Electric single-wheel actuator for a motor vehicle

Abstract

The invention relates to an electric single-wheel actuator for a motor vehicle, comprising a suspension strut (1) which can be positioned on a motor vehicle body via a strut mount, and having an actuator (2), which, in the region of the strut mount, is steering-torque-transmittingly connected to the suspension strut (1) such that a strut-mount steering mechanism is formed, wherein the actuator (2) is positioned to the side of the strut mount or the suspension strut (1) and wherein at least a two-stage gear combination is provided in order to introduce the torque of the actuator (2) at the strut mount.

Description

[0001] Description

[0002] title

[0003] Electric single wheel actuator for a

[0004] The present invention relates to an electric single wheel actuator for a motor vehicle according to the preamble of claim 1.

[0005] State of the art

[0006] The steering torque of a steering system is amplified by a servo gear, enabling easy steering. Future steer-by-wire steering systems will eliminate the mechanical connection between the steering wheel and the steered wheels. The steering angle set on the steering wheel is detected by a sensor and electronically transmitted to a steering actuator, which then adjusts the vehicle's front wheels accordingly. Typically, the translational movement of a steering rack is transmitted to tie rods, which pivot the wheels. However, the kinematics limit the maximum steering angle at the front wheels.

[0007] In decentralized steering systems, each steered wheel is assigned its own steering actuator, allowing each wheel to be controlled individually. This makes it possible to increase the maximum steering angle. Since the central steering actuator in the middle of the vehicle is eliminated, this can result in space savings for the vehicle manufacturer. In addition, decentralized steering systems enable new functions such as a parking brake function by turning the wheels in opposite directions. For decentralized individual wheel actuators, it is common practice to use a ball screw drive. However, the translational movement of the ball screw rod must be converted back into a rotational movement to pivot the wheel. This takes up a lot of installation space. Wheel suspensions with conventional steering systems exhibit a phenomenon called bump steer. Ideally, the steering angle does not change when a vehicle wheel is compressed vertically. However, this cannot normally be prevented.

[0008] From DE 10 2020 213 664 A1, it is known to provide an electric single-wheel actuator comprising a pivoting support, which can be pivoted by an electric motor. Furthermore, from DE 10 2017 106 826 A1, a suspension strut for a motor vehicle is known, wherein the suspension strut has a steering actuator for adjusting a steering angle. The steering actuator is mounted in an extension of the longitudinal axis of the suspension strut.

[0009] With independent wheel actuators, steering via a strut mount on the independent wheel suspension is advantageous, and not just for cost reasons. Typically, an actuator is located at the top of both strut mounts, which transmits a corresponding steering torque to the wheels. However, positioning the actuator in the area of ​​the strut mounts requires the front of the vehicle to be built significantly higher. Especially with electric vehicles, the front of such vehicles is usually kept low to achieve the lowest possible aerodynamic drag. The currently used strut mount arrangements, which are based on planetary roller gears or similar and accommodate a corresponding motor as an extension of the strut mount, are counterproductive in this case. This arrangement requires considerably more installation space upwards.

[0010] Advantages of the invention

[0011] The present invention relates to an electric single wheel actuator and to a motor vehicle containing the same with the characterizing features of the independent patent claims.

[0012] Thus, the invention provides an electric independent wheel actuator for a motor vehicle, which has a spring strut that can be positioned on a vehicle body via a strut mount. Furthermore, the electric independent wheel actuator comprises an actuator that is operatively connected to the spring strut in the area of ​​the strut mount to transmit steering torque, corresponding to a strut mount steering system. The actuator is positioned to the side of the strut mount or spring strut.

[0013] The particular advantage of this approach is that, in conventional strut mount steering systems, a corresponding actuator is provided in the extension of the longitudinal axis of a spring strut, thus resulting in a high body structure. According to the invention, the actuator is positioned to the side of the spring strut and thus no longer in an aligned arrangement positioned in extension of the spring strut, but rather in an angled configuration. Furthermore, according to the invention, at least two transmissions are combined to achieve the required transmission ratio.

[0014] The actuator concept according to the invention provides for a steering actuator to be mounted on the chassis, with the corresponding torque being introduced at the top mount of a McPherson wheel suspension. One advantage of the chassis connection is the decoupling of the actuator mass from the unsprung mass.

[0015] In addition, the center of the vehicle remains free at the front, allowing for a large frunk. A frunk is the trunk space under the hood.

[0016] There are only minor restrictions on the steerable angle range. By applying the steering torque at the strut mount, the area around the wheel carrier remains free. This allows the wheel carrier to be freely dimensioned to enable a maximum angular range while simultaneously avoiding collisions. This allows for a wide steering angle range.

[0017] Furthermore, the steering angle is decoupled from the suspension, which means there is no bump-steer effect.

[0018] Further advantageous embodiments of the present invention are the subject of the dependent claims. In a first embodiment, a worm gear is connected to the actuator. This creates a 90° deflection to enable the introduction of torque at the strut mount. The second gear stage is implemented by a spur gear, which is larger in size than the worm gear. The spur gear enables an axial offset relative to the worm gear.

[0019] The worm gear is well suited for medium gear ratios. A spur gear as the final gear stage enables the remaining gear ratio to achieve the required torque. Depending on the installation space, the spur gear can be designed as a 180° half-disk, for example. This allows a steering angle of + / -90° to be achieved while still maintaining a compact design.

[0020] This design leaves space free in the area of ​​the lower wishbone and wheel carrier, allowing for axle adjustments to expand the steering angle range. The orthogonal orientation between the engine and transmission is advantageous for integration.

[0021] In a second design, a strain wave gear is connected to the actuator via a belt drive. Compared to the first embodiment, the gear combination does not provide a 90° deflection, but rather a parallel axis offset, which can be adapted to the available installation space or the connection to the chassis by increasing the center distance of the belt drive. The belt drive is well suited for low torque transmission and smaller gear ratios. The strain wave gear as the second gear stage enables a high gear ratio towards the steering torque in accordance with the requirements of the chassis. Advantageously, the axially parallel arrangement leaves the installation space towards the chassis / bonnet almost unobstructed.

[0022] In a third design, a belt drive is connected to the engine output shaft. The second gear stage for achieving the target torque is designed as a multi-stage planetary gear. This enables high steering torques. The belt drive introduces a parallel axis offset between the engine output and the steering torque transmission via the planetary gear on the strut mount. This axis offset can be adapted to the available installation space or the chassis connection by increasing the center distance of the belt drive.

[0023] In a fourth design, a high-ratio gearbox, such as a multi-stage planetary gearbox, is used as the first gear ratio and a bevel gearbox for a 90° deflection as the second stage. The compact design thanks to the 90° deflection enables integration under the hood despite the large multi-stage planetary gearbox. Depending on the installation space, the second bevel gear can, for example, be designed as a 180° cone. This allows a steering angle of + / -90° to be achieved while keeping installation space free. Alternatively, the meshing of the bevel gears can also be mirrored, i.e. from below, which allows the actuator to be positioned somewhat lower.

[0024] In a fifth embodiment, a strain wave gear is mounted on the engine as the first transmission. To introduce the steering torque at the strut mount, a bevel gear ratio close to i=1 is used, since the strain wave gear already achieves a high transmission ratio (i=50...150) of the engine torque. This allows the concept to be integrated compactly. The 90° deflection enables integration under the hood. Depending on the installation space, the second bevel gear can, for example, be designed as a 180° cone. This allows a steering angle of + / -90° to be achieved while keeping installation space free. Alternatively, the second bevel gear could also be mounted mirrored on the damper strut.

[0025] In a sixth embodiment, a single-stage planetary gear is mounted on the engine as the first gear ratio. To transmit the steering torque to the strut mount, a worm gear with a 90° deflection is mounted on the planetary gear. In contrast to the fourth embodiment, a worm gear is particularly well-suited for medium gear ratios. This allows the planetary gear to be designed for a lower gear ratio, meaning a 1- to 2-stage planetary gear may be sufficient. In a seventh embodiment, two worm gears are combined. The double 90° deflection allows the engine to be mounted parallel to the suspension strut.

[0026] Advantageously, the invention also provides a motor vehicle, in particular an electrically powered motor vehicle. This motor vehicle has, for example, electric individual wheel actuators of the above-described form, preferably in the area of ​​each front axle wheel.

[0027] Short description of the drawings

[0028] Embodiments of the present invention are illustrated in the figures and explained in more detail in the following description of the figures.

[0029] It shows:

[0030] Fig. 1 shows an electric single-wheel actuator according to a first embodiment of the present invention,

[0031] Fig. 2 a side view of the electric single wheel actuator according to Fig. 1 ,

[0032] Fig. 3 is a side view of an electric single wheel actuator according to a second embodiment of the present invention

[0033] Fig. 4 a top view of the electric single wheel actuator according to Fig. 3

[0034] Fig. 5 is a side view of an electric single wheel actuator according to a third embodiment of the present invention

[0035] Fig. 6 a top view of the electric single wheel actuator according to Fig. 5

[0036] Fig. 7 is a side view of an electric single-wheel actuator according to a fourth embodiment of the present invention. Fig. 8 is a plan view of the electric single-wheel actuator according to Fig. 7, wherein the bevel gear is designed as a 180° half-disk.

[0037] Fig. 9 is a plan view of an electric single-wheel actuator according to a fifth embodiment of the present invention

[0038] Fig. 10 a side view of the electric single wheel actuator according to Fig. 9

[0039] Fig. 11 is a side view of an electric single-wheel actuator according to a sixth embodiment of the present invention

[0040] Fig. 12 a top view of the electric single wheel actuator according to Fig. 11

[0041] Fig. 13 is a side view of an electric single-wheel actuator according to a seventh embodiment of the present invention

[0042] Fig. 14 another side view of the electric single wheel actuator according to Fig. 13

[0043] Character description

[0044] 1 and 2 show an electric single-wheel actuator according to a first embodiment of the present invention. The single-wheel actuator comprises a spring strut 1, wherein a torque of an actuator 2 is introduced at the upper end of the spring strut, where the spring strut is positioned in the top mount. For this purpose, the torque of the actuator 2 is transmitted via a two-stage gear system. The first gear stage is a worm gear 3, which realizes a 90° deflection and positions the actuator 2 to the side of the top mount. The second gear stage is implemented by a spur gear 4, which enables an axial offset relative to the worm gear. FIGS. 3 and 4 show an electric single-wheel actuator according to a second embodiment of the present invention. In this arrangement, a wave gear 6 is connected to the actuator 2 via a belt drive 5, wherein the actuator 2 is positioned parallel to the spring strut 1.

[0045] Fig. 5 and Fig. 6 show an electric single-wheel actuator according to a third embodiment of the present invention. A belt drive 7 is connected to the output shaft of the actuator 2. The second gear stage for achieving the target torque is designed as a multi-stage planetary gear 8.

[0046] Fig. 7 shows an electric single-gear actuator according to a fourth embodiment of the present invention. A high-ratio, multi-stage planetary gear 9 is used as the first gear ratio, and a bevel gear 10 for a 90° deflection is used as the second gear stage.

[0047] In Fig. 8 the electric single wheel actuator according to Fig. 7 can be seen again, whereby the bevel gear 11 is designed as a 180° half-disk.

[0048] Figs. 9 and 10 show an electric single-wheel actuator according to a fifth embodiment of the present invention. A strain wave gear 12 is used as the first high gear ratio. A bevel gear 13 is used as the second gear stage for 90° deflection.

[0049] Figures 11 and 12 illustrate an electric single-wheel actuator according to a sixth embodiment of the present invention. A single-stage planetary gear 14 is mounted on the actuator 2 as the first transmission. To introduce the steering torque at the strut mount, a worm gear 15 with a 90° deflection is mounted on the planetary gear.

[0050] Figures 13 and 14 show an electric single-wheel actuator according to a seventh embodiment of the present invention. Two worm gears 16, 17 are combined. The two 90° deflections allow the motor to be positioned parallel to the suspension strut 1.

Claims

Claims 1 . Electric single-wheel actuator for a motor vehicle, comprising a spring strut (1) which can be positioned on a motor vehicle body via a strut bearing and with an actuator (2) which, in the region of the strut bearing, is in a steering torque-transmitting operative connection with the spring strut (1) to form a strut bearing steering, characterized in that the actuator (2) is positioned laterally of the strut bearing or the spring strut (1), and in that at least one two-stage gear combination is provided in order to introduce the torque of the actuator (2) at the strut bearing.

2. Electric single-wheel actuator according to claim 1, characterized in that the actuator (2) is an electric motor.

3. Electric single-wheel actuator according to claim 1 or 2, characterized in that the first gear stage is a worm gear (3), whereby a 90° deflection is achieved, and that the second gear stage is a spur gear (4), whereby an axial offset is achieved.

4. Electric single-wheel actuator according to claim 3, characterized in that the spur gear on the dome bearing is designed as a 180° half-disk.

5. Electric single-wheel actuator according to claim 1 or 2, characterized in that the first gear stage is a belt drive (5), whereby a parallel axis offset is achieved, and that the second gear stage is a wave gear (6).

6. Electric single-wheel actuator according to claim 1 or 2, characterized in that the first gear stage is a belt transmission (7), whereby a parallel axis offset is achieved, and that the second gear stage is a multi-stage planetary gear (8).

7. Electric single-wheel actuator according to claim 1 or 2, characterized in that the first gear stage is formed by a multi-stage planetary gear (9) or by a wave gear (12), and that the second gear stage is a bevel gear (10, 13), whereby a 90° deflection to the dome bearing is achieved.

8. Electric single-wheel actuator according to claim 7, characterized in that the bevel gear (11) on the dome bearing is designed as a 180° cone.

9. Electric single-wheel actuator according to claim 1 or 2, characterized in that the first gear stage is a single-stage planetary gear (14) and that the second gear stage is a worm gear (15), whereby a 90° deflection is achieved.

10. Electric single-wheel actuator according to claim 1 or 2, characterized in that the first gear stage and the second gear stage are each formed by a worm gear (16, 17), whereby a 180° deflection is achieved.

11. Motor vehicle, in particular an electrically driven motor vehicle, comprising an electric single-wheel actuator (10, 20) according to one of the preceding claims.

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