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 motor vehicle.

[0002] DE 10 2021 133 268 A1 discloses an electric drive of a vehicle, which consists of two electric traction machines arranged axially next to one another in series, each of which drives two vehicle wheels via a reduction gear and which are operatively connected to a gear.

[0003] DE 10 2020 000 191 A1 describes a drive device for electrically driving wheels of a motor vehicle, comprising an electric machine, a first output shaft via which a first of the wheels can be driven by the electric machine, and a second output shaft via which a second of the wheels can be driven by the electric machine.

[0004] DE 346 221 A discloses a differential gear equipped with bevel friction wheels, in which friction discs are rigidly mounted on nested shafts.

[0005] DE 10 2020 104 857 A1 discloses a drive arrangement for an electric drive axle, comprising a housing in which a first electric drive motor and a second electric drive motor are arranged.

[0006] Furthermore, DE 10 2020 113 192 A1 discloses a transmission for transmitting power from two electric motors to two wheels.

[0007] The object of the present invention is to provide an electric drive device for a motor vehicle so that a particularly efficient operation of the electric drive device can be realized.

[0008] This object is achieved by an electric drive device having the features of patent claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0009] The invention relates to an electric drive device, also referred to as an electric drive system or simply as a 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, 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 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 is thus rotatable about a first machine axis of rotation relative to the first stator.By means of the first electric machine, a first vehicle wheel, also simply referred to as the first wheel, of a vehicle axle, also simply referred to as the axle, of the motor vehicle can be driven via the first rotor of the first electric machine. The electric drive device has a first drive shaft, which is connected, in particular permanently, in a rotationally fixed manner to the first rotor and via which the first vehicle wheel of the vehicle axle can be driven, in particular purely electrically, by means of the first electric machine, in particular by means of the 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. As a result, the first drive shaft can be driven and thus rotated about the first machine axis of rotation 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.

[0010] The electric drive device also has a second electric machine, which is provided in addition to the first electric machine and 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 is thus rotatable about a second machine axis of rotation relative to the second stator. In particular, the electric machines are arranged coaxially to one another so that the machine axes of rotation coincide. By means of the second electric machine, in particular by means of the second rotor, a second vehicle wheel of the vehicle axle, also simply referred to as the second wheel, can be driven, in particular purely electrically. In particular, the second electric machine can drive the second vehicle wheel, in particular purely electrically, via its second rotor.For this purpose, the electric drive device has a second drive shaft arranged coaxially to the first drive shaft, which second drive shaft is connected, in particular permanently, in a rotationally fixed manner 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, whereby the second drive shaft can be driven and thus rotated 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, such 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 via the first drive shaft by the first electric machine, i.e. by the first rotor, 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 in order to thereby drive the first vehicle wheel, the second vehicle wheel is not arranged downstream of the first rotor and upstream of the first vehicle wheel in the first torque flow, wherein the first drive shaft is arranged downstream of the first rotor and upstream of the first vehicle wheel in the first torque flow. Furthermore, it is provided in particular that the second vehicle wheel can be driven by means of the second electric machine, in particular by means of 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 thereby drive the second vehicle wheel, the first vehicle wheel is not arranged downstream of the second rotor and upstream of the second vehicle wheel in the second torque flow, wherein in particular the second drive shaft is arranged downstream of the second rotor and upstream of the second vehicle wheel in the second torque flow. The electric drive device is thus a dual drive in which the electric machines are wheel-specific electric machines. This means that the first vehicle wheel can be driven by means of the first electric machine, bypassing the second vehicle wheel, and that the second vehicle wheel can be driven by means of the second electric machine, bypassing the first vehicle wheel.When reference is made above and below to the vehicle wheels, this refers to the first vehicle wheel and the second vehicle wheel, unless stated otherwise. In the fully manufactured state of the motor vehicle, the vehicle wheels of the vehicle axle are arranged on opposite sides of the motor vehicle in the transverse direction of the motor vehicle. The vehicle wheels 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 motor vehicle. If the motor vehicle is driven along the ground while being supported downwards on the ground in the vertical direction of the motor vehicle via the ground contact elements, the ground contact elements roll, in particular directly, on the ground. By driving the vehicle wheels, the motor vehicle as a whole can be driven, in particular purely electrically.

[0011] For example, 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, namely the aforementioned vehicle axle as the first vehicle axle and at least or exactly one second vehicle axle. The previous and following statements regarding the first vehicle axle can be readily applied to the second vehicle axle and vice versa. For example, the respective electric machine is designed as a respective axial flux machine (AFM).

[0012] The electric drive device also has a differential gear, which is also simply referred to as a differential. The drive shafts are coupled to one another via the differential gear. The differential gear has the function, which is sufficiently well known from the general prior art, that the differential gear allows different speeds of the drive shaft and thus of the vehicle wheels when the motor vehicle is cornering, in particular such that the vehicle wheel on the outside of the curve and the associated drive shaft, by which the vehicle wheel on the outside of the curve can be driven or is driven, rotates or can rotate at a higher speed than the vehicle wheel on the inside of the curve and the associated drive shaft, by which the vehicle wheel on the inside of the curve can be driven or is driven.In particular, for example, the drive shafts are coupled to one another via the differential gear in such a way that when the motor vehicle is raised such that the vehicle wheels are suspended in the air and thus have no contact with the ground and one of the drive shafts is rotated about the respective machine axis of rotation in a first direction of rotation, the other drive shaft is driven by the one drive shaft via the differential gear in such a way that the other drive shaft is rotated about the other machine axis of rotation in a second direction of rotation opposite to the first directions of rotation, so that the drive shafts rotate in opposite directions, specifically about the respective machine axis of rotation. In particular, it can be provided that the differential gear is arranged between the electrical machines 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 rotation axes also coincide.

[0013] The electric drive device also has a first gear which is, in particular permanently, connected in a rotationally fixed manner to the first drive shaft and has helical teeth, thus having a first helical toothing, in particular a first helix angle. The electric drive device also has a second gear provided in addition to the first gear, which is, in particular permanently, connected in a rotationally fixed manner to the second drive shaft and has helical teeth, such that the second gear has a second helical toothing, in particular with a second helix angle. Since the first gear is connected in a rotationally fixed manner to the first drive shaft, the first gear belongs to the first drive shaft and vice versa. Since the second gear is connected in a rotationally fixed manner to the second drive shaft, the second gear belongs to the second drive shaft and vice versa.In principle, it is conceivable for the respective gear to be formed integrally with the respective associated drive shaft, so that, for example, the respective gear and the respective associated drive shaft can be formed integrally, i.e., from a single piece. Alternatively, it is conceivable for the respective gear and the respective associated drive shaft to be formed separately from one another and, in particular, permanently connected to one another in a rotationally fixed manner.The feature that the respective gearwheel and the respective associated drive shaft are formed from a single piece is to be understood as meaning that the respective gearwheel and the respective associated drive shaft are not formed as components formed separately from one another and connected to one another, but rather the respective gearwheel and the respective associated drive shaft are formed from a single piece and are thus formed by a monoblock formed in one piece, i.e. formed from a single piece, or are formed as such a monoblock.

[0014] In the electric drive device according to the invention, it is provided that the drive shafts are rotatable relative to one another and fixedly coupled to one another in the axial direction of the respective drive shaft. This means that the drive shafts are coupled or connected to one another in such a way that the drive shafts are rotatable relative to one another about the respective machine axis of rotation. The drive shafts are coupled, i.e., connected, to one another, in particular simultaneously, in such a way that relative movements between the drive shafts in the axial direction of the respective drive shaft are prevented, in particular while the drive shafts are rotatable relative to one another about the respective machine axis of rotation.As a result, forces resulting from the helical gears, also known as axial forces, acting in the axial direction of the respective drive direction can be advantageously compensated, so that excessively high drag losses, particularly in bearings provided for supporting the drive shafts, can be avoided. This means that operation directly with the drive device can be carried out with a particularly high overall efficiency, and therefore with particularly low efficiency, especially even at high drive shaft speeds. The invention is based in particular on the following findings and considerations: The helical gears can cause axial forces under torque, i.e. particularly when the respective drive shaft and thus the respective associated gear are driven by the respective rotor, which axial forces should be supported by the aforementioned bearings.If the axial forces are not compensated for, or are only compensated for inadequately, 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 to compensate for, the axial forces, whereby excessively high drag losses can be avoided and, as a result, particularly efficient operation of the electric drive device can be achieved. 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, the respective drive shaft each has two separately formed shaft parts, which are connected to one another in a rotationally fixed manner but can be displaced relative to one another in the axial direction of the respective drive shaft.The axial forces could then be mutually supported via, for example, two axial bearings in the thrust and tension directions, particularly without significant differential speeds. The invention now enables a particularly advantageous support, in particular compensation, of the axial forces, thus achieving a particularly high level of efficiency, particularly overall efficiency, of the drive device. The respective drive shaft does not have to be constructed in multiple parts but can, for example, be formed in one piece, i.e., in a single piece, thereby enabling particularly efficient operation of the drive device in a particularly simple and cost-effective manner.

[0015] According to the invention, a first helix angle of the first gear and a second helix angle of the second gear are essentially the same but oriented in opposite directions. The invention advantageously makes it possible to support, in particular compensate, the axial forces resulting from the helical gearing against each other or against each other. Supporting significant forces via housings or rapidly rotating bearings can be avoided, so that bearings can be dimensioned particularly small. The mutual support, in particular compensation, of the axial forces achieved by the invention takes place without major differential speeds in support bearings and / or in the aforementioned axial bearings and is therefore independent of the speed and without drag losses at high drive torques, which can advantageously result in a particularly high overall efficiency of the drive device.

[0016] In an advantageous embodiment of the invention, a tie rod is provided which is formed separately from the drive shafts and is preferably designed as a single piece, i.e. is formed from a single piece. The tie rod is firmly 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 rotational axis on a surface of the second drive shaft which points away from the first drive shaft in the axial direction of the respective drive shaft.As a result, the drive shafts can be firmly coupled to one another in a particularly advantageous manner in the axial direction of the respective drive shaft and, at the same time, can be rotated relative to one another in the respective machine rotational axis, so that particularly efficient operation can be achieved in a particularly simple manner.

[0017] When reference is made above and below to the axial direction, this refers, unless otherwise stated, to the axial direction of the respective drive shaft. Thus, the term "and in axial" refers to the axial direction of the respective drive shaft, whose respective axial direction coincides with the respective machine axis of rotation.

[0018] In order to be able to axially and firmly connect the drive shafts to one another in a particularly simple and thus advantageous manner, so that relative movements in the axial direction between drive shafts are prevented, it is provided in a further embodiment of the invention 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 relative movements in the axial direction between the tie rod and the first drive shaft are prevented.

[0019] A further embodiment of the invention is characterized in that a first longitudinal region of the tie rod is arranged in a hollow, second longitudinal region of the first drive shaft and is screwed, in particular directly, to the first drive shaft in the hollow, second longitudinal region. This ensures particularly efficient operation of the drive device in a particularly space-saving manner. For example, the first drive shaft is also designed as a hollow shaft.

[0020] The tie rod and the first drive shaft are, for example, screwed together in such a way that the tie rod, in particular in the first length range, has a first thread, in particular a first external thread. In this case, the first drive shaft, in particular in the second length range, has, for example, a second thread corresponding to the first thread, which is in particular designed as an internal thread. The threads are preferably screwed directly to one another or into one another, whereby the tie rod is screwed directly to the first drive shaft. As a result, the tie rod and the first drive shaft can be connected to one another in a particularly simple and space-saving manner, in particular in such a way that relative movements in the axial direction between the tie rod and the first drive shaft are prevented.

[0021] In order to axially and firmly connect the drive shafts to one another in a particularly space-saving and thus efficient manner and at the same time to allow the drive shafts to be rotatable relative to one another about the respective machine axis of rotation, a further embodiment of the invention provides that the electric drive device has a retaining ring which is formed separately from the drive shafts and separately from the tie rod and is arranged on the tie rod, via which retaining ring the tie rod is supported on the surface, in particular in such a way that the retaining ring is supported at least indirectly on the surface in the axial direction. In particular, the retaining ring which is formed separately from the drive shafts and separately from the tie rod is fixed in the axial direction to the tie rod, i.e. is connected to the tie rod in such a way that relative movements in the axial direction between the retaining ring and the tie rod are prevented.

[0022] It has proven particularly advantageous if an axial bearing is provided which is designed separately from the drive shafts, separately from the tie rod, and separately from the retaining ring, and is arranged in the axial direction of the respective drive shaft between the surface and the retaining ring, and is designed, for example, as a rolling bearing, via which the retaining ring and, via the retaining ring, the tie rod and, via the tie rod, the first drive shaft are supported on the surface in the axial direction of the respective drive shaft and 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 designed as a hollow shaft.This allows for particularly advantageous support, particularly compensation of axial forces, to be achieved in a particularly space-efficient manner, thus enabling particularly efficient operation of the electric drive system. References to the axial bearing above and below refer to the first axial bearing, unless otherwise stated.

[0023] In order to support, in particular compensate, the axial forces in a particularly simple and thus space-saving, weight-saving, and cost-effective manner, and consequently to achieve particularly efficient operation of the drive device, a further embodiment of the invention provides that the respective drive shaft has a respective groove in which a respective retaining ring, formed 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 the retaining element is also referred to as a snap ring.By means of the respective retaining ring, a respective axle shaft gear of the differential gear, which is connected in a rotationally fixed manner to the respective drive shaft and is provided in particular in addition to the respective gear wheel, 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 running parallel to the axial direction or coinciding with the axial direction via the axle shaft gears and differential gears of the differential gear meshing with the axle shaft gears, and in a second load direction opposite to the first load direction, running parallel to the axial direction or coinciding with the axial direction, via a housing of the differential gear, also referred to as a differential housing or differential housing.

[0024] For example, the differential gear is designed as a bevel gear differential, also known as a cone differential, or a ball differential. In this case, it is particularly provided that the respective axle shaft gear and the respective differential gear are designed as a respective bevel gear. In particular, the respective differential gear and the respective axle shaft gear are each a respective additional gear.

[0025] In order to support and, in particular, compensate for the axial forces particularly advantageously and thus realize particularly efficient operation of the drive device, a further embodiment of the invention provides that the differential housing has the aforementioned housing, also referred to as the transmission housing, which preferably has at least or exactly two separately formed and interconnected housing parts, which are assembled in particular in the axial direction. This is to be understood in particular that the transmission housing is axially divided, so that, for example, the housing parts follow one another in the axial direction.

[0026] Preferably, the housing parts are connected to each other in a non-destructive manner.

[0027] It has proven particularly advantageous if the housing parts are connected to one another by means of screws, in particular screws which can be removed without causing any damage.

[0028] Furthermore, it would be conceivable for the transmission housing to be designed so that it cannot be dismantled, with the transmission housing being manufactured, for example, by casting, i.e., cast, so that, for example, the transmission housing is designed as a cast component. Furthermore, it would be conceivable for the housing parts to be riveted together and thus connected to one another, so that the housing part can be designed in several parts, in particular in two parts, but cannot be dismantled. Furthermore, it would be conceivable for the housing parts to be welded together and thus connected to one another, so that the transmission housing would be designed in several parts, in particular in two parts, but cannot be dismantled.

[0029] The gearbox housing can be disassembled, in particular when the housing parts are designed separately from one another and are connected to one another in a non-destructive manner. In particular when the housing parts are designed separately from one another and are connected to one another in a non-destructive manner, the respective securing element can, for example, first be mounted, after which the housing parts can be connected to one another, in particular screwed together. In this way, for example, the respective securing element can be provided as a respective, precisely fitting and backlash-free securing ring in the respective groove, i.e. can be arranged in the respective groove. Alternatively, the respective groove would have to be designed deeper, for example, so that the respective securing element can engage, in particular completely, in the respective groove when the respective drive shaft is passed through the respective axle shaft gear.

[0030] In order to support, in particular compensate, the axial forces particularly advantageously and consequently achieve particularly efficient operation, the invention provides that the electric drive device has an axial bearing, also referred to as a second axial bearing, which is formed separately from the drive shafts and arranged in the axial direction of the respective drive shaft between the drive shafts and within the differential gear, in particular within the gear housing. The second axial bearing supports the drive shafts against one another in the axial direction of the respective drive shaft and is rotatably mounted relative to one another. The second axial bearing is preferably 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. This way, additional loading of the differential gears and the transmission housing due to axial forces can be avoided.

[0031] 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 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.

[0032] The drawing shows: Fig. 1 shows a partial schematic sectional view of the first embodiment of an electric drive device for a motor vehicle; Fig. 2 shows a further schematic sectional view of the drive device according to the first embodiment; Fig. 3 shows a partial schematic sectional view of the second embodiment of the drive device.

[0033] In the figures, identical or functionally identical elements are provided with the same reference symbols.

[0034] Fig. 1 shows a partial schematic sectional view of a first embodiment of an electric drive device 10 of a motor vehicle, also referred to simply as a vehicle. The motor vehicle, preferably designed as a motor vehicle, in particular a passenger car, has at least or exactly two vehicle axles arranged one after the other in the vehicle's longitudinal direction and thus one behind the other, namely a first vehicle axle and a second vehicle axle. The first vehicle axle is in Fig. 1 is shown particularly schematically and designated by 12. The first vehicle axle 12 has the electric drive device 10. In addition, the vehicle axle 12 has, in particular precisely, 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 motor vehicle in the transverse direction of the motor vehicle. The vehicle wheels 14 and 16 are ground contact elements of the motor vehicle, which can be or is supported on a ground downwards in the vertical direction of the motor vehicle via the ground contact elements. By means of the drive device 10, the vehicle wheels 14 and 16 and thus the motor vehicle can be driven, in particular purely electrically. For this purpose, the electric drive device 10 has a first electric machine 18, which is designed as a first axial flux machine.The first electrical machine 18 has a first stator 20 and a first rotor 22, which can be driven by the stator 20 and is thus rotatable about a first machine axis of rotation 24 relative to the stator 20. Furthermore, the drive device 10 has a second electrical machine 26, which is provided in addition to the first electrical machine 18 and is designed as a second axial flux machine. The second electrical machine 26 has a second stator 28 and a second rotor 30, which can be driven by the second stator 28 and is thus rotatable about a second machine axis of rotation 32 relative to the stator 28. It can be seen that the electrical machines 18 and 26 are arranged coaxially to one another, so that the rotors 22 and 30 are arranged coaxially to one another 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 device 10 has a first drive shaft 34, which is connected, in particular permanently, in a rotationally fixed manner to the rotor 22 and is thus rotatable about the machine rotation axis 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 which is provided in addition to the drive shaft 34 and is designed separately from the drive shaft 34 and which is connected, in particular permanently, in a rotationally fixed manner to the rotor 30 and is thus rotatable about the machine rotation axis 24, 32 relative to the stator 28.Thus, the drive shafts 34, 36 are arranged coaxially with each other. The vehicle wheel 16 can be driven by the rotor 30 and thus by the electric motor 26 via the drive shaft 36, bypassing the vehicle wheel 14.

[0035] The drive device 10 has 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 rotational axes 24, 32 relative to the housing 38. The drive device 10 also comprises a differential gear 40, also simply referred to as a differential, which in this case is designed as a bevel differential. The bevel differential is also referred to as a bevel gear differential. It can be seen that in the axial direction of the respective drive shaft 34, 36, whose respective axial direction coincides with the respective machine rotational axes 24, 32, the differential gear 40 is arranged between the electric machines 18 and 26. The differential gear 40 is arranged in the housing 38. The drive shafts 34 and 36 are coupled to one another via the differential gear 40, in particular in a torque-transmitting manner.

[0036] The drive device 10 has a first gear 42, which is connected, in particular permanently, in a rotationally fixed manner to the first drive shaft 34 and thus belongs to the drive shaft 34 and vice versa. In the present case, the drive shaft 34 and the associated gear 42 are formed from a single piece, thus being designed as a single part or in one piece. The drive device 10 also has a second gear 44, which is connected, in particular permanently, in a rotationally fixed manner to the drive shaft 36 and thus belonging to the drive shaft 36 and vice versa. In the present case, the drive shaft 36 and the associated gear 44 are designed as a single piece, i.e., they are formed from a single piece and thus in one piece.

[0037] The differential gear 40 has a gear housing 46, which is also referred to as a housing or differential housing. Furthermore, the differential gear 40 has differential gears 48 and 50, which are third gears provided in addition to the gears 42 and 44. The respective differential gear 48, 50 is designed here as a respective bevel gear. The respective differential gear 48, 50 is rotatably mounted on the gear housing 46 about a differential gear rotation axis 52 common to the differential gears 48 and 50 relative to the gear housing 46, wherein the differential gear rotation axis 52, also referred to as the differential axis, runs perpendicular to the respective machine rotation axis 24, 32. In particular, it is provided that the gear housing 46 is rotatable about the respective machine rotation axis 24, 32 relative to the respective drive shaft 34, 36.Furthermore, the differential gear 40 has a first axle shaft gear 54, which is connected, in particular permanently, in a rotationally fixed manner to the first drive shaft 34 and which meshes, i.e., is engaged, in particular directly, with the differential gears 48 and 50. The differential gear 40 also has a second axle shaft gear 55, which is connected, in particular permanently, in a rotationally fixed manner to the second drive shaft 36 and which meshes, i.e., is engaged, in particular directly, with the differential gears 48 and 50. The axle shaft gears 54 and 55 are also referred to as output gears and are additional, third gears, wherein in the present case the respective axle shaft gear 54, 55 is designed as a respective bevel gear.In particular, the differential gears 48 and 50 are rotatably mounted on the gear housing 46 in such a way that the respective differential gear 48, 50 is rotatable about the differential gear rotation axis 52 relative to the gear housing 46, but the respective differential gear 48, 50 is rotatable with the gear housing 46 about the respective machine rotation axis 24, 32, so that, for example, the respective differential gear 48, 50 is connected to the gear housing 46 in a rotationally fixed manner for rotations about the machine rotation axis 24, 32 or is held on the gear housing 46 in a rotationally fixed manner.

[0038] The respective gears 42, 44 are helically toothed, so that gear 42 has a first helical toothing with a first helix angle, and the second gear 44 has a second helical toothing with a second helix angle. It is preferably provided that the helix angles are equal, with helix angles preferably being oriented in opposite directions.

[0039] In particular, during operation of the drive device 10, wherein the electric motors 18 and 26 drive the drive shafts 34 and 36 and the vehicle wheels 14 and 16 during operation, the helical gears can cause axial forces. Axial forces are understood to be forces acting in the axial direction of the respective drive shaft 34, 36 and thus of the respective electric machine 18, 26 and the drive device 10 as a whole. In order to be able to support, in particular compensate, these axial forces particularly advantageously, in particular in such a way that the axial forces support one another and thus compensate one another, it is provided in the drive device 10 that the drive shafts 34 and 36 are rotatable relative to one another and are firmly coupled to one another in the axial direction of the respective drive shaft 34, 36.

[0040] As from Fig. 2, in the first embodiment, a tie rod 56 is provided for this purpose, which is formed separately from the drive shafts 34 and 36 and is preferably made from a single piece and is firmly connected to the first drive shaft 34 in the axial direction of the respective drive shaft 34, 36. When reference is made previously and hereinafter to the axial direction, this is to be understood, unless otherwise stated, as the axial direction of the respective drive shaft 34, 36 and thus of the respective electrical machine 18, 26 and the drive machine 10 as a whole. The respective drive shaft 34, 36 is formed as a respective hollow shaft. The tie rod 56 penetrates the second drive shaft 36, which is formed as a hollow shaft. In addition, the tie rod 56 is indirectly supported in the axial direction on a surface 58 of the second drive shaft 36 pointing away from the first drive shaft 34 in the axial direction.In the second embodiment, the surface 58 extends in a plane which is perpendicular to the axial direction. The tie rod 56 is screwed directly to the drive shaft 34 and is thereby firmly connected to the drive shaft 34 in the axial direction. For this purpose, a first longitudinal region L1 of the tie rod 56 is arranged in a hollow longitudinal region L2 of the drive shaft 34, wherein the longitudinal region L1 and thus the tie rod 56 is screwed directly to the drive shaft 34 in the longitudinal region L2 and thus in the drive shaft 34. For this purpose, the tie rod 56 has a first thread in the longitudinal region L2 designed as an external thread 60, and the drive shaft 34 has a second thread in the longitudinal region 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 one another, whereby the tie rod 56 is screwed directly to the drive shaft 34, in this case such that the tie rod 56 is screwed directly into the drive shaft 34. As a result, the tie rod 56 is firmly connected to the drive shaft 34 in the axial direction. This means that the tie rod 56 and the drive shaft 34 are connected to one another in such a way that relative movements in the axial direction between the tie rod 56 and the drive shaft 34 are prevented.

[0041] Also provided is a retaining ring 64 formed separately from the drive shafts 34 and 36 and separately from the tie rod 56. In addition, a support element 66 is provided, which in this case is designed as a thrust washer. The support element 66 is formed separately from the retaining ring 64, separately from the drive shafts 34 and 36, and separately from 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 relative movements in the axial direction 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 device 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 formed separately from the support element 66, separately from the retaining ring 64, as well as separately from the tie rod 56, and also separately from the drive shafts 34 and 36. The tie rod 56 is supported axially 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 supported axially 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 on the one hand directly on the surface 58 and on the other hand indirectly and via the support element 66 on the retaining ring 64.

[0042] Out of Fig. 2 that the gear housing 46 is constructed in multiple parts, in this case in two parts, and in particular has precisely two housing parts 70 and 72, which are constructed separately from one another and are connected to one another, in particular in a non-destructive manner. In this case, the gear housing 46 is divided in the axial direction, so that the housing parts 70 and 72 are joined together in the axial direction. This ensures particularly simple assembly of the drive device 10. The drive device 10 has a second axial bearing 74, which is provided in addition to the first axial bearing 68 and is arranged in the differential gear 40, in particular in the gear housing 46. For example, the axial bearing 68 and / or the axial bearing 74 is constructed 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 on one another in the axial direction and are rotatably mounted on one another via the axial bearing 74.

[0043] Out of Fig. 1 and Fig. 2 that the electric machine 18 and the first drive shaft 34 are assigned a first gear device 76, also referred to as the first final gear ratio or providing a first final gear ratio, via which the vehicle wheel 14 can be driven by the drive shaft 34. Accordingly, the second electric machine 26 and the second drive shaft 36 are assigned a second gear device 78, also referred to as the second final gear ratio or providing a second final gear ratio, via which the vehicle wheel 16 can be driven by the second drive shaft 36. The respective gear device 76, 78 is also referred to as a final drive. In the first embodiment, the respective gear device 76, 78 is designed as a respective planetary gear, which is also referred to as a planetary set or planetary gear set. The respective gear 42, 44 is a respective sun gear of the respective planetary gear.The respective planetary gear also has a respective ring gear 80, which is, for example, in particular permanently, non-rotatably connected to the housing 38. Furthermore, the respective planetary gear has, for example, a respective planet carrier 82, also referred to as a web, which is rotatable, for example, about the respective machine rotational axis 24, 32 relative to the housing 38. The respective planetary gear also has respective planet gears 84, which are rotatably mounted on the respective planet carrier 82 of the respective planetary gear.The respective planetary gear of the respective planetary gear is connected, on the one hand, in particular directly, to the respective sun gear of the respective planetary gear and, on the other hand, in particular directly, to the respective ring gear 80 of the respective planetary gear, wherein, for example, meshing of the respective sun gear of the respective planetary gear with the respective ring gear 80 of the respective planetary gear is avoided. The respective planet carrier 82 is a respective output of the respective planetary gear, which can drive the respective vehicle wheel 14, 16 via its respective output. The respective sun gear of the respective planetary gear is a respective input of the respective planetary gear, which can be driven by the respective drive shaft 34, 36 via its respective input.

[0044] Fig.3 shows a detail in a 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.

[0045] 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 respective securing element 90, 92, designed as a respective retaining ring, is partially arranged in the respective groove 86, 88, wherein the respective axle shaft gear 54, 55, which is connected in a rotationally fixed manner to the respective drive shaft 34, 36, is fixed in the axial direction to the respective drive shaft 34, 36 by means of the respective securing element 90, 92, so that relative movements in the axial direction between the respective drive shaft 34, 36 and the respective, associated axle shaft gear 54, 55 are prevented.For this purpose, the respective axle shaft gear 54, 55 is arranged in the axial direction between the respective securing element 90, 92 (circlip) and on the respective stop 94, 96 of the respective drive shaft 34, 36, so that the respective axle shaft gear 54, 55 is fixed in the axial direction to the respective drive shaft 34, 36 by means of the respective stop 94, 96 and by means of the respective securing element 90, 92. This also allows for a particularly advantageous support, in particular installation, of the axial forces.

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 of equal size and oriented in opposite directions, , 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. [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) and 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 (46) 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.

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