DRIVE UNIT FOR A MOTOR VEHICLE, ESPECIALLY FOR A PASSENGER VEHICLE

Description

[0001] The invention relates to a drive device for a motor vehicle, in particular for a passenger car.

[0002] A drive device for a motor vehicle using axial flux machines is known from CN 113 085 518 A.

[0003] DE 10 2015 000 466 B4 discloses a drive device for a motor vehicle. Furthermore, WO 2018 / 150010 A1 discloses an axle drive unit for an electrically powered motor vehicle.

[0004] The object of the present invention is to provide a drive device for a motor vehicle so that a particularly advantageous drive of the motor vehicle can be realized.

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

[0006] The invention relates to a drive device, also referred to as an axle drive, for a motor vehicle, in particular for a passenger car. This means that the motor vehicle, in its fully manufactured state, has the drive device and can be driven by means of the drive device, in particular purely electrically. In particular, the motor vehicle has at least one vehicle axle, also referred to simply as an axle, which has at least or exactly two vehicle wheels, also referred to simply as wheels. As will be explained in more detail below, the vehicle wheels can be driven by means of the drive device, in particular purely electrically, whereby the motor vehicle can be driven, in particular purely electrically. In particular, the vehicle wheels are arranged on sides of the motor vehicle, also referred to as the vehicle, that are opposite one another in the transverse direction of the vehicle.

[0007] The drive device has a first output shaft, from which or via which a first of the vehicle wheels of the vehicle axle can be driven. For this purpose, for example, the first vehicle wheel is or can be coupled to the first output shaft in a torque-transmitting manner. The drive device has a second output shaft arranged coaxially to the first output shaft, from which or via which the second vehicle wheel of the vehicle axle of the motor vehicle can be driven. For this purpose, for example, the second vehicle wheel is or can be coupled to the second output shaft in a torque-transmitting manner. The drive device also comprises a differential gear, via which the output shafts can be driven. In other words, the output shafts can be driven by the differential gear. The differential gear is designed, for example, as a bevel differential, which is also referred to as a bevel gear differential.Of course, it is conceivable that the differential gear is designed as a different type of differential gear. As is already well known from the general prior art, the differential gear is designed in particular to permit different speeds of the output shafts and thus of the vehicle wheels, for example when the motor vehicle is cornering, in particular such that the vehicle wheel on the outside of the curve rotates or can rotate at a higher speed than the vehicle wheel on the inside of the curve, in particular while the vehicle wheels are drivable or are driven by the drive device. The drive device also has three axial flux machines arranged coaxially to one another and coaxially to the output shafts, namely a first axial flux machine, a second axial flux machine, and a third axial flux machine.The respective axial flux machine has a respective stator and at least two or exactly two rotors, which can be driven by means of the respective stator and are thus rotatable about a respective machine axis of rotation relative to the respective stator. The respective rotor of the respective axial flux machine is arranged in the axial direction of the respective axial flux machine between the respective rotors of the respective axial flux machine, wherein the respective axial direction of the respective axial flux machine coincides with the respective machine axis of rotation. In particular, the axial flux machines are arranged one after the other in the axial direction of the respective axial flux machine, in particular completely, and thus one behind the other. The rotors of the first axial flux machine are connected to one another in a rotationally fixed manner and thus form a first overall rotor.The rotors of the second axial flux machine are connected to each other in a rotationally fixed manner, thus forming a second rotor assembly. The rotors of the third axial flux machine are connected to each other in a rotationally fixed manner, thus forming a third rotor assembly.

[0008] The first output shaft can be driven by the first axial flux machine, in particular by the overall rotor of the first axial flux machine, bypassing the differential gear. This means that, with respect to a first torque flow, via which a respective first torque can be transmitted from the overall rotor of the first axial flux machine to the first output shaft in order to thereby drive the first output shaft, the differential gear is not arranged in the first torque flow, or at least not in the first torque flow between the overall rotor of the first axial flux machine and the first output shaft, so that the respective first torque, on its path from the overall rotor of the first axial flux machine to or onto the first output shaft along the torque flow, does not flow via the differential gear, thus bypassing the differential gear.The second output shaft can be driven by means of the second axial flux machine, in particular by means of the overall rotor of the second axial flux machine, bypassing the differential gear. This means that, with respect to a second torque flow via which a respective second torque can be transmitted from the overall rotor of the second axial flux machine to or onto the second output shaft, the differential gear is not arranged in the second torque flow, or at least not in the second torque flow between the overall rotor of the second axial flux machine and the second output shaft. Thus, the respective second drive torque does not flow via the differential gear on its way from the overall rotor of the second axial flux machine to or onto the second output shaft along the torque flow, and thus bypasses the differential gear.In other words, the first or second axial flux machine can provide the respective first or second torque via its entire rotor in order to thereby drive the first or second output shaft.The respective first or second torque is transmitted via the first or second torque flow from the overall rotor of the first or second axial flux machine to or to the first or second output shaft, wherein the respective first or second torque, when it has flowed along the first or second torque flow from the overall rotor of the first or second axial flux machine to or onto the first or second output shaft and has thus reached the first or second output shaft, has not flowed via the differential gear from the overall rotor of the first or second axial flux machine to or to the first or second output shaft.

[0009] The output shafts can be driven via the differential gear by means of the third axial flux machine, in particular by means of the overall rotor of the third axial flux machine. This means that the third axial flux machine can provide a respective third torque to drive the respective output shaft via its overall rotor.In relation to a third torque flow, via which the respective third torque can be transmitted from the overall rotor of the third axial flux machine to the respective output shaft, the differential gear is arranged in the third torque flow and upstream of the respective output shaft and downstream of the overall rotor of the third axial flux machine, so that the respective third torque flows on its way from the overall rotor of the third axial flux machine to or onto the respective output shaft via the differential gear from the overall rotor of the third axial flux machine to or onto the respective output shaft.For this purpose, it is provided, for example, that the entire rotor of the third axial flux machine is connected, in particular in a rotationally fixed manner, to an input element of the differential gear, wherein, for example, the input element of the differential gear, which is also simply referred to as differential, is a differential cage.

[0010] In an advantageous embodiment of the invention, a first freewheel is provided, via which the first output shaft of the first axial flux machine can be driven, bypassing the differential gear. A second freewheel is also provided, via which the second output shaft of the second axial flux machine can be driven, bypassing the differential gear.

[0011] In an advantageous embodiment of the invention, a first, frictionally engaged or positively engaged shifting element is provided, by means of which the first output shaft of the first axial flux machine can be driven, bypassing the differential gear. A second, frictionally engaged or positively engaged shifting element is also provided, by means of which the second output shaft of the second axial flux machine can be driven, bypassing the differential gear.

[0012] The invention is based, in particular, on the following findings and considerations: The drive device according to the invention is based on a so-called dual-motor drive unit, since a respective electric machine is provided for each output shaft and thus for each output shaft side, in this case in the form of the first electric machine or the second electric machine. This allows for particularly advantageous driving dynamics, since, in particular, torque distribution, also known as torque vectoring, and other driving dynamics interventions can be implemented.Starting with this dual-motor drive unit, the dual-motor drive unit is supplemented by a third electric machine, with all of the electric machines being designed as axial-flux machines, which in particular enables a particularly advantageous support operation, also known as boost operation or boost mode. The design of the electric machines as axial-flux machines allows the required axial installation space to be kept to a minimum. Vehicles equipped with a dual-motor drive unit are generally high-performance vehicles. This high performance is provided by powerful electric machines, which, however, cannot usually be optimally designed for a normal driving cycle in which high power levels are not required. Smaller electric machines are generally more efficient in conventional everyday driving cycles.The goal is to replicate the functionality of a dual-motor drive unit in the vehicle, but ideally without any efficiency penalty. Especially with an axial-flux machine, radial scaling to increase power and torque has a negative impact on the permissible maximum speed. Since the radial installation space for electric machines is generally limited, and thus also the power and torque per electric machine, the third electric machine enables advantageous power scaling. Depending on the radial dimensioning of the respective overall rotor of the respective axial-flux machine, speed limits may arise. Smaller rotor dimensions enable higher speeds.By appropriately dimensioning the motors, the two electric motors connected to the output shafts can rotate faster than the third axial flux motor used as a boost electric motor, thus enabling a higher top speed of the vehicle. The third axial flux motor, also known as the power electric motor, could thus be decoupled above a certain speed. In other words, starting from a dual-motor drive unit, the third axial flux motor is used as a boost or power electric motor or electric machine, which is connected to the differential gear, from which the output shafts lead, in particular as differential shafts, onto which the first axial flux motor and the second axial flux motor can act.In particular, it is conceivable that the first or second axial flux machine can be connected via a respective transmission element, such as a freewheel, or via an actuated or actuable switching element, such as a friction clutch or a dog clutch, or can act on the respective output shaft, in particular bypassing the differential gear.

[0013] The invention enables particularly efficient operation with a particularly high power density, as the three axial flux machines can be arranged coaxially. In particular, this allows for advantageous scalability. Axial flux machine rotors with smaller diameters can be used, enabling a higher maximum speed, thus also enabling single-threaded transmissions with high maximum speeds.

[0014] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings.

[0015] The drawing shows: Fig. 1 is a schematic representation of a first embodiment of a drive device for a motor vehicle, in particular for a passenger car; and Fig. 2 is a schematic representation of a second embodiment of the drive device.

[0016] Fig. 1 shows a schematic representation of a first embodiment of a drive device 10 for a motor vehicle, in particular for a passenger car. The motor vehicle is also referred to as a motor vehicle or vehicle and has, for example, at least or exactly two vehicle axles arranged one after the other in the longitudinal direction of the vehicle, also simply referred to as axles. The respective 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 vehicle. As will be explained in more detail below, the vehicle wheels of one of the vehicle axles can be driven, in particular purely electrically, by means of the drive device 10.When reference is made below to the vehicle wheels, unless otherwise stated, this refers to the vehicle wheels of one vehicle axle that can be driven by the drive device 10. The drive device 10 has a first output shaft 12, via which a... Fig. 1 The first of the vehicle wheels, designated 14, is driven. Furthermore, the drive device 10 has a second output shaft 16, via which the Fig. 1 designated 18, can be driven. Furthermore, the drive device 10 has a differential gear 20, which in the first embodiment is designed as a bevel gear differential and has a differential carrier 22 as the input element. The output shafts 12 and 16 are arranged coaxially to one another and rotatable about a common output shaft axis of rotation relative to a housing 24 of the drive device 10. The differential gear 20, which is also simply referred to as a differential, is arranged coaxially to the output shafts 12 and 16 and is thus rotatable about the output shaft axis of rotation relative to the housing 24. In particular, the differential carrier 22 is rotatable about the output shaft axis of rotation relative to the housing 24. Arranged on the differential carrier 22 are differential gears 26, which are rotatable about a common differential gear axis of rotation relative to the differential carrier 22 and also, for example, relative to one another.The differential gear rotation axis runs perpendicular to the output shaft rotation axis. In the first embodiment, the respective differential gear 26 is designed as a gear, in particular as a bevel gear. A first output gear 28 of the differential is rotationally fixedly connected to the output shaft 12, and a second output gear 30 of the differential gear 20 is rotationally fixedly connected to the output shaft 16. The output gears 28 and 30 are gears, in particular bevel gears, with the respective output gear 28, 30 meshing with the differential gears 26. Thus, the output gears 28 and 30 can rotate with the output shafts 12 and 16 about the output shaft rotation axis relative to the housing 24.

[0017] The drive device 10 further comprises three axial flux machines 32a-b arranged coaxially to one another and coaxially to the output shafts 12 and 16 and coaxially to the differential gear 20. The axial flux machine 32a is referred to as the first axial flux machine, the axial flux machine 32b as the second axial flux machine, and the axial flux machine 32c as the third axial flux machine. It can be seen that the third axial flux machine 32c is arranged between the axial flux machines 32a and 32b in the axial direction of the axial flux machines 32a-c. Each axial flux machine 32a-c has a respective stator 34a-c, which is connected in a rotationally fixed manner to the housing 24. Furthermore, each axial flux machine 32a-c has two rotors 36, 38, and 40, respectively. The stator 34a is arranged in the axial direction of the axial flux machine 32a between the rotors 36 of the axial flux machine 32a.Accordingly, the rotor 34b of the axial flux machine 32b is arranged between the rotors 38 of the axial flux machine 32b in the axial direction of the axial flux machine 32b. Accordingly, the rotor 34c of the axial flux machine 32c is arranged between the rotors 40 of the axial flux machine 32c in the axial direction of the axial flux machine 32c.

[0018] The rotors 40 are connected in a rotationally fixed manner to the differential carrier 22, so that the differential gear 20 can be driven by the rotors 40. Consequently, the output shafts 12 and 16 can be driven via the differential gear 20 by the rotors 40 and thus by the axial flux machine 32c. By driving the output shafts 12 and 16, the vehicle wheels 14 and 18 are driven. The output shaft 12 can be driven by the rotors 36 and thus by the axial flux machine 32a, bypassing the differential gear 20, and the output shaft 16 can be driven by the rotors 38 and thus by the axial flux machine 32b, bypassing the differential gear 20. The drive device 10 has a first transmission element 42 assigned to the output shaft 12 and the rotors 36 and a second transmission element 44 assigned to the output shaft 16 and the rotors 38.The output shaft 12 can be driven by the rotors 36 via the transmission element 42, bypassing the differential, and the output shaft 16 can be driven by the rotors 38 via the transmission element 44, bypassing the differential gear 20. For example, the transmission element 42, 44 is designed as a freewheel. Furthermore, it is conceivable that the respective transmission element 42, 44 is designed as a switching element that can be actuated, for example, as a frictional switching element such as a friction clutch, in particular a multi-plate clutch, or a positive switching element such as a dog clutch. A respective bearing of the respective output shaft 12, 16 is shown in FIG. Fig. 1 designated 46 and 48 respectively.

[0019] In addition, Fig. 1 It can be seen that a respective planetary gear set 50, 52 is assigned to the respective output shaft 12, 16. The respective planetary gear set 50, 52 has a respective sun gear 54, a respective planet carrier 56, and a respective ring gear 58. For example, the ring gear 58 is connected in a rotationally fixed manner to the housing 24. Furthermore, the respective planetary gear set 50, 52 has respective planet gears 60, which are rotatably mounted on the respective planet carrier 56 of the respective planetary gear set 50, 52. The respective sun gear 54 is connected in a rotationally fixed manner to the respective output shaft 12, 16. Furthermore, the respective vehicle wheel 14, 18 is connected to the respective planet carrier 56 in a torque-transmitting manner.

[0020] The axial flux machine 32c, arranged between the axial flux machines 32a and 32b, is a central electrical machine, also referred to as the main motor or efficiency motor, and is connected to the differential. For example, the axial flux machines 32a and 32b are so-called boost motors. The output shafts 12 and 16, designed as differential shafts, lead from the differential gear 20 to gears, which in this case are designed as the planetary gear sets 50 and 52. It can be seen that the output shafts 12 and 16 penetrate the rotors 36 and 38, or the respective rotor shafts of the rotors 36 and 38, as well as the respective hub areas of the axial flux machines 32a and 32b. The respective boost motor 32a or 32b provided on each side can be or is coupled to the respective differential shaft, for example, via a transmission element 42, 44 designed as a freewheel or a switching element.A respective freewheel can be integrated into the respective hub area of ​​the respective boost motor 32 a, b. The freewheels are located, for example, either in the hub bore, as shown, or engage a shaft section on the outside of the hub. These freewheels have, for example, a centrifugally activated sprag system. Hydrodynamic sprag lift-off is also conceivable. At zero speed or a low absolute speed of the respective boost motor, which is also referred to as a boost electric machine, the freewheel sprags do not contact the shaft or hub bore. This reduces friction and wear on the sprags. Above a certain speed, the sprags contact and can exert their locking effect. The locking effect occurs as soon as the speed of the respective boost motor reaches or exceeds the speed of the differential shafts.Only when both sides are in the locked state with the respective freewheel in the locked state can a torque from the boost motors be transmitted that is evenly distributed between both sides. The freewheels can also be locked selectively if torque intervention is desired on only one side. Such a freewheel could be conceivable as a transmission element 42 or 44. As an alternative to freewheels, a switchable, i.e. actuatable, switching element, for example in the form of a friction clutch or a dog clutch, can be used as the transmission element 42, 44. The boost motors 32a, b only output the respective torque in one direction and, for example, during forward travel if only freewheels are used as transmission elements 42, 44. If switching elements are used as transmission elements 42, 44, the respective boost motor 32a, b can also be operated in reverse.When using freewheels as transmission elements 42, 44, the following can be provided in particular: The two axial flux machines 32a and 32b, designed for example as boost motors, can generate propulsion torques independently of one another, in particular during forward travel. When the boost motors 32a, b are switched on, the torque distribution between the two wheels 14, 18 is controlled via these two boost motors 32a, b. When using switching elements, the following can apply: The two boost motors 32a, b can generate propulsion torques or braking torques independently of one another, in particular during forward and reverse travel. When the boost motors 32a, b are switched on, the torque distribution between the two wheels 14, 18 is controlled via these two boost motors 32a, b.In general, speed limits arise depending on the radial dimensioning of the rotor and the rotor design of an axial flux machine rotor; smaller rotor dimensions enable higher speeds. The boost motors 32a, b are thus advantageously decoupled above a certain speed. If they were not decoupled, the maximum speed corresponding to the total installed electric motor power of the three axial flux machines 32a-c on this axle could not be achieved, and the front axle of the vehicle would have to contribute the necessary power for the maximum speed. The aim of the present invention is to develop an efficient electric drive system for moderate driving requirements that is not oversized for these requirements.An efficiency-optimized electric machine 32c can be used, which generally also has a lower power output and a lower maximum torque. The boost motors 32a, b are only used in the comparatively rare cases of high power requirements or torque intervention at the respective wheel 14, 18. The losses caused by the electrical drag torque of a boost motor 32a, b, each designed as a permanent-magnet electric machine, and the bearing losses that would otherwise arise in the bearings of the respective rotor are eliminated. In principle, very high power densities and torque densities can be achieved through the use of axial-flux machines.When using centrifugally activated freewheels as transmission elements 42, 44, the output shafts should already be rotating, or the vehicle should be at a minimum speed or in the process of accelerating, since the centrifugally activated sprags only engage at a certain speed and can only then lock. When accelerating from a standstill or from low speed, there should be no noticeable activation of the boost motors 32a, b. When using switching elements as transmission elements 42, 44 and conventional freewheels with constantly applied sprags, these restrictions do not exist.

[0021] Fig. 2 shows a schematic representation of a second embodiment of the drive device 10. In this case, the differential gear 20 has, in particular, in addition to the output shafts 12 and 16, differential shafts 62 and 64 which are provided, in particular, in addition to the output shafts 12 and 16, and which are arranged coaxially to one another and coaxially to the output shafts 12 and 16. The output gear 28 is connected in a rotationally fixed manner to the differential shaft 62 and the output gear 30 is connected in a rotationally fixed manner to the differential shaft 64. Via the transmission element 42, the rotors 36 and, via these, the output shaft 12 can be driven by the differential shaft 62 and thus by the axial flux machine 32c, so that the axial flux machine 32c can drive the rotors 36 and, via these, the output shaft 12 via the differential gear 20.Via the transmission element 44, the differential shaft 64 can drive the rotors 38 and, via these, the output shaft 16, so that the axial flux machine 32c can drive the rotors 38 via the differential gear 20 and, via these, the output shaft 16. Bearings for the differential shafts 62 and 64 are designated 66 and 68. The respective transmission element 42, 44 can be, for example, a freewheel or a particularly actuatable shifting element, such as a frictional shifting element or a positive shifting element. For example, the axial flux machines 32a and 32b are designed as efficiency motors or efficiency machines, with the axial flux machine 32c, in particular, being designed as a boost motor, i.e., as a boost machine.In particular, the axial flux machines 32a and 32b are electric machines with relatively low power and torque, whereby the axial flux machines 32a and 32b are permanently connected to the vehicle wheels 14 and 18. The boost motor 32c engages, for example, during forward travel via the respective transmission element 42, 44 via the respective differential shaft 62, 64 to the output. The respective transmission element 42, 44 is, for example, a centrifugally activated freewheel in which, due to sprag lift-off, there is no contact of the sprags when the boost motor 32c is inactive, and thus no additional drag losses and wear on the freewheel are generated. Optionally, the axial flux machine 32c can be designed as a power machine, in particular with maximum power requirements. The wheel-specific drive torque and braking torque of the two efficiency machines 32a, b are available immediately.The power machine 32c has short engagement times because no active shifting element is actuated and no synchronization of a shifting element is required if the transmission elements 42 and 44 are advantageously designed as freewheels. Even with one-sided slippage, a high torque can advantageously be generated at the opposite non-slipping wheel, in particular a maximum torque of the respective efficiency machine 32a, b plus half the available torque of the power machine 32c, with the respective efficiency machine 32a, b additionally supporting or braking a slipping side if necessary. Torque requirements, power requirements, and maximum speed requirements are thus advantageously met with the embodiment of the invention from . Fig. 2 with only one gear. The ability to decouple the boost motor in favor of maximum speed is so advantageous with the embodiment of the invention from Fig. 2 Also possible with transmission elements 42, 44 designed as freewheels if the maximum speed of the efficiency motor is higher than the maximum speed of the boost motor. In this operating situation, the maximum speed is only achieved with the two efficiency motors, since the boost motor remains decoupled. This allows particularly high performance to be achieved, especially on a rear axle.

[0022] Furthermore, it is conceivable that the axial flow machine 32c is designed as an efficiency machine with relatively low power and torque and, in particular, as in the first embodiment of the invention, Fig. 1, is permanently connected to the vehicle wheels 14 and 18 via the differential. In this case, for example, the axial flux machines 32a and 32b are designed as boost motors, which can be switched on or off for each output shaft 12, 16 during forward travel via the respective transmission element 42, 44, which is designed in particular as a centrifugal freewheel, since the clamping bodies do not engage when the boost motors 32a, b are deactivated and thus there are no additional drag losses and wear on the freewheel. Wheel-specific drive torque from the two boost motors 32a and 32b is quickly available. Wheel-specific braking torque cannot be generated directly when freewheels are used as transmission elements 42, 44 with the two boost motors 32a, b), but this is possible indirectly. The central axial flux machine 32c, for example, sets the target braking torque.The boost motor 32a or b on the wheel side that still requires drive torque adds the necessary additional torque to achieve the required torque at the wheel. The boost motors 32a, b have short engagement times because no active shifting element is activated and no synchronization of a shifting element is required. Thus, torque, power, and top speed requirements can also be advantageously met with this single-gear embodiment of the invention. The boost motors can be deactivated to benefit top speed. List of reference symbols

[0023] 10 Drive unit 12 Output shaft 14 Vehicle wheel 16 Output shaft 18 Vehicle wheel 20 Differential gear 22 Differential carrier 24 Housing 26 Differential gear 28 Output gear 30 Output gear 32 a-c Axial flux machine 34 a-c Stator 36 Rotor 38 Rotor 40 Rotor 42 Transmission element 44 Transmission element 46 Bearing 48 Bearing 50 Planetary gear set 52 Planetary gear set 54 Sun gear 56 Planetary carrier 58 Ring gear 60 Planetary gear 62 Differential shaft 64 Differential shaft 66 Bearing 68 Bearing

Claims

1. Drive apparatus (10) for a motor vehicle, comprising: - a first output shaft (12) via which a first vehicle wheel (14) of a vehicle axle of the motor vehicle can be driven, - a second output shaft (16) which is arranged coaxially to the first output shaft (12), and via which a second vehicle wheel (18) of the vehicle axle of the motor vehicle can be driven, - a differential gear (20) via which the output shafts (12, 16) can be driven, and - three axial flow machines (32a-c) arranged coaxially to one another and coaxially to the output shafts, namely: ∘ a first axial flow machine (32a), by means of which the first output shaft (12) can be driven with bypassing of the differential gear (20), ∘ a second axial flow machine (32b), by means of which the second output shaft (16) can be driven with bypassing of the differential gear (20), and ∘ a third axial flow machine (32c) which is arranged between the first axial flow machine (32a) and the second axial flow machine (32b) in the axial direction of the axial flow machines (32a-c), and by means of which the output shafts (12, 16) can be driven via the differential gear (20).

2. Drive apparatus (10) according to claim 1, characterized by: - a first switching element (42) which is designed as a first freewheel, and via which the first output shaft (12) can be driven by the first axial flow machine (32a) with bypassing of the differential gear (20), and - a second switching element (44) which is designed as a second freewheel (44), and via which the second output shaft (16) can be driven by the second axial flow machine (32b) with bypassing of the differential gear (20).

3. Drive apparatus (10) according to claim 1, characterized by: - a first switching element (42) which is designed as a first frictional or form-fitting switching element, and by means of which the first output shaft (12) can be driven by the first axial flow machine (32a) with bypassing of the differential gear (20), and - a second switching element (44) which is designed as a second frictional or form-fitting switching element, and by means of which the second output shaft (16) can be driven by the second axial flow machine (32b) with bypassing of the differential gear (20).

4. Drive apparatus (10) according to claim 1, characterized by: - a first switching element (42) which is designed as a first freewheel, and via which the first output shaft (12) can be driven by the third axial flow machine (32c) with involvement of the differential gear (20), and - a second switching element (44) which is designed as a second freewheel, and via which the second output shaft (16) can be driven by the third axial flow machine (32c) with involvement of the differential gear (20).

5. Drive apparatus (10) according to claim 1, characterized by: - a first switching element (42) which is designed as a first frictional or form-fitting switching element, and by means of which the first output shaft (12) can be driven by the third axial flow machine (32c) with involvement of the differential gear (20), and - a second switching element (44) which is designed as a second frictional or form-fitting switching element, and by means of which the second output shaft (16) can be driven by the third axial flow machine (32c) with involvement of the differential gear (20).