DE102022214006A1 - Single wheel actuator for a steering system of a motor vehicle and steering system - Google Patents

Abstract

The invention relates to an individual wheel actuator (1, 101, 201, 301) for a steering system, in particular a steer-by-wire steering system, of a motor vehicle, with a drive unit (20, 120, 220, 320) which is designed to carry out an axial movement of the push rod (14) from a first position arranged essentially in the housing interior (12) to a second position extended essentially from the housing (10), wherein the individual wheel actuator (1, 101, 201, 301) has a suspension (24, 124, 224, 324) on a third axial end section (22, 122, 222, 322), which is designed to suspend the individual wheel actuator (1, 101, 201, 301) on the body in a pendulum manner, wherein a degree of freedom of a pendulum movement is determined by a a first pivot axis (A1) arranged substantially perpendicular to a longitudinal axis of the push rod (14) and a second pivot axis (A2) arranged substantially perpendicular to the longitudinal axis of the push rod (14). The invention further relates to a steering system.

Description

The invention relates to an individual wheel actuator for a steering system of a motor vehicle.

The invention further relates to a steering system for a motor vehicle.

State of the art

In conventional steering systems, the desired steering angle is transmitted from the steering wheel to the two front wheels via a mechanical connection. The steering torque is amplified by a servo gear to enable easy steering.

In future steer-by-wire steering systems, the mechanical connection between the steering wheel and the steered wheels will be eliminated. The steering angle set on the steering wheel is recorded by a sensor and transmitted electronically to the steering actuator, which then adjusts the front wheels accordingly.

The steering system can act centrally, meaning that the steering actuator controls both wheels simultaneously. The translational movement of a rack is usually transferred to the tie rods, which pivot the wheels. However, the kinematics limit the maximum steering angle on the front wheels.

In decentralized steering systems, each steered wheel is assigned its own steering actuator, which means that each wheel can 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.

In addition, it is known to transmit the rotation of an electric motor via a worm gear in order to pivot the steered wheel. Since the electric motor is attached to the chassis, a universal joint must be arranged to transmit the rotary motion. In this way, a vertical movement of the wheel carrier caused by the compression movement can be compensated.

DE 102020213664 A1 discloses an electric single wheel actuator for a motor vehicle with a double wheel carrier, which consists of an axle carrier and a swivel carrier and wherein the swivel carrier is rotatably mounted within the axle carrier, with an electric motor which swivels the swivel carrier via a gear, wherein the electric motor is arranged on the axle carrier.

The object of the invention is to provide a compact single wheel actuator. This should use a small installation space.

This object is solved by the subject matter of claim 1.

Disclosure of the invention

The present invention provides an individual wheel actuator for a steering system, in particular a steer-by-wire steering system, of a motor vehicle.

The single wheel actuator comprises a housing and a push rod which is arranged at least in sections in a housing interior, which is mounted in the housing and is connected at a second axial end section arranged opposite to the first axial end section to a universal joint (19) or joint head (18) which can be coupled to a wheel carrier.

In addition, the single wheel actuator comprises a drive unit which is designed to carry out an axial movement of the push rod from a first position arranged substantially in the housing interior to a second position substantially extended out of the housing.

The individual wheel actuator further comprises a suspension at a third axial end portion which is designed to suspend the individual wheel actuator from the body in a pendulum manner, wherein a degree of freedom of a pendulum movement is defined by a first pivot axis arranged substantially perpendicular to a longitudinal axis of the push rod and a second pivot axis arranged substantially perpendicular to the longitudinal axis of the push rod.

The present invention further provides a steering system, in particular a steer-by-wire steering system, for a motor vehicle, with a plurality of individual wheel actuators according to the invention, which are designed to steer the wheel connected to a respective individual wheel actuator.

One idea of the present invention is to provide a single wheel actuator which enables a compact arrangement.

In order to shorten the overall length of the independent wheel actuator and to improve the flexibility of vehicle installation, both the body suspension of the independent wheel actuator and the The axial position of the two pivot axes can be positioned anywhere relative to the push rod axis.

The axial position can be placed either at one end of the housing or in the middle area of the housing - depending on the conditions in the vehicle.

The provision of the suspension, which is designed to suspend the individual wheel actuator from the body in a pendulum manner, wherein a degree of freedom of a pendulum movement is defined by a first pivot axis arranged substantially perpendicular to a longitudinal axis of the push rod and a second pivot axis arranged substantially perpendicular to the longitudinal axis of the push rod, advantageously enables an articulated suspension of the individual wheel actuator, wherein the joint is formed by two virtual axes, i.e. pivot axes, which are perpendicular to one another and substantially perpendicular to the axis of the push rod.

The suspension thus ensures the degrees of freedom of rotation around these two axes. These two axes also prevent the entire single wheel actuator from rotating around the push rod axis.

Advantageous embodiments and further developments emerge from the subclaims and from the description with reference to the figures.

According to a preferred development, the first pivot axis is arranged essentially perpendicular to the second pivot axis. This advantageously results in an effective pivotability of the individual wheel actuator in relation to the pivot axes aligned with the longitudinal axis of the push rod.

According to a further preferred development, it is provided that the first pivot axis and/or the second pivot axis intersects with the longitudinal axis of the push rod. This results in an optimal alignment of the pivot axes with respect to the longitudinal axis of the push rod.

According to a further preferred development, a first anti-twisting device is arranged on the first axial end section of the push rod, which is designed to arrange the push rod in a rotationally fixed manner in the housing by means of a complementary shape of the first anti-twisting device and the push rod. The anti-twisting device thus advantageously enables a rotation-free axial movement of the push rod.

According to a further preferred development, the first anti-twisting device is designed to support the push rod radially in the housing interior. The anti-twisting device thus fulfills a dual function of preventing rotation and supporting the push rod. This advantageously eliminates the need for a separate radial bearing for the push rod.

According to a further preferred development, a second anti-twisting device for the push rod is arranged on the second axial end section of the push rod. This advantageously enables the push rod to be anti-twisting in the area of the universal joint or the joint head.

According to a further preferred development, it is provided that the housing has an extension limiter of the push rod formed by a plate, which is designed to provide a stop for the first anti-twisting device arranged on the first axial end section of the push rod. This advantageously enables a limitation of an axial movement of the push rod.

According to a further preferred development, the housing has a retraction limiter on a section arranged adjacent to the suspension of the individual wheel actuator, which is designed to provide a stop for the first anti-twisting device arranged on the first axial end section of the push rod. This advantageously enables a limitation of an axial movement of the push rod.

According to a further preferred development, it is provided that an axial position of the retraction limit and/or the extension limit is adjustable, and wherein the retraction limit and/or the extension limit has an end position damping.

This allows for flexible adjustability, allowing the corresponding individual wheel adjuster to be adapted to a particular installation situation or vehicle model.

According to a further preferred development, it is provided that the first pivot axis and the second pivot axis of the individual wheel actuator are arranged adjacent to a connection of an electrical line of the drive unit or along an axial length of the electrical machine.

This makes it possible to keep the connection of the electrical line of the drive unit as short as possible. It also makes it possible for the cable of the electrical line to move as little as possible, which leads to less wear.

According to a further preferred development, it is provided that the drive unit has an electrical machine arranged axially parallel to the longitudinal axis of the push rod, which is connected to a ball screw drive by means of a toothed belt, wherein a ball nut of the ball screw drive is designed to translate a rotation of the ball nut caused by the toothed belt into a translational movement of the push rod engaged with the ball nut. This enables an efficient translation of the rotational movement of the electrical machine into a translational movement of the push rod.

According to a further preferred development, it is provided that the drive unit has an electrical machine arranged axially parallel to the longitudinal axis of the push rod, which is connected by means of a toothed belt to a planetary roller screw drive, which is designed to translate a rotation of the planetary roller screw drive caused by the toothed belt into a translational movement of the push rod engaged with the planetary roller screw drive.

Due to smaller thread flanks, the planetary roller screw drive can achieve significantly larger slow-speed ratios than a ball screw drive. Ball screw drive pitches of less than 5 mm/rev are unusual. With the planetary roller screw drive, pitches of up to 1 mm/rev are possible. This means that the gear ratio of the belt stage can be up to a factor of 5 smaller than with a ball screw drive, which makes significantly smaller belt pulleys possible.

Furthermore, the planetary roller screw drive has a significantly higher load capacity than a ball screw drive of the same dimensioning within the same installation space due to the large number of thread flanks involved in the power transmission.

The basic friction is higher with planetary roller screw drives due to the slightly lower efficiency and the possibility of mounting the planetary gears with selective assembly and preload. This can be advantageous for imprinting a toe-in without electrical power. A reset due to external forces can only be maintained by the internal friction of the actuator without additional motor power.

The planetary screw drive can also be synchronized - so there is no slip between the drive and the output - or it can be operated without synchronization, which requires additional monitoring of the slip between the drive and the output using sensors.

According to a further preferred development, it is provided that the drive unit has an electrical machine arranged concentrically to the longitudinal axis of the push rod, which has a hollow shaft for internally receiving the push rod, wherein the electrical machine is coupled to a planetary roller screw drive or ball screw drive arranged concentrically to the longitudinal axis of the push rod, which is designed to translate a rotation of the planetary roller screw drive or ball screw drive caused by the electrical machine into a translational movement of the push rod engaged with the planetary roller screw drive or ball screw drive.

This means that the transmission gear can be omitted in the concentric system. Because a pre-stage gear is not required, both installation space and costs are saved. Due to the high transmission ratios that can be achieved with a planetary roller screw drive, a direct drive with a motor can be implemented without an additional gear stage. A ball screw drive with a higher transmission ratio (e.g. 5 mm pitch) can also be used if the motor is designed for higher torques at lower speeds. The motor is designed as a hollow shaft motor with a performance curve adapted to the system.

The described designs and further training courses can be combined as desired.

Further possible embodiments, further developments and implementations of the invention also include combinations of features of the invention described above or below with respect to the embodiments that are not explicitly mentioned.

Short description of the drawings

The accompanying drawings are intended to provide a further understanding of embodiments of the invention. They illustrate embodiments and, in conjunction with the description, serve to explain principles and concepts of the invention.

Other embodiments and many of the advantages mentioned arise with regard to the Drawings. The elements shown in the drawings are not necessarily to scale.

• 1 eine schematische Darstellung eines Einzelradstellers für ein Lenksystem gemäß einer ersten Ausführungsform der Erfindung;
• 2 eine schematische Darstellung einer Karosserieaufhängung des Einzelradstellers für das Lenksystem gemäß der ersten Ausführungsform der Erfindung;
• 3 eine schematische Darstellung des Einzelradstellers für das Lenksystem gemäß einer zweiten Ausführungsform der Erfindung;
• 4 eine schematische Darstellung des Einzelradstellers für das Lenksystem gemäß einer dritten Ausführungsform der Erfindung; und
• 5 eine schematische Darstellung des Einzelradstellers für das Lenksystem gemäß einer vierten Ausführungsform der Erfindung;

Show it:

• 1 a schematic representation of an individual wheel actuator for a steering system according to a first embodiment of the invention;
• 2 a schematic representation of a body suspension of the independent wheel actuator for the steering system according to the first embodiment of the invention;
• 3 a schematic representation of the individual wheel actuator for the steering system according to a second embodiment of the invention;
• 4 a schematic representation of the individual wheel actuator for the steering system according to a third embodiment of the invention; and
• 5 a schematic representation of the individual wheel actuator for the steering system according to a fourth embodiment of the invention;

In the figures of the drawings, identical reference symbols designate identical or functionally identical elements, parts or components, unless otherwise stated.

The 1 The single wheel actuator 1 shown for a steering system, in particular a steer-by-wire steering system, of a motor vehicle comprises a housing 10 and a push rod 14 arranged at least in sections in a housing interior 12.

The push rod 14 is mounted at a first axial end portion 14a in the housing 10 and is connected at a second axial end portion 14b arranged opposite to the first axial end portion 14a to a joint head 18 which can be coupled to a wheel carrier 16.

The single wheel actuator 1 further comprises a drive unit which is designed to carry out an axial movement of the push rod 14 from a first position arranged essentially in the housing interior 12 to a second position essentially extended out of the housing 10.

Furthermore, a first anti-twisting device 26 is arranged on the first axial end section 14a of the push rod 14, which is designed to arrange the push rod 14 in a rotationally fixed manner relative to the housing by means of a complementary shape of the first anti-twisting device 26 and the push rod 14. The first anti-twisting device 26 is designed to radially support the push rod 14 in the housing interior 12 and to secure it against rotation.

The housing 10 also has an extension limit 30 of the push rod 14 formed by a plate. The extension limit 30 is designed to provide a stop for the first anti-twisting device 26 arranged on the first axial end section 14a of the push rod 14.

The housing 10 further comprises a retraction limiter 32 on a section arranged adjacent to the suspension 24 of the single wheel actuator 1. The retraction limiter 32 is designed to provide a stop for the first anti-twisting device 26 arranged on the first axial end section 14a of the push rod 14.

An axial position of the retraction limit 32 and/or the extension limit 30 is adjustable. The retraction limit 32 and/or the extension limit 30 also has an end position damping.

The drive unit also has an electrical machine arranged axially parallel to the longitudinal axis of the push rod 14, which is connected to a ball screw drive 40 by means of a toothed belt 38. A ball nut 42 of the ball screw drive 40 is designed to translate a rotation of the ball nut 42 caused by the toothed belt 38 into a translational movement of the push rod 14 engaged with the ball nut 42.

The electric machine provides torque and angle of rotation, transmitting both via a belt stage to an axis-parallel ball nut 42.

The ball nut 42 is rotatably mounted in the housing 10 of the single wheel actuator 1, but is essentially not axially displaceable. The ball nut 42 transmits the rotational movement via balls to an axially movable push rod 14, which has a ball thread on the circumference that is operatively connected to the balls.

The push rod 14 is prevented from rotating relative to the housing 10 by a positive-locking complementary form of bushing
and housing guide. The anti-twisting device also serves as a radial bearing. The push rod 14 is thus set in an axial movement when the ball nut 42 rotates. The push rod 14 extends and retracts from the housing 10, making the single wheel actuator 1 telescopic.

At the wheel-side end of the push rod 14 is the joint head 18, which is formed by a ball and also allows two rotational movements perpendicular to the push rod axis. A pin of the joint head is mounted in the wheel carrier 16.

2 shows a schematic representation of a body suspension 24 of the independent wheel actuator 1 for the steering system according to the first embodiment of the invention.

The individual wheel actuator 1 further comprises a suspension 24 at a third axial end section 22, which is designed to suspend the individual wheel actuator 1 on the body in a pendulum manner, wherein a degree of freedom of a pendulum movement is defined by a first pivot axis A1 arranged substantially perpendicular to a longitudinal axis of the push rod 14 and a second pivot axis A2 arranged substantially perpendicular to the longitudinal axis of the push rod 14.

The first pivot axis A1 is arranged substantially perpendicular to the second pivot axis. Optionally, it can be provided that the first pivot axis and/or the second pivot axis intersect with the longitudinal axis of the push rod.

The first pivot axis A1 and the second pivot axis A2 of the single wheel actuator 1 are arranged adjacent to a connection of an electrical line 34 of the drive unit.

The suspension 24 of the single wheel actuator 1 ensures the degrees of freedom of rotation about the two axes. These two axes also prevent rotation of the entire actuator about the push rod axis or rotation of the entire actuator about a push rod axis.

3 shows a schematic representation of the individual wheel actuator 101 for the steering system according to a second embodiment of the invention.

The drive unit has an electrical machine arranged axially parallel to the longitudinal axis of the push rod 14, which is connected to a planetary roller screw drive 44 by means of a toothed belt 38. The planetary roller screw drive 44 is designed to translate a rotation of the planetary roller screw drive 44 caused by the toothed belt 38 into a translational movement of the push rod 14 engaged with the planetary roller screw drive 44.

The individual wheel actuator 101 further comprises a suspension 124 at a third axial end portion 122, which is designed to suspend the individual wheel actuator 1 on the body in a pendulum manner, wherein a degree of freedom of a pendulum movement is defined by a first pivot axis A1 arranged substantially perpendicular to a longitudinal axis of the push rod 14 and a second pivot axis A2 arranged substantially perpendicular to the longitudinal axis of the push rod 14.

Furthermore, a first anti-twisting device 126 is arranged on the first axial end section 14a of the push rod 14, which is designed to arrange the push rod 14 in a rotationally fixed manner relative to the housing by means of a complementary shape of the first anti-twisting device 126 and the push rod 14. The first anti-twisting device 126 is designed to radially support the push rod 14 in the housing interior 12 and to secure it against rotation.

The housing 10 also has an extension limiter 130 of the push rod 14 formed by a plate. The extension limiter 130 is designed to provide a stop for the first anti-twisting device 126 arranged on the first axial end section 14a of the push rod 14.

The housing 10 further comprises a retraction limiter 132 on a section arranged adjacent to the suspension 124 of the single wheel actuator 1. The retraction limiter 132 is designed to provide a stop for the first anti-twisting device 126 arranged on the first axial end section 14a of the push rod 14.

An axial position of the retraction limit 132 and/or the extension limit 130 is adjustable. The retraction limit 132 and/or the extension limit 130 also has an end position damping.

4 shows a schematic representation of the individual wheel actuator 201 for the steering system according to a third embodiment of the invention.

The drive unit also has an electric machine arranged concentrically to the longitudinal axis of the push rod 14, which has a hollow shaft for internally receiving the push rod 14.

The individual wheel actuator 201 further comprises a suspension 224 at a third axial end section 222, which is designed to suspend the individual wheel actuator 1 on the body in a pendulum manner, wherein a degree of freedom of a pendulum movement is defined by a first pivot axis A1 arranged substantially perpendicular to a longitudinal axis of the push rod 14 and a second pivot axis A2 arranged substantially perpendicular to the longitudinal axis of the push rod 14.

The first pivot axis A1 and the second pivot axis A2 of the single wheel actuator 201 are further arranged along an axial length of the electric machine 236.

At the wheel end of the push rod 14 there is a universal joint 19, which has two rota tion movements perpendicular to the push rod axis. A second anti-twisting device 228 of the push rod 14 is arranged on the second axial end section 14b of the push rod 14.

The electric machine is coupled to a planetary roller screw drive 46 arranged concentrically to the longitudinal axis of the push rod 14, which is designed to translate a rotation of the planetary roller screw drive 46 caused by the electric machine into a translational movement of the push rod 14 engaged with the planetary roller screw drive 46. As an alternative to the planetary roller screw drive 46, a ball screw drive can be provided.

The electric machine provides torque and angle of rotation, transferring both to a nut of the planetary roller screw drive 46. This is rotatably mounted, but essentially not axially displaceable. The nut transfers the rotational movement via threaded push rods to an axially movable threaded rod, which has a thread on the circumference. The rod is secured against rotation at the interface to the wheel carrier 16.

The supporting torque is provided by the wheel carrier 16. Thus, the push rod 14 is set in an axial movement when the nut rotates. The push rod 14 extends and retracts from the housing 10, whereby the individual wheel actuator 201 becomes telescopic.

A further shortening of the overall length of the single wheel actuator 201 is achieved by the absence of a second push rod bearing. The bearing of the push rod 14 is taken over directly by the planetary roller screw drive, which in turn is attached to the body via the housing 10 in an articulated and torsion-proof manner.

In this respect, it is expedient if the pivot axes are placed close to the nut in order to ensure that the smallest possible bending moment is transferred to the housing 10 via the planetary roller screw drive 44, particularly in the case of dynamic force excitations perpendicular to the rod axis. The stop positions of the wheel are determined by the holding torque of the electric machine. An additional mechanical stop limitation can be implemented at the end of the electric machine via a stop point fixed to the housing and/or a sleeve between the wheel carrier 16 and the electric machine.

5 shows a schematic representation of the individual wheel actuator 301 for the steering system according to a fourth embodiment of the invention.

According to the present embodiment, the single wheel actuator 301 has an alternative anti-twisting device, which is implemented by complementary shapes between an inner contour of the push rod 14 designed as a hollow shaft and a rod guided inside the push rod 14.

The electric machine is coupled to a ball screw drive 40 arranged concentrically to the longitudinal axis of the push rod 14, which is designed to translate a rotation of the P ball screw drive 40 caused by the electric machine into a translational movement of the push rod 14 engaged with the ball screw drive 40. As an alternative to the ball screw drive 40, a planetary roller screw drive can be provided.

The first pivot axis A1 and the second pivot axis A2 of the single wheel actuator 301 are further arranged along an axial length of the electric machine 336.

At the wheel-side end of the push rod 14 is the joint head 18, which is formed by a ball and also allows two rotational movements perpendicular to the push rod axis. A pin of the joint head is mounted in the wheel carrier 16.

A second anti-twisting device 328 of the push rod 14 is arranged on the second axial end section 14b of the push rod 14, in particular adjacent to the joint head 18.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• DE 102020213664 A1 [0008]

Claims (14)

Single wheel actuator (1, 101, 201, 301) for a steering system, in particular a steer-by-wire steering system, of a motor vehicle, with: a housing (10) and a push rod (14) arranged at least in sections in a housing interior (12), which is mounted in the housing (10) and is connected at a second axial end section (14b) arranged opposite to the first axial end section (14a) to a universal joint (19) or joint head (18) that can be coupled to a wheel carrier (16); and a drive unit (20, 120, 220, 320) which is designed to carry out an axial movement of the push rod (14) from a first position arranged essentially in the housing interior (12) to a second position which is essentially extended out of the housing (10), wherein the single wheel actuator (1, 101, 201, 301) has a suspension (24, 124, 224, 324) at a third axial end section (22, 122, 222, 322), which is designed to suspend the single wheel actuator (1, 101, 201, 301) on the body in a pendulum-like manner, wherein a degree of freedom of a pendulum movement is determined by a first pivot axis (A1) arranged essentially perpendicular to a longitudinal axis of the push rod (14) and a second pivot axis arranged essentially perpendicular to the longitudinal axis of the push rod (14). (A2) is defined. Single wheel adjuster after Claim 1 , wherein the first pivot axis (A1) is arranged substantially perpendicular to the second pivot axis (A2). Single wheel adjuster after Claim 1 or 2 , wherein the first pivot axis (A1) and/or the second pivot axis (A2) intersects with the longitudinal axis of the push rod (14). Single wheel actuator according to one of the preceding claims, wherein a first anti-twisting device (26, 126) is arranged on the first axial end section (14a) of the push rod (14), which is designed by means of a complementary shape of the first anti-twisting device (26, 126) and the push rod (14) to arrange the push rod (14) in the housing (10) in a rotationally fixed manner. Single wheel adjuster after Claim 3 , wherein the first anti-twisting device (26, 126) is designed to radially mount the push rod (14) in the housing interior (12). Single wheel actuator according to one of the Claims 1 until 3 , wherein a second anti-twisting device (228) of the push rod (14) is arranged at the second axial end portion (14b) of the push rod (14). Single wheel actuator according to one of the Claims 4 until 6 , wherein the housing (10) has an extension limit (30, 130) of the push rod (14) formed by a plate, which is designed to provide a stop for the first anti-twisting device (26, 126) arranged on the first axial end section (14a) of the push rod (14). Single wheel actuator according to one of the Claims 4 until 7 , wherein the housing (10) has a retraction limiter (32, 132) on a section arranged adjacent to the suspension (24, 124) of the individual wheel actuator (1, 101), which is designed to provide a stop for the first anti-twisting device (26, 126) arranged on the first axial end section (14a) of the push rod (14). Single wheel adjuster after Claim 7 or 8th , wherein an axial position of the retraction limit (32, 132) and/or the extension limit (30, 130) is adjustable, and wherein the retraction limit (32, 132) and/or the extension limit (30, 130) has an end position damping. Single wheel actuator according to one of the preceding claims, wherein the first pivot axis (A1) and the second pivot axis (A2) of the single wheel actuator (1, 101) are arranged adjacent to a connection of an electrical line (34, 134) of the drive unit (20, 120) or along an axial length of the electrical machine (236, 336). Single wheel actuator according to one of the preceding claims, wherein the drive unit (20) has an electric machine (36) arranged axially parallel to the longitudinal axis of the push rod (14), which is connected to a ball screw drive (40) by means of a toothed belt (38), wherein a ball nut (42) of the ball screw drive (40) is designed to translate a rotation of the ball nut (42) caused by the toothed belt (38) into a translational movement of the push rod (14) engaged with the ball nut (42). Single wheel actuator according to one of the Claims 1 until 10 , wherein the drive unit (120) has an electric machine (136) arranged axially parallel to the longitudinal axis of the push rod (14), which is connected by means of a toothed belt (38) to a planetary roller screw drive (44) which is designed to translate a rotation of the planetary roller screw drive (44) caused by the toothed belt (38) into a translational movement of the push rod (14) engaged with the planetary roller screw drive (44). Single wheel actuator according to one of the Claims 1 until 10 , wherein the drive unit (220, 320) has an electrical machine (236, 336) arranged concentrically to the longitudinal axis of the push rod (14), which has a hollow shaft for internally receiving the push rod (14), wherein the electrical machine is coupled to a planetary roller screw drive (46) or ball screw drive (40) arranged concentrically to the longitudinal axis of the push rod (14), which is designed to translate a rotation of the planetary roller screw drive (46) or ball screw drive (40) caused by the electrical machine into a translational movement of the push rod (14) engaged with the planetary roller screw drive or ball screw drive (46). Steering system, in particular a steer-by-wire steering system, for a motor vehicle, with a plurality of individual wheel actuators (1, 101, 201, 301) according to one of the Claims 1 until 13 which are designed to steer the wheel connected to a respective individual wheel actuator (1, 101, 201, 301).

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