CN213974162U

CN213974162U - Actuator for steer-by-wire device and steer-by-wire device

Info

Publication number: CN213974162U
Application number: CN202021421336.2U
Authority: CN
Inventors: H·施万肯; R·邓科; F·布林克曼; M·德卡瓦略; H-J·简
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2019-07-19
Filing date: 2020-07-17
Publication date: 2021-08-17
Anticipated expiration: 2030-07-17
Also published as: DE102019210756A1; DE102019210756B4

Abstract

An actuator (20) of a steer-by-wire apparatus, the actuator having a spindle driver (21) having: a spindle (22) with a spindle thread (22g) axially displaceable relative to the actuator (20); and a spindle nut (23) which is mounted in a positionally fixed manner in the actuator (20) and has a nut thread (23g), wherein at least in the region of the end faces (23s, 24s) of the spindle nut (23) scraping elements (227, 327, 427, 225, 325, 425) are arranged, wherein the scraping elements (227, 327, 427, 225, 325, 425) surround the spindle (22) and have at least one radially inwardly extending scraping lip (226, 326, 426, 228, 328, 428). The scraping lip touches the spindle (22) at least partially and only at the top circle (22k) of the spindle.

Description

Actuator for steer-by-wire device and steer-by-wire device

Technical Field

The utility model relates to a drive-by-wire turns to actuator and drive-by-wire of device and turns to the device.

Background

It is known from the prior art to provide a sealing element in a spindle drive which is formed by a fixedly mounted spindle nut and an axially displaceable spindle only, in order to retain a lubricating material or lubricant within the end-side boundary of the spindle nut. It is thus possible to achieve a continuous supply of lubricant to the transmission thread formed by the nut thread and the external thread of the spindle. Especially in the case of high friction of the spindle drive, for example formed by self-locking trapezoidal threads, lubricants are necessary for reducing the friction. Furthermore, the lubricant prevents premature wear of the spindle drive. High lateral forces are generated due to the wheels of the vehicle when turning. Furthermore, the steering device in a motor vehicle is guided by the wheels so that the steering device must be able to receive lateral forces. Here, an unintentional adjustment of the wheel steering angle should be prevented. Thus, a trapezoidal thread spindle drive is suitable, since it is self-locking and therefore no further locking mechanism has to be provided.

A spindle drive and an actuator having such a spindle drive are known, for example, from DE 102016209036 a 1. On the end side of the fixedly supported spindle nut, sealing elements are provided which engage between the flanks of the spindle thread and reach the thread root (root circle). By these sealing and scraping elements (extractions) the lubrication material is prevented from being squeezed out of the lateral boundaries of the spindle nut. When designing the radially inwardly projecting sealing and scraping lips, it is noted that they have the same thread pitch and are designed such that the sealing and scraping lips form at least one thread turn. However, additional friction is generated in the spindle drive due to the engagement between the sides. Therefore, the efficiency of the steer-by-wire apparatus is low. Furthermore, in the event of a change in the direction of rotation of the spindle nut, the sealing and scraping lips snapping or briefly slipping out of the thread can lead to premature wear of the sealing elements and to an insufficient supply of lubricant.

SUMMERY OF THE UTILITY MODEL

The object of the invention is to improve a sealing element such that on the one hand a sufficient sealing effect is obtained, while on the other hand the sealing element has a significantly longer durability and exhibits here less friction than conventional sealing elements for spindle drives.

In order to achieve this object, an actuator for a steer-by-wire steering device and such a steering device are proposed.

The utility model relates to an actuator of steer-by-wire device, the actuator has spindle drive, spindle drive has: a spindle with spindle threads axially displaceable relative to the actuator; and a spindle nut with a nut thread, which is mounted in a stationary manner in the housing of the actuator, wherein a wiper element is arranged at least in the region of the end face of the spindle nut. The scraping element surrounds the spindle and has at least one radially inwardly directed scraping lip. As already described with respect to the prior art, it is important for the service life and efficiency of the spindle drive that the one or more sealing elements keep the lubricating material within the axial boundaries of the spindle nut. Thus, a lubricating material is available within the drive thread between the engaged thread flanks of the spindle and the spindle nut.

In order to lubricate the drive thread sufficiently, it must therefore be provided that sufficient lubricating material is present in the thread groove or thread turns of the main shaft. In order to achieve this object, it is proposed according to the invention that the wiping lip touches (tangieren) the spindle only at the apex circle of the spindle. In other words, such a scraping lip is only in contact with the outer region of the spindle thread (i.e. the thread head or the top circle). Such a wiper lip effects a pressing of the lubricating material into the thread groove if the spindle nut is rotated and thus the spindle is axially displaced relative to the spindle nut and the actuator of the steer-by-wire device. Thereby intentionally allowing the lubricating material located in the thread groove to leave the lateral boundaries of the actuator or spindle nut. However, in the spindle drive for the steer-by-wire apparatus, a lubricating material generally used is grease having a high viscosity. The viscosity of the lubricating material is selected in such a way that sufficient lubricity is present even at lower temperatures. However, the lubricating material is viscous or sticky, so that it always adheres to the spindle and does not fall off the spindle threads, for example due to gravity, in the normal to higher operating temperature range of-40 degrees celsius to +130 degrees celsius. Therefore, if the grease pressed into the thread groove of the spindle by the wiper lip is transported away from the spindle nut together with the spindle, the lubricating material does not leave the spindle. Because the spindle does not rotate, the grease cannot leave the spindle due to rotational forces or centrifugal forces. If the spindle is now displaced again in the other direction with a change in the direction of rotation, the lubricating material previously pressed into the thread groove is always available when the various regions in the spindle come into engagement with the thread turns of the nut thread of the spindle nut.

In a preferred embodiment, the scraping element is coupled to the spindle nut, preferably held in the region of the end face of the spindle nut in a form-fitting and/or force-fitting and/or material-fitting manner. The coupling of the scraping elements to the spindle nut is rotationally fixed, so that the scraping elements are firmly held at the respective end side even in the case of the highest rotational speed of the spindle nut.

Preferably, the scraping element is formed by a holding ring having a scraping lip arranged thereon. In this case, the wiping lip is coupled to the retaining ring in a form-fitting and/or force-fitting and/or material-fitting manner. Preferably, the scraping lip is injection molded on or vulcanized with the axial side face and/or the inner side face of the retaining ring. In particular, the retaining ring is held in the region of the end face of the spindle nut, at least with a portion of its inner or outer side face, preferably in a form-fitting and/or force-fitting and/or material-fitting manner. Preferably, the retaining ring is pressed or pressed into the hollow-cylindrical end region of the spindle nut.

Preferably, the scraping lip is designed as at least one radially inwardly directed circumferential projection. The circumferential projection is designed such that this projection touches the top circle of the spindle thread. In other words, the scraping lip fits around the tip circle of the spindle thread. Here, the scraping effect is always such that: when the spindle, due to its axial displacement, slides to some extent over the scraping lip and thus scrapes the lubricating material from the thread head, the lubricating material is pressed into the thread groove (as already mentioned above).

According to one advantageous embodiment of the wiping lip, the wiping lip is formed by two or more lip segments spaced apart from one another, which are arranged in particular radially symmetrically and which touch the tip circle of the spindle thread. By "radially symmetrical" is meant that the lip segments are arranged in evenly spaced relation around the main shaft thread. The lip segments have the same angle with each other. The lip segment thus forms an interrupted, yet still circumferential scraping lip. The lip segments can also be arranged axially spaced apart from one another and radially overlapping. In this case, the lip segments always surround the spindle, so that a circumferential scraping effect and pressing of the lubricating material into the thread groove are achieved.

According to one advantageous embodiment, the one or more projections, viewed in axial section, have substantially the following shape:

-a semi-circular shape,

a rectangle, in particular a rectangle with a chamfer arranged radially inwards, at least on one side,

-a trapezoidal shape,

a waveform (particularly sinusoidal or cosine-shaped),

a rectangular base body with lateral recesses and a profile formed radially inwardly.

By the above-described shape of the projection, depending on the design of the thread (e.g. the pitch in the case of a trapezoidal thread) a sufficient scraping effect or pressing of the lubricating material into the thread groove can be achieved. These projections can be selected in particular in terms of their width or axial extension such that they are wider than the thread pitch.

According to another preferred embodiment, said scraping lip is formed of an elastic material or elastomer, such as rubber. The above-mentioned materials allow these scraping lips to enclose the top circle of the spindle thread with a certain pretension, especially if this has to be done due to an even better sealing. However, due to the elasticity of the material, the pretension can be kept low or omitted, so that no disadvantageous additional friction is generated, which could have a negative effect on the efficiency of the spindle drive. The pretensioning force causes a particularly good enveloping of the spindle thread in the continuous wiping lip, so that the wiping effect or the pressing of the lubricating material into the thread groove can be further optimized in this way.

According to one embodiment of the actuator, the spindle nut can have a substantially hollow-cylindrical section in the region of at least one end face. Preferably, the hollow-cylindrical section is delimited by a shoulder in the spindle nut, so that a cavity surrounding the shoulder is formed between the shoulder and the scraping element arranged at the end side and the spindle, which cavity is provided as a reservoir for lubricant. It is thus achieved that a greater amount of scraped-off lubricating material can be accumulated in the reservoir. It is thus ensured that the entire lubricating material can be utilized and that no lubricating material is unnecessarily squeezed out beyond the boundaries of the spindle nut. As mentioned above, it is always important that the lubricating material is retained within the grooves of the spindle threads.

According to a development of the actuator, the at least one scraping element is arranged axially spaced apart from the at least one internal thread of the spindle nut, preferably in the region of the end face of the spindle nut and/or in the region within the spindle nut between the first end face and/or the second end face. The spindle drive is designed to: the drive screw always has a sufficient load-bearing capacity to enable the wheels to be guided, taking into account the lateral forces in a truck (PKW) chassis. It is not necessary here for the spindle nut to have a somewhat continuous internal thread over the entire length. Thus, the spindle nut may, for example, be designed such that a nut thread having a plurality of thread turns is arranged towards one end side. A further nut thread, which likewise has a plurality of thread turns, is arranged in the spindle nut towards the other end side or away from the above-mentioned nut thread. It is hereby achieved that only so much thread turns are in engagement with the main shaft that the load-bearing capacity is sufficient and at the same time axial displacement of the main shaft can be achieved under operating conditions. Thereby, significantly fewer thread flanks are in contact with each other than in the case where there may be thread turns over the entire length of the spindle nut. Thus, an improved efficiency can be achieved with such a spindle nut, since the friction is reduced, since fewer thread flanks engage each other in comparison. At the same time, a cavity serving as a lubricant reservoir should be formed between the two nut threads and the end face. Thus, during the assembly of the spindle drive, a sufficient filling with the lubricating material can be achieved in a sufficient form over the service life.

According to another aspect, the present invention relates to a steer-by-wire apparatus having the above actuator. A steer-by-wire device is a device which is decoupled in the mechanical sense, wherein a mechanical control movement of the steering wheel by the driver is converted into an electrical control signal and is transmitted, in particular, by means of a controller which then actuates the actual system components (here actuators) in a purely electrical manner. Interference with the driving dynamics of the motor vehicle can thus be achieved very simply by means of the electrical connection between the steering wheel and the steer-by-wire device.

Drawings

The invention is described below with the aid of preferred embodiments with reference to the accompanying drawings. Shown in the drawings are:

figure 1 shows an actuator according to the known prior art,

figure 2 shows a cross-sectional view of a spindle drive of an actuator according to the invention,

figures 3a, 3b show further cross-sectional views of a spindle drive of an actuator according to the invention,

figures 4a, 4b show further cross-sectional views of the spindle drive of the actuator according to the invention,

fig. 5 shows a cross-sectional view of different embodiments of a scraping element according to the invention, and

fig. 6 shows a further cross-sectional view of the spindle drive of the actuator according to the invention.

Detailed Description

Fig. 1 shows a known actuator 20 of a steer-by-wire device, in which a spindle drive 21 is arranged, which comprises: a spindle 22 having a spindle thread 22g and a spindle axis a, and a spindle nut 23. The spindle nut 23 has a first 25 and a second 27 scraping element, which are received in

annular grooves

29, 30, respectively. Therefore, a solution is proposed to seal the spindle nut 23 against the spindle 22 against grease escape. The actuator 20 has a housing 31 in which the spindle nut 23 is rotatably supported by means of a first rolling bearing 32 and a second rolling bearing 33 and is axially fixed in the direction of the spindle axis a. A pulley 34 is arranged on the spindle nut 23 in a rotationally fixed manner, which can be driven by an electric motor 36 via a belt drive 35. The spindle 22 is connected at its two ends to bearing

sleeves

37, 38, which are supported and guided in the housing 31. The bearing sleeves are themselves connected to the

joint pins

39, 40 at the ends facing away from the spindle. The actuator 20 is preferably used in a steer-by-wire arrangement for a rear axle steering arrangement of a motor vehicle. When the spindle, which is fixed in a rotationally fixed manner relative to the housing 31, is axially displaced by the actuator, which is fixed to the vehicle body, as a result of the rotation of the spindle nut, which is fixed in axial position, the two

joint pins

39, 40 are indirectly or directly connected to the wheel carrier of the rear wheel by means of a (not illustrated) steering rod, and thus the steering angle of the rear wheel can be adjusted simultaneously. The actuator 20 illustrated in fig. 1 acts centrally on both rear wheels simultaneously and is therefore fastened, for example, in the middle region of the motor vehicle or supported on the vehicle body. It is also within the scope of the invention to have an actuator that acts on only one rear wheel. Such actuators have a universal joint on their housing, which is supported on the vehicle body or the auxiliary frame. The joint pin is connected to the main shaft, in particular by means of a bearing sleeve therebetween, so that the actuator is realized as a variable-length component. Extension or retraction of the spindle causes a change in the steering angle of the wheels.

Fig. 2 shows a spindle drive according to the invention in a sectional view, which spindle drive can also be correspondingly mounted in the actuator according to fig. 1. The spindle nut 23 surrounds the spindle 22 and has two nut thread sections which are arranged spaced apart from the end sides 23s, 24 s. On the end sides 23s, 24s of the spindle nut 23, scraping

elements

225, 227 are arranged. The scraping

elements

225, 227 are formed by holding rings 225r, 227r on which scraping lips 226, 228 are arranged. For this purpose, a connection location 227v is exemplarily shown, in which the scraping lip 227, for example formed of rubber or an elastomeric material, is fixed with the retaining ring 227r by means of vulcanization. The scraping lips 226, 228 lie on the top circle of the spindle 22 and thus tangentially touch the outer lateral surface of the spindle thread 22 g. The scraping

elements

225, 227 enclose, at the end face of the spindle nut 23,

sections

205, 207 which are designed, for example, in the form of a hollow cylinder. If the spindle 22 is now displaced axially by rotating the spindle nut 23, on the one hand excess lubricating material is collected in the hollow-

cylindrical sections

205, 207. On the other hand, by abutting the

scraper elements

225, 227 tangentially, the lubricating material is pressed into the thread groove of the thread 225g of the spindle 22. This lubricating material adheres in the thread grooves due to its high viscosity and is therefore available again for the drive threads when the spindle 22 is displaced, the lubricating material engaging with the spindle thread 22g in the thread turns of the spindle nut 23.

Fig. 3a and 3b show the spindle nut 23 and the end-side ends 23s, 24s of the spindle 22 in a sectional view, respectively. In the embodiment according to fig. 3a and 3b, similar to the embodiment according to fig. 2, scraping

elements

325 and 327 are provided which, instead of engaging into the thread grooves, scrape or press grease from the tip circle of the spindle thread 22g of the spindle 22 during axial transport of the spindle 22. In the embodiment according to fig. 3a, a scraping element 327 is inserted into the end side 24s of the spindle nut 23, which scraping element is axially supported on the shoulder 23a in the direction of the spindle thread. The scraper element is axially fixed in the spindle nut 23 by a retaining ring 327r which is pressed into the end-side end 24s of the spindle nut 23. In the embodiment according to fig. 3b, a scraping element 325 is provided, which is held by a retaining ring 325r on the end-side end 23s of the spindle nut 23. Axial support is achieved at the shoulder 23 b. The

scraper elements

325, 327 each enclose hollow-

cylindrical sections

305, 307, which serve as reservoirs for lubricant. The lubricant can accumulate in the manner already mentioned in connection with fig. 2 and can provide permanent lubrication of the spindle drive.

An embodiment similar to that of fig. 3a and 3b is shown in fig. 4a and 4 b. At the end sides 23s, 24s, the holding

ring

425r or 427r is pressed into the hollow-

cylindrical sections

405, 407. In contrast to the form-fitting axial fixing according to the embodiment of fig. 3a or 3b, the actual scraping lip of the

scraping elements

425, 427 holds the

scraping lip

426 or 428 to the retaining ring in a material-fitting manner. The

wiper lips

426, 428 are formed here from an elastomer which is injection molded onto the retaining rings 425r, 427 r. Alternatively, the scraping lips may also be vulcanized with a retaining ring formed of steel, so that the scraping lips ensure scraping of the lubricating material into the thread grooves of the threads 22g of the spindle 22 over the service life of the spindle drive.

Fig. 5 shows five different shapes or profiles of the scraping

lips

426, 428 which, together with the holding rings 425r, 427r, constitute the

scraping elements

425, 427. Of these five different scraper elements, the retaining rings 425r, 427r are correspondingly identically designed. However, on the inner side there is a differently designed contour of the wiping lip. The cross-sectional views of these five different scraping lips according to fig. 5 are shown as follows:

a scraping lip in the form of a rectangular-shaped

protrusion

426a, 428a, wherein the radially inwardly directed edge with respect to the longitudinal axis a is provided with a radius or with a chamfer,

projections

426b, 428b designed as rectangles,

projections

426c, 428c in the form of trapezoids which taper radially inwards,

426d, 428d show projections formed, for example, in a semicircular to parabolic shape, and

426e, 428e show the projections in the form of a wave profile (sinusoidal or cosine).

Fig. 6 shows a spindle drive similar to the embodiment according to fig. 2. The spindle nut 23 surrounds the spindle 22 and is in engagement with the spindle thread 22g with its two nut thread sections 23g, which are arranged on the inner wall of the spindle nut 23. On the end sides 23s, 24s, respectively, wiping

elements

525, 527 are provided. The scraping

elements

525, 527 are each held on the respective end side of the spindle nut by a holding

ring

525r, 527 r. The retaining ring 525r at the end side 23s is pressed onto the cylindrical end-side section of the spindle nut. In the scraping element 527, the retaining ring 527r is pressed into the spindle nut 23 in the hollow-cylindrical section 507 at the end side 24 s. The scraping

lips

526, 528 are designed in a different way than in the above-mentioned embodiments. Except that the scraping lip is formed by a substrate arranged inside the holding

ring

525r or 527 r. The base body extends radially inward, so that it has, radially inside, two annular cavities arranged at the end on the wiper element, which in turn open into two lips which come into contact with the tip circle of the spindle thread 22g of the spindle 22. The scraping lips are formed with a cavity concavely formed in a cross section between the scraping

lips

525, 527. The cavity is formed radially outward. In this advantageous embodiment, the lubricant can be transported in the cavity accordingly. After fitting the scraping elements 527, between the scraping elements and the shoulder on the end side 24s of the spindle nut 23 there is also a hollow-cylindrical section 507, which, like the above-mentioned embodiments, serves as a reservoir for lubricant.

All the embodiments mentioned above show advantageous scraping elements to ensure the supply of lubricant in the actuators of the steer-by-wire device. The lubrication absolutely required to avoid premature wear is of critical importance in spindle drives, in particular for motor vehicle steering systems. By means of the above-mentioned embodiments, an optimum scraping effect or pressing of the lubricating material into the thread grooves for supplying the spindle drive with lubricating material can be achieved as desired.

List of reference numerals

20 actuator

21 spindle driver

22 spindle

22g main shaft thread

22k main axis top circle

23 spindle nut

23a shoulder

23b shoulder

Thread of 23g spindle nut

23s end side

24s end side

25 scraping element

27 scraping element

29 annular groove

30 annular groove

31 shell

32 first rolling bearing

33 second rolling bearing

34 belt wheel

35 Belt

36 electric motor

37 support sleeve

38 support sleeve

39 universal joint pin

40 universal joint pin

205, 305, 405, are hollow cylindrical sections

207, 307, 407, 507 hollow cylindrical sections

225, 325, 425, 525 scraping element

225r, 325r, 425r, 525r retaining ring

226, 326, 426, 526 scraping lip

227, 327, 427, 527 scraping element

227r, 327r, 427r, 527r retaining ring

228, 328, 428, 528 scraping lip

227v connection position

426a, 428a rectangular protrusions with rounded corners

426b, 428b rectangular projection

426c, 428c trapezoidal projection

426d, 428d semicircular projections

426e, 428e wave-shaped bulge

a main shaft axis

Claims

1. An actuator (20) of a steer-by-wire apparatus, the actuator having a spindle drive (21) with: a spindle (22) with a spindle thread (22g) axially displaceable relative to the actuator (20); and a spindle nut (23) which is mounted in a positionally fixed manner in the actuator (20) and has a nut thread (23g), wherein at least one scraping element (227, 327, 427, 225, 325, 425) is arranged in the region of an end face (23s, 24s) of the spindle nut (23), wherein the scraping element (227, 327, 427, 225, 325, 425) surrounds the spindle (22) and has at least one radially inwardly directed scraping lip (226, 326, 426, 228, 328, 428),

it is characterized in that the preparation method is characterized in that,

the scraping lip (226, 326, 426, 228) touches the spindle (22) only at the top circle (22k) of the spindle.

2. Actuator according to claim 1, wherein the scraping element (227, 327, 427, 225, 325, 425) is coupled with the spindle nut (23), held in the region of an end side (23s, 24s) of the spindle nut (23) with a form-fit and/or force-fit and/or material-fit.

3. Actuator according to claim 1 or 2, characterized in that the scraping element (227, 327, 427, 225, 325, 425) is formed by a retaining ring (227r, 327r, 427r, 225r, 325r, 425r) having a scraping lip (226, 326, 426, 228, 328, 428) arranged thereon, wherein the scraping lip is coupled with the retaining ring (227r, 327r, 427r, 225r, 325r, 425r) in a form-fitting and/or force-fitting and/or material-fitting manner, in particular is injection molded on or vulcanized with an end side and/or inner side of the retaining ring; and the retaining ring (227r, 327r, 427r, 225r, 325r, 425r) is held in the region of the end face (23s, 24s) of the spindle nut (23) at least in the form-fitting and/or force-fitting and/or material-fitting manner of its inner or outer side.

4. Actuator according to claim 3, wherein the scraping lip (226, 326, 426, 228, 328, 428) is designed as at least one radially inwardly directed circumferential projection, which projection touches the top circle (22k) of the spindle thread (22 g).

5. Actuator according to claim 3, wherein the scraping lip (226, 326, 426, 228, 328, 428) is formed by two or more lip segments spaced apart from each other, which lip segments are arranged radially symmetrically and which lip segments touch the top circle (22k) of the spindle thread (22 g).

6. An actuator according to claim 4, wherein the one or more protrusions have one of the following shapes, viewed in axial cross-section:

a rectangle (426b, 428b), in particular a rectangle (426a, 428a) with a chamfer arranged radially inwards, at least on one side,

-trapezoids (426c, 428c),

-a semi-circle (426d, 428d),

-a waveform (426e, 428e),

a rectangular base body (526, 528) with lateral recesses, in particular a rectangular base body with an inner, radially outwardly concavely formed contour.

7. Actuator according to one of claims 1-2, 4-5, wherein the scraping lip (226, 326, 426, 228, 328, 428) is formed from an elastic material, such as rubber, or an elastomer, so that the scraping lip encloses the top circle (22k) of the spindle thread (22g), in particular with a pretension.

8. Actuator according to one of claims 1 to 2, 4 to 5, wherein the spindle nut (23) has a hollow-cylindrical section in the region of the end sides (23s, 24s), which hollow-cylindrical section is delimited by a shoulder (23a, 23b) in the spindle nut (23) in such a way that a cavity (205, 207, 305, 307, 405, 407, 507) surrounding the shoulder is formed between the shoulder and the scraping element (227, 327, 427, 225, 325, 425) arranged at the end side and the spindle (22), which cavity is provided as a reservoir for lubricant.

9. Actuator according to one of claims 1 to 2, 4 to 5, characterized in that the at least one scraping element (227, 327, 427, 225, 325, 425) is arranged axially spaced apart from at least one nut thread (23g) of the spindle nut (23), in the region of an end side (23s, 24s) of the spindle nut (23), and/or in the region within the spindle nut (23), respectively between the end side (23s, 24s) and the nut thread (23g) of the spindle nut (23).

10. A steer-by-wire arrangement having an actuator (20) according to any one of claims 1 to 9, characterized in that the steer-by-wire arrangement is in particular a rear axle steering arrangement.