Electric drive system for a motor vehicle, in particular for a motor car, and methods for operating such an electric drive system

Abstract

Electric drive system (10) for a motor vehicle, comprising: - a first electric machine (18) which has a first rotor (22); - a second electric machine (26) which has a second rotor (30) arranged coaxially to the first rotor (22); - a planetary differential gear (36) arranged coaxially to the first rotor (22), which has a planet carrier (38), a first sun gear (40) and a second sun gear (42); - an input planetary gear ratio (50) comprising an input sun gear (52), an input planetary carrier (54) connected non-rotatably to the planet carrier (38) and an input ring gear (56) connected non-rotatably to a housing (34) of the electric drive system (10); - a first switching element (SE1) which is designed to connect the first rotor (22) to the planet carrier (38) in a rotationally fixed manner; - a second switching element (SE2) which is designed to connect the second rotor (30) to the input sun wheel (52) in a rotationally fixed manner; - a third switching element (Se3) designed to connect the first rotor (22) to the first sun gear (40) in a rotationally fixed manner; and - a fourth switching element (SE4) which is designed to connect the second rotor (30) to the second sun wheel (42) in a rotationally fixed manner.

Description

[0001] The invention relates to an electric drive system for a motor vehicle, in particular for a car. Furthermore, the invention relates to a method for operating such an electric drive system.

[0002] DE 10 2018 128 836 B3 discloses a transmission device for a motor vehicle, comprising a planetary gear with a drive sun gear, a ring gear fixed to the housing and several stepped planetary gears.

[0003] DE 10 2020 119 290 A1 discloses an electric drive system for a motor vehicle with two electric machines, wherein an input gear ratio and four shifting elements are provided. A first of the shifting elements is designed to connect a first rotor in a rotationally fixed manner to a differential housing of a differential gear. A second of the shifting elements is designed to connect a second rotor in a rotationally fixed manner to an input spur gear of the input gear ratio. A third of the shifting elements is designed to connect the first rotor in a rotationally fixed manner to a first output shaft of the differential gear. A fourth of the shifting elements is designed to connect the second rotor in a rotationally fixed manner to a second output shaft of the differential gear.

[0004] The object of the present invention is to provide an electric drive system for a motor vehicle and a method for operating such an electric drive system, so that a particularly compact design and a particularly advantageous drivability of the drive system can be realized.

[0005] This object is achieved by an electric drive system having the features of patent claim 1 and by a method having the features of patent claim 8. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0006] 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, also simply referred to as a vehicle. This means that the motor vehicle, preferably designed as a motor vehicle, in particular as a passenger car, has the electric drive system in its fully manufactured state and can be driven, in particular purely electrically, by means of the electric drive system. Thus, the motor vehicle is preferably a hybrid vehicle or an electric vehicle, in particular a battery-electric vehicle (BEV). For example, in its fully manufactured state, the motor vehicle has at least or exactly two vehicle axles arranged consecutively and thus one behind the other in the longitudinal direction of the motor vehicle, also simply referred to as axles.Each vehicle axle has at least or exactly two vehicle wheels, also simply referred to as wheels. The vehicle wheels of the vehicle axles are ground contact elements by means of which the motor vehicle can be or is supported downwards on a ground in the vertical direction of the vehicle. The respective vehicle wheels are arranged on opposite sides of the motor vehicle in the transverse direction of the vehicle. If the motor vehicle is driven along the ground while being supported downwards on the ground in the vertical direction of the vehicle via the vehicle wheels (ground contact elements), the vehicle wheels roll, in particular directly, on the ground. The vehicle wheels of at least or exactly one of the vehicle axles or both vehicle axles can be driven, in particular purely electrically, by means of the electric drive system.When reference is made below to vehicle wheels, unless otherwise stated, this refers to the vehicle wheels that can be driven by means of the electric drive system, which are also referred to as drive wheels.

[0007] The electric drive system has a first electric machine which has a first rotor. For example, the first electric machine has a first stator, by means of which the first rotor can be driven and can therefore be rotated about a first machine axis of rotation relative to the stator. The first electric machine can, for example, via its first rotor, provide first drive torques for driving the vehicle wheels and thus the motor vehicle. The electric drive system also has a second electric machine which has a second rotor. In particular, the second electric machine has a second stator, by means of which the second rotor can be driven and can therefore be rotated about a second machine axis of rotation relative to the second stator. The rotors and thus the electric machines are arranged coaxially to one another such that the machine axes of rotation coincide.The electric drive system also has a planetary differential gear. The planetary differential gear is a differential gear, also simply referred to as a differential, which is designed in a planetary design. The planetary differential gear has a planet carrier, which is also referred to as the first planet carrier, a first sun gear, and a second sun gear. The planet carrier, the first sun gear, and the second sun gear are first gear elements of the planetary differential gear, also simply referred to as a differential. The electric drive system has a housing in which, for example, the planetary differential gear is at least partially arranged. In particular, when the respective first gear element is not connected to the housing in a rotationally fixed manner, the respective first gear element is rotatable about a first planetary gear axis of rotation relative to the housing.The planetary differential gear is arranged coaxially to the first rotor and thus also coaxially to the second rotor, so that the first planetary gear axis of rotation coincides with the respective machine axis of rotation.

[0008] The electric drive system also has an input planetary gear ratio, which is provided in particular in addition to the planetary differential gear. The input planetary gear ratio is a first planetary gear set or is also referred to as a first planetary gear set. The input planetary gear ratio has an input sun gear as the third sun gear and an input planetary carrier as the second planetary carrier. The input planetary carrier is connected, in particular permanently, in a rotationally fixed manner to the first planetary carrier of the planetary differential gear. Furthermore, the input planetary gear ratio has an input ring gear as the first ring gear, which is connected, in particular permanently, in a rotationally fixed manner to the housing of the electric drive system.

[0009] The electric drive system further comprises a first switching element which is designed to connect the first rotor in a rotationally fixed manner to the first planet carrier. When reference is made to the planet carrier below, this refers to the first planet carrier unless otherwise stated. In other words, the first rotor can be connected in a rotationally fixed manner to the first planet carrier by means of the first switching element. In particular, the first switching element can be switched between a first coupled state and a first uncoupled state. In the first coupled state, the first rotor is connected in a rotationally fixed manner to the planet carrier by means of the first switching element. In the first uncoupled state, the first switching element releases the first rotor for rotation about the machine axis of rotation and thus about the first planetary gear axis of rotation relative to the planet carrier.In other words, in the first decoupling position, the first rotor and the planet carrier are rotatable relative to one another about the first planetary gear axis of rotation or about the respective machine axis of rotation. The respective machine axis of rotation and the first planetary gear axis of rotation are collectively referred to as the axis of rotation or main axis of rotation, which runs in the axial direction of the electric drive system or coincides with the axial direction of the electric drive system. The input sun gear, the input planet carrier, and the input ring gear are second gear elements of the input planetary transmission. In particular, when the respective second gear element is not connected to the housing in a rotationally fixed manner, the respective second gear element is rotatable relative to the housing about a second planetary gear axis of rotation.In particular, it is conceivable that the input planetary gear ratio is arranged coaxially to the planetary differential gear so that the planetary gear rotation axes coincide.

[0010] 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 first decoupling position causing the first decoupling state.

[0011] The electric drive system has a second switching element which is designed to connect the second rotor in a rotationally fixed manner to the input sun gear. In other words, the second switching element can be used to connect the second rotor in a rotationally fixed manner to the input sun gear. For example, the second switching element can be switched between a second coupled state and a second uncoupled state. In the second coupled state, the second rotor is connected in a rotationally fixed manner to the input sun gear by means of the second switching element. In the second uncoupled state, the second switching element releases the second rotor for rotation about the respective machine axis of rotation relative to the input sun gear, such that in the second uncoupled state the second rotor and the input sun gear can be rotated relative to one another about the respective machine axis of rotation and in particular about the second planetary gear axis of rotation.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.

[0012] The electric drive system further comprises a third switching element configured to connect the first rotor to the first sun gear in a rotationally fixed manner. In other words, the first rotor can be connected to the first sun gear in a rotationally fixed manner by means of the third switching element. 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 first rotor is connected to the first sun gear in a rotationally fixed manner by means of the third switching element.In the third decoupling state, the third switching element releases the first rotor for rotation about the respective machine rotational axis or about the first planetary gear rotational axis relative to the first sun gear, so that in the third decoupling state, the first rotor and the first sun gear are rotatable relative to one another about the respective machine rotational axis or about the first planetary gear rotational 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 bringing about the third coupling state and at least one third decoupling position bringing about the third decoupling state.

[0013] The electric drive system also includes a fourth switching element configured to connect the second rotor to the second sun gear in a rotationally fixed manner. In other words, the fourth switching element connects the second rotor to the second sun gear in a rotationally fixed manner. For example, the fourth switching element can be switched between a fourth coupling state and a fourth decoupling state. In the fourth coupling state, the fourth switching element connects the second rotor to the second sun gear in a rotationally fixed manner.In the fourth decoupling state, the fourth switching element releases the second rotor for rotation about the respective machine rotational axis and about the first planetary gear rotational axis relative to the second sun gear, so that in the fourth decoupling state, the second rotor and the second sun gear can be rotated relative to one another about the respective machine rotational axis and about the first planetary gear rotational axis coinciding therewith.

[0014] For example, the fourth switching element can be moved, in particular translationally and / or relative to the housing, between at least one fourth coupling position causing the fourth coupling state and at least one fourth decoupling position causing the fourth decoupling state.

[0015] The invention enables a particularly compact design or construction of the electric drive system to be realized. The planetary differential gear can be configured as an integrated planetary differential, in particular with the input planetary gear ratio as the gear ratio stage, so that particularly advantageous drivability can be achieved in a particularly space-efficient manner. The switching elements enable advantageous and space-efficient switchability of the electric drive system, so that particularly good drivability can be achieved. The invention is based on the finding that with independent wheel drives, a respective torque can be provided at the respective drivable vehicle wheel by the electric machine assigned to the respective vehicle wheel. As a result, the electric machines are usually only lightly utilized and operate inefficiently.Solving this problem usually requires a lot of installation space. The problems and disadvantages mentioned above can now be avoided by the invention. In particular, the differential makes it possible to connect both output sides, i.e. both drivable vehicle wheels, in particular permanently, to one sideshaft each. The switching elements can be used as changeover switches to selectively and as needed switch between different operating modes of the electric drive system. For example, it is possible to switch selectively between a first differential operation with exactly one of the electric machines, a second differential gear with the other, geared electric machine, or a torque distribution operation also known as torque vectoring operation, in particular as individual wheel drive.In the first differential mode, for example, it is provided that the vehicle wheels are driven exclusively by one of the electric machines, in particular by the first electric machine, with respect to the electric machines. In the second differential mode, for example, it is provided that the vehicle wheels are driven exclusively by the other electric machine, in particular by the second electric machine, with respect to the electric machines. In the torque distribution mode, a single-wheel drive can be implemented in which, for example, a first of the vehicle wheels is driven by the first electric machine and the second vehicle wheel is driven by the second electric machine.It is possible to merge the differential and the input planetary gear ratio, also known as the planetary gear set, into one assembly in order to achieve a particularly small installation space requirement.

[0016] In the context of the present disclosure, ordinal numbers such as "first", "first", "second", "second", etc. are not necessarily used to indicate or imply a number or quantity, but rather to clearly refer to terms to which the ordinal numbers are assigned or to which the ordinal numbers refer. However, at least four switching elements are provided, namely the first switching element, the second switching element, the third switching element, and the fourth switching element, so that the second switching element is provided in addition to the first switching element, the third switching element is provided in addition to the first switching element and the second switching element, and the fourth switching element is provided in addition to the first, second, and third switching elements.

[0017] In the context of the present disclosure, the feature that two components, such as the planet carrier and the input planet carrier, are connected to one another in a rotationally fixed manner, is to be understood as meaning that the components connected to one another in a rotationally fixed manner are arranged coaxially to one another and, in particular when the components are driven, rotate together or simultaneously about a component rotation axis common to the components, such as the respective planetary gear rotation axis, at 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 to one another in such a way that torques can be transmitted between the components, wherein, when the components are connected to one another in a rotationally fixed manner, the components are also connected to one another in a torque-transmitting manner.

[0018] The feature that two components are permanently connected to one another in a torque-transmitting manner means that a switching element is not provided that can be switched between a coupled state connecting the components to one another in a torque-transmitting manner and a decoupling state in which no torque can be transmitted between the components via the switching element. Rather, the components are always and therefore permanently connected to one another in a torque-transmitting manner, i.e., they are 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, or vice versa.In particular, the feature that two components are permanently connected to one another in a rotationally fixed manner is to be understood as meaning that a switching element is not provided which can be switched between a coupling state connecting the components to one another in a rotationally fixed manner and a decoupling state in which the components are decoupled from one another and can be rotated relative to one another so that no torque can be transmitted between the components via the switching element, but rather the components are always, and therefore permanently, connected or coupled to one another in a rotationally fixed manner.

[0019] The feature that two components can be connected to one another in a rotationally fixed or torque-transmitting manner is understood to mean that a switching element, such as the first switching element, is assigned to the components, wherein the switching element can be switched between at least one coupled state and at least one uncoupled state. In the coupled state, the components are connected to one another in a rotationally fixed or torque-transmitting manner by means of the switching element. In the uncoupled state, the components are decoupled from one another, such that in the uncoupled state the components are rotatable relative to one another, in particular about the component rotation axis, and in particular such that no torque can be transmitted between the components via the switching element.Thus, “rotatably fixed” is to be understood as follows in particular: A rotatably fixed connection between two, in particular rotatably mounted, elements means that the two elements are arranged coaxially to one another and connected to one another in such a way that they rotate at the same angular velocity. A rotatably fixed connection of an element such as the input ring gear to the housing means that the element is connected to the housing in such a way that it cannot be rotated relative to the housing. Furthermore, the terms “axial” and “in the axial direction” refer to the aforementioned axis of rotation or to a direction of the axis of rotation, with respect to which the rotors and the planetary differential gear and preferably also the input planetary gear ratio are arranged coaxially to one another.

[0020] In order to be able to realize particularly advantageous drivability in a particularly space-efficient manner, a further embodiment of the invention provides a first output planetary gear ratio, which is also referred to as a second planetary gear set or is designed as a second planetary gear set. The first output planetary gear ratio has a first output sun gear as the fourth sun gear, which is connected, in particular permanently, in a rotationally fixed manner to the first sun gear. The first output planetary gear ratio has a first output planet carrier as the third planet carrier. In addition, the first output planetary gear ratio has a first output ring gear as the second ring gear, which is connected, in particular permanently, in a rotationally fixed manner to the housing.The first output planetary gear ratio is provided in addition to the differential and in addition to the input planetary gear ratio, so that the fourth sun gear, the third planet carrier, and the second ring gear, thus the first output sun gear, the first output planet carrier, and the first output ring gear, are third gear elements of the first output planetary gear ratio. Particularly when the respective third gear element is not rotationally fixedly connected to the housing, the respective third gear element is rotatable about a third planetary gear axis of rotation relative to the housing. For example, the first output planetary gear ratio can be arranged coaxially with the planetary differential gear, so that the third planetary gear axis of rotation coincides with the first planetary gear axis of rotation.

[0021] A second output planetary gear ratio is also provided, which is a third planetary gear set. In particular, the second output planetary gear ratio is provided in addition to the first output planetary gear ratio and in addition to the input planetary gear ratio and also in addition to the planetary differential gear. The second output planetary gear ratio has a second output sun gear as the fifth sun gear, which is connected, in particular permanently, in a rotationally fixed manner to the second sun gear. The second output planetary gear ratio has a second output planetary carrier as the fourth planet carrier. In addition, the second output planetary gear ratio has a second output ring gear as the third ring gear, which is connected, in particular permanently, in a rotationally fixed manner to the housing. The second output sun gear, the second output planetary carrier, and the second output ring gear are fourth gear elements of the second output planetary gear ratio.In particular, when the respective fourth gear element is not connected to the housing in a rotationally fixed manner, the respective fourth gear element can be rotated about a fourth planetary gear axis of rotation relative to the housing. In particular, the output planetary gear ratios are arranged coaxially to one another, such that the third planetary gear axis of rotation coincides with the fourth planetary gear axis of rotation, or vice versa. In particular, the second output planetary gear ratio is arranged coaxially to the planetary differential gear, such that the fourth planetary gear axis of rotation coincides with the first planetary gear axis of rotation. By using the output planetary gear ratios, a particularly advantageous gear ratio and thus particularly good drivability of the electric drive system can be achieved in a particularly space-efficient manner.

[0022] A further embodiment is characterized in that the first switching element and the third switching element are combined to form a first coupling switching element. The third coupling switching element can be actuated by means of a first common actuator of the electric drive system. This means that the electric drive system has the first actuator, by means of which the coupling switching element and thus the first switching element and the third switching element can be actuated. Thus, by means of the first actuator, the first switching element can be switched between the first coupling state and the first decoupling state and the third switching element can be switched between the third coupling state and the third decoupling state, in particular in the following way. For example, the first coupling switching element can be switched between at least one first connection state and at least one second connection state by means of the first actuator.In the first connection state, for example, the first coupling state and the third decoupling state are set, i.e., activated or engaged, in particular simultaneously, so that, for example, in the first connection state, the first switching element is in the first coupling state and the third switching element is in the third decoupling state. In the second connection state, the third coupling state and the first decoupling state are set, i.e., activated, in particular simultaneously, so that, for example, in the second connection state, the third switching element is in the third coupling state and the first switching element is in the first decoupling state.For example, by means of the first actuator, the first coupling switching element can be switched into at least one first neutral state, in which, in particular simultaneously, the first decoupling state and the third decoupling state are set, i.e. engaged or activated, so that, for example, in the first neutral state, the first switching element is in the first decoupling state and the third switching element is in the third decoupling state. For example, by means of the first actuator, the first coupling switching element can be moved, in particular relative to the housing and / or translationally, between at least one first connection position bringing about the first connection state and at least one second connection position bringing about the second connection state and, for example, also between at least one first neutral position bringing about the first neutral state.

[0023] Furthermore, it is preferably provided that the second switching element and the fourth switching element are combined to form a second coupling switching element, which can be actuated by means of a second common actuator of the electric drive system. Thus, the electric drive system preferably also has the second actuator, by means of which the second coupling switching element can be actuated, i.e., switched. For example, the second coupling switching element can be switched between at least a third connection state and at least a fourth connection state by means of the second actuator. In the third connection state, for example, in particular simultaneously, the second coupling state and the fourth decoupling state are set, i.e., activated or engaged, so that, for example, in the third connection state, the second switching element is in the second coupling state and the fourth switching element is in the fourth decoupling state.In the fourth connection state, for example, in particular simultaneously, the fourth coupling state and the second decoupling state are engaged, i.e. activated or engaged, so that, for example, in the fourth connection state, the fourth switching element is in the fourth coupling state and the second switching element is in the second decoupling state. Furthermore, it is conceivable for the second coupling switching element to be switchable into a second neutral state by means of the second actuator. In the second neutral state, for example, in particular simultaneously, the fourth decoupling state and the second decoupling state are set, i.e. engaged or activated, so that, for example, in the second neutral state, the fourth switching element is in the fourth decoupling state and the second switching element is in the second decoupling state.Thus, by means of the second actuator, the second switching element and the fourth switching element can be switched simultaneously, in particular between the second coupling state, the second decoupling state, the fourth coupling state, and the fourth decoupling state. For example, by means of the second actuator, the second coupling switching element can be moved, in particular relative to the housing and / or translationally, between at least one third connection position effecting the third connection state and at least one fourth connection position effecting the fourth connection state, as well as, for example, also between at least one second neutral position effecting the second neutral state. This allows the installation space requirement to be kept particularly low.

[0024] In order to be able to achieve a particularly small installation space requirement, particularly in the axial direction of the electric drive system and thus viewed along the axis of rotation, it is provided in a further embodiment of the invention that with regard to the axial direction of the electric drive system, that is to say in the axial direction of the electric drive system, the first rotor, the third switching element, the first switching element, the first sun gear, the second sun gear, the input sun gear, the second switching element, the fourth switching element and the second rotor are arranged in the order mentioned, that is to say in the order in which they are named, one after the other and thus one after the other or behind the other.In other words, it is preferably provided that in the axial direction of the electric drive system, the first rotor, the third switching element, the first switching element, the first sun gear, the second sun gear, the input sun gear, the second switching element, the fourth switching element and the second rotor are arranged successively in the following order, that is to say one behind the other or one after the other: The first rotor - the third switching element - the first switching element - the first sun gear - the second sun gear - the input sun gear - the second switching element - the fourth switching element - the second rotor.In other words, it is preferably provided that in the axial direction of the electric drive system the third switching element is connected to the first rotor, the first switching element to the third switching element, the first sun gear to the first switching element, the second sun gear to the first sun gear, the input sun gear to the second sun gear, the second switching element to the input sun gear, the fourth switching element to the second switching element and the second rotor to the fourth switching element.

[0025] In a further, particularly advantageous embodiment of the invention, it is provided that first planetary gears are arranged, in particular rotatably, or held on the planet carrier of the planetary differential gear. The respective first planetary gear meshes with the first sun gear. Furthermore, it is preferably provided that second planetary gears, provided in addition to the first planetary gears, are arranged, in particular rotatably, or held, on the planet carrier (first planet carrier), wherein the respective second planetary gear meshes with the second sun gear. It is preferably provided that meshing of the first planetary gears with the second sun gear is omitted, and it is preferably provided that meshing of the second gears with the first sun gear is omitted.Furthermore, it is preferably provided that each of the first planetary gears meshes, in particular precisely, with each of the second planetary gears, thereby forming a planetary gear group. This allows the installation space requirement to be kept particularly low.

[0026] In order to be able to keep the installation space requirement of the planetary differential gear and thus of the electric drive system particularly small, it is provided in a further embodiment of the invention that input planetary gears are rotatably arranged, in particular held, on the input planetary carrier as third planetary gears, wherein the second planetary gears are provided in addition to the first planetary gears, and wherein the third planetary gears are provided in addition to the first and second planetary gears. In order to be able to keep the installation space requirement particularly small, it is preferably provided that in each case, in particular precisely, one of the input planetary gears is arranged coaxially to in each case, in particular precisely, one of the second planetary gears, thereby forming a respective second planetary gear group.

[0027] In this case, it is preferably provided that the respective planetary gears of the respective second planetary gear group, which are arranged coaxially to one another, are rotatably arranged, in particular held or mounted, on a common planetary gear bolt, whereby the installation space requirement, the weight and the costs can be kept particularly low. It has proven particularly advantageous if the planetary gear bolt is designed as a single piece, i.e. as a single part. This means that the planetary gear bolt is formed from a single piece and is thus designed as a monoblock or as a monoblock. In other words, it is preferably provided that the planetary gear bolt is designed as a single-piece and thus integrally manufactured, integral body which is not composed of several parts formed separately from one another and connected to one another, but rather the planetary gear bolt is designed as a single piece.Preferably, the planetary gear bolt is formed from a metallic material, in particular from a steel, so that the respective planetary gear bolt is preferably designed as a steel bolt.

[0028] 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 embodiments of the first aspect of the invention are to be regarded as advantages and advantageous embodiments of the second aspect of the invention, and vice versa.

[0029] In order to be able to realize particularly advantageous operation, one embodiment of the second aspect of the invention provides that, for a first efficient mode of operation, the first switching element is closed, the second switching element is open, the third switching element is open, and the fourth switching element is open. Thus, it is preferably provided that, in the first efficient mode of operation, the first switching element is in the first coupling state, the second switching element is in the second decoupling state, the third switching element is in the third decoupling state, and the fourth switching element is in the fourth decoupling state.

[0030] In order to achieve particularly advantageous drivability, a further embodiment of the invention provides that, for a second efficient mode, the first switching element is open, the second switching element is closed, the third switching element is open, and the fourth switching element is open. In other words, it is preferably provided that, in the second efficient mode, the first switching element is in the first decoupling state, the second switching element is in the second coupling state, the third switching element is in the third decoupling state, and the fourth switching element is in the fourth decoupling state.

[0031] A further embodiment is characterized for realizing a particularly advantageous operation in that, for a drive mode also referred to as boost mode or acceleration mode, the first switching element is closed, the second switching element is closed, the third switching element is open, and the fourth switching element is open. In other words, it is preferably provided that, during drive mode, the first switching element is in the first coupling state, the second switching element is in the second coupling state, the third switching element is in the third decoupling state, and the fourth switching element is in the fourth decoupling state.

[0032] Finally, it has proven particularly advantageous for realizing a particularly advantageous driving operation if, for a torque distribution operation of the electric drive system, also referred to as torque vectoring operation, the first switching element is open, the second switching element is open, the third switching element is closed, and the fourth switching element is closed. In other words, it is provided that, in the torque distribution operation, the first switching element is in the first decoupling state, the second switching element is in the second decoupling state, the third switching element is in the third coupling state, and the fourth switching element is in the fourth coupling state.

[0033] In the first efficiency mode, for example, a journey, in particular a purely electric journey, of the motor vehicle in normal differential operation is possible, wherein, for example, the vehicle wheels are driven exclusively by the first electric machine with respect to the electric machines. In this case, for example, the second electric machine is detached, and therefore uncoupled from the rest of the electric drive system, so that the second electric machine is preferably not dragged along. This can ensure particularly efficient operation. In the second efficiency mode, for example, a journey, in particular a purely electric journey, is possible, wherein, for example, the vehicle wheels are driven exclusively by the second electric machine with respect to the electric machines.The second electric motor is geared particularly advantageously, particularly through the input planetary gear ratio, so that a particularly high output torque can be achieved to drive the vehicle wheels. In particular, normal differential operation can be realized in the second efficiency mode, thereby enabling particularly efficient operation. In particular, it is possible to decouple the first electric motor from the rest of the electric drive system in the second efficiency mode, thus decoupling it from the rest of the electric drive system so that, for example, the first electric motor is not dragged along.

[0034] Boost mode enables, for example, strong acceleration and, in particular, a strong start of the motor vehicle, for example, from an initially stationary position. In boost mode, torque distribution, i.e., so-called torque vectoring, can be implemented, for example. In boost mode, the vehicle wheels are driven, for example, by both electric motors, in particular such that the vehicle wheels are driven by the first electric motor, in particular directly, and by the second electric motor, in particular with a transmission, in particular simultaneously. Furthermore, the invention makes it possible to implement a single-wheel drive, in particular for high-performance torque distribution travel.For example, in the torque distribution mode, the vehicle wheels are driven by both electric machines, in particular simultaneously, in particular, for example, in such a way that an individual wheel drive can be or is represented.

[0035] The first efficiency mode, the second efficiency mode, the boost mode (drive mode) and the torque distribution mode (torque vectoring mode) are, for example, the previously mentioned operating modes of the electric drive system, wherein switching between the operating modes can be carried out particularly advantageously and in particular at least almost without load interruption by means of the switching elements.

[0036] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawings. 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 alone in the figures, can be used not only in the respective specified combinations, but also in other combinations or on their own, without departing from the scope of the invention.

[0037] The drawing shows: Fig. 1 is a schematic representation of an electric drive system for a motor vehicle, and Fig. 2 a switching table to illustrate different operating modes of the electric drive system.

[0038] In the figures, identical or functionally identical elements are provided with the same reference numerals.

[0039] Fig. 1 shows a schematic representation of an electric drive system 10 for a motor vehicle, also referred to as a vehicle. The electric drive system 10 is a drive device. The motor vehicle, also simply referred to as a vehicle, has the electric drive system 10 in its fully manufactured state and can be driven by means of the electric drive system 10, in particular purely electrically. Furthermore, the motor vehicle in its fully manufactured state has at least or exactly two vehicle axles arranged one behind the other and thus consecutively in the longitudinal direction of the motor vehicle. Each vehicle axle has at least or exactly two vehicle wheels, wherein the respective vehicle wheels of the respective vehicle axle are arranged on opposite sides of the motor vehicle in the transverse direction of the motor vehicle.By means of the electric drive system 10, the vehicle wheels of at least one or both vehicle axles can be driven. The vehicle wheels of the motor vehicle that can be driven by the electric drive system 10 are shown in . Fig. 1 is shown particularly schematically and designated 12 and 14. The vehicle axle comprising the vehicle wheels 12 and 14 is designated 16.

[0040] 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 the stator 20 and is thereby rotatable relative to the stator 20 about a first machine rotation axis 24. Via its rotor 22, the first electric machine 18 can provide first drive torques for driving, in particular purely electrically, the vehicle wheels 12 and 14. The drive system 10 also has a second electric machine 26, which has a second stator 28 and a second rotor 30. The second rotor 30 can be driven by the second stator 28 and is thereby rotatable about a second machine rotation axis 32 relative to the stator 28 and also relative to a housing 34 of the electric drive system 10, wherein the rotor 22 is also rotatable about the machine rotation axis 24 relative to the housing 34. Fig. 1 shows that the rotors 22 and 30, and thus the electric machines 18 and 26, are arranged coaxially with one another, so that the machine rotation axes 24 and 32 coincide. Via its rotor 30, the second electric machine 26 can provide second drive torques for driving the vehicle wheels 12 and 14, in particular purely electrically.

[0041] The electric drive system 10 has a planetary differential gear 36, which is also simply referred to as a differential or differential gear. The differential can be driven by the respective electric machine 18, 26, so that the vehicle wheels 12 and 14 can be driven by the respective electric machine 18, 26 via the differential. For example, a respective input torque resulting from the respective drive torque can be introduced into the differential, whereby the differential can be driven. For example, the differential can provide a respective output torque resulting from the respective input torque for driving the respective vehicle wheel 12, 14. The differential has the function, sufficiently known from the general state of the art, that the differential can divide or distribute the respective input torque between the vehicle wheels 12 and 14.In addition, the differential allows for different rotational speeds of the vehicle wheels 12 and 14, for example when the motor vehicle is cornering, in particular such that the vehicle wheel 12, 14 on the outside of the curve can rotate at a higher rotational speed than the vehicle wheel 14, 12 on the inside of the curve, in particular while the vehicle wheels 12 and 14 are connected to the electric machine 18 and / or to the electric machine 26 in a torque-transmitting manner and can be driven or are driven by means of the electric machine 18 and / or by means of the electric machine 26.

[0042] The planetary differential gear has a first planet carrier 38, which is also simply referred to as the planet carrier. The planetary differential gear 36 also has a first sun gear 40 and a second sun gear 42. For example, the differential can provide the respective output torque via the respective sun gear 40, 42. As will be explained in more detail below, for example, a respective output torque resulting from the respective output torque can be transmitted to the respective vehicle wheel 12, 14 in order to thereby drive the respective vehicle wheel 12, 14. The output torque transmittable to the vehicle wheel 12 is illustrated by an arrow 44, and the output torque transmittable to the vehicle wheel 14 is illustrated by an arrow 46. The planet carrier 38 and the sun gears 40 and 42 are rotatable about a first planetary gear axis of rotation 48 relative to the housing 34.It can be seen that the differential is arranged coaxially to the electric machines 18 and 26, so that the first planetary gear rotation axis coincides with the machine rotation axes 24 and 32.

[0043] The drive system 10 has an input planetary gear ratio 50 as the first planetary gear set, which is provided in addition to the planetary differential gear 36. The input planetary gear ratio 50 has an input sun gear 52 as the third sun gear, an input planetary carrier 54 as the second planetary carrier, and an input ring gear 56 as the first ring gear. It can be seen that the input ring gear 56 is connected, in particular permanently, in a rotationally fixed manner to the housing 34. The input sun gear 52 and the input planetary carrier 54 can be rotated about a second planetary gear rotation axis 58 relative to the housing 34. For example, the input planetary gear ratio 50 is arranged coaxially with the differential and coaxially with the electric machines 18 and 26, so that the second planetary gear rotation axis 58 coincides with the first planetary gear axis 48 and with the machine rotation axes 24 and 32. Furthermore, Fig. 1 that the input planet carrier 54 (second planet carrier) is connected, in particular permanently, in a rotationally fixed manner to the first planet carrier 38.

[0044] The electric drive system 10 has a first switching element SE1, by means of which the first rotor 22 is rotationally fixedly connected to the first planetary carrier 38. A second switching element SE2 is also provided, by means of which the second rotor 30 is rotationally fixedly connected to the input sun gear 52. A third switching element SE3 is also provided, by means of which the first rotor 22 is rotationally fixedly connected to the first sun gear 40. Furthermore, the electric drive system 10 comprises a fourth switching element SE4, by means of which the second rotor 30 is rotationally fixedly connected to the second sun gear 42.

[0045] A first output planetary gear ratio 60 is also provided as a second planetary gear set, wherein the output planetary gear ratio 60 has a first output sun gear 62 as the fourth sun gear, a first output planetary carrier 64 as the third planetary carrier, and a first output ring gear 66 as the second ring gear. The first output ring gear 66 is connected, in particular permanently, in a rotationally fixed manner to the housing 34. The first output sun gear 62 is connected, in particular permanently, in a rotationally fixed manner to the first sun gear 40. The first output planetary gear ratio 60 is provided in addition to the differential and in addition to the input planetary gear ratio 50. The electric drive system 10 also includes a second output planetary gear ratio 68, which is provided in addition to the differential (planetary differential gear 36), in addition to the input planetary gear ratio 50, and in addition to the first output planetary gear ratio 60.The second output planetary gear ratio 68 has a second output sun gear 70 as the fifth sun gear, a second output planetary carrier 72 as the fourth planetary carrier, and a second output ring gear 74 as the third ring gear. It can be seen that the second output ring gear 74 is connected, in particular permanently, in a rotationally fixed manner to the housing 34. Furthermore, the second output sun gear 70 is connected, in particular permanently, in a rotationally fixed manner to the second sun gear 42. For example, the respective output planetary gear ratio 60, 68 can translate or convert the respective output torque that can be provided by the respective sun gear 40, 42 into the respective output torque illustrated by the respective arrow 44, 46, so that the respective vehicle wheel 12, 14 can be driven by the respective sun gear 40, 42 via the respective output planetary gear ratio 60, 68.

[0046] In the embodiment shown in the figures, the first switching element SE1 and the third switching element SE3 are combined to form a first coupling switching element KS1, which has a first switching part S1. As shown in Fig. 1 by a double arrow 76, the first switching part S1 can be moved, in particular translationally and / or relative to the housing 34, between at least one first connection position and at least one second connection position. In the first connection position, the first coupling switching element KS1 is in a first connection state, and in the second connection position, the first coupling switching element KS1 is in a second connection state.

[0047] In the first connection state, the first switching element SE1 is in its first coupling state, while the third switching element SE3 is in its third decoupling state. In other words, in the first connection state, the first switching element SE1 is closed, while the third switching element SE3 is open. In the second connection state, the third switching element SE3 is in its third coupling state, while the first switching element SE1 is in its first decoupling state. In other words, in the second connection state, the third switching element SE3 is closed, while the first switching element SE1 is open.

[0048] Furthermore, in the exemplary embodiment shown in the figures, the second switching element SE2 and the fourth switching element SE4 are combined or merged to form a second coupling switching element KS2, which has a second switching part S2. As illustrated by a double arrow 78, the second switching part S2 can be moved, in particular relative to the housing 34 and / or translationally, between at least one third connection position and at least one fourth connection position. In the third connection position, the coupling switching element KS2 is in a third connection state, and in the fourth connection position, the second coupling switching element KS2 is in a fourth connection state. In the third connection state, the second switching element SE2 is in its second coupling state, while the fourth switching element SE4 is in its fourth decoupling state.In the fourth connection state, the fourth switching element SE4 is in its fourth coupling state, while the second switching element SE2 is in its second decoupling state. In other words, in the third connection state, the second switching element SE2 is closed, while the fourth switching element SE4 is open. In the fourth connection state, the fourth switching element SE4 is closed, while the second switching element SE2 is open. For example, the first switching part S1 can be connected to the first switching element S1 by means of a... Fig. 1 particularly schematically shown, between the first connection position and the second connection position. For example, the second switching part S2 can be moved by means of a Fig. 1, the second actuator 82, which is particularly schematically illustrated, can be moved between the third connection position and the fourth connection position. The actuator 82 is provided in addition to the actuator 80, and the actuator 80 is provided in addition to the actuator 82. In particular, the actuator 80 is arranged externally with respect to the actuator 82, and preferably, the actuator 82 is arranged externally with respect to the actuator 80. It can be seen that the actuator 80 is a first actuator common to the switching elements SE1 and SE3, and the actuator 82 is a second actuator common to the switching elements SE2 and SE4.Viewed in the axial direction of the drive system 10 and thus along the machine rotational axis 24, 32 or the planetary gear rotational axis 48, 58, the first rotor 22, the third switching element SE3, the first switching element SE1, the first sun gear 40, the second sun gear 42, the input sun gear 52, the second switching element SE2, the fourth switching element SE4 and the second rotor 30 are arranged consecutively, i.e. one after the other, in the order in which they are mentioned.

[0049] First planetary gears of the planetary differential gear 36 are rotatably held on the first planetary carrier 38, wherein Fig. 1 of one of the first planetary gears is visible and is designated P1. In addition, second planetary gears of the planetary differential gear 36 are rotatably mounted on the first planet carrier 38, wherein Fig. 1, one of the second planet gears is shown and designated P2. The planet gears P1 mesh with the sun gear 40, and the planet gears P2 mesh with the sun gear 42. One of the first planet gears P1 and one of the second planet gears P2 mesh with each other, thus forming a first planet gear group. For example, the planet gears of the respective first planet gear group are arranged offset from each other, so that their axes of rotation run parallel to each other and are spaced apart from each other.

[0050] Third planetary gears are rotatably mounted on the input planet carrier 54, wherein Fig. 1, one of the third planetary gears is shown and designated P3. It can be seen that one of the planetary gears P3 is arranged coaxially to one of the planetary gears P2, whereby the respective third planetary gear P3 and the respective second planetary gear P2 arranged coaxially therewith form a second planetary gear group. The third planetary gears P3 are also referred to as input planetary gears. The respective planetary gears P2 and P3 of the respective second planetary gear group are arranged coaxially and can thus be rotated about a common planetary gear axis of rotation relative to the planet carrier 38 and relative to the input planetary carrier 54. In particular, the respective planetary gears P2 and P3 of the respective second planetary gear group, which are arranged coaxially to one another, are rotatably arranged on a common planetary gear bolt 55, which is in particular formed in one piece.The one-piece common planetary gear bolt 55 is thus part of the planetary carrier 38 and part of the planetary carrier 54.

[0051] Fig. Figure 2 shows a switching table illustrating four operating modes in which the electric drive system 10 can be selectively operated. A first of the operating modes is a first efficiency mode, designated E1, in which or for the implementation of which the switching element SE1 is closed, while the switching elements SE2, SE3, and SE4 are open, in particular simultaneously.

[0052] For example, the switching part S1 can be moved by means of the actuator 80 into a first neutral position, in particular relative to the housing 34 and / or translationally. In the first neutral position, the first coupling switching element KS1 is, for example, in a first neutral state in which the switching elements SE1 and SE3 are opened simultaneously, thus the first switching element SE1 is in its first decoupling state and the third switching element SE3 is in its third coupling state. For example, the second switching part S2 can be moved by means of the second stator 28, in particular translationally and / or relative to the housing 34, into at least one second neutral position in which the second coupling switching element KS2 is in a second neutral state. In the second neutral state, the switching elements SE2 and SE4 are opened, in particular simultaneously.In other words, for example, in the second neutral state, the fourth switching element SE4 is in its fourth decoupling state, while the second switching element SE2 is in its second decoupling state. Thus, to implement the first efficiency mode E1, for example, the first coupling switching element KS1 is in its first connection state, while the second coupling switching element KS2 is in its second neutral state.

[0053] A second of the operating modes is a second efficient mode, designated E2, in which or for the implementation of which the switching element SE2 is closed, while the switching elements SE1, SE3, and SE4 are open, in particular simultaneously. To implement the second efficient mode E2, for example, the second coupling switching element KS2 is in its third connection state, while the first coupling switching element KS1 is in its first neutral state.

[0054] A third operating mode is boost mode, designated B, which is also referred to as support mode, drive mode, or acceleration mode. In boost mode B, the switching elements SE1 and SE2 are closed simultaneously, while the switching elements SE3 and SE4 are open simultaneously. For this, for example, the first coupling switching element KS1 is in its first connection state, while the second coupling switching element KS2 is in its third connection state. A fourth operating mode is torque distribution mode, designated TV, which is also referred to as torque vectoring mode. In torque distribution mode TV, or to implement torque distribution mode TV, the switching elements SE1 and SE2 are open simultaneously, while the switching elements SE3 and SE4 are closed simultaneously.For this purpose, for example, the first coupling switching element KS1 is in its second connection state, while the second coupling switching element KS2 is in its fourth connection state.

[0055] The first output planetary gear 60 has fourth planetary gears, of which a fourth planetary gear designated P4 is shown. The fourth planetary gears P4 are rotatably mounted on the first output planetary carrier 64 and mesh, in particular simultaneously, with the first output sun gear 62 and with the first output ring gear 66. Fifth planetary gears are rotatably mounted on the second output planetary carrier 72, of which Fig.1, a planetary gear designated P5 can be seen. The fifth planetary gears P5 mesh, in particular simultaneously, with the second output sun gear 70 and with the second output ring gear 74. Furthermore, it can be seen that the respective vehicle wheel 12, 14 is connected, in particular permanently, to the respective output planetary carrier 64, 72 in a torque-transmitting manner, so that the respective output planetary carrier 64, 72 is a respective output of the respective output planetary gear ratio 60, 68. List of reference symbols 10 electric drive system 12 vehicle wheel 14 vehicle wheel 16 vehicle axles 18 first electric machine 20 first stator 22 first rotor 24 first machine rotation axis 26 second electric machine 28 second stator 30 second rotor 32 second machine rotation axis 34 housings 36 planetary differential gears 38 first planet carrier 40 first sun gear 42 second sun gear 44 Arrow 46 Arrow 48 first planetary gear rotation axis 50 Input planetary gear ratio 52 Input sun gear 54 Input planetary carrier 55 planetary gear bolts 56 Input ring gear 58 second planetary gear rotation axis 60 first output planetary gear ratio 62 first output sun gear 64 first output planet carrier 66 first output ring gear 68 second output planetary gear ratio 70 second output sun gear 72 second output planet carrier 74 second output ring gear 76 Arrow 78 Arrow 80 first actor 82 second actuator B Boost operation E1 first efficiency operation E2 second efficiency mode KS1 first coupling switching element KS2 second coupling switching element P1 first planet gear P2 second planet gear P3 third planet gear P4 fourth planet gear P5 fifth planet gear S1 first switching part S2 second switching part SE1 first switching element SE2 second switching element SE3 third switching element SE4 fourth switching element TV torque distribution operation

Claims

[1] Electric drive system (10) for a motor vehicle, comprising: - a first electrical machine (18) having a first rotor (22); - a second electrical machine (26) having a second rotor (30) arranged coaxially to the first rotor (22); - a planetary differential gear (36) arranged coaxially to the first rotor (22), which has a planet carrier (38), a first sun gear (40) and a second sun gear (42); - an input planetary gear ratio (50) which has an input sun gear (52), an input planetary carrier (54) connected in a rotationally fixed manner to the planetary carrier (38), and an input ring gear (56) connected in a rotationally fixed manner to a housing (34) of the electric drive system (10); - a first switching element (SE1) which is designed to connect the first rotor (22) to the planet carrier (38) in a rotationally fixed manner; - a second switching element (SE2) which is designed to connect the second rotor (30) in a rotationally fixed manner to the input sun gear (52); - a third switching element (Se3) which is designed to connect the first rotor (22) in a rotationally fixed manner to the first sun gear (40); and - a fourth switching element (SE4) which is designed to connect the second rotor (30) in a rotationally fixed manner to the second sun gear (42). [2] Electric drive system (10) according to claim 1, characterized by : - a first output planetary gear (60) having a first output sun gear (62) connected in a rotationally fixed manner to the first sun gear (40), a first output planetary carrier (64) and a first output ring gear (66) connected in a rotationally fixed manner to the housing (34); and - a second output planetary gear train (68) which has a second output sun gear (70) connected in a rotationally fixed manner to the second sun gear (42), a second output planetary carrier (72) and a second output ring gear (74) connected in a rotationally fixed manner to the housing (34). [3] Electric drive system (10) according to claim 1 or 2, characterized by , that - the first switching element (SE1) and the third switching element (SE3) are combined to form a first coupling switching element (KS1) which can be actuated by means of a first common actuator (80) of the electric drive system (10); and - the second switching element (SE2) and the fourth switching element (SE4) are combined to form a second coupling switching element (KS2) which can be actuated by means of a second common actuator (82) of the electric drive system (10). [4] Electric drive system (10) according to one of the preceding claims, characterized byin that, with respect to an axial direction, the first rotor (22), the third switching element (SE3), the first switching element (SE1), the first sun gear (40), the second sun gear (42), the input sun gear (52), the second switching element (SE2), the fourth switching element (SE4) and the second rotor (30) are arranged one after the other in the following order: the first rotor (22) - the third switching element (SE3) - the first switching element (SE1) - the first sun gear (40) - the second sun gear (42) - the input sun gear (52) - the second switching element (SE2) - the fourth switching element (SE4) - the second rotor (30). [5] Electric drive system (10) according to one of the preceding claims, characterized by , that: - first planetary gears (P1) are arranged on the planet carrier (38) and mesh with the first sun gear (40); - second planetary gears (P2) are arranged on the planet carrier (38), which mesh with the second sun gear (42), wherein one of the first planetary gears (P1) meshes with one of the second planetary gears (P2). [6] Electric drive system (10) according to claim 5, characterized by that input planetary gears (P3) are rotatably arranged on the input planetary carrier (54), wherein in each case one of the input planetary gears (P3) is arranged coaxially to one of the second planetary gears (P2). [7] Electric drive system (10) according to claim 6, characterized by that one of the input planetary gears (P3) and one of the second planetary gears (P2) is arranged on a common and one-piece planetary gear bolt (55). [8] Method for operating an electric drive system (10) according to one of the preceding claims 1 to 7, characterized bythat for a first efficiency operation (E1) the first switching element (SE1) is closed, the second switching element (SE2) is open, the third switching element (SE3) is open and the fourth switching element (SE4) is open. [9] Method according to claim 8, characterized by that for a second efficiency operation (E2) the first switching element (SE1) is open, the second switching element (SE2) is closed, the third switching element (SE3) is open and the fourth switching element (SE4) is open. [10] Method according to one of claims 8 to 9, characterized by that for a drive operation (B) the first switching element (SE1) is closed, the second switching element (SE2) is closed, the third switching element (SE3) is open and the fourth switching element (SE4) is open. [11] Method according to one of claims 8 to 10, characterized bythat for a torque distribution operation (TV) the first switching element (SE1) is open, the second switching element (SE2) is open, the third switching element (SE3) is closed and the fourth switching element (SE4) is closed.

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