Electric drive device for a motor vehicle

Abstract

Electric drive device (1) for a motor vehicle, comprising an electric machine (2) having a rotor (3), a planetary gear stage (13) having a sun gear (11), a planet carrier (8) with planet gears (10) and a ring gear (12), a switchable freewheel clutch (20) having a first clutch half (21), a second clutch half (23), a switching device (25) and an actuator (26), wherein the first clutch half (21) is rotationally fixed to a housing (5), characterized by an axial guide ring (15) which is designed to support the ring gear (12) in both axial directions (a), wherein the ring gear (12) is designed free of a rolling bearing directly supporting it, wherein the axial guide ring (15) is arranged radially inside and axially overlapping the freewheel clutch (20).

Description

[0001] The invention relates to an electric drive device for a motor vehicle according to the type defined in the preamble of claim 1.

[0002] DE 10 2019 114 139 B3 describes a prior art in the form of a motor vehicle transmission for coupling an electric motor to a drive train. A planetary gear stage comprising a sun gear, a planet carrier with planet gears, and a ring gear is provided between the electric motor and the drive train. Furthermore, a switchable freewheel is arranged in the vehicle transmission, which, via two coupling halves, is capable of switchably coupling the sun gear to a reference component, in particular a stationary housing, in such a way that the sun gear can optionally be freewheeled and / or locked relative to the housing. The features mentioned here with regard to DE 10 2019 114 139 B3 are also shown in the generic document US 2012 / 0 149 520 A1, which additionally shows an axial guide for the ring gear. An annular axial guide is known, in itself, from US 4 428 689 A. An electric drive device with a rotor arranged coaxially to a planetary gear stage and with a plate unit arranged axially on a side of the planetary gear stage facing away from the rotor is known from DE 10 2015 110 565 A1.

[0003] The object of the present invention is to provide an electric drive device for a motor vehicle that further improves the aforementioned prior art design by simplifying the structure, thereby saving installation space, components, and costs. The performance and durability of the electric drive device should not be compromised.

[0004] According to the invention, this object is achieved by an electric drive device for a motor vehicle having the features in claim 1, and in particular in the characterizing part of claim 1. Advantageous embodiments and further developments of the electric drive device according to the invention emerge from the subclaims dependent on this claim 1.

[0005] The invention is based on an electric drive device for a motor vehicle, which has an electric machine, wherein the electric machine in turn has a rotor. The electric drive device further comprises a planetary gear stage with a sun gear, a planet carrier with associated planet gears, and a ring gear. Furthermore, the electric drive device comprises a switchable one-way clutch, which has a first clutch half, a second clutch half, a switching element, and an actuator, wherein the first clutch half is connected to a housing in a rotationally fixed manner.

[0006] The inventive design of the electric drive device for a motor vehicle provides that the ring gear is designed without its own rolling bearing directly supporting the ring gear and is supported in both axial directions solely by an axial guide ring. The inventors take advantage of the fact that when two shafts of a planetary gear are radially mounted, the third shaft does not need to be radially mounted. The term "radial" always refers to a central axis of rotation of the sun gear, or the planet carrier, or the ring gear of the planetary gear (here the planetary gear ratio). A rolling bearing for the ring gear, which represents the component with the relatively largest diameter of the planetary gear ratio, can therefore be dispensed with. This saves costs, installation space, and weight of a relatively large rolling bearing.The axial guide ring for axial support of the ring gear brings advantages in terms of function and longevity of the planetary gear stage.

[0007] The feature that the ring gear is designed without its own rolling bearing directly supporting the ring gear means that the ring gear is at most indirectly supported by rolling bearings. Indirect mounting of the ring gear by means of a rolling bearing is therefore possible. By indirect mounting, we mean that the ring gear is not directly supported by rolling bearings, but rather a gear element arranged between the ring gear and a corresponding rolling bearing can be directly supported by rolling bearings. The gear element mentioned here, which is arranged between the ring gear and the rolling bearing, means a gear element that is not rotationally fixedly connected to the ring gear, so that differential speeds can occur between the mentioned gear element and the ring gear.For example, the ring gear can be mounted indirectly relative to the housing in that the planet carrier is mounted directly opposite the housing, but the ring gear is supported relative to the planet carrier (via intermediate planet gears) without an intermediate rolling bearing.

[0008] The ring gear itself is centered via the shafts of the two other elements of the planetary gear stage, i.e., the planetary gear carrier and the sun gear. The axial guide ring of the invention then serves only to prevent the ring gear from significantly shifting axially. Since, in the present design of the planetary gear stage, no significant axial forces act on the ring gear itself—it is centered via the other elements when not engaged and is fixed relative to the housing when engaged—a very simple axial guide via the axial guide ring is sufficient, which does not require high demands in terms of mechanical stability or frictional properties.

[0009] With regard to an indirect rolling bearing of the ring gear, for example, the rotor shaft of the electric machine is mounted on a rolling bearing directly opposite the housing and supports the sun gear, thus the sun gear is also mounted accordingly. The next element would then be the planet carrier, which, as described above, is also mounted directly opposite the housing on a rolling bearing. This design could, of course, be reversed, so that the sun gear would be mounted independently directly opposite the housing on a rolling bearing, and the planet carrier would be mounted indirectly opposite the housing via the rotor shaft.In both cases, the ring gear is indirectly supported on the housing through the interaction with the planetary gears located on the planetary gear carrier and the sun via this bearing of the sun gear on the one hand and the planetary gear carrier on the other hand and thus does not necessarily require its own direct rolling bearing opposite the housing, provided that the axial guide ring according to the invention is present.

[0010] The switchable overrunning clutch can interrupt the torque transmission between the rotor and an output of the electric drive device, so that the output can actually rotate with almost no loss relative to the rotor and drag losses can be avoided, e.g. in a situation in which the vehicle is actively driven exclusively by at least one other axle.

[0011] Furthermore, according to the invention, it is provided that the axial guide ring is arranged radially inside and axially overlapping the one-way clutch.

[0012] "Radially within" again refers to the central axis of rotation of the planetary gear stage and indicates that the axial guide ring is located in an area with smaller radii than the switchable overrunning clutch. "Axially overlapping," also referring to the same axis, indicates that the two axially overlapping components in question are arranged at least partially in an area of ​​the same axial coordinates in the axial direction of the planetary gear stage's axis of rotation.

[0013] According to an exceptionally advantageous development of the electric drive device according to the invention, it can now further be provided that the axial guide ring has a U-shaped cross-sectional contour. The axial guide ring can thus, for example, axially guide the ring gear itself or a disk connected to the ring gear, for example in the form of or as a section of a disk unit, and thus prevent the ring gear from axial displacement.

[0014] Advantageously, the axial guide ring is axially fixed and rotationally fixed to the housing, so that the ring gear is advantageously axially secured directly relative to the housing by means of the axial guide ring.

[0015] Throughout this disclosure, the terms "rotatably fixed" and "axially fixed" mean the following: Two rotatably mounted elements are non-rotatably connected to one another if they are arranged coaxially to one another and connected to one another in such a way that they rotate at the same angular velocity. An element is non-rotatably connected to the housing if it cannot be rotated relative to the housing. An element is axially fixed to another element if one element cannot be axially displaced relative to the other element with respect to the rotational axis of the planetary gear stage.

[0016] A further highly advantageous embodiment of the electric drive device according to the invention can further provide that the second clutch half of the switchable overrunning clutch is connected in a rotationally fixed manner to the ring gear, wherein a connecting element connected in a rotationally fixed manner to the ring gear and in a rotationally fixed manner to the second clutch half is arranged radially between a sun gear toothing of the sun gear and a ring gear toothing of the ring gear with respect to a rotational axis of the planetary gear stage. The switchable overrunning clutch between the ring gear and the housing is arranged in a very advantageous structural manner and enables an easy-to-assemble and very compact design of the electric drive device.

[0017] The arrangement of the connecting element in its radial position between the sun gear toothing and the ring gear toothing and thus the connection of the ring gear to the second coupling half radially inwards ensures a very compact design of the electric drive device in the radial direction.

[0018] According to a very advantageous development of the electric drive device according to the invention, the connecting element can have a cylinder section arranged coaxially to the axis of rotation of the planetary transmission stage.

[0019] Advantageously, the connecting element further comprises a plate unit that is non-rotatably connected to the cylinder section, wherein the plate unit is also non-rotatably connected to the ring gear. Advantageously, with regard to a torque flow emanating from the ring gear and extending to the second clutch half, the ring gear, the plate unit, and the cylinder section are arranged one after the other in the specified order.

[0020] Preferably, the rotor of the electric machine can be arranged coaxially with the planetary gear stage, and the plate unit can be arranged axially on a side of the planetary gear stage facing away from the rotor. The cylinder section is particularly advantageously located axially on a side of the plate unit facing away from the planetary gear stage, so that the rotor, the planetary gear stage, the plate unit, and the cylinder section follow one another in the axial direction in the specified order.

[0021] A further very advantageous embodiment can further provide for the connecting element to have a guide section designed to interact with the axial guide ring. Such a guide section of the connecting element can be used to axially guide the ring gear via the axial guide ring in the manner described above.

[0022] The guide section is preferably arranged radially within the cylinder section and axially overlapping the cylinder section. The guide section is connected in a rotationally fixed manner to the plate unit and in a rotationally fixed manner to the cylinder section.

[0023] In the preferred embodiment, in which the axial guide ring is arranged radially inside and axially overlapping the overrunning clutch, the guide section of the plate unit is therefore provided in this area, preferably as a guide section with two sides that are plane-parallel in the axial direction and that interact accordingly in a guide ring that is open radially outwards and has plane-parallel legs and has a U-shaped cross-sectional contour.

[0024] A further very advantageous embodiment of the electric drive device with such a cylinder section can further provide that it is arranged radially in relation to the axis of rotation in a region of the planet gear pins of the transmission stage that carry the planet carriers. The cylinder section is therefore located radially at the level of the planet gear pins of the planet carrier, on which the planet gears are correspondingly arranged. This ensures a compact design, in which the cylinder section is nested radially within the switchable one-way clutch and in which, particularly preferably, the axial guide ring and a corresponding guide section of the plate unit are again arranged axially within this cylinder section and overlap it. This enables a very compact design.

[0025] The switchable one-way clutch advantageously has a first one-way device which is designed to connect the ring gear to the housing in a rotationally fixed manner when the rotor is operated in a forward pull mode and which is designed to decouple the ring gear from the housing when the rotor is operated in a forward push mode.

[0026] The switchable one-way clutch advantageously has a second one-way clutch device designed to connect the ring gear to the housing in a rotationally fixed manner when the rotor is operated in a forward push mode or a reverse pull mode. By means of the second one-way clutch device, recuperative operation of the electric motor can be realized during forward operation of the associated motor vehicle, and driving operation of the electric motor can be realized during reverse operation of the motor vehicle.

[0027] Advantageously, the switchable one-way clutch has a switching device configured to deactivate and activate the first one-way device and / or the second one-way device. When the one-way device is deactivated, the respective one-way device cannot establish a rotationally fixed connection between the ring gear and the housing.

[0028] Particularly advantageously, the switchable one-way clutch comprises the first one-way device and the second one-way device as well as the switching device, wherein the switching device is specifically designed to activate and deactivate the second one-way device. In this embodiment, forward push operation can take place via the first one-way device. Furthermore, if desired, recuperative operation of the electric machine during forward operation of the motor vehicle can take place via the second one-way device, namely when the second one-way device is activated by means of the switching device. Likewise, reverse pull operation of the motor vehicle can be realized when the second one-way device is activated by means of the switching device.When the second freewheel device is deactivated by means of the switching device, the ring gear can be separated from the housing during forward thrust operation of the motor vehicle, so that sailing operation of the motor vehicle in the forward direction can be realized, for example when the rotor is stationary.

[0029] The actuator is advantageously designed to actuate the switching device. The actuator is, for example, a hydraulic actuator, such as a hydraulic cylinder, or an electromechanical actuator, such as a servomotor.

[0030] According to a particularly advantageous embodiment of the electric drive device according to the invention for a motor vehicle, the switchable one-way clutch can have a switching disc, wherein the actuator is designed to move this in a rotational manner. The switching disc is then part of the switching device. The switchable one-way clutch can be designed, in particular, in the manner described in the aforementioned prior art of DE 10 2019 114 139 B3.

[0031] The design of the shift disc can preferably be configured so that only one of the directions is switchable, namely the pull-reverse direction, which is equivalent to the push-forward direction. This then enables both reverse driving and forward recuperation. Switchability for the pull-forward direction, which is equivalent to the push-reverse direction, is not necessarily required. While this would allow the wheel to be disconnected from the output when reversing at high speed, i.e., during reverse push operation, this is not required in practice, so the design can be simplified accordingly.

[0032] A further very advantageous embodiment of the electric drive device can further provide for the actuator of the switchable overrunning clutch to be arranged in the housing or on the housing. Such an actuator arranged in or on the housing is easily accessible should maintenance or the like become necessary. According to a very advantageous development, the actuator can be arranged, in particular, radially outside the clutch halves and axially overlapping at least one of the clutch halves. This again saves installation space in the axial direction, and the radially outer actuator enables simple actuation of the switching disc, which is easy to maintain if necessary.

[0033] Further advantageous embodiments of the electric drive device according to the invention also emerge from the exemplary embodiment which is illustrated in more detail below with reference to the figure.

[0034] The only attached figure shows a schematic sectional view through a part of an electric drive device relevant to the invention.

[0035] In the presentation of the Fig. 1 shows a section of an electric drive device 1. The section is shown above the axis of rotation A, which also defines the axial direction a and the radial direction r. A rotor 3 of an electric machine 2 rotates about this axis of rotation A. In the exemplary embodiment shown here, the electric machine 2 is designed as an axial flux machine. The rotor 3, of which only the half located to the right in the electric machine 2 or to the right of a stator 30 is shown here, is mounted relative to a housing 5 via a rolling bearing 6. It is connected in a rotationally fixed manner to a rotor shaft 4, which is designed in several parts. It is mounted indirectly via the rolling bearing 6 of the rotor 3, which is designed as an angular contact ball bearing, and is further supported on the housing via a needle bearing 28.

[0036] On the side of the electric machine 2 facing away in the axial direction a, an output 7 to a wheel of the motor vehicle is shown. This output 7 is connected via the output shaft 18 by means of a spline toothing designated 19 in a rotationally fixed manner to a planetary gear carrier 8 as the output element of a planetary gear stage 13.

[0037] In the particularly advantageous embodiment shown here, the electric drive device 1 is designed such that the electric motor 2 drives only a single wheel of the motor vehicle. A complete electrically driven axle of the motor vehicle thus advantageously contains two electric drive devices 1 according to the invention.

[0038] The planet carrier 8 has planet gear pins 9 that project axially toward the electric machine 2. Planet gears 10, one of which can be seen here, are mounted on these planet gear pins 9 via a planet gear bearing device 33, which here is designed in the form of two angular contact ball bearings 33.1 and 33.2. A sun gear 11, which here is advantageously formed by a toothing of the rotor shaft 4, meshes radially inward with the planet gears 10. In addition to the sun gear 11 and the planet carrier 10, the planetary gear ratio stage 13 has a ring gear 12. The planetary gear ratio stage 13 is designed to convert the torque between the rotor 3 and the output 7.

[0039] The ring gear 12 dispenses with its own direct rolling bearing relative to the housing or other components and instead is supported indirectly on the housing 5 via the angular contact ball bearings 33.1 and 33.2 of the planet gears 10 and via bearings 14.1 and 14.2 of the planet gear carrier 8. The planet gear carrier 8 is mounted directly opposite the housing by means of the bearings 14.1 and 14.2.

[0040] To ensure that the ring gear 12 cannot perform any significant movements in the axial direction a, in the exemplary embodiment shown here, an axial guide ring 15 is provided on the housing 5. This axial guide ring has a U-shaped contour in cross-section, so that two legs protrude radially outwards and the U-shaped contour is open radially on the outside. The axial guide ring 15 is axially and rotationally fixedly connected to the housing 5 and is arranged coaxially to the axis of rotation A. A guide section 16, which is designed as a disc-shaped extension of a connecting element 24, protrudes into the U-shaped contour of the axial guide ring 15, which does not represent a rolling bearing but merely a support for the guide, since a high-quality axial bearing is not necessary here. The connecting element 24 is rotationally fixedly connected to the ring gear 12 and accordingly rotates at the same angular velocity as the ring gear 12.

[0041] The electric drive device 1 in the illustration of the Fig. 1 also includes a switchable one-way clutch 20 with a first clutch half 21 and a second clutch half 22. The first clutch half 21 is designed as a ring and is non-rotatably connected to the housing 5 via a freewheel carrier 23. The second clutch half 22 is designed as an annular disc with internal teeth, which sits on a connecting element 24 and is non-rotatably connected to it by the teeth. The connecting element 24 has a cylindrical section 27, which is non-rotatably connected to the plate unit 17, whereby the second clutch half 22 is non-rotatably connected to the ring gear 12 indirectly via the connecting element 24 and the plate unit 17.The switchable overrunning clutch 20 thus acts on the ring gear 12, so that it is either released or, in overrun or pull operation, blocks or releases a connection between the ring gear 12 and the housing 5, depending on the switching position of a switching disc used as a switching device 25. The switching device 25 can be actuated via an actuator 26, wherein this actuator 26, which is operatively connected to the switching device 25 via the connection indicated by dashed lines, is located radially outside the switchable overrunning clutch 20 in the housing 5.

[0042] For design reasons, the switchable freewheel clutch 20 is arranged in the position shown between the ring gear 12 and the housing 5, so that the first clutch half 21 is connected to the housing 5 in a rotationally fixed manner. When the second clutch half 22 is decoupled from the first clutch half 21 and thus from the housing 5, the switching disc 25 holds down the corresponding pawls, analogous to the design of DE 10 2019 114 139 B3. This is the case in forward thrust operation when the forward thrust side is deactivated. A non-switchable freewheel function can be arranged in the freewheel 16, in particular between the two clutch halves 21, 22. Between the second clutch half 22 and the housing 5 orThe switching disc 25 is then located on the housing-mounted freewheel carrier 23. Depending on the switching position, spring-loaded pawls act in the opposite direction of rotation of the freewheel function between the clutch halves 21, 22, either released or held down. This results in two switching states: a freewheel state and a fully coupled braking state in which both directions are blocked.

[0043] This design, in which there is no separate bearing for the ring gear 12, but only an axial guide via the axial guide ring 15 is provided, allows a very compact design in both the axial and radial directions of the electric drive device 1 due to the nesting of the elements, which is made possible in particular by the plate unit 17, the cylinder section as connecting element 24 and the guide section 16.

[0044] With the advantageous structure of the execution of the Fig. 1, the plate unit 17 of the connecting element 24 is arranged, with respect to the axial direction a, on a side of the planetary gear stage 13 facing away from the electric machine 2. Furthermore, the cylinder section 27 is arranged, with respect to the axial direction, on a side of the plate unit 17 facing away from the planetary gear stage 13. The guide section 16 is arranged axially overlapping and radially inward of the cylinder section 27, with the U-shaped contour of the axial guide ring 15 being open radially outward, so that the guide section 16 engages radially inward into the axial guide ring 15.

[0045] The axial guide ring 15 is, with respect to the rotational axis A, advantageously arranged in a radially inner edge region of the planetary gear bolts 9, so that a circle indicated by the axial guide ring 15 lies radially within a circle which is arranged coaxially to the rotational axis A and whose circular line intersects the rotational axes of the planetary gears 10.

[0046] The switchable one-way clutch 20 is arranged axially overlapping the cylinder section 27 and also axially overlapping the axial guide ring 15, wherein the switchable one-way clutch 20 is arranged radially outside the cylinder section 27. List of reference symbols 1 electric drive device 2 Electric machine 3 Rotor 4 Rotor shaft 5 housings 6 bearings (of the rotor) 7 Downforce 8 planet carriers 9 planetary gear bolts 10 planetary gears 11 Sun gear 12 ring gear 13 planetary gear ratios 14.1, 14.2 Bearing 15 Axial guide ring 16 Guide Section 17 Plate unit 18 Output shaft 19 Spline shaft 20 switchable freewheel clutch 21 first coupling half 22 second coupling half 23 freewheel carrier 24 connecting element 25 switching disc 26 Actuator 27 cylinder sections (of 24) 28 needle bearings 30 Stator A axis of rotation a Axial direction R Radial direction

Claims

[1] Electric drive device (1) for a motor vehicle, with an electric machine (2) which has a rotor (3), with a planetary gear transmission stage (13) which has a sun gear (11), a planet carrier (8) with planet gears (10) and a ring gear (12), with a switchable freewheel clutch (20) which has a first clutch half (21), a second clutch half (23), a switching device (25) and an actuator (26), wherein the first clutch half (21) is connected in a rotationally fixed manner to a housing (5), characterized by an axial guide ring (15) which is designed to support the ring gear (12) in both axial directions (a), wherein the ring gear (12) is designed free of a rolling bearing directly supporting it, wherein the axial guide ring (15) is arranged radially inside and axially overlapping the one-way clutch (20). [2] Electric drive device (1) according to claim 1, characterized bythat the axial guide ring (15) has a U-shaped cross-sectional contour. [3] Electric drive device (1) according to claim 1 or 2 characterized by that the second coupling half (22) is connected in a rotationally fixed manner to the ring gear (12), wherein a connecting element (24) which is connected in a rotationally fixed manner to the ring gear (12) and in a rotationally fixed manner to the second coupling half (22) is arranged radially between a sun gear toothing of the sun gear (11) and a ring gear toothing of the ring gear (12) with respect to a rotational axis (A) of the planetary transmission stage (13). [4] Electric drive device (1) according to claim 3, characterized by that the connecting element (24) has a cylinder section (27) arranged coaxially to the axis of rotation (A) of the planetary transmission stage (13). [5] Electric drive device (1) according to claim 4, characterized by a plate unit (17) by means of which the cylinder section (27) is connected in a rotationally fixed manner to the ring gear (12). [6] Electric drive device (1) according to claim 5, characterized by that the rotor (3) is arranged coaxially to the planetary gear stage (13) and the plate unit (17) is arranged axially on a side of the planetary gear stage (13) facing away from the rotor (3), wherein the cylinder section (27) is arranged axially on a side of the plate unit (17) facing away from the planetary gear stage (13). [7] Electric drive device (1) according to claim 5 or 6, characterized by that the connecting element (24) has a guide section (16) which is designed to cooperate with the axial guide ring (15). [8] Electric drive device (1) according to one of claims 4 to 7, characterized bythat the cylinder section (27) is arranged radially in a region of the planetary gear pins (9) of the planet carrier (8) of the planetary gear stage (13) carrying the planetary gears (10) relative to the rotational axis (A) of the planetary gear stage (13). [9] Electric drive device (1) according to one of the preceding claims, characterized by that the switchable freewheel clutch (20) has a switching disc as a switching device (25), wherein the actuator (26) is designed to move this in a rotational manner. [10] Electric drive device (1) according to one of the preceding claims, characterized by that the actuator (26) of the switchable overrunning clutch (20) is arranged in the housing (5). [11] Electric drive device (1) according to one of the preceding claims, characterized bythat the actuator (26) of the switchable overrunning clutch (20) is arranged radially outside the clutch halves (21, 22) and / or axially overlapping with at least one of the clutch halves (21, 22).

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