Actuator device for an electromechanical steering system

Abstract

Actuator device (1) for an electromechanical steering arrangement of a motor vehicle, comprising a reduction gear and a drive unit (13) operatively connected thereto, characterized in that the reduction gear has at least one first spindle drive (2), wherein the at least first spindle drive (2) has an axially fixed and at least indirectly rotatable first threaded nut (4), an axially fixed and rotatable second threaded nut (5), and a first threaded spindle (8) longitudinally displaceable relative to the threaded nuts (4, 5) with a first spindle section (10) and a second spindle section (11) arranged non-rotatably thereto, wherein the first spindle section (10) is operatively connected to the first threaded nut (4) and the second spindle section (11) is operatively connected to the second threaded nut (5).and wherein a rotary actuation of the first threaded nut (4) sets the first threaded spindle (8) into a longitudinal movement, which in turn causes a rotational movement of the second threaded nut (5).

Description

[0001] The invention relates to an actuator device for an electromechanical steering arrangement of a motor vehicle. Furthermore, the invention relates to an electromechanical steering arrangement comprising such an actuator device, as well as to a motor vehicle having such a steering arrangement.

[0002] In motor vehicles with electromechanical steering systems, a steering command manually initiated by the driver into the steering wheel is detected by sensors and transmitted electrically via a control unit to an electromechanical steering actuator, which executes the steering command mechanically. The steering wheel is mechanically decoupled from the chassis, and the vehicle's steering is controlled electronically. Such purely electronic steering systems are also called steer-by-wire steering systems. The advantage is that a mechanical connection between the individual steering components, such as a steering column, is eliminated, making the entire steering system more compact and, above all, lighter.

[0003] Due to the mechanical decoupling of the steering wheel from the chassis, no force feedback is initially available at the steering wheel when the steering actuator is operated and the wheel angle is adjusted, although this is generally desirable. The lack of haptic feedback makes it difficult for the driver to reliably assess current driving situations and perform appropriate steering maneuvers, which impairs vehicle steerability and thus driving safety.

[0004] To achieve force feedback or restoring torque, also known as force feedback, even with an actuator module that is mechanically decoupled from the steering wheel, a force feedback actuator is provided. This actuator is designed to generate a driving-situation-dependent force feedback or restoring torque at the steering shaft or directly at the steering wheel, which provides haptic force feedback for the driver. In other words, a familiar steering feel is replicated for the driver by adjusting a restoring torque on the steering wheel.

[0005] DE 10 103 667 A1 discloses an actuator for a steer-by-wire steering system of a vehicle. The steering system comprises an output shaft, an electric drive, and a reduction gear between the electric drive and the output shaft. The electric drive has at least two electric motors.

[0006] DE 10 2009 028 568 A1 discloses a device for locking a linear actuator, comprising a motor-driven, non-self-locking travel screw whose spindle forms the main output. The device is characterized by the fact that it additionally contains a self-locking travel screw whose spindle or nut is connected to the motor via a gear, either permanently or via a switchable coupling that is open when de-energized. A special feature is that the component of the self-locking travel screw that is not connected to the motor forms a stop for the spindle, which is axially adjusted according to the targeted axial displacement of the spindle while simultaneously being self-locking.

[0007] DE 10 2018 111 035 A1 discloses a ball screw drive with a right-hand-left thread, which comprises a spindle with a left-hand thread groove and a right-hand thread groove. The spindle is received in a first nut with a through-opening, wherein the inner side of the first nut has a thread groove which, together with the left-hand thread groove of the spindle, forms a first spiral channel. This first spiral channel is part of a closed first ball orbit assigned to the first nut. In addition, a second nut is provided, which also has a through-opening and a thread groove which, together with the right-hand thread groove of the spindle, forms a second spiral channel, which is part of a closed second ball orbit. The spindle has an overlap region in which the left-hand and right-hand thread grooves overlap.

[0008] DE 10 2013 212 209 B3 discloses an actuator comprising a first and a second contact element, wherein an adjustment device is provided for moving the second contact element relative to the first in a translational displacement direction. The adjustment device includes a support element arranged between the two contact elements, a drive motor, and two rotatably mounted spindle nuts driven by the drive motor. Furthermore, two limit switches are provided that limit the displacement path between the contact elements. These limit switches are attached to a switch carrier that is mounted on the support element.

[0009] DE 200 21 675 U1 discloses a device comprising a machine bed and a column oriented in an upright position, which extends along a first coordinate axis (Z-axis). The column contains counter-rotating threads consisting of a positive threaded portion and a counter-threaded portion, which are rotatably mounted along the Z-axis. Furthermore, the document describes a worktable assembly that can be moved back and forth along the Z-axis, as well as a toolholder assembly that also moves along the Z-axis, but in the opposite direction to the worktable assembly.

[0010] DE 103 26 179 A1 discloses a rolling element thread device comprising a spindle with a spindle axis and two different, helical rolling element grooves. The device also includes a first and a second rolling element nut, which are designed as threaded nuts and are rotatable independently of each other. Through the coordinated rotation of the two threaded nuts, the spindle can be displaced along its spindle axis or rotated about it.

[0011] EP 0 251 884 B1 discloses a control device for the simultaneous longitudinal movement of multiple elements at different speeds. This device comprises a screw with at least two threads of different pitches, on which at least two nuts with corresponding pitches move. The threads of the screw are designed to have a flat thread profile and are intertwined, whereby the threads of one thread cross those of the other in the same direction but with different pitches. The outer surface of the screw forms a cylindrical shell with a constant cross-section over its entire length.

[0012] The object of the present invention is to provide an actuator device for an electromechanical steering assembly without gear play and with reduced torque fluctuations. This object is achieved by an actuator device having the features of claim 1 and by an electromechanical steering assembly having the features of claim 10. Preferred or advantageous embodiments of the invention emerge from the subclaims, the following description, and the accompanying figures.

[0013] An actuator device according to the invention for an electromechanical steering arrangement of a motor vehicle comprises, according to a first aspect of the invention, a reduction gear and a drive unit operatively connected thereto, wherein the reduction gear has at least one first spindle drive, wherein the at least first spindle drive has an axially fixed and at least indirectly rotatably drivable first threaded nut, an axially fixed and rotatably drivable second threaded nut, and a first threaded spindle that is longitudinally displaceable relative to the threaded nuts and has a first spindle section and a second spindle section that is arranged in a rotationally fixed manner thereto, that the first spindle section is operatively connected to the first threaded nut and the second spindle section is operatively connected to the second threaded nut, and that a rotational actuation of the first threaded nut sets the first threaded spindle in a longitudinal movement,which in turn causes a rotational movement of the second threaded nut. The actuator device advantageously functions as a force-feedback actuator in a steer-by-wire system.

[0014] The first spindle drive of the reduction gear is designed in two stages, whereby a torque introduced into the first threaded nut is converted by the reduction gear with a specific transmission ratio and transmitted to the output of the reduction gear.

[0015] An at least indirect manual rotation of the axially immovable first threaded nut about its own longitudinal axis sets the first threaded spindle of the first spindle drive, which is operatively connected thereto, into a longitudinal movement relative to the first and second threaded nuts, wherein the first threaded spindle, as a result of its axial movement, sets the second threaded nut, which is also axially immovable but rotatably arranged and operatively connected thereto, into a rotational movement about its own longitudinal axis.

[0016] The first threaded nut is understood as a manually operable drive element of the actuator device, via which a user of the steering assembly can introduce a torque into the reduction gear. In this case, the second threaded nut serves as the output element of the actuator device. Conversely, drive power can be introduced into the reduction gear by the drive unit, so that in this case, the first threaded nut functions as the output of the reduction gear, whereby the user of the steering assembly can haptically perceive the torque applied to the first threaded nut as resistance.

[0017] The first spindle drive is designed as a screw drive and has a limited stroke that correlates with the desired number of revolutions on the steering wheel or the first threaded nut. This also allows for the integration of a mechanical end stop into the first spindle drive. The position of the respective end stop limits the travel of the threaded spindle. Alternatively, the end stop can be a shaped element that limits the axial movement of the first threaded spindle.

[0018] The drive unit is preferably controllable by a control unit in order to generate a restoring torque, for example as a function of a steering angle of steerable wheels of the vehicle and / or a rotational position of one or more threaded nuts, in order to provide the user with a familiar driving or steering feeling by means of haptic feedback during use of the steering arrangement, in particular during a steering operation.

[0019] According to one embodiment, the drive unit is operatively connected to the first threaded nut or to the second threaded nut via a first gear stage. The drive unit therefore acts either on the first threaded nut of the first spindle drive or on the second threaded nut of the first spindle drive. The first gear stage can be designed as a belt drive, in particular as a traction drive, or as a friction gear or the like. The first gear stage can realize a gear ratio of 1:1. However, different gear ratios are also possible. Accordingly, the drive unit is arranged offset axially parallel to a longitudinal or rotational axis of the first spindle drive, thereby achieving an axially compact design of the actuator device.

[0020] The desired increase or decrease ratio of the reduction gear can be set differently. In one embodiment, a thread of the first spindle section has a first pitch angle, while a thread of the second spindle section has a second pitch angle, and the first and second pitch angles are unequal. The pitch angles of the threads of the spindle sections of the first spindle drive are designed such that a slight rotation of the first threaded nut is converted into a correspondingly larger rotation of the second threaded nut.

[0021] Alternatively or additionally, the first spindle section has a smaller outer diameter than the second spindle section, which also allows a specific increase or decrease ratio to be set. By combining different outer diameters and different pitch angles on the threads of the spindle sections, comparatively high reduction ratios can be achieved even with a two-stage first spindle drive.

[0022] In an alternative embodiment, the reduction gear further comprises, in addition to the first spindle drive, a second spindle drive operatively connected to the first spindle drive, wherein the second spindle drive comprises an axially fixed and at least indirectly rotatably drivable third threaded nut, an axially fixed and rotatably drivable fourth threaded nut, and a second threaded spindle which is longitudinally displaceable relative to the third and fourth threaded nuts and has a third spindle section and a fourth spindle section arranged in a rotationally fixed manner thereto, wherein the third spindle section is operatively connected to the third threaded nut and the fourth spindle section is operatively connected to the fourth threaded nut, wherein the third threaded nut is operatively connected to the second threaded nut of the first spindle drive via a second gear stage, wherein the second gear stage is designed toto transmit the rotational movement of the second threaded nut of the first spindle drive to the third threaded nut of the second spindle drive, wherein a rotational movement of the third threaded nut sets the second threaded spindle into a longitudinal movement, which in turn causes a rotational movement of the fourth threaded nut.

[0023] In this case, the reduction gear is designed with four stages, namely a two-stage first spindle drive and a two-stage second spindle drive, with the two spindle drives connected in series. The reduction gear converts a torque applied by the user to the first threaded nut through the reduction gear at a specific gear ratio. This allows the gear ratio spread to be increased. Conversely, the drive unit can transmit a restoring torque to the first threaded nut via the reduction gear.

[0024] The second gear stage can be designed, analogously to the first gear stage, as a belt drive, in particular as a traction drive, or as a friction gear or the like. The second gear stage can achieve a gear ratio of 1:1. However, different gear ratios are also possible. This allows the two spindle drives to be arranged offset from one another, parallel to their axes. In particular, the two spindle drives can be arranged axially overlapping, thereby achieving an axially compact design of the actuator device. The second gear stage can also be designed such that the spindle drives are arranged coaxially and axially adjacent to one another.

[0025] At least an indirect manual rotation of the axially immovable first threaded nut about its own longitudinal axis sets the first threaded spindle of the first spindle drive into a longitudinal movement relative thereto. As a result of its axial movement, the first threaded spindle sets the likewise axially immovable but rotatable second threaded nut into a rotational movement about its own axis of rotation. The second gear stage transmits the rotational movement of the second threaded nut to the third threaded nut, preferably in the same direction of rotation.In an analogous manner, the second threaded spindle of the second spindle drive is set into a longitudinal movement relative to the third and fourth threaded nuts by the rotation of the third threaded nut operatively connected thereto, whereby the second threaded spindle, as a result of its axial movement, sets the fourth threaded nut, which is also axially immovable but rotatable and operatively connected thereto, into a rotational movement about its own longitudinal axis.

[0026] In this case, the first threaded nut of the first spindle drive is to be understood as a manually operable drive element of the actuator device, whereas the fourth threaded nut of the second spindle drive in this case serves as the output element of the actuator device.

[0027] Preferably, a thread of the third spindle section has a third pitch angle, while a thread of the fourth spindle section has a fourth pitch angle, wherein the third and fourth pitch angles are unequal. The threads are preferably external threads. The pitch angles of the threads of the spindle sections of the first and second spindle drive are designed such that a slight rotation of the first threaded nut is converted into a correspondingly larger rotation of the fourth threaded nut.

[0028] Alternatively or additionally, the third spindle section has a smaller outer diameter than the fourth spindle section. By combining different outer diameters and different pitch angles on the threads of the spindle sections, the reduction ratio can be further increased with the two two-stage spindle drives compared to the first embodiment with only one spindle drive.

[0029] Preferably, the drive unit is operatively connected to the first, second, third, or fourth threaded nut via a third gear stage. The third gear stage can achieve a gear ratio of 1:1. However, other gear ratios are also possible. The third gear stage can be designed as a belt drive, in particular as a traction drive, or as a friction gear or the like. Accordingly, the drive unit is arranged offset axially parallel to a longitudinal or rotational axis of the first and / or second spindle drive, thereby achieving an axially compact design of the actuator device.

[0030] In principle, for all embodiments, the drive unit can be connected at any point in the power flow of the reduction gear. However, the drive unit can be designed more compactly and / or with lower performance if the gear ratio of the reduction gear is utilized to transmit the restoring torque. For the design alternative with exactly one first spindle drive, this means that the drive unit is advantageously connected to the second threaded nut. For the design alternative with two operatively connected spindle drives, this means that the drive unit is advantageously connected to the third threaded nut, preferably to the fourth threaded nut.

[0031] Preferably, the first threaded nut is connected in a rotationally fixed manner to a rotatably mounted drive component. The drive component is particularly designed to be set into a rotational movement at least indirectly manually, i.e., by the user of the steering assembly. The drive component can be tubular or sleeve-shaped. The drive component is preferably designed to be connected at least indirectly in a rotationally fixed manner to a steering wheel of the motor vehicle. The first threaded nut is preferably arranged spatially within the drive component, preferably pressed therein, i.e., connected at least non-positively.

[0032] Preferably, the second, third, and / or fourth threaded nut is also spatially arranged within a rotatably mounted receiving tube and is connected thereto in a rotationally fixed manner. The receiving tube can be provided or configured to interact with a gear stage and transmit the forces from the respective threaded nut. A receiving tube can achieve a more uniform power transmission.

[0033] Preferably, the respective spindle drive is designed as a rolling contact drive, a recirculating ball drive, a planetary rolling contact drive, or the like. If the spindle drive is designed as a recirculating ball drive, a plurality of rolling elements are arranged between the respective threaded spindle and the associated threaded nuts. In this sense, the respective spindle drive is preferably designed as a recirculating ball drive or a ball screw drive.

[0034] A ball screw drive can transmit high axial and radial forces. It also enables low-backlash, low-noise operation of the actuator device. By appropriately selecting the rolling elements, the friction behavior of each spindle drive can be precisely adjusted. Due to the elastic behavior of the rolling elements, even surface smoothing of the rolling partners that occurs over their service life does not lead to noise or play in the ball screw drive. Using a ball screw drive without a ball return system also allows for a particularly smooth running. The smaller the thread pitch, the higher the efficiency of the actuator device. Alternatively, the screw drive could be designed as a sliding screw drive, particularly as a trapezoidal screw drive.

[0035] The term "operatively connected" means that two transmission elements can be directly connected to one another, or that there are additional transmission elements between two transmission elements, for example, one or more shafts or wheels, in particular gears or belt pulleys. An operative connection is therefore understood to mean either a direct or at least an indirect connection between two elements. Thus, the two operatively connected elements can be connected either directly or via additional elements.

[0036] It is also conceivable for the actuator device to have three or more spindle drives, with each additional spindle drive having two threaded nuts and a threaded spindle. The spindle drives are connected in series, i.e., arranged one behind the other in the power flow.

[0037] According to a further aspect, the invention relates to an electromechanical steering arrangement for a motor vehicle, comprising an actuator device according to the preceding embodiments. It is conceivable to install the actuator device in the steering column or steering shaft arranged on the steering wheel, or to arrange it within the steering wheel. The first threaded nut can be connected to the steering wheel directly or via a shaft.

[0038] According to a further aspect of the invention, the invention relates to a motor vehicle, in particular a passenger car, a commercial vehicle or a truck, comprising such an electromechanical steering arrangement.

[0039] Further measures improving the invention are described in more detail below together with the description of two preferred embodiments of the invention with reference to the two figures. Fig. 1 a simplified schematic longitudinal sectional view of an actuator device according to the invention for an electromechanical steering arrangement of a motor vehicle according to a first embodiment, and Fig. 2 a simplified schematic longitudinal sectional view of the actuator device according to the invention according to a second embodiment.

[0040] According to the Fig. 1 and Fig. 2 shows two different embodiments of an actuator device 1 according to the invention for an electromechanical steering arrangement of a motor vehicle (not shown in detail here).

[0041] After Fig. 1, the actuator device 1 comprises a reduction gear configured as a first spindle drive 2 and a drive unit 13 operatively connected thereto. The drive unit 13 is an electric motor comprising a stator (not shown here) fixed to the housing, and a rotor (also not shown here) rotatably mounted relative to the stator. By energizing and controlling the stator, the rotor is set in rotation, allowing torque to be transmitted to the reduction gear. The drive unit 13 is controllable by a control unit (not shown here).

[0042] The first spindle drive 2 is designed in two stages and has an axially immovable and at least indirectly rotatably drivable first threaded nut 4, a second threaded nut 5 axially adjacent thereto, which is likewise axially immovable and rotatably drivable, and a first threaded spindle 8 that is longitudinally displaceable relative to the threaded nuts 4, 5. The first threaded spindle 8 has a first spindle section 10 with an external thread 10a and a second spindle section 11 with an external thread 11a that is integrally connected thereto. The first spindle section 10 projects axially into the first threaded nut 4 at least in sections, and the second spindle section 11 projects axially into the second threaded nut 5 at least in sections. Thus, the two threaded nuts 4, 5 of the first spindle drive 2 are sleeve-shaped and radially enclose the first threaded spindle 8.The first spindle section 10 also has a smaller outer diameter than the second spindle section 11.

[0043] The first spindle drive 2 is designed as a ball screw drive, wherein a plurality of rolling elements - not shown here - are arranged spatially between the first spindle section 10 of the first threaded spindle 8 and the first threaded nut 4, and wherein a plurality of rolling elements - also not shown here - are arranged spatially between the second spindle section 11 of the first threaded spindle 8 and the second threaded nut 5.

[0044] The two threaded nuts 4, 5 each have an internal thread 4a, 5a complementary to the external threads 10a, 11a of the two spindle sections 10, 11. The external thread 10a of the first spindle section 10 is thus operatively connected to the internal thread 4a of the first threaded nut 4 for torque transmission. The external thread 11a of the second spindle section 11 is operatively connected to the internal thread 5a of the second threaded nut 5 for torque transmission. Furthermore, the pitch angle of the external thread 10a of the first spindle section 10 and the pitch angle of the external thread 11a of the second spindle section 11 are unequal. Relative to a rotational axis A1 of the first spindle drive 2, the pitch angle of the external thread 11a of the second spindle section 11 is greater than the pitch angle of the external thread 10a of the first spindle section 10. The different pitch angles are shown in Fig. 1 by three parallel lines on the first and second spindle sections 10, 11, respectively. The first threaded nut 4 is connected in a rotationally fixed manner to a rotatably mounted drive component 19, which is, for example, a steering shaft, which can be at least indirectly connected in a rotationally fixed manner to a steering wheel of the motor vehicle (not shown here).

[0045] Upon manual actuation of the drive component 19 by the user of the steering assembly, the first threaded nut 4 is set into a rotational movement about the rotation axis A1, whereby the first threaded spindle 8 is set into a longitudinal or axial movement along the rotation axis A1 by the rotational actuation of the first threaded nut 4. The longitudinal movement of the first threaded spindle 8, in turn, causes a rotational movement of the second threaded nut 5 about the rotation axis A1.

[0046] The drive unit 13 is connected to the second threaded nut 5 via a first gear stage 15 designed as a belt drive. The first gear stage 15 comprises an input shaft 20, which is at least indirectly connected in a rotationally fixed manner to a rotor shaft (not shown here) of the drive unit 13. A first pulley 21 is attached to the input shaft 20. This first pulley transmits the drive power of the drive unit 13 via a first belt 23 to a second pulley 22, which is arranged in a rotationally fixed manner on the outer circumference 24 of the second threaded nut 5.

[0047] Depending on the current driving situation of the motor vehicle, a restoring torque perceptible by the user of the steering arrangement can be generated via the drive unit 13, so that the user haptically perceives a driving or steering feeling that is familiar to him despite the mechanical decoupling of the steering wheel from the steerable wheels of the motor vehicle.

[0048] At each end of the first spindle drive 2, an end stop 30a, 30b is arranged to limit the axial travel of the first threaded spindle 8. The end stops 30a, 30b have axial end faces, with the threaded spindle 8 having end faces complementarily formed thereto.

[0049] The Fig. The embodiment shown in Figure 2 is based on the Fig. 1. The structure of the first spindle drive 2 is identical with the exception of the connection of the drive unit 13 to the reduction gear, so reference is made to the above explanations to avoid repetition.

[0050] After Fig. 2, the reduction gear of the actuator device 1 has, in addition to the first spindle drive 2, a second spindle drive 3 operatively connected thereto. The second spindle drive 3 is also designed in two stages and has an axially immovable and at least indirectly rotationally drivable third threaded nut 6, a fourth threaded nut 7 axially adjacent thereto, which is likewise axially immovable and rotationally drivable, and a second threaded spindle 9 which is longitudinally displaceable relative to the threaded nuts 6, 7. The second threaded spindle 9 has a third spindle section 12 with an external thread 12a and a fourth spindle section 14 with an external thread 14a, which is connected in one piece thereto. The third spindle section 12 projects axially into the third threaded nut 6 at least in sections, and the fourth spindle section 14 projects axially into the fourth threaded nut 7 at least in sections.Thus, the two threaded nuts 6, 7 of the second spindle drive 3 are sleeve-shaped and radially enclose the second threaded spindle 9. The third spindle section 12 also has a smaller outer diameter than the fourth spindle section 14.

[0051] To simplify the production of the reduction gear, the first and third threaded nuts 4, 6 and the second and fourth threaded nuts 5, 7 can each be identically designed. Likewise, the two threaded spindles 8, 9 can be identically designed.

[0052] The second spindle drive 3 is also designed as a ball screw drive, wherein a plurality of rolling elements - not shown here - are arranged spatially between the third spindle section 12 of the second threaded spindle 9 and the third threaded nut 6, and wherein a plurality of rolling elements - also not shown here - are arranged spatially between the fourth spindle section 14 of the second threaded spindle 9 and the fourth threaded nut 7.

[0053] The two threaded nuts 6, 7 each have an internal thread 6a, 7a complementary to the external threads 12a, 14a of the two spindle sections 12, 14. The external thread 12a of the third spindle section 12 is thus operatively connected to an internal thread 6a of the third threaded nut 6 for torque transmission. The external thread 14a of the fourth spindle section 14 is operatively connected to the internal thread 7a of the fourth threaded nut 7 for torque transmission. A pitch angle of the external thread 12a of the third spindle section 12 and a pitch angle of the external thread 14a of the fourth spindle section 14 are unequal. Relative to a rotational axis A2 of the second spindle drive 3, the pitch angle of the external thread 14a of the fourth spindle section 14 is greater than the pitch angle of the external thread 12a of the third spindle section 12. The different pitch angles are in Fig. 2 by three parallel lines on the first and second spindle sections 10, 11, respectively, and on the third and fourth spindle sections 12, 14, respectively. The third threaded nut 6 is spatially accommodated within a rotatably mounted receiving tube 18 and is connected thereto in a rotationally fixed manner.

[0054] However, the receiving tube 18 can be omitted to simplify the construction of the steering arrangement and to save the required installation space.

[0055] Upon manual actuation of the drive component 19 by the user of the steering assembly, the first threaded nut 4 is set into a rotational movement about the rotational axis A1 of the first spindle drive 2, whereby the first threaded spindle 8 is set into a longitudinal or axial movement along the rotational axis A1 by the rotational actuation of the first threaded nut 4. The longitudinal movement of the first threaded spindle 8, in turn, causes a rotational movement of the second threaded nut 5 about the rotational axis A1.

[0056] The second threaded nut 5 is operatively connected to the receiving tube 18 of the second spindle drive 3 via a second gear stage 16 designed as a belt drive. The second gear stage 16 comprises a third belt pulley 26 arranged in a rotationally fixed manner on the outer circumference 24 of the second gear nut 5, which third belt pulley 26 transmits drive power from the first spindle drive 2 to the second spindle drive 3, here a fourth belt pulley 27 arranged in a rotationally fixed manner on the outer circumference 25 of the receiving tube 18, via a second belt 28. The fourth belt pulley 27 can also be arranged in a rotationally fixed manner directly on the outer circumference of the third threaded nut 6. In other words, the second gear stage 16 is designed to transmit the rotational movement of the second threaded nut 5 of the first spindle drive 2 to the third threaded nut 6 of the second spindle drive 3. A rotational movement of the third threaded nut 6 sets the second threaded spindle 9 into a longitudinal movement.The longitudinal movement of the second threaded spindle 9 in turn causes a rotational movement of the fourth threaded nut 7 about the rotation axis A2 of the second spindle drive 3.

[0057] In this embodiment, the drive unit 13 is connected to the fourth threaded nut 7 via a third gear stage 17 designed as a belt drive. The third gear stage 17 is identical to the first gear stage 15 according to Fig. 1, so that the same reference numerals are used for the components of the belt drive. However, the second belt pulley 22 is arranged in a rotationally fixed manner on an outer circumference 29 of the fourth threaded nut 7. The operation of the drive unit 13 is also identical to the embodiments with regard to Fig. 1.

[0058] Of course, it is conceivable that the reduction gear of the actuator device 1 also has more than two spindle drives, which are connected in series and operatively connected to one another via corresponding gear stages. Furthermore, the gear stages can be designed in any desired manner. Other types of traction drives are conceivable, for example, chain drives, friction gears, or the like. Furthermore, it is conceivable that the first threaded nut 4 and the drive component 19 are formed as a single piece, or that the first threaded nut 4 is integrated into a steering shaft of the motor vehicle.

[0059] At both ends of the second spindle drive 3, an end stop 30a, 30b is arranged to limit the axial travel of the second threaded spindle 9. The end stops 30a, 30b have axial end faces, with the second threaded spindle 9 having end faces complementarily formed thereto. Alternatively, the end stops 30a, 30b can be configured analogously to Fig.1 be arranged at the ends of the first spindle drive 2. List of reference symbols 1 actuator device 2 First spindle drive 3 Second spindle drive 4 First threaded nut 4a Internal thread of the first threaded nut 5 Second threaded nut 5a Internal thread of the second threaded nut 6 Third threaded nut 6a Internal thread of the third threaded nut 7 Fourth threaded nut 7a Internal thread of the fourth threaded nut 8 First threaded spindle 9 Second threaded spindle 10 First spindle section 10a Thread or external thread of the first spindle section 11 Second spindle section 11a Thread or external thread of the second spindle section 12 Third spindle section 12a Thread or external thread of the third spindle section 13 Drive unit 14 Fourth spindle section 14a Thread or external thread of the fourth spindle section 15 First gear stage 16 Second gear stage 17 Third gear stage 18 receiving tube 19 Drive component 20 Input shaft 21 First pulley 22 Second pulley 23 First belt 24 Outer circumference of the second threaded nut 25 Outer circumference of the receiving tube 26 Third pulley 27 Fourth pulley 28 Second belt 29 Outer circumference of the second threaded nut 30a, 30b End stop A1 Rotation axis of the first spindle drive A2 Rotation axis of the second spindle drive

Claims

[1] Actuator device (1) for an electromechanical steering arrangement of a motor vehicle, comprising a reduction gear and a drive unit (13) operatively connected thereto, characterized byin that the reduction gear has at least one first spindle drive (2), wherein the at least first spindle drive (2) has an axially fixed and at least indirectly rotationally drivable first threaded nut (4), an axially fixed and rotationally drivable second threaded nut (5) and a first threaded spindle (8) which is longitudinally displaceable relative to the threaded nuts (4, 5) and has a first spindle section (10) and a second spindle section (11) arranged in a rotationally fixed manner thereto, wherein the first spindle section (10) is operatively connected to the first threaded nut (4) and the second spindle section (11) is operatively connected to the second threaded nut (5), and wherein a rotational actuation of the first threaded nut (4) sets the first threaded spindle (8) in a longitudinal movement, which in turn brings about a rotational movement of the second threaded nut (5). [2] Actuator device (1) according to claim 1, characterized bythat a thread (10a) of the first spindle section (10) has a first pitch angle, wherein a thread (11a) of the second spindle section (11) has a second pitch angle, wherein the first and second pitch angles are unequal. [3] Actuator device (1) according to claim 1 or claim 2, characterized by that the first spindle section (10) has a smaller outer diameter than the second spindle section (11). [4] Actuator device (1) according to one of claims 1 to 3, characterized by that the drive unit (13) is operatively connected to the first threaded nut (4) or the second threaded nut (5) via a first gear stage (15). [5] Actuator device (1) according to one of claims 1 to 3, characterized bythat the reduction gear further comprises a second spindle drive (3) operatively connected to the first spindle drive (2), wherein the second spindle drive (3) has an axially fixed and at least indirectly rotatably drivable third threaded nut (6), an axially fixed and rotatably drivable fourth threaded nut (7), and a second threaded spindle (9) which is longitudinally displaceable relative to the third and fourth threaded nuts (6, 7) and has a third spindle section (12) and a fourth spindle section (14) arranged in a rotationally fixed manner thereto, wherein the third spindle section (12) is operatively connected to the third threaded nut (6) and the fourth spindle section (14) is operatively connected to the fourth threaded nut (7), wherein the third threaded nut (6) is operatively connected to the second threaded nut (5) of the first spindle drive (2) via a second gear stage (16), wherein the second gear stage (16) is designed toto transmit the rotational movement of the second threaded nut (5) of the first spindle drive (2) to the third threaded nut (6) of the second spindle drive (3), wherein a rotational movement of the third threaded nut (6) sets the second threaded spindle (9) into a longitudinal movement, which in turn causes a rotational movement of the fourth threaded nut (7). [6] Actuator device (1) according to claim 5, characterized by that a thread (12a) of the third spindle section (12) has a third pitch angle, wherein a thread (14a) of the fourth spindle section (14) has a fourth pitch angle, wherein the third and fourth pitch angles are unequal. [7] Actuator device (1) according to claim 5 or claim 6, characterized by that the third spindle section (12) has a smaller outer diameter than the fourth spindle section (14). [8] Actuator device (1) according to one of claims 5 to 7, characterized bythat the drive unit (13) is operatively connected to the first, second, third or fourth threaded nut (4, 5, 6, 7) via a third gear stage (17). [9] Actuator device (1) according to one of the preceding claims, characterized by that the first threaded nut (4) is connected in a rotationally fixed manner to a rotatably mounted drive component (19). [10] Electromechanical steering arrangement comprising an actuator device (1) according to one of the preceding claims.

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