Electric drive device for a motor vehicle

Abstract

Electric drive device (10) for a motor vehicle, with at least one electric machine (12) for driving the motor vehicle, with a planetary gear set (26) having a ring gear (28), via which the motor vehicle can be driven by the electric machine (12), and with a housing (32) in which the planetary gear set (26) is arranged, wherein: - the electrical machine (12) is designed as an axial flux machine which has two rotors (14, 16) and a stator (18) which is arranged in the axial direction (22) of the electrical machine (12) between the rotors (14, 16) which are rotatable relative to the stator (18); - the stator (18) has a partial region (TB) projecting outwardly beyond the rotors (14, 16) in the radial direction (24) of the electric machine (12), on which a projection (36) is provided which: o extends in the axial direction (22) of the electric machine (12) over one of the rotors (14, 16), o the one rotor (16) arranged in the axial direction (22) of the electric machine (12) between the planetary gear set (26) and the stator (18) overlaps outwards in the radial direction (24) of the electric machine (12), o forms a ring gear carrier (40) to which the ring gear (28) formed separately from the ring gear carrier (40) is connected in a rotationally fixed manner, and o has a plug-in toothing (42) as the first toothing, which engages in a corresponding second toothing (44) of the housing (32), and wherein o the stator (18) is formed integrally with the projection (36).

Description

The invention relates to an electric drive device for a motor vehicle, in particular for a motor vehicle, according to claim 1.DE 10 2022 102 130 A1 discloses a drive device which has an electric machine designed as an axial flow machine and a transmission designed as a planetary transmission.DE 10 2018 107 207 A1 describes an electromechanical vehicle drive system which correspondingly describes an electric motor, a motor and transmission housing and an epicyclic gear train with at least one ring gear which is accommodated in the transmission housing.DE 10 2018 123 733 A1 discloses a ring gear carrier for receiving a ring gear in a transmission housing of a planetary transmission.DE 198 05 676 A1 describes a Hirth front-toothed machine element.DE 10 2009 018 409 A1 discloses a ring gear which comprises a wall with toothing on a periphery of the wall. It is also provided that the wall of the ring gear is provided by at least one reinforcing material layer in the region where the toothing is present on the circumference.It is the object of the present invention to provide an electric drive device for a motor vehicle, so that a particularly advantageous noise behavior of the drive device can be realized.This object is achieved by an electric drive device having the features of claim 1.Advantageous embodiments with expedient developments of the invention are specified in the other claims.The invention relates to an electric drive device for a motor vehicle, also referred to simply as a vehicle. This means that the motor vehicle, which is preferably designed as a motor vehicle, in particular as a passenger vehicle, has the electric drive device in its completely produced state and can be driven electrically, in particular purely, by means of the electric drive device. For this purpose, the electric drive device has at least one electric machine, by means of which the motor vehicle can be driven, in particular purely electrically. The drive device also has a planetary gear set, also referred to as a planetary gear set or planetary gear set, by means of which the motor vehicle can be driven by the electric machine. The planetary gear set has a ring gear. For example, the planetary gear set also has a sun gear and a planetary carrier as well as planetary gears which are rotatably held on the planetary carrier. The sun gear meshes with the respective planetary gear, wherein a meshing of the sun gear with the ring gear is omitted. For example, the ring gear meshes with the respective planetary gear. The electric drive device also has a housing in which the planetary gear set is arranged. For example, the ring gear is connected, in particular permanently, rotationally fixedly to the housing. The sun gear and the planet carrier are rotatable relative to the housing about a planetary gear set rotational axis, for example. For example, the sun gear is an input of the planetary gear set, also referred to as a drive, via whose input torques that can be provided or are provided by the electric machine can be introduced into the planetary gear set. The planet carrier is preferably an output of the planetary gear set, also referred to as an output, via the output of which a respective output torque resulting from the respective drive torque introduced into the planetary gear set can be discharged from the planetary gear set, i.e. provided by the planetary gear set.Preferably, the housing is formed from die casting. In other words, the housing is preferably designed as a die casting component and is thus produced by a die casting process. In particular, the ring gear is arranged at least partially, in particular at least predominantly and thus at least to an extent of more than half or completely, in the housing.In order to be able to realize a particularly advantageous noise behavior of the electric drive device and thus a particularly high driving comfort of the motor vehicle, it is provided according to the invention that the electric machine is designed as an axial flux machine, which has two rotors and a stator, by means of which the rotors can be driven and thereby can be rotated about a machine rotational axis relative to the stator. The rotors are also referred to as rotor elements and are, for example, components of an overall rotor which has the rotors as the rotor elements. In particular, the rotors are connected to one another in a rotationally fixed manner, in particular permanently. For example, the rotors, and therefore the rotor elements, are designed as rotor disks. The stator is arranged in the axial direction of the electric machine, the radial direction of which runs perpendicular to the axial direction of the electric machine, between the rotors rotatable about the machine axis of rotation relative to the stator, wherein the axial direction of the electric machine coincides with the machine axis of rotation. Thus, for example, the rotors each have a first sub-region, wherein the first sub-regions are spaced apart from one another in the axial direction of the electric machine. The stator is arranged at least partially between the first sub-regions in the axial direction of the electric machine, such that at least a second sub-region of the stator is arranged between the first sub-regions of the rotors in the axial direction of the electric machine, such that the first sub-region of a first of the rotors is overlapped by the third sub-region along the machine rotation axis and in the process viewed from the first rotor to the second rotor. Accordingly, for example, the first partial region of the second rotor is overlapped, that is to say covered, by the third partial region, as viewed along the machine rotation axis and from the second rotor toward the first rotor.If the axial direction is mentioned above and below, this should be understood to mean, unless otherwise stated, the axial direction of the electric machine and thus of the ring gear and of the planetary gear set as a whole. If the radial direction is mentioned above and below, this should be understood to mean, unless otherwise stated, the radial direction of the electric machine and thus of the ring gear and of the planetary gear set. Thus, the term "axial" means the axial direction of the electric machine and thus of the electric drive device as a whole, and the term "radial" means the radial direction of the electric machine and thus of the ring gear and of the planetary gear set. The stator has a portion which projects outwards beyond the rotors in the radial direction of the electric machine, the circumferential direction of which portion runs around the axial direction and thus around the machine axis of rotation, and is also referred to as a stator portion. If the term partial region is mentioned above and below, this is to be understood as meaning the stator partial region, unless otherwise stated. This means that the partial region, viewed in the radial direction of the electric machine towards the outside, is arranged further outward than the rotors. A protrusion is provided on the partial region of the stator, which extends over one of the rotors in the axial direction of the electric machine. In other words, the protrusion protrudes in the axial direction from an end side of the stator facing the planetary gear set in the axial direction, in such a way that the protrusion extends away from the end side in the axial direction and extends toward the planetary gear, wherein the protrusion extends in the axial direction beyond the one rotor. The protrusion extends in the axial direction beyond the one rotor in such a way that the protrusion overlaps, i.e. covers, the one rotor outwards, in particular completely, in the radial direction of the machine. In this case, the one rotor is arranged in the axial direction between the planetary gear set and the stator, that is to say the axial end side. The protrusion forms a ring gear carrier, in particular in such a way that the ring gear carrier is connected integrally to the protrusion. Within the scope of the present disclosure, the feature that two components are formed integrally with one another is to be understood to mean that the components are formed integrally with one another, that is to say from a single piece. In other words, the components are not formed separately from one another or are connected to one another, but rather the components are formed from a single piece, with the result that the components are formed by a one-piece, that is to say one-piece monoblock which is formed in one piece and is thus formed from a single piece and is therefore produced integrally.The ring gear formed separately from the hollow carrier is connected to the ring gear carrier in a rotationally fixed manner. In particular, the ring gear formed separately from the ring gear carrier is also connected to the ring gear carrier in such a way that relative movements occurring in the axial direction between the ring gear and the ring gear carrier are prevented. Furthermore, the protrusion has a spline, which is also referred to as first toothing. The spline of the projection is also referred to as first spline. If the above and in the following discussion is with regard to the spline, this is to be understood as meaning, unless otherwise stated, the first spline of the projection. The spline, and therefore the first spline, engages in a corresponding second spline of the housing, wherein, for example, the second spline or the second spline is formed. In particular, the spline toothing, and therefore the first toothing, is arranged on an axial end side of the projection, the axial end side of which faces the second toothing in the axial direction. In particular, the axial end face of the protrusion faces in the axial direction an axial end face of the housing, on the axial end face of which the second toothing can be formed. The spline extends, for example, in the radial direction. In other words, for example, the teeth of the spline extend in the radial direction. This means that the respective tooth of the spline toothing protrudes in the axial direction from the axial end face of the protrusion and extends, in particular elongated, in the radial direction. Because the spline teeth engage in the second teeth of the housing, a particularly advantageous connection of the ring gear carrier and thus of the ring gear to the housing in a rotationally fixed manner can be realized. In addition, a particularly precise and easily realizable alignment of the ring gear carrier and thus of the ring gear relative to the housing can be represented.In order to be able to realize a particularly advantageous noise behavior of the drive device, it is provided in one embodiment of the invention that the ring gear carrier is formed from a fiber-reinforced plastic. This makes it possible, for example, to avoid an excessive transmission of oscillations from the ring gear carrier to the housing, as a result of which undesirable noises that can be perceived in the interior of the motor vehicle by persons who are in the interior can be avoided.In principle, it would be conceivable for the protrusion to be formed separately from the sub-region and thus separately from the stator and, in particular permanently, to be connected in a rotationally fixed manner to the sub-region and thus to the stator.In order to realize a particularly advantageous noise behavior, it is also provided in a further embodiment of the invention that the protrusion is formed integrally with the sub-region and integrally with the stator. In other words, it is preferably provided that the stator and the protrusion are formed from a single piece, and therefore in one piece with one another. In other words, the stator and the protrusion are thus not formed separately from one another and are connected to one another, but rather the stator and the protrusion are preferably formed by a one-piece, therefore one-piece monoblock which is formed in one piece and is thus formed from a single piece, that is to say is integrally produced.It is thus preferably conceivable for the stator to be formed from the aforementioned fiber-reinforced plastic, as a result of which a particularly advantageous noise behavior can be represented.A further embodiment of the invention is characterized in that the spline is designed as a segmented spline. Planar intermediate segments are arranged, for example, in the circumferential direction between the teeth of the spline, in particular in such a way that a respective one of the planar intermediate segments is arranged, in particular exactly, between two teeth of the spline that are directly adjacent in the circumferential direction. In particular, the respective planar intermediate segment is to be understood as a respective wall region of the projection, wherein the wall region extends, for example, in a plane which runs perpendicular to the axial direction. In this way, a particularly advantageous connection of the protrusion to the housing can be realized, whereby a particularly advantageous noise behavior can be produced.To realize a particularly advantageous noise behavior, it has been shown to be particularly advantageous if the spline toothing is designed as a Hirth toothing.In a further, particularly advantageous embodiment of the invention, it is provided that screws are arranged between the teeth of the spline in the circumferential direction of the electric machine, the circumferential direction of which screws runs around the axial direction and thus around the machine rotational axis, by means of which screws the spline is tensioned against the second spline in the axial direction of the electric machine. For example, the screws pass through the planar intermediate segments, as a result of which the protrusion can be connected to the housing in a particularly advantageous and rotationally fixed manner. Very preferably, a respective one of the screws is provided for each planar intermediate segment, in particular exactly, so that, in order to create a particularly advantageous noise behavior, the projection can be connected to the housing in a particularly advantageous manner in a rotationally fixed manner.In a further embodiment of the invention, it is provided that the ring gear is connected to the ring gear carrier in a rotationally fixed manner via a further spline. As a result, a particularly simple and fixed connection of the ring gear to the ring gear carrier can be realized, wherein at the same time a particularly advantageous noise behavior can be realized.A further embodiment of the invention is distinguished by a sleeve which is formed separately from the ring gear and separately from the ring gear carrier and is arranged, in particular directly, on an outer circumference of the ring gear carrier facing away from the ring gear in the radial direction of the electric machine, in particular in such a way that the sleeve directly touches the outer circumference and thus the ring gear carrier. The sleeve is firmly connected to the ring gear carrier, so that relative rotations between the ring gear carrier and the sleeve as well as relative movements occurring in the axial direction between the ring gear carrier and the sleeve are prevented. At least one respective longitudinal region of the ring gear carrier and of the ring gear, which extends in the axial direction of the electric machine and therefore runs in the axial direction of the electric machine, is overlapped outwards in the radial direction by the sleeve. This can prevent, for example, excessive expansion or fanning out of the ring gear carrier in the radial direction outwards, whereby a particularly advantageous noise behavior can be realized.In order to advantageously avoid excessive fanning out or expansion of the ring gear carrier that takes place in the radial direction outwards, it is provided in a further embodiment of the invention that the sleeve is formed from a steel.Finally, it has been shown to be particularly advantageous for realizing a particularly advantageous noise behavior if the housing and the ring gear carrier are arranged radially spaced apart from one another, whereby an air gap is provided in the radial direction between the housing and the ring gear carrier, which air gap extends in the circumferential direction of the electric machine completely circumferentially around the ring gear carrier.Furthermore, it is preferably provided that the ring gear carrier has a free end which is opposite the stator in the axial direction, that is to say the axial end face of the stator, at which free end the ring gear carrier and the protrusion as a whole end in the axial direction, wherein the free end is spaced apart from the housing, in particular completely, both in the radial direction and in the axial direction.The invention is based in particular on the following findings and considerations: A particularly efficient possibility of being able to reduce a high-speed electric motor, such as the axial flow machine, by an appropriate amount with respect to its rotational speed, consists of a single-stage planetary transmission. Thus, the planetary gear set is preferably provided as a single-stage planetary gear. For example, the sun gear can be driven by the electric machine, in particular by the overall rotor, wherein the electric machine can provide the respective drive torque, for example, via its overall rotor. The sun gear meshes with a suitable number of the planet gears carried by the planet carrier which is the output of the planetary gear set. The ring gear is also provided, which is likewise in engagement with the planetary gears. A potential risk of such an arrangement may be a rigid fixing of the ring gear to and in particular in the housing of the electric drive device, which is also referred to as an electric drive unit, which may lead to an unsatisfactory noise behavior of the electric drive device, which behavior is also referred to as NVH behavior (noise vibration"), since oscillations of the ring gear can be transmitted to the housing via an excessively strong connection of the ring gear to the housing if no corresponding countermeasures are taken. Moreover, excessive rigid attachment of the ring gear to the housing may possibly result in undesirably low efficiency of the planetary gear set, particularly due to over-determined planetary gear set with a plurality of planetary gears. The number of planetary gears is, for example, 3 or 4. such an excessive transmission of vibrations can be avoided by a sufficiently large gear play and / or bearing play, which, however, is associated with the disadvantage of an increased to excessive play in the planetary gear set, which can unduly impair the driving comfort. The aforementioned problems and disadvantages can now be avoided by the invention.The sleeve is also referred to as a collar and is, for example, pressed and / or shrunk onto the ring gear carrier. It is thus conceivable, for example, for the sleeve and the ring gear carrier to form a cross-press fit, by means of which the sleeve is firmly connected to the ring gear carrier. For example, the sleeve is shrunk onto the ring gear carrier and thereby firmly connected to the ring gear carrier. For example, the sleeve is formed from a first material, wherein, for example, the ring gear is formed from a second material. The second material may be the same material as the first material. Preferably, it is provided that the first material and the second material have the same modulus of elasticity and / or the same coefficient of thermal expansion. It is thus conceivable for the sleeve and the ring gear to be formed from the same steel.In particular when the ring gear carrier is formed from the mentioned fiber-reinforced plastic, the ring gear carrier is produced, for example, by injection molding, i.e. is formed from an injection molded polymer which is reinforced by means of reinforcing fibers, in particular by means of short reinforcing fibers, in particular in arbitrary and / or arbitrary direction, in particular in such a way that the reinforcing fibers are embedded in the polymer. The reinforcing fibers may comprise glass fibers and / or carbon fibers. In order to realize an advantageously rotationally fixed connection between the ring gear and the ring gear carrier, it is conceivable that an outer circumference of the ring gear facing outwards in particular in the radial direction of the electric machine and facing the ring gear carrier is microtoothed, i.e. provided with a microtoothing which has, for example, axially aligned microtoothings running in the axial direction, for example with a height of a few tenths of a millimeter running in the radial direction. Alternatively or additionally, for example, the outer circumference of the ring gear facing the ring gear carrier in the radial direction and the ring gear carrier form a press fit, by means of which the ring gear is firmly connected to the ring gear carrier, to the ring gear carrier, that relative rotations between ring gear and ring gear carrier as well as relative movements occurring in the axial direction between the ring gear and the ring gear carrier are prevented. For example, during the assembly of the electric drive device, the ring gear is fixedly connected to the ring gear carrier in such a way that the ring gear is pressed axially into the ring gear carrier. During the mounting of the ring gear on the ring gear carrier, for example, the microtoothings themselves intersect in the ring gear carrier, in particular in the fiber-reinforced plastic, in such a way that the microtoothing intersects micronotches in the ring gear carrier, in particular the fiber-reinforced plastic, as a result of which a positive fit is formed between the ring gear and the ring gear carrier, by means of which the ring gear carrier is connected particularly firmly to the ring gear.It is conceivable that the protrusion has a first wall thickness, also referred to as first wall thickness, in a first longitudinal region of the protrusion running in the axial direction, the first longitudinal region of which forms the ring gear carrier, wherein, for example, the protrusion has a second wall thickness, which is smaller than the first wall thickness and also referred to as second wall thickness, in a second longitudinal region extending in the axial direction, and wherein the second longitudinal region adjoins the ring gear carrier in the axial direction towards the axial end side of the stator. For example, the first longitudinal region and / or the second longitudinal region of the projection is tubular. On the one hand, an advantageous stiffness of the ring gear carrier can thus be realized. On the other hand, a particularly low weight of the output can be ensured overall. It is furthermore conceivable that the first longitudinal region of the wall thickness that is greater than the wall thickness of the second wall, in particular only during the assembly of the ring gear on the ring gear carrier, wherein, for example after the assembly of the ring gear on the ring gear carrier, the first longitudinal region is machined, in particular milled, in such a way that the wall thickness of the first longitudinal region is reduced, in particular in such a way that the finished state of the drive device of the first longitudinal region and the second longitudinal region have the same wall thickness.It is furthermore conceivable for the spline toothing of the protrusion to be arranged on an outer circumference of the protrusion that is drawn towards the housing in the radial direction, so that, for example, the second toothing is arranged on an inner circumference of the housing facing the first toothing in the radial direction.If the ring gear carrier formed, for example, from the fiber-reinforced plastic is arranged adjacent to a structural element of the drive device formed from a composite material, such as, for example, the stator, it is advantageous to form this structural element and the ring gear carrier or the protrusion from a single piece and, in the process, from fiber-reinforced plastic.At least the following advantages can be realized by the invention:particularly advantageous noise behavior of the drive device, in particular by utilizing the fiber-reinforced plastic, by means of which vibrations can be advantageously damped; the fiber-reinforced plastic can in particular prevent intrinsic vibrations of the ring gear induced by a tooth engagement of the ring gear from being transferred to the housing, in particular to the surfaces thereof;particularly high efficiency of the planetary gearing with little play due to the in particular radially flexible ring gear carrier, which enables an advantageous self-alignment of the ring gear via the planetary gears with which the ring gear meshes;Construction which is favourable in weight and advantageously a small number of parts of the drive device.Further findings on which the invention is based are that axial flux machines (AFM), in particular with a flat cylindrical central stator, the diameter of which is substantially greater than its axial thickness, and which is located between two disk-shaped parts which are particularly round axially through a central bore in the stator, can drive a motor vehicle particularly efficiently and effectively.The stator is usually fixedly connected to the housing, also referred to as motor housing, which contains, for example, the entire electric machine and possibly further components, in order to form the electric drive device, which can deliver the respective drive torque, also referred to as motor torque, in order to drive the motor vehicle. In this case, for example, a reaction torque of the stator, the reaction torque of which is equal in magnitude to the drive torque provided by the electric machine but opposite in terms of its effective directions, is absorbed by the housing. Usually, the reaction torque is introduced into the housing via a multi-screw flange connection between the stator and the housing, wherein the flange connection is located outside the rotor or overall rotor. In most applications, such as automotive engineering, aeronautical, marine, etc., it is advantageous from several points of view, such as overall effect burr, size, mass, etc., if the axial flow machine is running at an advantageously high rotational speed, which is, for example, greater by a factor of 5 to 8 inclusive than an output rotational speed of a drive element, which is, for example, embodied as the vehicle wheel or propeller, etc.The use of a coaxial planetary transmission, as formed for example by the planetary gear set, for enabling such a rotational part difference is advantageous.A particularly advantageous arrangement for such a transmission is a single-stage planetary transmission, such as in particular in the form of the planetary gear set, wherein for example the in particular central sun gear can be driven or is driven by the entire rotor.The planet gears, which are rotatably mounted on, in particular on, the common planet carrier, would come to an advantageously small diameter with the sun gear. In addition, the planetary gears with the in particular central ring gear would come to an advantageously large diameter, such as is larger than the advantageously small diameter. In order to achieve an advantageous transmission range, in particular in such a way that, as described above, the axial flow machine or the overall rotor rotates 5-8 times faster than the drive element, it is advantageous if the ring gear is connected, in particular permanently, in a rotationally fixed manner to the housing, wherein the planet carrier forms the output and thus a, for example, concentric output shaft of the planetary gear set. A reaction torque of the ring gear which is fixed relative to the housing and the reaction torque of which is equal to the output torque minus the drive torque is supported by the housing. A fixed and in this case in particular direct metallic fastening of the ring gear to the housing formed for example from light metal casting can lead to noise problems in that oscillations of the ring gear can be transmitted and amplified via surfaces of the housing to a surrounding area of the drive device.In addition, an epicyclic arrangement as described above is overdetermined due to numerous load paths through the plurality of planet gears. As a result, a load carried by each planet wheel does not correspond to the theoretical value of the transmitted torque divided by the number of planet wheels, also referred to simply as planets, through which it is passed, but is likely to be different for each planet due to unavoidable manufacturing tolerances. This implies the susceptibility to a higher torque load for each of the planet gears. The gearing should therefore be designed to be able to withstand a higher torque than theoretical, thereby losing to some extent the advantage of load distribution to the plurality of planetary meshes. Such over-determined designs are also prone to increased tooth flank friction or even jamming. It is conceivable and known to provide sufficient play of the toothing and / or sufficient play in bearings such as planetary gear bearings, for example, in order to avoid these disadvantages. It should be noted, however, that although increased tooth flank friction or even jamming can be successfully avoided, the non-uniform load distribution through the plurality of planetary gears can thereby only be reduced to a certain limited extent. This is to be taken into account in the dimensioning of planetary gear seats according to the prior art and leads, for example, to a greater tooth width than would be required for an ideal coordinated transmission with uniform torque distribution to the plurality of planets with the same safety factor for the same application.The invention makes it possible to avoid the above-mentioned disadvantages and those which are listed once again below:the non-uniform load distribution over the plurality of planet gears with their effects on the dimensioning of the planetary gear (planetary gear set);the above mentioned noise problems.In order to realize a construction that is advantageous in terms of installation space, it is advantageous for the planetary gear set, also referred to as a planetary gear set, to be designed such that an outer diameter of the ring gear is somewhat greater than an outer diameter of the rotors and lies clearly above an outer diameter of the stator.For example, it is conceivable that the stator encloses windings and cores of poles in a fiber-reinforced polymer housing, wherein for example the polymer housing is formed integrally with the projection. The reaction torque of the stator can be conducted into the housing via the polymer housing, for example. In view of a magnitude of magnetic forces between the stator and the rotors of the axial flux machine, rigid stator mounting of the stator to the housing is of great advantage.In order to avoid excessive noise problems, the protrusion forming in the ring gear carrier is provided, which protrusion is preferably formed from the fiber-reinforced plastic, also referred to as fiber-reinforced polymer, from which the ring gear carrier is formed. For example, a microtoothed connection is provided between the preferably metallic ring gear and the ring gear carrier preferably formed from the fiber-reinforced plastic. For this purpose, the ring gear, also referred to as a ring gear, has, for example, the aforementioned microtoothings, in particular as micro-wedges, in particular on its outer circumference facing the ring gear carrier in the radial direction. The respective micro-toothing has, for example, a height running in the radial direction and a width running in the circumferential direction of the electric machine of a few tenths of a millimeter each. For example, the microtoothings are arranged uniformly distributed in the circumferential direction of the electric machine. In the circumferential direction between the microtoothings, for example, in particular smooth, sections in particular of the outer circumference of the ring gear are provided, wherein for example these sections of the outer circumference of the ring gear form a respective press fit with an in particular smooth inner circumference of the ring gear carrier facing the outer circumference of the ring gear in the radial direction, whereby the ring gear is rotationally fixedly connected to the ring gear carrier and in particular in such a way that relative movements occurring in the axial direction between the ring gear and the ring gear carrier are prevented. A radial extension or extension of the ring gear carrier can be only a few millimeters, for example. The sleeve, which is designed, for example, as a steel sleeve and which is placed, for example, on the outer circumference of the ring gear carrier, can stabilize the ring gear carrier here and, in addition, stabilize the ring gear, in particular in the radial direction via the latter. Since, for example, the coefficient of thermal expansion of the ring gear is equal to the coefficient of thermal expansion of the sleeve, no problems occur during a thermal cycle, in particular as long as the limit operating temperature of one of the materials involved and, in the process, for example of the fiber-reinforced plastic is not exceeded.Even if, for example, the planetary gear set, also referred to as a planetary drive, is arranged as close as possible to or next to the axial flux machine, in particular in the axial direction of the electric machine, an axial extension of the one rotor and an unavoidable play between the one rotor and the planetary gear set can define a minimum axial distance between the stator, in particular its stator housing, around the ring gear. By utilizing this in particular unavoidable axial distance, in particular the axial length of the drive-in device can be advantageously kept short.The protrusion is, for example, a preferably thin-walled, axial and preferably tubular extension of the stator, in particular of the stator housing. The projection extends over the one rotor on the planetary gear set and thus on the transmission side and, for example, even further up to one end of an axial end face or end face of the planetary gear set, which face in particular faces away from the stator in the axial direction. The protrusion forming, for example, an in particular tubular extension is formed, for example, integrally with the stator housing and thus with the stator, so that it is conceivable for the stator, in particular the stator housing, and the protrusion to be formed from the same fiber-reinforced plastic. One purpose of the projection, which is designed, for example, as an axial tube extension, is to make possible a particularly favorable mounting of the ring gear. In order to achieve this, the ring gear is fixed, for example, by the aforementioned micro-toothing on, in particular in, the projection. In this case, the protrusion, which is designed, for example, as a polymeric ring gear bearing, cannot introduce the reaction torque of the ring gear radially into the housing, but rather has, for example, the mentioned air gap and thus a radial play with respect to the housing and transmits the reaction torque of the ring gear, optionally together with axial forces, over an axial distance between a planetary toothing system and the stator or the stator housing, wherein the axial forces result, for example, from a helical toothing system of the ring gear. The invention enables a particularly high reactive torque load of the stator housing, in particular its structure, since, in comparison with conventional solutions in which the stator-housing connection is loaded only by the motor drive torque, while the ring gear reaction torque and the axial force are introduced radially directly into the housing, the arrangement according to the invention disclosed here loads the stator-housing connection with the full drive torque of the drive device and with the axial ring gear force. In order to cope with this load of the in particular separable connection of the in particular fiber-reinforced protrusion to the in particular cast housing, which is formed for example from a light metal alloy, which is formed for example on an aluminum alloy, in particular an aluminum casting alloy, or a magnesium alloy, in particular magnesium casting alloy, a Hirth toothing is used for example as the plug toothing, in order to realize here by means of an in particular axial form fit between the protrusion and the housing. A radial extension of the spline toothing, in particular of the Hirth toothing, can extend from just above an outer diameter of the rotor up to the height of the outer diameter of the stator. As a result, the radial overall dimensions of the stator remain unaffected, and the segmentation of the spline (toothed segments alternate with smooth sectors again and again) offers a required space for a plurality of clamping screws for axially securing the spline within the same inner and outer diameters. Advantageously, these screws are designed as waisted shaft screws. This also allows stiffening and increased flatness of the stator assembly in the housing to be achieved. Similar to a radial dimension, an axial dimension of the stator-housing connection as well as the total mass also remain unaffected by the described embodiment.In addition to the stationary, torque-loaded connections between metallic and non-metallic components, which connections are possibly provided above, the likewise torque-loaded axial extension of the projection of the stator, in particular of the stator housing, which projection is configured, for example, as a tubular extension, can be taken into consideration, wherein, for example, the projection can receive the ring gear at its axial end facing away from the axial end face of the stator. The torque load received by the protrusion may correspond to the reaction torque of the sun gear. The axial load transmitted by the projection corresponds to the axial tooth force of the helical tooth system of the ring gear. Due to the large outer diameter of the projection typical for axial flow machines, the reaction torque-induced shear stresses are very low. The same applies to the tensile or compressive stresses induced by the axial force of the ring gear, so that the resulting Von Mises stress ends further below the load-bearing capacity of the protrusion. Therefore, the projection, which is formed for example as a tubular extension, can be thin-walled. This achieves sufficient torsional rigidity and at the same time adequate radial flexibility, which is particularly advantageous. By means of finite element analysis (FEA), this radial flexibility can be optimized by taking into account, for example, a multiplicity of tangential, axial or 45°-inclined slots, in particular of the protrusion, in order to further increase a radial flexibility of the protrusion, in particular up to a customized, favorable amount, without impairing a sufficient axial rigidity of the protrusion.Theoretically, the radial forces of the meshings between the plurality of planet gears and the sun gear cancel each other out. In practice, this will not be the case in every position of the ring gear due to unavoidable tolerances such as, for example, tooth system errors of rotating parts and will lead to the above-described unequal load distribution between the plurality of planetary gears. By having the protrusion of the stator, in particular of the stator housing, have an advantageous radial flexibility and enable the ring gear to self-align with the planetary gears with which it meshes. This self-alignment tends autonomously to reach the equilibrium position of the acting forces, which is given when the load is distributed evenly on all planets. This self-alignment occurs because the equilibrium position mentioned coincides with the position of the minimum energy, whereby an equal or at least substantially more uniform load distribution is achieved over the plurality of planet gears, whereby overload situations of one of the divided torque paths are avoided. The maximum remanent magnitude of the non-uniform planetary gear load is determined by the tailored radial stiffness of the ring gear carrier or the projection. Advantageous results are obtained with planetary gear sets having three equi-spaced planets with synchronous engagement, since such a construction enables stable self-alignment comparable to the stability of a tripod. The projection of the stator, in particular stator housing, which projection is loaded by the reaction torque, is configured for example as a tubular extension, wherein the projection is not rigidly radially supported over a suitable axial length and the ring gear in particular receives at the end of the projection opposite the axial end face of the stator and preferably provides a customized radial flexibility for the ring gear for self-alignment is particularly advantageous, whereby in particular an advantageous noise behavior of the drive device can be realized.The extent of the radial self-alignment of the ring gear over the planetary meshes will be on the order of the position and gear tolerances of precision gear parts, i.e., on the order of a low to medium two digit number of micrometers. The maximum frequency of self-alignment corresponds to the output speed of the driving means. The frequency of self-alignment is typically below 25 hertz in automotive applications, for example, and reaches a maximum of 50 hertz in high speed highway drives.Since, preferably in the invention, there is no rigid metallic contact between the ring gear and the housing, an advantageous noise behavior of the drive device can be realized.Due to the self-alignment capability of the ring gear, the play and / or the bearing play does not have to be increased beyond a favorable minimum value, which improves the driving comfort by reducing the overall gear play.Further advantages, features and details of the invention will become apparent from the following description of a preferred exemplary embodiment and with reference to the drawing. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and / or shown alone in the single figure can be used not only in the respectively specified combination but also in other combinations or alone without departing from the scope of the invention.The single FIG. shows a schematic longitudinal sectional view of a portion of an electric drive device for a motor vehicle.The single FIG. shows a detail in a schematic longitudinal sectional view of an electric drive device 10 for a motor vehicle, which is also referred to simply as a vehicle. This means that the motor vehicle, which is preferably designed as a motor vehicle, in particular as a passenger vehicle, has the electric drive device 10 in its completely produced state and can be electrically driven, in particular purely, by means of the electric drive device 10. For this purpose, the electric drive device 10 has at least one electric machine 12, which is designed as an axial flow machine (AFM). The electric machine 12 has two rotors, also referred to as rotor elements, namely a first rotor 14 and a second rotor 16. The rotors 14 and 16 are connected to one another in a rotationally fixed manner, for example, in particular permanently. The electric machine 12 also has a stator 18, which is arranged at least partially between the rotors 14 and 16 in the axial direction of the electric machine 12, the radial direction of which runs perpendicular to the axial direction of the electric machine 12. The rotors 14 and 16 are, for example, part of an overall rotor 20 of the electric machine 12, which can provide drive torques for driving the motor vehicle via its overall rotor 20. The axial direction of the electric machine 12 and thus of the drive device 10 as a whole is illustrated in the figure by a double arrow 22, and the radial direction of the electric machine 12 and thus of the drive device 10 as a whole is illustrated by a double arrow 24.The drive device 10 also has a planetary gear set 26, also referred to as a planetary gear set or planetary gear set, which comprises a ring gear 28. Furthermore, the planetary gear set 26 has a sun wheel, which cannot be seen in the figure, and a planetary carrier, which cannot be seen in the figure. Furthermore, the planetary gear set 26 comprises planetary gears, which are also referred to as planets. Of the planetary gears of the planetary gear set 26, a partial planetary gear designated by 30 can be seen in the figure. The respective planetary gear 30 meshes, simultaneously, with the sun gear and with the ring gear 28, wherein a meshing of the sun gear with the ring gear 28 is omitted.The drive device 10 also has a housing 32, in which the planetary gear set 26 is arranged. For example, the housing 32 is designed as a die-casting component and is thus produced by die-casting.The sun gear and planet carrier are rotatable about a planetary gear set rotational axis relative to the housing 32. The electric machine 12, the entire rotor 20 of which is rotatable about an engine rotational axis relative to the housing 32, can provide the aforementioned drive torques via its entire rotor 20 for driving the motor vehicle, which can be driven by the entire rotor 20 via the planetary gear set 26 and thus by means of the electric machine 12. In this case, for example, the sun wheel is connected or connectable to the overall rotor 20 in a torque-transmitting, in particular rotationally fixed manner. In particular, it is conceivable for the sun gear to be connected to the overall rotor 20 in a permanently transmitting torque, in particular permanently rotationally fixedly. The sun gear is an input of the planetary gear set 26, also referred to as a drive, via the input of which the respective drive torque provided or provided by the overall rotor 20 can be introduced into the planetary gear set 26. The ring gear 28 is permanently connected to the housing 32 in a rotationally fixed manner. The planet carrier of the planetary gear set 26 is an output of the planetary gear set 26, also referred to as output, via the output of which a respective output torque resulting from the respective drive torque introduced into the planetary gear set 26 via the input thereof can be discharged from the planetary gear set 26, and can therefore be provided by the planetary gear set 26, wherein the motor vehicle can be driven by means of the respective output torque.In order to be able to realize a particularly advantageous noise behavior of the drive device 10, the stator 18, in particular its stator housing 34, has a partial region TB which projects outwards the rotors 14 and 16 in the radial direction of the electric machine 12 and thus projects outwards from the rotors 14 and 16 in the radial direction of the electric machine 12. A protrusion 36 is provided on the partial region TB, which protrusion is formed integrally with the stator housing 34 and thus with the stator 18 in the exemplary embodiment shown in the figure. That is, the stator housing 34 and the projection 36, that is, the stator 18 and the projection 36 are formed of a single piece. In the exemplary embodiment shown in the figure, the protrusion 36 and thus the stator housing 34 are formed from a fiber-reinforced plastic.As can be seen from the FIG., the protrusion 36 extends from an axial end face 38 of the stator 18, in particular of the stator housing 34, which faces the planetary gear set 26 in the axial direction of the electric machine 12 in such a way that the protrusion 36 extends away from the axial end face 38 in the axial direction of the electric machine 12 and extends beyond the rotor 16, as a result of which the rotor 16, which is arranged between the planetary gear set 26 and the stator 18, that is to say the stator housing 34 and in the present case the axial end face 38, is overlapped in the radial direction of the electric machine 12 outwards by the protrusion 36, in particular completely. In the present case, the protrusion 36 surrounds the rotor 16 in the circumferential direction of the electric machine 12 running around the axial direction of the electric machine 12, in particular in a completely circumferential manner. The overall rotor 20 can be driven by means of the stator 18 and can thereby be rotated about a machine rotational axis relative to the stator 18. For example, the planetary gear set rotational axis coincides with the engine rotational axis, so that the electric machine 12 is arranged coaxially with the planetary gear set 26.The protrusion 36 which is formed in one piece per se, that is to say formed from a single piece and which is formed in the present case in one piece with the stator housing 34, forms a ring gear carrier 40, to which the ring gear 28 which is formed separately from the ring gear carrier 40 and thus separately from the protrusion 36 is connected in a rotationally fixed manner, in particular permanently. Furthermore, the protrusion 36 is connected, in particular permanently, rotationally fixedly to the housing 32, such that the ring gear 28 is connected permanently rotationally fixedly to the housing 32 by means of the ring gear carrier 40. Furthermore, the projection 36 has a spline 42 as a first toothing which engages in a corresponding second toothing 44 of the housing 32. In this case, the second toothing 44 is preferably designed as a second spline toothing. It can be seen that the spline 42 is arranged on an axial end face 46 of the projection 36 facing the toothing 44 in the axial direction of the electric machine 12, wherein teeth of the spline 42 extend away from the axial end face 46 in the axial direction of the electric machine 12. One of the teeth of the spline 42 is visible in the figure and is denoted 48. The second toothing 44 is arranged on an axial end face 50 of the housing 32 facing the axial end face 46 of the protrusion 36 in the axial direction of the electric machine 12, wherein teeth of the toothing 44 project from the axial end face 50 of the housing 32 towards the axial end face 46 in the axial direction of the electric machine 12. One of the teeth of the toothing 44 can be seen in the figure and is denoted by 52.An outer circumference of the ring gear 28 facing outwards in the radial direction of the electric machine 12 and facing the ring gear carrier 40 in the radial direction of the electric machine 12 is denoted by 54 in the figure. An inner circumference of the ring gear carrier 40 facing inward in the radial direction of the electric machine 12 and facing the outer circumference 54 in the radial direction of the electric machine 12 is denoted by 56, the outer circumference 54 facing the inner circumference 56 in the radial direction of the electric machine 12. For example, the ring gear 28 has on its outer periphery 54 a toothing which is in particular designed as a microtoothing and is also referred to as a connecting toothing. For example, the ring gear carrier 40 and the ring gear 28 are connected to one another in a rotationally fixed manner in such a way that the ring gear 48 is pressed into the ring gear carrier 40 or the ring gear carrier 40 is pressed onto the ring gear 28. When the ring gear 28 is pressed into the ring gear carrier 40 or when the ring gear carrier 40 is pressed onto the ring gear 28, teeth of the connecting toothing of the ring gear 28 itself intersect, that is to say independently into the ring gear carrier 40, in particular into the fiber-reinforced plastic and very particularly into the plastic matrix thereof, as a result of which a positive connection is formed between the ring gear 28 and the ring gear carrier 40, in particular between the outer circumference 54 and the inner circumference 56. Thus, the ring gear 28 and the ring gear carrier 40 are connected to each other in a rotationally fixed manner in a positive-locking manner. In particular, the ring gear 28 and the ring gear carrier 40 are connected to one another in such a way that both relative rotations between the ring gear 28 and the ring gear carrier 40 and relative movements between the ring gear 28 and the ring gear carrier 40 occurring in the axial direction of the electric machine 12 are prevented. In addition, because the spline 42 engages in the toothing 44, the protrusion 36 is connected to the housing 32 in a rotationally fixed manner in a positive-locking manner.For example, the spline 42 is designed as segmented toothing, wherein it is preferably provided that, in particular also, the toothing 44 is designed as segmented toothing. This means that first partial regions of the axial end face 46 are arranged in the circumferential direction between the teeth of the spline 42. The first partial regions of the axial end face 46 are also referred to as first intermediate segments. The first partial regions of the axial end face 46 are first wall regions of the protrusion 36. This means, for example, that the first partial regions of the axial end face 46 extend in a plane which runs perpendicular to the axial direction of the electric machine 12. Accordingly, for example, second partial regions of the axial end face 50 are arranged between the teeth of the toothing 44 in the circumferential direction of the electric machine 12, the second partial regions of which partial regions are also referred to as second intermediate segments. Thus, the second partial regions of the axial end face 50 are second wall regions of the housing 32. This means that, for example, the second partial regions of the axial end face 50 extend in a second plane which runs perpendicular to the axial direction of the electric machine 12. For example, the first partial regions are separated from the second partial regions in the axial direction by an air gap, for example.The respective first partial region of the axial end face 46 is assigned exactly one respective one of the second partial regions of the axial end face 50, wherein the respective first partial region and the respective second partial region assigned to the respective first partial region form a respective partial region pair. For example, at least or exactly one screw 58 is assigned to the respective partial region pair, which screw penetrates the respective partial regions of the respective partial region pair. The spline 42 is clamped against the toothing 44 in the axial direction of the electric machine 12 by means of the screws 58, wherein it is provided in the present case, for example, that the first partial regions are clamped against the second partial regions in the axial direction by means of the screws 58. For example, the spline 42 and / or the toothing 44 is designed as a hirt toothing. For example, the ring gear 28 is formed from a metallic material of value, in particular from a steel.The drive device 10 has a sleeve 60 which is formed separately from the ring gear 28 and separately from the ring gear carrier 40 and thus separately from the projection 36 and is formed, for example, from the same metallic material, in particular from the same steel, from which the ring gear 28 is also formed. An outer circumference of the ring gear carrier 40 facing outwards in the radial direction of the electric machine 12 and facing away from the outer circumference 54 in the radial direction of the electric machine 12, and facing away from the inner circumference 56 and from the ring gear 28 and facing the sleeve 60 in the radial direction of the electric machine 12 is denoted by 62 in the figure. The sleeve 60 is arranged on the outer periphery 62 in such a way that the sleeve 60 directly contacts the outer periphery 62 and thus the ring gear carrier 40. With respect to the ring gear carrier 40 and the ring gear 28, the sleeve 60 is positioned in the axial direction of the electric machine 12 in such a way that at least one respective length region of the ring gear carrier 40 and of the ring gear 28 running in the axial direction of the electric machine 12 is overlapped by the sleeve 60 outwards in the radial direction of the electric machine 12. In the present case, the ring gear 28 and the ring gear carrier 40 are overlapped by the sleeve 60 outwards in the radial direction of the electric machine 12 over more than half of their respective length running in the axial direction of the electric machine 12, in particular over their respective entire length running in the axial direction of the electric machine 12, whereby an advantageous connection of the ring gear 28 to the ring gear carrier 40 can be ensured.Furthermore, in the drive device 10, it is provided that an air gap L is arranged between the housing 32 and the ring gear carrier 40 in the radial direction of the electric machine 12 and between the sleeve 60 and the housing 32 in the present case in the radial direction of the electric machine 12, which air gap is bounded in the outward radial direction of the electric machine 12 directly by the housing 32 and in the inward radial direction of the electric machine 12 directly by the sleeve 60. The air gap L extends in the circumferential direction of the electric machine 12 running around the machine rotation axis and thus around the axial direction of the electric machine 12 completely circumferentially around the sleeve 60 and around the ring gear carrier 40. In the present case, the air gap L extends over more than half of the respective length of the ring gear carrier 40, of the ring gear 28 and of the sleeve 60 running in the axial direction of the electric machine 12, In the present case, it is provided that the air gap L extends in the axial direction of the electric machine 12 over the respective entire length of the ring gear 28, of the ring gear carrier 40 and of the sleeve 60 running in the axial direction of the electric machine 12.The protrusion 36 has a free axial end E, which is opposite the axial end face 38 of the stator 18, that is to say of the stator housing 34, in the axial direction of the electric machine 12. The protrusion 36 and the ring gear carrier 40 terminate at the end E in the axial direction of the electric machine 12, wherein the end E is completely spaced apart from the housing 32 both in the radial direction and in the axial direction of the electric machine 12.

Claims

Electric drive device (10) for a motor vehicle, having at least one electric machine (12) for driving the motor vehicle, having a planetary gear set (26), via which the motor vehicle can be driven by the electric machine (12), and having a housing (32), in which the planetary gear set (26) is arranged, wherein: - the electric machine (12) is designed as an axial flux machine, which has two rotors (14, 16) and a stator (18), which is arranged in the axial direction (22) of the electric machine (12) between the rotors (14, 16) rotatable relative to the stator (18); - the stator (18) has a subregion (TB), which projects outwards beyond the rotors (14, 16) in the radial direction (24) of the electric machine (12) and on which a protrusion (36) is provided, which: o extends in the axial direction (22) of the electric machine (12) beyond one of the rotors (14, 16), o overlaps the one rotor (16) arranged in the axial direction (22) of the electric machine (12) between the planetary gear set (26) and the stator (18) outwards in the radial direction (24) of the electric machine (12), o forms a ring gear carrier (40) to which the ring gear (28) formed separately from the ring gear carrier (40) is connected in a rotationally fixed manner, and o has a spline toothing (42) as first toothing which engages in a corresponding second toothing (44) of the housing (32), and wherein o the stator (18) is formed integrally with the projection (36).Electric drive device (10) according to Claim 1, characterized in that the ring gear carrier (40) is formed from a fibre-reinforced plastic.Electric drive device (10) according to one of the preceding claims, characterized in that the spline toothing (42) is designed as a segmented toothingElectric drive device (10) according to one of the preceding claims, characterized in that the spline toothing (42) is designed as a Hirth toothing.Electric drive device (10) according to one of the preceding claims, characterized in that screws (58) are arranged between teeth (48) of the spline (42) in the circumferential direction of the electric machine (12), by means of which screws the spline (42) is tensioned against the second spline (44) in the axial direction (22) of the electric machine (12).Electric drive device (10) according to one of the preceding claims, characterized in that the ring gear (28) is connected to the ring gear carrier (40) in a rotationally fixed manner via a further spline toothing.Electric drive device (10) according to one of the preceding claims, characterized bya sleeve (60) which is formed separately from the ring gear (28) and separately from the ring gear carrier (40) and is arranged on an outer circumference (62) of the ring gear carrier (40) facing away from the ring gear (28) in the radial direction (24) of the electric machine (12) and is fixedly connected to the ring gear carrier (40) and by means of which sleeve at least one respective length region of the ring gear carrier (40) and of the ring gear (28) running in the axial direction (22) of the electric machine (12) is overlapped outwards in the radial direction (24) of the electric machine (12).Electric drive device (10) according to Claim 7, characterized in that the sleeve (60) is formed from a steel.Electric drive device (10) according to one of the preceding claims, characterized in that an air gap (L) is provided between the housing (32) and the ring gear carrier (40) in the radial direction (24) of the electric machine (12), said air gap extending completely circumferentially around the ring gear carrier (40) in the circumferential direction of the electric machine (12).

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