Electric drive unit for a motor vehicle, in particular for a motor car

Abstract

The invention relates to an electric drive device (10) for a motor vehicle, comprising a first electric machine (18) having a first rotor (22), a first drive shaft (34) connected non-rotatably to the first rotor (22), via which a first vehicle wheel (14) of a vehicle axle (12) can be driven by means of the first electric machine (18), and a second electric machine (26) having a second rotor (30), with a second drive shaft (36) connected non-rotatably to the second rotor (30) and arranged coaxially to the first drive shaft (34), via which a second vehicle wheel (16) of the vehicle axle (12) can be driven by means of the second electric machine (26).According to the invention, a differential gear (40) is provided, via which the drive shafts (34, 36) are coupled to each other, with a helical first gear (42) which is non-rotatably connected to the first drive shaft (34), and with a helical second gear (44) which is non-rotatably connected to the second drive shaft (36), wherein a first helix angle of the first gear (42) and a second helix angle of the second gear (44) are essentially the same size and oriented in opposite directions.

Description

[0001] The invention relates to an electric drive device for a motor vehicle, in particular for a car. DE 10 2020 104 857 A1 discloses a drive arrangement for an electric drive axle as known, comprising a housing in which a first electric drive motor and a second electric drive motor are arranged. Furthermore, DE 10 2020 113 192 A1 discloses a transmission for transmitting power from two electric motors to two wheels.

[0002] The object of the present invention is to create an electric drive device for a motor vehicle in such a way that a particularly efficient operation of the electric drive device can be achieved.

[0003] This problem is solved by an electric drive device with the features of claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0004] The invention relates to an electric drive device, also referred to as an electric drive system or simply as a drive unit, for a motor vehicle, also referred to simply as a vehicle. This means that the motor vehicle, preferably designed as a motor vehicle, in particular as a passenger car, in its fully manufactured state, has the electric drive device and can be driven by means of the electric drive device, in particular purely electrically. The electric drive device comprises 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 thereby rotated about a first axis of rotation of the machine relative to the first stator.The first electric machine, via its first rotor, drives a first wheel of a vehicle axle (also referred to simply as the axle), which is also referred to simply as the first wheel. The electric drive unit has a first drive shaft, which is permanently and non-rotatably connected to the first rotor. The first wheel of the vehicle axle can be driven, particularly purely electrically, by means of the first electric machine, specifically by means of its rotor. This means that the first electric machine can provide at least a first drive torque via the first rotor, which can be transmitted from the first rotor to the first drive shaft. This allows the first drive shaft to be driven and thus rotatable about the first axis of rotation of the machine relative to the first stator.By driving the first drive shaft, the first vehicle wheel can be driven, so that the first vehicle wheel can be driven by the first drive shaft and via the first drive shaft by the first rotor and thus by the first electric machine.

[0005] The electric drive system also includes a second electric machine in addition to the first electric machine, which has a second rotor. In particular, the second electric machine has a second stator by means of which a second rotor can be driven and thus rotated about a second axis of rotation relative to the second stator. Specifically, the electric machines are arranged coaxially to each other, so that their axes of rotation coincide. By means of the second electric machine, and in particular by means of the second rotor, a second vehicle wheel of the vehicle axle, also referred to simply as the second wheel, can be driven, in particular purely electrically. Specifically, the second electric machine can drive the second vehicle wheel, in particular purely electrically, via its second rotor.For this purpose, the electric drive unit has a second drive shaft arranged coaxially to the first drive shaft, which is permanently and rotationally fixed to the second rotor. The second vehicle wheel can be driven via the second drive shaft by means of the second electric machine, in particular by means of the second rotor. For example, the second electric machine can provide at least a second drive torque via its second rotor, which can be transmitted from the second rotor to the second drive shaft, thereby enabling the second drive shaft to be driven and thus rotatable about the second machine axis of rotation relative to the second stator. By driving the second drive shaft, the second vehicle wheel of the vehicle axle can be driven, so that the second vehicle wheel can be driven by the second drive shaft and, via the second drive shaft, by the second rotor and thus by the second electric machine.In particular, it is provided that the first vehicle wheel can be driven by the first electric machine, i.e., by the first rotor, via the first drive shaft, bypassing the second vehicle wheel. This means that, with respect to a first torque flow along which the first drive torque can be transmitted from the first rotor to the first vehicle wheel to drive it, the second vehicle wheel is not located in the first torque flow downstream of the first rotor and upstream of the first vehicle wheel, with the first drive shaft being located in the first torque flow downstream of the first rotor and upstream of the first vehicle wheel. Furthermore, it is specifically provided that the second vehicle wheel can be driven by the second electric machine, in particular by the second rotor, via the second drive shaft, bypassing the first vehicle wheel.This means that, with respect to a second torque flow along which the second drive torque can be transmitted from the second rotor to the second vehicle wheel, and thus drive the second vehicle wheel, the first vehicle wheel is not located in the second torque flow downstream of the second rotor and upstream of the second vehicle wheel, with the second drive shaft in particular being located in the second torque flow downstream of the second rotor and upstream of the second vehicle wheel. The electric drive system is therefore a dual drive, in which the electric machines are wheel-specific. This means that the first vehicle wheel can be driven by the first electric machine, bypassing the second vehicle wheel, and that the second vehicle wheel can be driven by the second electric machine, bypassing the first vehicle wheel.When the vehicle wheels are mentioned before and below, unless otherwise specified, this refers to the first and second vehicle wheels. In the fully assembled state of the motor vehicle, the vehicle wheels are arranged on opposite sides of the vehicle in the transverse direction. The vehicle wheels are ground contact elements by which the vehicle can be supported or is supported downwards against the ground in the vertical direction. When the vehicle is driven along the ground while supported downwards in the vertical direction by the ground contact elements, the ground contact elements roll along the ground, particularly directly. The vehicle as a whole, and especially purely electrically, can be propelled by driving the vehicle wheels.

[0006] For example, the motor vehicle has at least or exactly two axles arranged consecutively and thus one behind the other in the longitudinal direction of the vehicle, namely the aforementioned axle as the first axle and at least or exactly one second axle. The preceding and following descriptions of the first axle can readily be applied to the second axle and vice versa. For example, the respective electric machine is designed as an axial flux machine (AFM).

[0007] The electric drive unit also includes a differential gear, which is also simply referred to as the differential. The drive shafts are coupled to each other via the differential gear. The differential gear has the function, well known from the prior art, that when the vehicle is cornering, it allows for different rotational speeds of the drive shaft and thus of the vehicle wheels, in particular such that the outer wheel and its associated drive shaft, which drives or can drive the outer wheel, rotate or can rotate at a higher speed than the inner wheel and its associated drive shaft, which drives or can drive the inner wheel.In particular, the drive shafts are coupled to each other via the differential gear in such a way that when the vehicle is raised so that the vehicle wheels are in the air and therefore have no contact with the ground, and one of the drive shafts is rotated around the respective machine axis of rotation in a first direction, the other drive shaft is consequently driven by the first drive shaft via the differential gear in such a way that the other drive shaft is rotated around the other machine axis of rotation in a second direction opposite to the first, so that the drive shafts rotate in opposite directions around their respective machine axis of rotation. In particular, it can be provided that the differential gear is arranged between the electric motors in the axial direction of the respective drive shaft and thus along the respective machine axis of rotation.Since the drive shafts are arranged coaxially to each other, their axial directions coincide, and the machine's axes of rotation also coincide.

[0008] The electric drive device also includes a first gear, which is permanently and non-rotatably connected to the first drive shaft and has helical teeth, thus having a first helical tooth profile, in particular a first helix angle. The electric drive device also includes a second gear, in addition to the first gear, which is permanently and non-rotatably connected to the second drive shaft and has helical teeth, such that the second gear has a second helical tooth profile, in particular a second helix angle. Since the first gear is non-rotatably connected to the first drive shaft, the first gear belongs to the first drive shaft and vice versa. Since the second gear is non-rotatably connected to the second drive shaft, the second gear belongs to the second drive shaft and vice versa.In principle, it is conceivable that each gear is formed integrally with its corresponding drive shaft, so that, for example, the gear and its associated drive shaft can be formed as a single unit, i.e., from a single piece. Alternatively, it is conceivable that each gear and its corresponding drive shaft are formed separately and, in particular, permanently and rotationally fixedly connected to each other.The characteristic that the respective gear and the respective associated drive shaft are formed from a single piece means that the respective gear and the respective associated drive shaft are not designed as separately formed and connected components, but rather the respective gear and the respective associated drive shaft are formed from a single piece and thus formed by a monoblock formed in one piece, i.e., formed from a single piece, or designed as such a monoblock.

[0009] In the electric drive device according to the invention, the drive shafts are rotatable relative to each other and rigidly coupled to each other in the axial direction of the respective drive shaft. This means that the drive shafts are coupled or connected to each other in such a way that they are rotatable relative to each other about the respective machine axis of rotation, and, in particular, simultaneously, the drive shafts are coupled, i.e., connected, in such a way that relative movements between the drive shafts in the axial direction of the respective drive shaft are prevented, especially while the drive shafts are rotatable relative to each other about the respective machine axis of rotation.This allows for the advantageous compensation of axial forces, also known as axial forces, resulting from the helical gears and acting in the axial direction of the respective drive direction. This prevents excessively high drag losses, particularly in the bearings used to support the drive shafts. Consequently, the drive unit can be operated directly with a particularly high overall efficiency, even at high drive shaft speeds, thus achieving exceptional efficiency. The invention is based in particular on the following findings and considerations: Under torque, that is, especially when the respective drive shaft and thus the respective associated gear are driven by the respective rotor, the helical gears can generate axial forces that should be supported by the aforementioned bearings.Without adequate compensation of axial forces, this can lead to high drag losses in the bearings, particularly at high speeds, and thus to an insufficiently high overall efficiency. The invention now makes it possible to advantageously support, and in particular compensate, the axial forces, thereby avoiding excessively high drag losses and consequently enabling particularly efficient operation of the electric drive system. In principle, it would be conceivable to design the drive shafts and any associated rotor shafts of the rotors in two parts, so that, for example, each drive shaft has two separately designed shaft sections which are rotationally fixed but axially displaceable relative to each other along the respective drive shaft.The axial forces could then be mutually supported, for example, by two axial bearings in the thrust and tension directions, particularly without significant differential rotational speeds. The invention enables a particularly advantageous support, especially compensation, of the axial forces, thus allowing for a particularly high efficiency, especially overall efficiency, of the drive unit. The respective drive shaft need not be multi-part but can, for example, be formed in one piece, making particularly simple and cost-effective operation of the drive unit highly efficient.

[0010] According to the invention, the first helix angle of the first gear and the second helix angle of the second gear are essentially the same but oriented in opposite directions. The invention advantageously enables the axial forces resulting from the helical gearing to be mutually supported or, in particular, compensated. Supporting significant forces via housings or high-speed bearings can be avoided, allowing for particularly small bearing dimensions. The mutual support, and especially the compensation, of the axial forces achievable by the invention occurs without significant differential rotational speeds in the support bearings and / or in the aforementioned axial bearings, and thus is independent of rotational speed without drag losses at high drive torques, which can advantageously result in a particularly high overall efficiency of the drive system.

[0011] In an advantageous embodiment of the invention, a tie rod is provided that is separate from the drive shafts and is preferably formed in one piece. The tie rod is rigidly connected to the first drive shaft in the axial direction of the respective drive shaft. This means that the tie rod is connected to the first drive shaft in such a way that relative movements between the tie rod and the first drive shaft in the axial direction of the respective drive shaft are prevented. The second drive shaft is designed as a hollow shaft because the tie rod penetrates the hollow shaft. The tie rod is at least indirectly supported in the axial direction of the respective drive shaft, and thus along the respective machine axis of rotation, on a surface of the second drive shaft that projects away from the first drive shaft in the axial direction of the respective drive shaft.This allows the drive shafts to be rigidly coupled to each other in a particularly advantageous way in the axial direction of the respective drive shaft and simultaneously rotatable relative to each other in the respective machine axis of rotation, so that a particularly efficient operation can be represented in a particularly simple way.

[0012] When the axial direction is mentioned before and below, this refers, unless otherwise specified, to the axial direction of the respective drive shaft. Thus, the term "and in axial" means the axial direction of the respective drive shaft, whose axial direction coincides with the respective machine's axis of rotation.

[0013] In order to connect the drive shafts axially in a particularly simple and therefore advantageous way, so that axial relative movements between drive shafts are prevented, a further embodiment of the invention provides that the tie rod is screwed to the first drive shaft, in particular directly, and is thereby firmly connected to the first drive shaft in the axial direction of the respective drive shaft, so that axial relative movements between the tie rod and the first drive shaft are prevented.

[0014] A further embodiment of the invention is characterized in that a first longitudinal section of the tie rod is arranged in a hollow, second longitudinal section of the first drive shaft and is screwed to the first drive shaft, particularly directly, within the hollow, second longitudinal section. This ensures particularly efficient operation of the drive unit in a space-saving manner. For example, the first drive shaft can also be designed as a hollow shaft.

[0015] The tie rod and the first drive shaft are, for example, screwed together such that the tie rod, particularly in the first length section, has a first thread, in particular a first external thread. The first drive shaft, for example, has a second thread corresponding to the first thread, particularly in the second length section, which is preferably designed as an internal thread. Preferably, the threads are screwed directly together or into one another, thereby screwing the tie rod directly to the first drive shaft. This allows the tie rod and the first drive shaft to be connected in a particularly simple and space-saving manner, in particular in such a way that axial relative movements between the tie rod and the first drive shaft are prevented. To connect the drive shafts axially in a particularly space-saving and therefore efficient manner, while simultaneously allowing the drive shafts to rotate relative to each other about their respective machine axis of rotation, a further embodiment of the invention provides that the electric drive unit has a retaining ring, formed separately from the drive shafts and the tie rod, and arranged on the tie rod. The tie rod is supported on the surface by this retaining ring, in particular such that the retaining ring is supported at least indirectly on the surface in the axial direction. Specifically, the retaining ring, formed separately from the drive shafts and the tie rod, is fixed to the tie rod in the axial direction, i.e., connected to the tie rod in such a way that axial relative movements between the retaining ring and the tie rod are prevented.

[0016] It has proven particularly advantageous to provide an axial bearing, designed separately from the drive shafts, the tie rod, and the retaining ring, arranged in the axial direction of the respective drive shaft between the surface and the retaining ring, and designed, for example, as a rolling bearing. This bearing supports the retaining ring, and, via the retaining ring, the tie rod, and, via the tie rod, the first drive shaft in the axial direction of the respective drive shaft, and allows it to be rotatably mounted on the surface. It has proven particularly advantageous if the retaining ring and / or the axial bearing, which is also referred to as the first axial bearing, are arranged in the second drive shaft, which is designed as a hollow shaft.This allows for a particularly advantageous support, especially compensation of axial forces, to be achieved in a particularly space-saving manner, thus enabling particularly efficient operation of the electric drive unit. When the axial bearing is mentioned before and below, this refers, unless otherwise specified, to the first axial bearing.

[0017] In order to support and, in particular, compensate for axial forces in a particularly simple and therefore space-saving, weight-saving, and cost-effective manner, and consequently to achieve particularly efficient operation of the drive unit, a further embodiment of the invention provides that each drive shaft has a groove in which a retaining ring, designed separately from the respective drive shaft and also referred to as a retaining element, is arranged. For example, the retaining element is a snap ring or is also referred to as a snap ring.By means of the respective retaining ring, each axle shaft gear of the differential gear, which is connected to the respective drive shaft in a rotationally fixed manner and is provided in addition to the respective gear, is fixed to the respective drive shaft in the axial direction of the respective drive shaft, so that relative movements occurring in the axial direction of the respective drive shaft between the respective drive shaft and the respective axle shaft gear are prevented.This makes it possible, for example, to support and, in particular, to compensate for the axial forces in a first load direction parallel to or coinciding with the axial direction via the axle shaft gears and the differential gears meshing with the axle shaft gears, and in a second load direction opposite to the first load direction, parallel to or coinciding with the axial direction, via a housing of the differential gear also referred to as a differential housing or differential housing.

[0018] For example, the differential gear is designed as a bevel gear differential, also known as a bevel differential or ball differential. In this design, the respective axle shaft gear and the respective differential gear are each configured as a bevel gear. Specifically, the respective differential gear and the respective axle shaft gear are each a further gear.

[0019] In order to support and, in particular, compensate for the axial forces particularly advantageously, and thus to achieve particularly efficient operation of the drive unit, a further embodiment of the invention provides that the differential housing comprises the aforementioned housing, also referred to as the gearbox housing, which preferably has at least or exactly two separately designed and interconnected housing parts, which are assembled, in particular, in the axial direction. This means, in particular, that the gearbox housing is axially divided, such that, for example, the housing parts follow one another in the axial direction.

[0020] Preferably, the housing parts are connected to each other in a way that allows them to be removed without damage.

[0021] It has proven particularly advantageous if the housing parts are connected to each other by means of screws, especially in a non-destructive manner.

[0022] Furthermore, it is conceivable that the gearbox housing is not designed to be disassembled, for example, by casting, meaning it is a single cast component. It is also conceivable that the housing parts are riveted together, resulting in a multi-part, particularly two-part, housing that is not designed to be disassembled. Finally, it is conceivable that the housing parts are welded together, resulting in a multi-part, particularly two-part, gearbox housing that is not designed to be disassembled.

[0023] The gearbox housing is disassemblable, particularly when the housing parts are designed separately and connected in a non-destructive manner. Specifically, when the housing parts are designed separately and connected in a non-destructive manner, the respective locking element can be installed first, after which the housing parts can be connected, particularly by bolting them together. This allows, for example, the respective locking element to be provided as a precisely fitting, backlash-free retaining ring in the respective groove. Alternatively, the respective groove could be made deeper so that the respective locking element can fully engage in the groove when the respective drive shaft passes through the respective axle gear.

[0024] To support and, in particular, compensate for axial forces with particular advantage, and consequently achieve particularly efficient operation, a further embodiment of the invention provides that the electric drive unit has an axial bearing, also referred to as a second axial bearing, which is arranged separately from the drive shafts in the axial direction of the respective drive shaft between the drive shafts and within the differential gear, in particular within the gear housing. This axial bearing supports the drive shafts in the axial direction of their respective drive shafts and allows them to be rotatably mounted relative to one another. Preferably, the second axial bearing is designed as a rolling bearing, which ensures particularly low-friction mounting. In particular, the second axial bearing can function or be designed as a central support bearing.In this way, additional stress on the differential gears and the gearbox housing due to axial forces can be avoided.

[0025] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0026] The drawing shows in: Fig. 1. Partially a schematic sectional view of the first embodiment of an electric drive device for a motor vehicle; Fig. 2. Partially shown, a further schematic sectional view of the drive device according to the first embodiment; Fig. 3. Partially a schematic sectional view of the second embodiment of the drive device.

[0027] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0028] Fig. Figure 1 shows a schematic sectional view of a first embodiment of an electric drive unit 10 of a motor vehicle, also referred to simply as a vehicle. The motor vehicle, preferably designed as a car, in particular a passenger car, has at least or exactly two axles arranged consecutively in the longitudinal direction, namely a first axle and a second axle. The first axle is in Fig. Figure 1, in particular schematically represented and designated by 12, shows the first vehicle axle 12, which includes the electric drive unit 10. Furthermore, the vehicle axle 12 has, in particular, two vehicle wheels, also simply referred to as wheels, namely a first vehicle wheel 14 and a second vehicle wheel 16. The vehicle wheels 14 and 16 are arranged on opposite sides of the vehicle in the transverse direction of the vehicle. The vehicle wheels 14 and 16 are ground contact elements of the vehicle, which can be supported or is supported downwards in the vertical direction of the vehicle by means of the ground contact elements. By means of the drive unit 10, the vehicle wheels 14 and 16, and thus the vehicle, can be driven, in particular purely electrically. For this purpose, the electric drive unit 10 includes a first electric machine 18, which is designed as a first axial flux machine.The first electric machine 18 has a first stator 20 and a first rotor 22, which can be driven by means of the stator 20 and is therefore rotatable about a first machine axis of rotation 24 relative to the stator 20. Furthermore, the drive unit 10 includes a second electric machine 26, which is designed as a second axial flux machine. The second electric machine 26 has a second stator 28 and a second rotor 30, which can be driven by means of the second stator 28 and is therefore rotatable about a second machine axis of rotation 32 relative to the stator 28. It can be seen that the electric machines 18 and 26 are arranged coaxially with each other, so that the rotors 22 and 30 are arranged coaxially with each other and the machine axes of rotation 24 and 32 coincide. The machine axes of rotation 24 and 32 are collectively referred to as the axis of rotation.The vehicle wheel 14 can be driven by means of the rotor 22 and thus by means of the electric machine 18, bypassing the vehicle wheel 16, and the vehicle wheel 16 can be driven by means of the rotor 30 and thus by means of the electric machine 26, bypassing the vehicle wheel 14. The drive unit 10 has a first drive shaft 34, which is permanently connected to the rotor 22 and thus rotatable about the machine's axis of rotation 24, 32 relative to the stator 20. The vehicle wheel 14 can be driven by the rotor 22 and thus by the electric machine 18 via the drive shaft 34, bypassing the vehicle wheel 16. The drive device 10 has a second drive shaft 36, provided in addition to the drive shaft 34 and designed separately from the drive shaft 34, which is permanently connected to the rotor 30 and is thus rotatable about the machine axis of rotation 24, 32 relative to the stator 28.Thus, the drive shafts 34 and 36 are arranged coaxially to each other. The vehicle wheel 16 can be driven by the rotor 30, and therefore by the electric machine 26, via the drive shaft 36, bypassing the vehicle wheel 14.

[0029] The drive unit 10 comprises a housing 38 in which the electric machines 18 and 26 and the drive shafts 34 and 36 are arranged. The rotors 22 and 30 and the drive shafts 34 and 36 are rotatable about the respective machine axis of rotation 24, 32 relative to the housing 38. The drive unit 10 also includes a differential gear 40, also referred to simply as a differential, which in this case is designed as a bevel gear differential. The bevel gear differential is also called a bevel gear differential. It can be seen that the differential gear 40 is arranged between the electric machines 18 and 26 in the axial direction of the respective drive shafts 34, 36, whose respective axial direction coincides with the respective machine axis of rotation 24, 32. The differential gear 40 is arranged in the housing 38. The drive shafts 34 and 36 are coupled to each other, in particular for torque transmission, via the differential gear 40.

[0030] The drive unit 10 has a first gear 42, which is permanently and rotationally fixedly connected to the first drive shaft 34 and thus belongs to the drive shaft 34, and vice versa. In this case, the drive shaft 34 and the associated gear 42 are formed from a single piece, i.e., they are integrally formed. The drive unit 10 also has a second gear 44, which is permanently and rotationally fixedly connected to the drive shaft 36 and thus belongs to the drive shaft 36, and vice versa. In this case, the drive shaft 36 and the associated gear 44 are integrally formed, i.e., formed from a single piece and thus as a single unit.

[0031] The differential gear 40 has a gearbox housing 46, which is also referred to as the housing or differential housing. Furthermore, the differential gear 40 has differential gears 48 and 50, which are third gears in addition to the gears 42 and 44. The respective differential gear 48, 50 is designed as a bevel gear. The respective differential gear 48, 50 is rotatably mounted on the gearbox housing 46 about a common differential gear axis 52 relative to the gearbox housing 46, with the differential gear axis 52, also referred to as the differential axis, being perpendicular to the respective machine axis of rotation 24, 32. In particular, the gearbox housing 46 is rotatable about the respective machine axis of rotation 24, 32 relative to the respective drive shaft 34, 36.Furthermore, the differential gear 40 has a first axle gear 54, which is connected, in particular permanently and non-rotatably, to the first drive shaft 34 and which meshes, in particular directly, with the differential gears 48 and 50. The differential gear 40 also has a second axle gear 55, which is connected, in particular permanently and non-rotatably, to the second drive shaft 36 and which meshes, in particular directly, with the differential gears 48 and 50. The axle gears 54 and 55 are also referred to as output gears and are additional, third gears, wherein in this case the respective axle gear 54, 55 is designed as a bevel gear.In particular, the compensating gears 48 and 50 are rotatably mounted on the gearbox housing 46 in such a way that, although the respective compensating gear 48, 50 is rotatable about the compensating gear axis 52 relative to the gearbox housing 46, the respective compensating gear 48, 50 is rotatable with the gearbox housing 46 about the respective machine axis 24, 32, so that, for example, the respective compensating gear 48, 50 is rotationally fixed to the gearbox housing 46 or held rotationally fixed on the gearbox housing 46 for rotations about the machine axis 24, 32.

[0032] The respective gears 42 and 44 are helical, such that gear 42 has a first helical tooth with a first helix angle and the second gear 44 has a second helical tooth with a second helix angle. It is preferably provided that the helix angles are equal, and preferably the helix angles are oriented in opposite directions.

[0033] Particularly during operation of the drive unit 10, where the electric machines 18 and 26 drive the drive shafts 34 and 36 and the vehicle wheels 14 and 16, the helical gears can cause axial forces. These axial forces are understood to be forces acting in the axial direction on the respective drive shafts 34 and 36, and thus on the respective electric machines 18 and 26, and on the drive unit 10 as a whole. In order to support these axial forces particularly advantageously, and especially to compensate for them, in such a way that the axial forces support each other and thus compensate for each other, the drive unit 10 is designed so that the drive shafts 34 and 36 are rotatably coupled to each other in the axial direction of their respective drive shafts 34 and 36.

[0034] As from Fig. As can be seen in Figure 2, in the first embodiment a tie rod 56, preferably formed from a single piece and separate from the drive shafts 34 and 36, is provided for this purpose. This tie rod 56 is rigidly connected to the first drive shaft 34 in the axial direction of the respective drive shafts 34 and 36. When the axial direction is mentioned before and below, unless otherwise specified, this refers to the axial direction of the respective drive shafts 34 and 36 and thus of the respective electric machines 18 and 26, and of the drive machine 10 as a whole. The respective drive shafts 34 and 36 are designed as hollow shafts. The tie rod 56 penetrates the second drive shaft 36, which is also designed as a hollow shaft. Furthermore, the tie rod 56 is indirectly supported in the axial direction by a surface 58 of the second drive shaft 36 that projects axially away from the first drive shaft 34.In the second embodiment, the surface 58 extends in a plane perpendicular to the axial direction. The tie rod 56 is screwed directly to the drive shaft 34 and thus rigidly connected to it in the axial direction. For this purpose, a first length section L1 of the tie rod 56 is arranged in a hollow length section L2 of the drive shaft 34, wherein the length section L1, and thus the tie rod 56, is screwed directly to the drive shaft 34 in the length section L2. For this purpose, the tie rod 56 has a first thread in the length section L2, designed as an external thread 60, and the drive shaft 34 has a second thread in the length section L2, corresponding to the first thread, in the form of an internal thread 62.The external thread 60 and the internal thread 62 are screwed directly into each other, thereby screwing the tie rod 56 directly to the drive shaft 34, in this case such that the tie rod 56 is screwed directly into the drive shaft 34. This firmly connects the tie rod 56 to the drive shaft 34 in the axial direction. This means that the tie rod 56 and the drive shaft 34 are connected in such a way that any relative movement in the axial direction between the tie rod 56 and the drive shaft 34 is prevented.

[0035] A retaining ring 64, separate from the drive shafts 34 and 36 and separate from the tie rod 56, is also provided. Furthermore, a support element 66 is provided, which in this case is designed as a thrust washer. The support element 66 is separate from the retaining ring 64, the drive shafts 34 and 36, and the tie rod 56. The retaining ring 64 is arranged on the tie rod 56 and is preferably fixed to the tie rod 56 in the axial direction, so that axial relative movements between the retaining ring 64 and the tie rod 56 are preferably prevented. The support element 66 is secured to the tie rod 56 in the axial direction by means of the retaining ring 64. The drive unit 10 also has a first axial bearing 68, which is arranged in the axial direction between the surface 58 and the support element 66 and in the axial direction between the retaining ring 64 and the surface 58.The first axial bearing 68 is separate from the support element 66, the retaining ring 64, the tie rod 56, and the drive shafts 34 and 36. The tie rod 56 is axially supported on the surface 58 via the retaining ring 64, the support element 66, and the first axial bearing 68, and is rotatably mounted on the surface 58, so that the drive shaft 34 is axially supported on the surface 58 and thus on the drive shaft 36 via the tie rod 56, the retaining ring 64, the support element 66, and the first axial bearing 68, and is rotatably mounted on the surface 58 and thus on the drive shaft 36. For this purpose, for example, the axial bearing 68 is supported in the axial direction directly on the surface 58 on the one hand and indirectly on the other hand and is supported via the support element 66 on the retaining ring 64.

[0036] Out of Fig. Figure 2 clearly shows that the gearbox housing 46 is multi-part, in this case two-part, and in particular comprises two housing parts 70 and 72, which are designed separately from each other and are connected to each other, in particular in a way that allows for non-destructive detachment. In this case, the gearbox housing 46 is divided in the axial direction, so that the housing parts 70 and 72 are joined in the axial direction. This ensures particularly simple assembly of the drive unit 10. The drive unit 10 has a second axial bearing 74 in addition to the first axial bearing 68, which is arranged in the differential gear 40, in particular in the gearbox housing 46. For example, the axial bearing 68 and / or the axial bearing 74 is designed as a rolling bearing. The axial bearing 74 is arranged separately from the drive shafts 34 and 36 and separately from the tie rod 56.The axial bearing 74 is arranged in the axial direction between the drive shafts 34 and 36, wherein the drive shafts 34 and 36 are supported against each other in the axial direction and rotatably mounted against each other via the axial bearing 74.

[0037] Out of Fig. 1 and Fig. Figure 2 shows that a first transmission device 76, also referred to as a first final drive or providing a first final drive, is assigned to the electric machine 18 and the first drive shaft 34, via which the vehicle wheel 14 can be driven by the drive shaft 34. Accordingly, a second transmission device 78, also referred to as a second final drive or providing a second final drive, is assigned to the second electric machine 26 and the second drive shaft 36, via which the vehicle wheel 16 can be driven by the second drive shaft 36. The respective transmission devices 76, 78 are also referred to as final drives. In the first embodiment, the respective transmission devices 76, 78 are designed as planetary gear sets, which are also referred to as planetary gear sets. The respective gear 42, 44 is a sun gear of the respective planetary gear set.Each planetary gear set also includes a ring gear 80, which is, for example, permanently and non-rotatably connected to the housing 38. Furthermore, each planetary gear set includes, for example, a planet carrier 82, also referred to as a web, which is rotatable about the respective machine axis of rotation 24, 32 relative to the housing 38. Each planetary gear set also includes planet gears 84, which are rotatably mounted on the respective planet carrier 82 of the respective planetary gear set.Each planet gear of the respective planetary gear unit is directly connected to the respective sun gear of the respective planetary gear unit, and also directly connected to the respective ring gear 80 of the respective planetary gear unit, whereby, for example, the respective sun gear of the respective planetary gear unit does not mesh with the respective ring gear 80 of the respective planetary gear unit. The respective planet carrier 82 is a respective output of the respective planetary gear unit, which can drive the respective vehicle wheel 14, 16 via its respective output. The respective sun gear of the respective planetary gear unit is a respective input of the respective planetary gear unit, which can be driven by the respective drive shaft 34, 36 via its respective input.

[0038] Fig.Figure 3 shows a partial schematic sectional view of a second embodiment of the electric drive device 10. In the second embodiment, the tie rod 56 and thus the retaining ring 64 and the support element 66 are not provided, so that, for example, the axial bearing 68 is also not provided.

[0039] In the second embodiment, the first drive shaft 34 has a first groove 86, and the second drive shaft 36 has a second groove 88. The grooves 86 and 88 are not provided in the first embodiment. A locking element 90, 92, designed as a retaining ring, is partially arranged in each respective groove 86, 88, whereby the respective axle gear 54, 55, which is rotationally fixed to the respective drive shaft 34, 36, is axially fixed to the respective drive shaft 34, 36 by means of the respective locking element 90, 92, so that axial relative movements between the respective drive shaft 34, 36 and the respective associated axle gear 54, 55 are prevented.For this purpose, the respective axle gear 54, 55 is arranged axially between the respective retaining element 90, 92 (retaining ring) and at the respective stop 94, 96 of the respective drive shaft 34, 36, so that the respective axle gear 54, 55 is fixed axially to the respective drive shaft 34, 36 by means of the respective stop 94, 96 and by means of the respective retaining element 90, 92. This also provides a particularly advantageous support, especially for installation, of the axial forces. Reference symbol list 10 electric drive unit 12 vehicle axle 14 first vehicle wheel 16 second vehicle wheel 18 first electric machine 20 first stator 22 first rotor 24 first machine axis 26 second electric machine 28 second stator 30 second rotor 32 second machine axis 34 first drive shaft 36 second drive shaft 38 cases 40 Differential gears 42 first gear 44 second gear 46 Gearbox housing 48 Compensating wheel 50 compensating wheel 52 Compensating wheel pivot axis 54 Axle shaft wheel 55 Axle shaft wheel 56 tie rods 58 area 60 external threads 62 internal threads 64 retaining ring 66 Support element 68 first axial bearing 70 Housing part 72 Housing part 74 second axial bearing 76 Gearbox unit 78 Gearbox unit 80 Ring gear 82 planetary carriers 84 planetary gear 86 Nut 88 Nut 90 locking element 92 Safety element 94 attacks 96 attacks L1 first length range L2 second length range QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2020 104 857 A1

[0001] DE 10 2020 113 192 A1

[0001]

Claims

[1] An electric drive device (10) for a motor vehicle, comprising a first electric machine (18) having a first rotor (22), a first drive shaft (34) connected in a rotationally fixed manner to the first rotor (22), via which a first vehicle wheel (14) of a vehicle axle (12) of the motor vehicle can be driven by means of the first electric machine (18), a second electric machine (26) having a second rotor (30), a second drive shaft (36) connected in a rotationally fixed manner to the second rotor (30) and arranged coaxially to the first drive shaft (34), via which a second vehicle wheel (16) of the vehicle axle (12) can be driven by means of the second electric machine (26), a differential gear (40) via which the drive shafts (34, 36) are coupled to one another, a helical-toothed first gear (42) connected in a rotationally fixed manner to the first drive shaft (34),with a helical-toothed second gear (44) connected to the second drive shaft (36) in a rotationally fixed manner, wherein the drive shafts (34, 36) are rotatable relative to one another and are rigidly coupled to one another in the axial direction of the respective drive shaft (34, 36), wherein a first helix angle of the first gear (42) and a second helix angle of the second gear (44) are substantially equal and oriented in opposite directions. [2] Electric drive device (10) according to claim 1, characterized bya tie rod (56) formed separately from the drive shafts (34, 36), which is fixedly connected to the first drive shaft (34) in the axial direction of the respective drive shaft (34, 36), penetrates the second drive shaft (36) formed as a hollow shaft and is at least indirectly supported in the axial direction of the respective drive shaft (34, 36) on a surface (58) of the second drive shaft (36) pointing away from the first drive shaft (34) in the axial direction of the respective drive shaft (34, 36). [3] Electric drive device (10) according to claim 2, characterized by that the tie rod (56) is screwed to the first drive shaft (34) and is thereby firmly connected to the first drive shaft (34) in the axial direction of the respective drive shaft (34, 36). [4] Electric drive device (10) according to claim 3, characterized bythat a first length region (L1) of the tie rod (56) is arranged in a hollow, second length region (L2) of the first drive shaft (34) and is screwed to the first drive shaft (34) in the hollow, second length region (L2). [5] Electric drive device (10) according to one of claims 2 to 4, characterized by a retaining ring (64) formed separately from the drive shafts (34, 36) and separately from the tie rod (56) and arranged on the tie rod (56), via which the tie rod (56) is supported on the surface (58) in the axial direction of the respective drive shaft (34, 36). [6] Electric drive device (10) according to claim 5, characterized byan axial bearing (68) formed separately from the drive shafts (34, 36), separately from the tie rod (56), and separately from the retaining ring (64), arranged in the axial direction of the respective drive shaft (34, 36) between the surface (58) and the retaining ring (64), via which the retaining ring (64) and, via this, the tie rod (56) are supported on the surface (58) in the axial direction of the respective drive shaft (34, 36) and are rotatably mounted on the surface (58). [7] Electric drive device (10) according to one of the preceding claims, characterized bythat the respective drive shaft (34, 36) has a respective groove (86, 88) in which a respective retaining ring (90, 92) is arranged, which is formed separately from the respective drive shaft (34, 36), and by means of which a respective axle shaft gear (54, 55) of the differential gear (40), which is connected in a rotationally fixed manner to the respective drive shaft (34, 36), is fixed to the respective drive shaft (34, 36) in the axial direction of the respective drive shaft (34, 36). [8] Electric drive device (10) according to one of the preceding claims, characterized by that the differential gear (40) has a gear housing (56) which has two housing parts (70, 72) which are formed separately from one another and connected to one another. [9] Electric drive device (10) according to claim 8; characterized by that the housing parts (70, 72) are connected to each other by means of screws. [10] Electric drive device (10) according to one of the preceding claims, characterized by an axial bearing (74) which is formed separately from the drive shafts (34, 36), arranged between the drive shafts (34, 36) in the axial direction of the respective drive shaft (34, 36) and arranged within the differential gear (40), via which axial bearing the drive shafts (34, 36) are supported on one another in the axial direction of the respective drive shaft (34, 36) and are rotatably mounted on one another.

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