able to realize a particularly compact design of the electric drive system and a particularly advantageous drive, it is provided according to the invention that the electric drive system has a first switching element, which is designed to connect the first output shaft to the first element in a rotationally fixed manner. In other words, the first output shaft can be connected to the first element in a rotationally fixed manner by means of the first switching element.

For example, the first rotor is coupled, in particular permanently, torque-transmitting, in particular non-rotatably, to the second element, that is, connected.

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 output shaft is connected to the first element in a rotationally fixed manner by means of the first switching element. In the first decoupling state, the first switching element allows relative rotations between the output shaft and the first element about the first planetary gear set rotation axis. For example, the first switching element can be moved, 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 first decoupling position causing the first decoupling state.

According to the invention, a second switching element is also provided, which is designed or intended to connect the first output shaft to the third element in a rotationally fixed manner. In other words, the first output shaft can be connected to the third element in a rotationally fixed manner by means of the second switching element. In particular, the second switching element can switch between a second coupling state and a second Decoupling state can be switched. In the second coupling state, the first output shaft is rotationally connected to the third element by means of the second switching element. In the second decoupling state, the second switching element allows relative rotations between the first output shaft and the third element about the first planetary gear set rotation axis. 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.

According to the invention, the electric drive system also includes a third switching element, which is designed or intended to couple the second rotor to the fourth element, in particular in a torque-transmitting and most particularly non-rotatable manner, in such a way that the second rotor is provided or can be provided by the second electrical machine via the second rotor , second drive torques can be introduced on the fourth element or via the fourth element into the coupling gear. In other words, the third switching element is designed or intended to couple the second rotor to the fourth element in such a way that the respective second drive torque, starting from the second electric machine or from the second rotor, is transmitted to the fourth element or via the fourth Element can be introduced into the coupling gear. Thus, for example, by means of the third switching element, the second rotor can be coupled to the fourth element in a torque-transmitting manner, in particular in a rotationally fixed manner. 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 fourth element in a torque-transmitting manner, in particular in a rotationally fixed manner, by means of the third switching element. In the third decoupling state, the second rotor is decoupled from the fourth element, so that no torques can be transmitted between the second rotor and the fourth element via the third switching element. In particular, for example, the third switching element allows relative rotations between the second rotor and the fourth element about the second planetary gear set rotation axis in the third decoupling state. 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. Overall, the invention enables the realization of a particularly compact and therefore space-saving coupling structure with an advantageously large number of functionalities. In particular, it is conceivable that the respective gear element is rotatably connected to a respective shaft of the first planetary gear set, in particular permanently, or that it also forms this respective shaft. Furthermore, for example, the respective component is rotatably connected to a respective shaft of the second planetary gear set, in particular permanently, or forms this shaft.

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.

A further embodiment is characterized in that first planet gears are rotatably held, that is, arranged on the second element. The first planet gears mesh, in particular permanently, with a first toothing of the first element. In addition, the first planet gears mesh, in particular simultaneously and/or permanently, with a third toothing of the third element. Second planet gears and third planet gears are preferably rotatably held on the fifth element, that is, arranged. The second planet gears mesh, in particular permanently, with a fourth toothing of the fourth element, and the third planet gears mesh, in particular permanently, with a sixth toothing of the sixth element. In particular, it is provided that the first planetary gears do not mesh with the fourth toothing and not with the sixth toothing and preferably also not with the second planetary gears and not with the third planetary gears. Furthermore, it is preferably provided that the second planet gears do not mesh with the first toothing and not with the third toothing and also not with the sixth toothing. Furthermore, it is preferably provided that the third planet gears do not mesh with the first toothing and not with the third toothing and also not with the fourth toothing. It is also provided that one of the second planet gears meshes, in particular precisely, with a respective one of the third planet gears, in particular permanently. This allows a particularly compact design of the electric drive system to be represented.

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 a number or set of elements or to imply, but in order to be able to clearly refer to terms to which the ordinal number words are assigned or to which the ordinal number words refer.

In a further, particularly advantageous embodiment of the invention, a first transmission stage is provided, which is arranged downstream of the first output shaft and the coupling gear and in particular upstream of a first of the vehicle wheels with respect to a first torque flow, for example the respective first output torque along the first torque flow from the Coupling gear and the first output shaft can be transmitted via the first gear ratio to or on the first vehicle wheel, so that the first gear ratio is arranged in the first torque flow and downstream of the first output shaft and 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. In this way, a particularly efficient drive of the vehicle wheels and thus of the motor vehicle can be achieved in a particularly space-saving manner.

In order to be able to implement a particularly advantageous drive in a particularly space-saving manner, 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 the second ring gear are.

A further embodiment is characterized in that the third switching element is designed to couple the second rotor to the fourth element in a rotationally fixed manner. In other words, it is preferably provided that the second rotor can be coupled to the fourth element in a rotationally fixed manner, that is to say connected, by means of the third switching element. Thus, for example, in the third coupling state, the second rotor is connected to the fourth element in a rotationally fixed manner by means of the third switching element. In the third decoupling state, the third switching element allows relative rotations to occur between the second rotor, in particular about the second planetary gear set rotation axis and the fourth element, whereby no torques can be transmitted between the second rotor and the fourth element. As a result, a particularly advantageous drive can be realized in a particularly space-saving manner.

A second aspect of the invention relates to a method for operating the 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, in particular efficient, operation, it has proven to be advantageous if the first switching element is closed, the second switching element is open and the third switching element is closed for a first torque shift operation of the drive system, also referred to as a first torque shift operation.

In order to be able to realize a particularly efficient operation, 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 drive system.

In order to be able to realize a particularly advantageous functionality in a particularly space-saving manner, 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 is closed and that third switching element are closed. During or in the first torque shift operation, for example, in relation to the electrical machines, only one of the electrical machines drives the vehicle wheels, or one of the electrical machines drives the vehicle wheels predominantly, i.e. significantly more strongly, compared to the other electrical machine, wherein a distribution of the drive torque provided or able to be provided by the electric machines via their rotors to the two vehicle wheels depends on a torque ratio and/or a speed ratio of the electric machines to one another. In or in the efficient operation, for example, the vehicle wheels and thus the motor vehicle are driven in relation to the two electric machines exclusively by means of one of the electric machines, in particular while the vehicle wheels are not driven by the other electric machine, in particular while the other electric machine is disabled. In efficient operation, for example, there is a 50:50 distribution of the respective drive torque provided by one electric machine between the two output shafts or the vehicle wheels. During or in the second torque shift operation, for example, the vehicle wheels are driven by means of both electric machines, in particular simultaneously, in particular with a 50:50 distribution of the drive torque provided by the electric machines via their rotors on the output shafts and thus the vehicle wheels, For example, both electric machines drive the vehicle wheels with equal power. Thus, for example, the second torque shift operation is a boost operation in which, for example, the motor vehicle can be accelerated particularly strongly.

It can be seen that in the first torque shift operation such a torque shift or torque distribution, in particular on the output shafts or on the vehicle wheels, can be realized such that a distribution or division of the one electric machine over the rotor of the one electric machine Available or provided drive torque on the vehicle wheels or on the output shafts by operating the other electric machine varies, that is, can be adjusted, in particular by the other electric machine selectively 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 other electric machine driving the coupling gear, that is the at least one gear element and/or the at least If a 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 that is different from the basic distribution to the output shafts and via these to the Vehicle wheels are divided or distributed, for example by varying the operation of the other electric machine, that is, for example by varying a torque provided by the other electric machine, in particular by the rotor of the other electric machine, for driving or braking the coupling gear, said distribution varies can be. 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, 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 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, namely a first vehicle wheel 14 and a second vehicle wheel 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 thus the motor vehicle as a whole can be driven, in particular purely, electrically. The vehicle wheels 14 and 16 are ground contact elements of the motor vehicle, which can be supported or is supported downwards on a floor in the vertical direction of the vehicle via the ground contact elements. 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 vehicle wheels 14 and 16 roll, in particular directly, on the ground. For this purpose, 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 is by means of the stator 20 can be driven and thereby rotatable 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. 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 axial direction therefore means the direction of an axis of rotation of the rotors 22, 28 of the electrical machines 18, 25, which in the exemplary embodiments shown here are arranged coaxially to one another, whose axes of rotation are therefore the same. In the context of this disclosure, the term “axial” always refers to the axis of rotation of the electrical machines 18, 25.

The drive system 10 also includes 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 results Output torque 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 can be driven by the output shaft 33 and thus via the output shaft 33 by the coupling gear 30 and 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 electrical 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 first planetary gear set 32 has a first element 36, a second element 38 and a third element 40. The 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 element 38 is a first planet carrier, which is also referred to as the 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.

Both planetary gear sets 32, 34 are arranged coaxially to the axis of rotation of the rotors 22, 28 in the exemplary embodiments.

It can be seen that the fifth element 44 is connected, in particular permanently, to the second element 38 in a rotationally fixed manner. In addition, the sixth element 46 is connected, in particular permanently, in a rotationally fixed manner to the second output shaft 35. The first rotor 22 is, in particular torque-transmitting and in particular rotationally fixed, coupled to the second element 38 and thus to the fifth element 44, that is to say connected in such a way that the first rotor 22 is provided or can be provided by the first electric machine 18 via the first rotor 22 Drive torques on the second element 38 or via the second element 38 can be introduced into the coupling gear 30. In the first embodiment shown in FIG. 1, the first rotor 22 is coupled, in particular permanently, in a rotationally fixed manner to the second element 38, that is to say connected. In order to be able to implement a particularly advantageous drive in a particularly space-saving manner, the drive system 10 has a first switching element SE1, which is designed to connect the first output shaft 33 to the first element 36 in a rotationally fixed manner. A second switching element SE2 is also provided, which is designed to connect the first output shaft 33 to the third element 40 in a rotationally fixed manner. A switching part 48 common to the switching elements SE1 and SE2 is provided, which is designed, for example, as a sliding sleeve and can be switched between a first state and a second state. In particular, the 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, in the first state, i.e. in the first coupling state, the output shaft 33 is connected in a rotationally fixed manner to the first element 36 by means of the switching part 48 and by means of the switching element SE1. In the second coupling state, the output shaft 33 is connected in a rotationally fixed manner to the third element 40 by means of the switching part 48 and by means of the second switching element SE2. In the first decoupling state (second state), the output shaft 33 is decoupled from the element 36, such that no torque can be transmitted between the output shaft 33 and the element 36 via the switching part 48 and the switching element SE1 and so that the output shaft 33 and the element 36 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 output shaft 33 is decoupled from the element 40 in such a way that no torque can be transmitted between the output shaft 33 and the element 40 via the switching part 48 and the switching element SE2 and so that the output shaft 33 and the element 40 can be rotated relative to each other about the planetary gear set rotation axis. In particular, the switching element SE1 and/or SE2 is a positive switching element, in particular a claw clutch, also simply referred to as a claw.

The drive system 10 also includes a third switching element SE3, which is designed to couple the second rotor 28, in particular torque-transmitting and most particularly rotationally fixed, to the fourth element 42, that is to say to connect the second rotor 28 via second drive torques provided or able to be provided to the second rotor 28 on the fourth Element 42 or via the fourth element 42 can be introduced into the coupling gear 30. For this purpose, for example, the switching element SE3 is assigned a switching part 49, which can be switched between a third coupling state and a third decoupling state. For example, the switching part 49 can be moved, in particular translationally and/or relative to the housing 24, between a third coupling position causing the third coupling state and a third decoupling position causing the third decoupling state. In the third coupling state, the second rotor 28 is connected to the element 42 in a torque-transmitting, in particular rotating, manner by means of the switching element SE3 and by means of the switching part 49. In the third decoupling state, the rotor 28 is decoupled from the element 42 in such a way that no torque can be transmitted between the rotor 28 and the element 42 via the switching element SE3 and the switching part 49, so that relative rotations between the rotor 28 occur in particular about the planetary gear set rotation axis and element 42 are allowed.

In the first embodiment, first planet gears 50 are rotatably held on the second element 38. The first planetary gears 50 mesh with a first toothing of the first element 36 and with a third toothing of the third element 40. Second planetary gears 52 are rotatably held on the fifth element 44, which is connected in a rotationally fixed manner to the second element 38, and on the fifth Element 44 also holds third planet gears 54 rotatably. The second planetary gears 52 mesh with a fourth toothing of the fourth element 42, and the third planetary gears 54 mesh with a sixth toothing of the sixth element 46. In addition, one of the second planetary gears 52 meshes, in particular precisely, with a respective one of the third Planetary gears 54. One of the first planetary gears 50 also meshes with one of the third planetary gears 54. The element 44 is therefore designed as a double planetary carrier, so that, for example, the planetary gearset 34 is designed as a double planetary gearset.

The first planetary gears 50 or the third planetary gears 54 can be designed as stepped planetary gears. If the first ring gear (third element 40) and the second ring gear (sixth element 46) have the same diameter or the same number of teeth, both the first planet gears 50 and the third planet gears 54 are designed as unstepped planet gears. If the two ring gears mentioned (third element 40, sixth element 46) have different diameters or numbers of teeth, either the first planetary gears 50 are stepped and the third planetary gears 54 are unstepped, or the first planetary gears 50 are unstepped and the third planetary gears are stepped.

Furthermore, the electric drive system 10 has a first transmission stage 56, which is arranged downstream of the first output shaft 33 and downstream of the coupling gear 30 and upstream of the first vehicle wheel 14 with respect to a first torque flow, so that the respective first output torque from the output shaft 33 via the first Gear ratio 56 can be transferred to or on the vehicle wheel 14. A second transmission stage 58 is also provided, which is arranged downstream of the second output shaft 35 and downstream of the coupling gear 30 and upstream of the vehicle wheel 16 with regard to a second torque flow. The respective second output torque can thus be transmitted from the output shaft 35 to the second vehicle wheel 16 via the second gear ratio 58. From Fig. 1 it can be seen that the respective transmission stage 56, 58 is a respective, further planetary gear set, which has a respective, seventh element 60, a respective, eighth element 62 and a respective, ninth element 64. In the first embodiment, the respective element 60 is a respective further sun gear, the respective element 62 is a respective further planet carrier, and the respective element 64 is a respective further sun gear. Furthermore, it is provided that the respective element 64 is connected to the housing 24, in particular permanently, in a rotationally fixed manner. Additional planet gears 66 are rotatably held on the respective element 62. The respective element 62 serves as an output of the respective transmission stage 56, 58, from whose output the respective vehicle wheel 14, 16 can be driven. In addition, for example, the respective element 60 serves as a respective input, at or via which the respective output torque provided or that can be provided by the respective output shaft 33, 35 can be introduced into the respective transmission stage 56, 58. In the present case, the respective element 60 is connected, in particular permanently, in a rotationally fixed manner to the respective output shaft 33, 35. In the first embodiment, the electrical machines 18 and 25 and the third switching element SE3 are arranged in the axial direction of the coupling gear 30 and thus along the planetary gear set rotation axis in the following order, that is, one behind the other: The first electrical machine 18 - the third switching element SE3 - the second electrical machine 25. Thus, viewed in the axial direction of the coupling gear 30, the formwork element SE3 connects to the electrical machine 18, and the electrical machine 25 connects to the switching element SE3.

Fig. 2 shows a second embodiment of the drive system 10. In the second embodiment, the electrical machines 18 and 25 and the switching element SE3 in the axial direction of the coupling gear 30, in particular in the following order and thus arranged one behind the other: The switching element SE3 - the electrical machine 25 - the electrical machine 18. Thus, viewed in the axial direction of the coupling gear 30, the electrical machine 25 connects to the switching element SE3 and the electrical machine 18 to the electrical machine 25. In the second embodiment, a connection of the first rotor 22 to the second element 38 and the fifth element 44, viewed in the axial direction, is arranged between the two planetary gear sets.

Fig. 3 shows a switching table to illustrate operations A, B and C of the drive system 10, also referred to as modes or operating modes. For or in the first operation A, the first switching element SE1 is closed, the second switching element SE2 is open and the third switching element SE3 closed. The first operation A is, for example, a first torque shift operation of the drive system 10. In or for the second 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 example, the second operation B is an efficient operation of the drive system 10. 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. The third operation D is, for example, a second torque shift operation of the drive system 10.

4 shows a schematic representation of a third embodiment of an electric drive system 10. The third embodiment differs from the first embodiment shown in FIG. 1 in only two respects: as an alternative to the arrangement of the transmission stages 56, 58, the transmission stages 56, 58 in the third embodiment is arranged upstream of the coupling gear 30 with respect to a torque flow emanating from the electrical 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 with regard to the torque flow emanating from the electric machines 18, 25.

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

In the third embodiment, the first rotor 22 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 translation stage 58 is connected to the fifth element 44 in a rotationally fixed manner. The second transmission stage 58 is advantageously arranged axially between the first electrical machine 18 and the coupling gear 30.

Furthermore, in the third embodiment, the second rotor 28 can be connected in a rotationally fixed manner to the seventh element 60 of the first transmission stage 56 by means of the third switching element SE, the eighth element 62 of the first transmission stage 56 being connected in a rotationally fixed manner to the fourth element 42. By means of the fourth switching element SE4, the second rotor 28 can be connected to the first rotor 22 in a rotationally fixed manner. When the fourth switching element SE4 is closed and the third switching element SE3 is open, both electrical machines 18, 25 can simultaneously introduce their power into the coupling gear 30 via the fifth element 44.

The third switching element SE3 is assigned a switching part 490, which can be switched between the third coupling state and a third decoupling state analogously to the switching part 49 of the first embodiment and the second embodiment. Here, the switching part 490 can be moved, in particular translationally and/or relative to the housing 24, between a third coupling position causing the third coupling state and a third decoupling position causing the third decoupling state. In the third coupling state, the second rotor 28 is connected to the fourth element 42 in a torque-transmitting manner by means of the third switching element SE3 and by means of the switching part 490, such that torques emanating from the second rotor 28 are introduced into the coupling gear at the fourth element 42 can. In the third decoupling state, the rotor 28 is decoupled from the element 42 in such a way that no torque can be introduced into the coupling gear 30 via the switching element SE3 and the switching part 49, starting from the second rotor 28 on the fourth element 42.

The fourth switching element SE4 is also assigned to the switching part 490 in the third exemplary embodiment. The fourth switching element SE4 and the third switching element SE3 advantageously have a common switching part and can be switched by a common actuator. The switching part 490 is advantageously permanently non-rotatable with the second rotor 28 connected, wherein the switching part 490 is arranged axially displaceable to the second rotor 28.

In the case of the third embodiment, the sixth element 46 is coupled, in particular in a rotationally fixed manner, to the second vehicle wheel 16 without an additional intermediate transmission stage. The first vehicle wheel 14 can be coupled to the first element 36, in particular in a rotationally fixed manner, by means of the first switching element SE1 without a further intermediate transmission stage. In addition, the first vehicle wheel 14 can be coupled, in particular in a rotationally fixed manner, to the third element 40 by means of the second switching element SE2 without a further 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 switching part

49, 490 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 more planetary gears

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

Mercedes-Benz Group AG patent claims

1. 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) and a third element (40) 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) connected in a rotationally fixed manner to the second output shaft (35), wherein the first rotor (22) is coupled to the second element (38) in such a way that first drive torques provided by the first electrical machine (18) via the first rotor (22) are transferred to the second element (38) into the coupling gear (30 ) can be initiated, characterized by:

- a first switching element (SE1), which is designed to connect the first output shaft (33) to the first element (36) in a rotationally fixed manner,

- a second switching element (SE2), which is designed to connect the first output shaft (33) to the third element (40) in a rotationally fixed manner, and

- a third switching element (SE3), which is designed to couple the second rotor (28) to the fourth element (42) in such a way that second drive torques provided by the second electrical machine (25) via the second rotor (28). can be introduced into the coupling gear (30) on the fourth element (42). 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) are rotatably held on the second element (38),

- 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),

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

- 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 second planet gears (52) meshes with a respective one of the third planet gears (54), 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 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 the 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 third switching element (SE3) is designed to rotationally couple the second rotor (28) to the fourth element (42). Method for operating an electric drive system according to one of the preceding claims, 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 according to one of claims 1 to 6, 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 according to one of claims 1 to 6, 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.