Electric drive device for propelling a vehicle

Abstract

Electric drive device (1) for propelling a vehicle with an electric motor (5), wherein the electric motor (5) has a rotor (6) and a stator (7) and wherein the rotor (6) and / or the stator (7) define an axis of rotation (11), with a locking device (13), wherein the locking device (13) comprises a locking element (18) which is rotationally fixed to the stator (7), a running element (14) which is rotationally fixed to the rotor (6), and an actuator (22), wherein the actuator (22) can switch the locking element (18) between a locked position and a release position, wherein the locking element (18) is rotationally fixed to the running element (14) in the locked position and releases the running element (14) in the release position, wherein the running element (14) has a toothing (17) on an end face axial with respect to the axis of rotation (11), into which the locking element (18) engages in a form-fitting manner in the locking position, the actuator (22) has an axial actuating drive (23), wherein the axial actuating drive (23) is designed to move the locking element (18) in an axial direction and to drive against the running element (14), characterized by that a gearbox is arranged between the axial actuator (23) and the locking element (18), which converts an axial stroke of the axial actuator (23) into an axial stroke of the locking element (18), wherein the gearbox has a release fork (24), wherein the release fork (24) is coupled to the axial actuator (23) at a first position (I) in the direction of rotation about the axis of rotation (11) and is stationary supported at a second, opposite position (II), and wherein the release fork (24) moves the locking element (18) in the axial direction, wherein the locking element (18) is designed as a locking ring (18), wherein the locking ring (18) has a mating tooth (19) and is displaceable by the gearbox in the axial direction.

Description

[0001] The invention relates to an electric drive device for driving a vehicle with an electric motor, wherein the electric motor has a rotor and a stator and wherein the rotor and / or the stator define an axis of rotation, with a locking device, wherein the locking device has a locking element which is coupled to the stator, a running element which is rotationally fixed to the rotor, and an actuator, wherein the actuator can switch the locking element between a locking position and a release position, wherein the locking element is rotationally fixed to the running element in the locking position and releases the running element in the release position.

[0002] Electric drives for vehicles offer an alternative to conventional combustion engines and have particular advantages over combustion engines for short and medium journeys. However, the substitution of combustion engines with electric drives necessitates a rethinking of how many vehicle functions are implemented.

[0003] German patent application DE 10 2010 049 601 A1 deals with the implementation of a parking brake for a vehicle with an electric drive. This document states that the parking brake function can, in principle, be achieved by the electric drive through the application of a holding current. However, this implementation would lead to an increase in energy consumption when stationary and thus a reduction in range. As an improvement, the document proposes the use of a braking device with a mechanical locking element. This locking element is positioned radially or axially towards a rotational axis of the electric drive and acts directly or indirectly on the wheel hub.

[0004] Document US 4,798,269 A relates to a braking mechanism that acts frictionally on a brake disc which is positively coupled to a shaft of an electric motor.

[0005] Document US 2011 / 0227435 A1 discloses a motor locking device for an electric motor and a corresponding drive train with the motor locking device. The motor locking device has a locking plate which can be inserted into the rotor of the electric motor in an axial direction by an actuator to lock the electric motor, so that the rotor is positively locked in place. Field of invention

[0006] The invention is based on the objective of proposing an improved or alternative locking device for an electric drive. This objective is achieved by an electric drive device with the features of claim 1. Preferred or advantageous embodiments are described in the dependent claims, the following description, and the accompanying figures.

[0007] The invention proposes an electric drive device suitable and / or designed for powering a vehicle. In particular, the electric drive device has a power output of more than 10 kW for powering the vehicle. The vehicle is preferably a passenger car or a truck.

[0008] The electric drive device comprises an electric motor designed to generate the drive torque for propelling the vehicle. The electric motor includes a stator arranged stationary within the electric drive device and a rotor rotating relative to it. Preferably, the rotor is designed as an internal rotor. The stator defines an axis of rotation by its geometry. Alternatively or additionally, the axis of rotation is defined by the rotation of the rotor.

[0009] In the most general embodiment of the invention, the rotor is coupled and / or couplingable to at least one wheel of the vehicle, so that the drive torque of the electric motor can be transmitted to the at least one wheel. In particular, the drive torque constitutes a main torque for the at least one wheel of the vehicle.

[0010] The electric drive device includes a locking mechanism for locking the rotor-coupled section relative to the stator-coupled section of the electric drive device. The locking mechanism secures the vehicle when parked on an incline or similar terrain and is thus preferably functionally equivalent to the conventional parking brake – also known as a handbrake – of a vehicle with an internal combustion engine. The locking mechanism is specifically designed as a parking lock and / or as a hill-hold assist and / or as a start-stop device.

[0011] The locking device comprises a locking element, a running element, and an actuator designed to actuate the locking element. In the most general embodiment of the invention, the running element and / or the locking element can be designed as separate components or component sections, or as component areas of other components of the electrical drive device.

[0012] The locking element is rotationally fixed to the stator, preventing any relative rotation. However, the locking element is preferably arranged to be axially displaceable relative to the stator along the axis of rotation. Additional components may be arranged between the stator and the locking element. For example, the electric drive device comprises a housing in which the stator is stationary and the locking element is arranged on or attached to the housing. Particularly preferably, the stator is attached to a housing cover and the locking element is arranged on or attached to the housing cover.

[0013] The running element is non-rotatably coupled to the rotor, so that it rotates or is carried along when the rotor and / or the at least one wheel rotates.

[0014] The actuator has an axial actuator. The axial actuator is designed to move the locking element (18) in an axial direction and to drive it against the running element (14).

[0015] The actuator is preferably electromechanical, but in alternative embodiments it can also be pneumatic or hydraulic. In particularly simple embodiments, even a manually operated actuator is possible. The actuator is designed to switch the locking element between a locked position and a released position. In the locked position, the locking element is rotationally fixed to the running element, thus preventing rotation of the rotor and / or the at least one wheel. In the released position, however, the locking element and the running element are decoupled from each other, allowing them to rotate relative to one another. Consequently, rotation of the rotor and / or the at least one wheel relative to the locking element is also possible.

[0016] The invention proposes that the running element has a toothed section on an end face axial with respect to the axis of rotation, into which the locking element engages in a positive-locking manner in the locked position. It is particularly preferred that the axial end face is arranged in a radial plane to the axis of rotation.

[0017] The advantage of the invention is that very high holding forces can be generated by the positive engagement of the locking element in the toothing, since the positive engagement prevents relative rotation between the locking element and the running element. Furthermore, by arranging the toothing on the axial end face, the installation space requirement is very small, allowing for easy integration of the locking device.

[0018] The toothing is preferably designed with an angular pitch from tooth to tooth of 0.5° to 5°. This relatively narrow angular pitch has the advantage that dead travel or wasted travel during activation of the locking device is kept very short, as it can engage in many relative positions of the locking element and the running element. It is further preferred that the toothing is arranged in a diameter range greater than 15 cm, preferably greater than 20 cm, so that sufficient leverage is provided for locking the running element. Due to the large diameter, it is also possible for the locking element and / or the running element to be made of plastic, which makes the electric drive device lighter and therefore more efficient, while simultaneously significantly reducing production costs. The toothing is particularly preferably designed to extend completely around the axis of rotation.

[0019] In a preferred embodiment of the invention, the electric drive device is designed as a wheel hub motor unit. In particular, the wheel hub motor unit is assigned to exactly one wheel of the vehicle, which it drives exclusively. The wheel hub motor unit is particularly preferably designed as a direct drive, so that the rotor is coupled to the wheel in a rotationally fixed and / or gearless manner, and both always have the same rotational speed. In a possible, particularly compact embodiment, the electric motor, in particular the rotor and / or the stator, and the wheel are arranged overlapping or even congruently in the radial direction with respect to the axis of rotation. Optionally, the electric drive device includes the wheel. In this embodiment, the advantages regarding the improved integration of the locking device into the electric drive device are particularly evident.

[0020] In a further development of the invention, particularly as a wheel hub motor unit, the gear teeth are arranged to overlap, and in particular be congruently, the rotor in the axial direction, especially in axial projection. As previously explained, the large diameter of the gear teeth allows for the application of high holding forces due to leverage principles, without risking overloading the locking element or the running element. Particularly preferably, the gear teeth are arranged to overlap, and in particular be congruently, the stator in the radial direction, so that, in a longitudinal section through the axis of rotation, the gear teeth are located in a corner region formed by the transition from rotor to stator. Positioning the gear teeth in this corner region achieves excellent space utilization and thus an improvement in the drive device.

[0021] In an advantageous embodiment of the invention, particularly configured as a wheel hub motor unit, the running element is designed as a ring element that is mounted on the rotor. In this embodiment, the rotor serves as a carrier for the running element, thus further reducing the installation space required for the locking device. The ring element preferably comprises a flange section that carries the toothing and extends in a radial plane to the axis of rotation, and a tube section that is inserted into the rotor and bears against the rotor with its radial outer surface. Alternatively, the running element is integrally incorporated into the rotor. For example, an end face, particularly a metallic end face of the rotor, can have a face toothing that forms the running element. The face toothing can be formed into the rotor, e.g., by embossing, or by machining.

[0022] In a preferred embodiment of the invention, the actuator comprises an axial actuator, in particular an electric axial actuator, wherein the axial actuator is configured to move the locking element in the axial direction and to move it against the running element, so that the locking element assumes the locking position. The axial actuator is preferably designed as a spindle drive, in particular with a trapezoidal thread. It is possible that a spindle nut is moved by an actuator motor and the spindle is extended and retracted, or that the spindle is moved by the actuator motor and the spindle nut is extended and retracted. The spindle drive is particularly preferably designed to be self-locking in order to reliably maintain the assumed position even in the event of a power failure.

[0023] From an installation space perspective, it is preferred if the axial actuator is arranged off-center to the axis of rotation and, in particular, in the radial area of ​​the gear teeth. For example, the spindle and / or spindle nut can be arranged overlapping the gear teeth in axial projection. Preferably, the actuator is oriented away from the electric motor and / or an interface to the at least one wheel in order to make optimal use of the available installation space. In a possible further development, the axial actuator includes a mechanical emergency interface at its free end, i.e., away from the gear teeth, which allows manual actuation of the axial actuator, e.g., in the event of a lack of electrical power. The locking element is moved from the locked position to the unlocked position via the mechanical emergency interface.

[0024] In a first possible embodiment of the invention, the locking element is mounted directly on the axial actuator, in particular on the end of the spindle, and is driven by it against the running element. In this embodiment, the locking element is designed as a spur gear element. The reaction forces are only transferred in the area of ​​the axial actuator into the stationary section of the electrical drive device, in particular into the housing.

[0025] In a possible further development of the invention, a spring accumulator is arranged between the axial actuator and the locking element. The spring accumulator is designed to be elastically deformable in the axial direction. The advantage of the spring accumulator is particularly evident when the axial actuator is overloaded or when the locking element and the running element are arranged in such a way that they cannot be pushed into one another. In this case, the axial actuator can still move to its end position without overload. With a slight relative rotation of the locking element and the running element, the elements can be positively engaged by the energy of the spring accumulator. The spring accumulator can be used in the first described embodiment or in the embodiments described below.

[0026] According to the invention, a transmission, in particular a lever mechanism, is arranged between the locking element and the axial actuator. The transmission serves to transmit or – in preferred embodiments – to convert the axial stroke of the axial actuator into an axial stroke of the locking element.

[0027] Within the scope of the invention, the transmission comprises a release fork, wherein the release fork is coupled at a first position in the direction of rotation to the axial actuator, e.g., via a claw, so that the axial actuator can move the release fork axially at the first position. At a second position opposite the first position, the release fork is stationary and supported. Thus, the release fork forms a rocker mechanism, with the second position defining a pivot point. The release fork transmits the axial stroke from the axial actuator to the locking element.

[0028] In one embodiment of the invention, the locking element is designed as a locking ring which has one or the mating teeth. The locking ring is moved axially by the transmission to be transferred from the release position to the locking position. It is particularly preferred that the locking ring bears circumferentially against the running element in the locking position, so that the teeth and mating teeth can engage positively in a 360° range around the axis of rotation. This design ensures that the required holding forces can be transmitted over a wide range, thus reducing the risk of overloading the locking device.

[0029] Preferably, the locking ring is arranged on the release fork or moved axially by it. For this purpose, the locking ring is connected to the release fork in opposing positions, with the positions being located between the first and second positions. Preferably, all four positions are evenly spaced at 90° intervals around the axis of rotation. An axial stroke of the axial actuator at the first position translates into an axial stroke of the locking ring with half the stroke height. This conversion allows the holding force of the axial actuator to be increased, ensuring the function of the locking device even with a small actuator. Furthermore, this design avoids tilting forces and enables smooth movement.

[0030] To prevent the locking ring from tilting, it can optionally be provided that the locking ring is supported against the stationary surrounding structure, in particular against the housing, by several spring devices distributed in the circumferential direction, which prevent the locking ring from tilting.

[0031] Optionally, the electric drive device includes sensors for detecting the locking position or the release position of the locking element.

[0032] Depending on the design, the electric drive device with the locking mechanism can achieve a variety of advantages: The locking device is reliable and, due to the arrangement of the gear teeth on an axial face, requires only small axial strokes, thus achieving short switching times of, for example, less than 300 ms between the release and locking positions. It requires minimal installation space, while the positive-locking coupling of the locking and running elements allows for high holding forces. Its own mass is low, as lightweight plastic components can be used for both the locking and running elements, preventing any unpleasant noise. Alternatively, the locking and / or running elements can be made of a metallic material. The fine angular divisions minimize dead travel, enabling the locking device to be activated in a wide variety of relative positions between the locking and running elements.Due to the preferred self-locking design of the axial actuator, the locking mechanism is bistable, as it remains self-holding in both the locked and unlocked positions when de-energized. The locking mechanism requires only a few components, making it robust, reliable, and resistant to failure.

[0033] Further features, advantages, and effects of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying figures. These show: Fig. 1 a schematic longitudinal section through a wheel hub motor unit as an embodiment of the invention; Fig. 2 a schematic three-dimensional representation of a locking device of the wheel hub motor unit in the Fig. 1; Fig. 3 an exploded view of the locking device in the Fig. 2; Fig. 4 a close-up of the axial actuator in the Fig. 2 and Fig. 3.

[0034] The Fig. Figure 1 shows a schematic sectional view of an electric drive device in the form of a wheel hub motor unit 1 as an embodiment of the invention. The wheel hub motor unit 1 is designed as a direct drive for a wheel 2 of a vehicle. The wheel 2 comprises a tire 3 which is mounted on a rim 4.

[0035] The wheel hub motor unit 1 comprises an electric motor 5, which has a rotor 6 and a stator 7. The rotor 6 is designed as an internal rotor and is mounted on an axle 9 via a bearing assembly 8. The rotor 6 is non-rotatably connected to the rim and thus to the wheel 2. The stator 7 is stationary and fixed to the axle 9 via one or more housing covers 10. In particular, the housing cover 10 is directly or indirectly connected to the axle 9. During operation, the rotor 6 rotates together with the wheel 2 relative to the stator 7 and the housing cover 10 about an axis of rotation 11.

[0036] For a high integration density, the rotor 6 and the stator 7 are arranged in a space within the wheel 2. In particular, the rotor 6 and / or stator 7 overlap radially with the wheel 2, especially with the tire 3 and / or the rim 4, with respect to the axis of rotation 11.

[0037] In the transition area between rotor 6 and stator 7, a mounting space 12 is shown in the form of a circumferential ring, which is bounded axially by the rotor 6 and radially outwards by the stator 7. In particular, the mounting space 12 overlaps the rotor 6 in the axial direction. Several components of an integrated locking device 13 are arranged in this mounting space 12, which are located in the Fig. 2 and Fig. 3 is shown. Fig. 2 and Fig. Figure 3 shows the locking device 13 in a schematic three-dimensional representation or in an exploded view.

[0038] The locking device 13 comprises a running element in the form of a ring element 14. The ring element 14 is made of, for example, a thermoplastic material and comprises a flange section 15 and a tube section 16. The flange section 16 extends in a radial plane perpendicular to the axis of rotation 11 and is arranged in the installation space 12. The tube section 16 is in the form of a straight hollow cylinder and projects into the rotor 6 and is rotationally fixed to it. A toothed section 17 is provided, in particular molded, on the axial end face of the flange section 15. The toothed section 17 faces away from the rotor 6. The toothed section 17 is circumferential, in particular continuous, with the teeth arranged radially to the axis of rotation 11. In particular, the toothed section 17 forms a toothed ring.The spacing of the teeth of the gear 17 in the direction of rotation around the axis of rotation 11 is selected such that an angular division in the direction of rotation between 0.5° and 5° results. With an exemplary diameter of the wheel 2 of 600 mm, a tooth is thus arranged every 2.6 mm to 26 mm relative to the running path of the wheel 2.

[0039] Furthermore, the locking device 13 comprises a locking element in the form of a locking ring 18, which is also made of, for example, a thermoplastic material. The locking ring 18 has a mating tooth 19 on an axial end face facing the ring element 14. This mating tooth 19 is designed to be complementary to the toothing, so that the toothing 17 and the mating tooth 19, when engaged, form a positive-locking connection with respect to the direction of rotation about the axis of rotation 11. The locking ring 18 and the mating tooth 19 are arranged in the installation space 12.

[0040] As can be seen from the Fig. To achieve the best result, the locking ring 18 is arranged axially displaceable or slidable on the housing cover 10 and thus relative to the stator 7 via a plurality of axially aligned springs 20. The springs 20 are fixed to the housing cover 10, and the locking ring 18 has a corresponding number of axially aligned guides 21. The locking ring 18 is guided axially in the hub area by the housing cover 10. As an anti-rotation device, the housing cover 10 has one or more guide lugs 34 that engage in corresponding recesses in the passage area of ​​the locking ring 18 and positively lock the locking ring 18 in the direction of rotation. This arrangement ensures that the locking ring 18 cannot rotate about the axis of rotation 11 relative to the housing cover 10 and thus to the stator 7. The locking ring 18 and stator 7 are thus arranged to be rotationally fixed relative to each other and at the same time axially displaceable relative to each other.

[0041] Functionally, the locking ring 18 can assume a locking position, in which the teeth 17 and the mating teeth 19 are engaged, thus forming a positive-locking connection in the direction of rotation. Since the locking ring 18 is rotationally fixed to the stator 7 and the ring element 14 is rotationally fixed to the rotor 6, relative rotation of the rotor 6 and stator 7 is prevented. Since the rotor 6 and wheel 2 are rotationally fixed to each other, rotation of the wheel 2 is also prevented. Thus, in the locked position of the locking ring 18, the locking device 13 acts as a parking brake for the wheel 2 and therefore for the vehicle. If, on the other hand, the locking ring 18 assumes a release position, so that the teeth 17 and mating teeth 19 are disengaged, the rotor 6 and stator 7 can rotate independently of the locking device 13, and the wheel 2 is also released.

[0042] The actuation of the locking ring 18 from the locked position to the released position and vice versa is implemented by an actuator 22. The actuator 22 comprises an axial actuator 23 and a release fork 24. The axial actuator 23 is arranged off-center to the rotational axis 11 and is attached to the housing cover 10. As can be seen in particular from the Fig. Figure 4, which shows the axial actuator 23 in a schematic longitudinal section, comprises an actuator 25 that drives a spindle nut 26. A spindle 27 is guided in the spindle nut 26 and is moved axially when the spindle nut 26 is rotated. The thread of the spindle nut 26 and the spindle 27 is designed as a self-locking thread, which is implemented, for example, as a trapezoidal thread. A claw 28 is attached to the free end of the spindle 27, which engages the release fork 24 at a first position I (see Fig. 2).

[0043] At a second, opposite position II, the release fork 24 is pivotally connected to the housing cover 10 via a pivoting device 29. In an axial plan view, the first position I and the second position II are arranged offset from each other by 180° about the axis of rotation 11. By actuating the axial actuator 23, the claw 28 is thus moved in the axial direction and the release fork 24 pivots like a rocker about the pivoting device 29.

[0044] At positions III and IV, which are offset from each other by 180° and from the first and second positions I and II by 90°, the release fork 24 and the locking ring 18 are pivotably connected to each other via drive pins 30. The drive pins 30 together form a pivot axis that runs through the axis of rotation 11 and is oriented perpendicular to it.

[0045] When the axial actuator 23 is actuated, the claw 28 is displaced axially by one stroke. This causes the release fork 24 to pivot about the pivoting device 29, so that the drive pins 30 are moved axially by approximately half the axial stroke. The movement of the drive pins 30 causes the locking ring 18 to be displaced axially, so that its mating teeth 19 engage with the teeth 17. The locking device 13 is in the locked position. Similarly, by moving the claw 28 in the opposite direction, the locking ring 18 is released from the ring element 14, and the locking device 13 releases the wheel 2. The required axial stroke of the claw 28 is, for example, 10 mm.

[0046] The locking device 13 can have sensors 31 which detect the state of the release fork 24, i.e., the difference between the locked and unlocked positions, and transmit this information, for example, to the vehicle's on-board electronics. As already explained, the axial actuator 23 is self-locking, making it bistable. In particular, no current needs to be supplied for the holding forces in either the locked or unlocked positions. In special conditions of the wheel hub motor unit 13, such as a power failure, it may be necessary for the locking device to be manually releasable. For this purpose, the actuator 25 has an emergency interface 32 located under a cap 33. Using a specially coded key or other tool, the actuator 25 can be turned via the emergency interface 32, thereby manually moving the locking device 13 from the locked position to the unlocked position. Reference symbol list 1 wheel hub motor unit 2 wheel 3 tires 4 rim 5 electric motor 6 Rotor 7 Stator 8 Storage facility 9-axis 10 Case covers 11 Rotation axis 12 Construction space 13 Locking device 14 Ring element 15 Flange section 16 Pipe section 17 Gearing 18 locking ring 19 Counter-gearing 20 springs 21 guided tours 22 Actuators 23 Axial actuator 24 Release fork 25 Actuator 26 Spindle nut 27 spindles 28 Claw 29 Swivel device 30 drive bolts 31 sensors 32 Emergency interface 33 cap 34 leading noses I first position II second position III Position IV position

Claims

[1] Electric drive device (1) for propelling a vehicle with an electric motor (5), wherein the electric motor (5) has a rotor (6) and a stator (7) and wherein the rotor (6) and / or the stator (7) define an axis of rotation (11), with a locking device (13), wherein the locking device (13) comprises a locking element (18) which is rotationally fixed to the stator (7), a running element (14) which is rotationally fixed to the rotor (6), and an actuator (22), wherein the actuator (22) can switch the locking element (18) between a locked position and a release position, wherein the locking element (18) is rotationally fixed to the running element (14) in the locked position and releases the running element (14) in the release position, wherein the running element (14) has a toothing (17) on an end face axial with respect to the axis of rotation (11), into which the locking element (18) engages in a form-fitting manner in the locking position, the actuator (22) has an axial actuating drive (23), wherein the axial actuating drive (23) is designed to move the locking element (18) in an axial direction and to drive against the running element (14), characterized by , that a gearbox is arranged between the axial actuator (23) and the locking element (18), which converts an axial stroke of the axial actuator (23) into an axial stroke of the locking element (18), wherein the gearbox has a release fork (24), wherein the release fork (24) is coupled to the axial actuator (23) at a first position (I) in the direction of rotation about the axis of rotation (11) and is stationary supported at a second, opposite position (II), and wherein the release fork (24) moves the locking element (18) in the axial direction, wherein the locking element (18) is designed as a locking ring (18), wherein the locking ring (18) has a mating tooth (19) and is displaceable by the gearbox in the axial direction. [2] Electric drive device (1) according to claim 1, characterized by , that the electric drive device (2) is designed as a wheel hub motor unit (1) . [3] Electric drive device (1) according to claim 1 or 2, characterized by , that the toothing (17) is arranged overlapping with the rotor (6) in the axial direction to the axis of rotation (11). [4] Electric drive device (1) according to any one of the preceding claims, characterized by , that the running element (14) is designed as a ring element (14) and is arranged on the rotor (6) or is integrally contained therein. [5] Electric drive device (1) according to any one of the preceding claims, characterized by , that the axial actuator (23) is arranged off-center to the axis of rotation (11). [6] Electric drive device (1) according to one of the preceding claims, characterized by, that a spring accumulator is arranged between the axial actuator (23) and the locking element (18). [7] Electric drive device (1) according to any one of the preceding claims, characterized by , that the locking ring (18) rests circumferentially against the running element (14) in the locking position.

Images