Steering device for a steer-by-wire steering system of a vehicle

Abstract

Steering device (1) for a steer-by-wire steering system of a vehicle, comprising - a steering rod (2) which is mounted to be linearly displaceable along its longitudinal axis (3), and - a bearing device (4) comprising at least one rolling element (5) which is designed for the rotationally secure bearing of the steering rod (2), wherein - the steering rod (2) comprises a running surface (6) on which the at least one rolling element (5) of the bearing device (4) rests, characterized in that - the storage facility (4) comprises at least one roller recirculation device (7), wherein - the roller recirculation device (7) comprises at least one rolling element recirculation channel (8) with a plurality of rolling elements (5) in the form of rollers arranged therein, which circulate in the rolling element recirculation channel (8) during a linear movement of the steering rod (2) along its longitudinal axis (3), wherein - a subset of the rolling elements (5) of the at least one roller recirculation device rests against the running surface (6) of the steering rod (2) in such a way that the steering rod (2) is thereby mounted in a rotationally secure manner.

Description

[0001] The invention relates to a steering device for a steer-by-wire steering system of a vehicle having the features of the preamble of claim 1.

[0002] A steer-by-wire steering system is a steering system in which the steering command is transmitted exclusively electrically or by signaling from the steering wheel to a steering device comprising a tie rod. The steering rod, which is mounted longitudinally displaceably and torsionally fixed to transmit the steering movement, interacts with at least one wheel of the vehicle, for example, the two front wheels. According to DE 10 2017 103 975 A1, in conventional steering systems, the steering movement is transmitted from the steering wheel to the steering rod via a rack and pinion connection. This rack and pinion connection not only allows for a mechanical transmission of the manual steering torque to the steering system but also prevents the steering rod from rotating. Since the rack and pinion connection is omitted in steer-by-wire steering systems, another means of ensuring that the steering rod is mounted to prevent rotation.For this purpose, it is known from DE 10 2017 103 975 A1 to ensure a torsion-proof mounting of the handlebar by means of a rolling element arranged between the handlebar and a housing. In DE 10 2019 208 451 A1, the handlebar is mounted in a torsion-proof manner by a roller unit. In EP 2 738 067 A1, the torsion protection is ensured by means of a plain bearing that rests against a non-rotationally symmetrical section of the handlebar.

[0003] The application is based on the object of specifying an improved steering device for a steer-by-wire steering system of a vehicle.

[0004] The object is solved by the features of independent claim 1. Further preferred embodiments of the invention can be found in the subclaims, the figures and the associated description.

[0005] Accordingly, the object is achieved by a steering device for a steer-by-wire steering system of a vehicle, comprising a steering rod which is mounted so as to be linearly displaceable along its longitudinal axis, and a bearing device comprising at least one rolling element which is designed to mount the steering rod in a rotationally secure manner, wherein the steering rod comprises a running surface against which the at least one rolling element of the bearing device bears, wherein the bearing device comprises at least one roller recirculating device, wherein the roller recirculating device comprises at least one rolling element recirculating channel with a plurality of rolling elements arranged therein in the form of rollers which rotate in the rolling element recirculating channel during a linear movement of the steering rod along its longitudinal axis, wherein a subset of the rolling elements of the at least one roller recirculating device bears against the running surface of the steering rod in such a way that the steering rod is mounted in a rotationally secure manner.

[0006] The roller recirculating device within the meaning of this application can also be referred to as a roller recirculating shoe.

[0007] Basically, different types of rollers can be used as rolling elements.

[0008] A rolling element circulation channel within the meaning of this application is characterized by the fact that the rolling elements located therein can rotate as often as desired; it is therefore a closed circuit.

[0009] By using the roller bearing assembly as a bearing device, any torsional torque acting on the handlebar can be reliably absorbed by the rolling elements of the roller bearing assembly, which are formed by rollers. The rollers as rolling elements offer the advantage, compared to balls, for example, that the contact area with the running surface is larger. Each roller-shaped rolling element contacts the running surface along a line. The subset of rolling elements that rests on the running surface creates several linear contact areas that reliably secure the handlebar against rotation. The linear contact areas are preferably aligned orthogonally to the longitudinal axis of the handlebar. A plurality of rolling elements of the roller bearing assembly are in contact with the running surface of the handlebar at the same time, while the remaining rolling elements are located in another section of the rolling element circulation channel.When the steering rod is displaced, the rolling elements rotate in the rolling element circulation channel, so that depending on the displacement position, different rolling elements belong to the subset that rests against the running surface. By distributing the forces among the multiple rolling elements in this subset, a low-friction, virtually wear-free, and precisely positioned bearing of the steering rod can be ensured. This also enables a displacement force in the longitudinal direction of the steering rod that is independent, or at least almost independent, of the acting torsional torques.

[0010] The rolling elements of the at least one recirculating roller assembly mount the steering rod in a rotationally secure manner, particularly with respect to rotation about the longitudinal axis of the steering rod. In this way, the counter-torque to the friction torque of any roller screw drive (e.g., a ball screw drive), as well as misuse and / or assembly torques, can be reliably absorbed by the rolling elements. Also, due to the connection of the tie rods to the steering rod by means of ball joints, unwanted rotational torques can occur on the steering rod, which can be absorbed by the proposed bearing assembly.

[0011] The rolling element circulation channel is preferably oriented such that the rolling elements located therein rotate within the rolling element circulation channel when the steering rod is displaced along its longitudinal axis. It goes without saying that the rolling elements, designed as rollers, rotate about their rotational axes; the rotational axis of the rolling elements is thus oriented orthogonally to the orbit defined by the rolling element circulation channel.

[0012] It is further proposed that the at least one rolling element circulation channel comprise the following sections: a support channel configured to guide rolling elements such that they come into contact with the running surface of the handlebar, a return channel configured to space the rolling elements guided therein from the running surface, a first deflection channel configured to guide the rolling elements from the support channel into the return channel, and a second deflection channel configured to guide the rolling elements from the return channel into the support channel. In this way, the rolling elements can rotate in the rolling element circulation channel as often as desired. This enables low-friction displacement of the handlebar along its longitudinal axis relative to the bearing device.

[0013] According to a preferred embodiment, the roller recirculating device comprises a tube, wherein the return channel runs through the interior of the tube, and / or the rolling elements in the support channel are supported at least partially by an outer surface of the tube, and / or the first deflection channel is made entirely or partially of plastic, and / or the second deflection channel is made entirely or partially of plastic, and / or the return channel is made entirely or partially of plastic. Due to its relatively short length, the tube can also be referred to as a tube section or sleeve.

[0014] The tube preferably has a rectangular profile. The tube can be made of hardened steel, for example. The tube can thus form the rolling bearing raceway of the recirculating roller bearing assembly and thus transfers the forces from the rolling elements into a housing, which can be, for example, the housing of a road wheel actuator. The tube can preferably be manufactured particularly cost-effectively by deep drawing or, alternatively, by cutting to length from a profile tube or from a strip by bending and welding. By specifically designing the tube wall thickness and / or length-to-width ratio, the stiffness and spring properties of the recirculating roller bearing assembly can be tailored to specific requirements. Alternatively, sections of the rectangular tube can be designed to be elastically springy, similar to a bending beam. By appropriately modifying the stiffness, edge stresses caused by the torque introduced by the steering rod can be reduced.The same can also be achieved by profiling and / or crowning the outer surface of the tube in the area of ​​the support channel, orthogonal to the longitudinal axis in a sectional view. Thus, the tube is an efficient and inexpensive means of designing the recirculating roller bearing system for the desired application.

[0015] If the first deflection channel, the second deflection channel, and / or the return channel are made of plastic, then this or these are preferably manufactured by injection molding. Further preferably, the radially inner guide surface of the first deflection channel, the second deflection channel, and the return channel is formed by exactly two plastic parts manufactured by injection molding; these two plastic parts each have positive-locking connecting means, for example in the form of a pin and pin receptacle, so that they can be connected.

[0016] Preferably, the running surface is flat, and the rolling elements are cylindrical rollers. This design allows the contact area between the running surface and the rolling elements to be increased, allowing for greater forces to be transmitted. Furthermore, the cylindrical rollers are preferably solid; this makes the rolling elements more stable and able to absorb higher forces.

[0017] In one embodiment, the rolling elements designed as rollers can also have a shell profile which is suitable for reducing edge stresses in the rolling contact during torque support of the steering rod.

[0018] According to a further preferred embodiment, it is proposed that the handlebar has a flat planar flattened portion to form the running surface, which flattened portion has a transverse extension orthogonal to the longitudinal axis of the handlebar, wherein the length of the rolling elements in the transverse direction corresponds to at least 0.5 times the transverse extension of the flattened portion, preferably at least 2 / 3 of the transverse extension of the flattened portion. Due to this ratio of the length of the rolling element, the flattened portion can advantageously be used for support, so that the largest possible support distance is created and rotation of the handlebar about its longitudinal axis can be reliably prevented. The flattened portion is preferably aligned parallel to the longitudinal axis of the handlebar. The rolling elements can also project beyond the flattened portion in the transverse direction, i.e. orthogonal to the longitudinal axis of the handlebar.In one embodiment, the flattening of the steering rod in a section orthogonal to the direction of displacement can also have a profiling which is suitable for reducing edge stresses in the rolling contact.

[0019] Preferably, the at least one roller recirculating device comprises at least two rolling element recirculating channels, each with a plurality of rolling elements arranged therein. This allows both the number of rolling elements available for support against the running surface of the steering rod to be increased and the support spacing to be increased, so that the load-bearing capacity of the bearing device can be increased and, accordingly, even larger torsional torques can be reliably absorbed.

[0020] If at least two rolling element circulation channels are provided, they preferably run parallel to each other.

[0021] For example, a single running surface can be provided, i.e. a surface that is not structurally divided and against which the rolling elements of different rolling element circulation channels can come into contact. Alternatively, the steering rod can also comprise two structurally separate running surfaces, wherein the separate running surfaces are each assigned to one of the at least two rolling element circulation channels. The structural separation of the running surfaces can be achieved, for example, by providing a web that extends in the direction of the longitudinal axis of the steering rod between two running surfaces. The web preferably projects out of the plane of the running surfaces in the direction of the roller circulation device. In order to be able to increase the height of the web, in a further embodiment the tube of the roller circulation device can have a clearance in the form of a groove or channel into which the web can then project.In this way, the bending resistance moment of the handlebar can be advantageously increased.

[0022] The rolling element circulation channels are arranged, for example, such that the rolling elements of each rolling element channel are spaced apart from the rolling elements of the adjacent rolling element circulation channel, so that the support distance can be increased even with shorter rollers. Alternatively, it is also possible for the rolling elements of adjacent rolling element circulation channels to abut one another in the transverse direction. The end faces of the rolling elements, designed as rollers, of adjacent rolling element circulation channels are thus either spaced apart from one another or they abut one another.

[0023] It is further proposed that in a sectional plane orthogonal to the longitudinal axis of the handlebar, a support distance is defined by the furthest apart contact points of the rolling element(s) on the corresponding running surface, which support distance corresponds to at least 0.2 times the maximum diameter of the handlebar in this sectional plane, more preferably at least 0.4 times and especially preferably at least 0.6 times the maximum diameter of the handlebar in this sectional plane. It has been shown that such a support distance is sufficient to achieve a sufficient support effect for the purpose of preventing rotation. If a single rolling element circulation channel is provided, the support distance is defined by the distance between the outermost contact points of a single rolling element on the running surface in said sectional plane.If, for example, two parallel rolling element circulation channels are provided, the support distance is defined by the furthest apart support points of the rolling elements from different rolling element channels on the running surface in the said cutting plane.

[0024] It is further proposed that the steering device comprise a roller screw drive, preferably a ball screw drive, which is configured to displace the steering rod along its longitudinal axis. By means of the proposed bearing device, co-rotation of the steering rod, which in this embodiment can form the threaded spindle in one section, can be reliably and frictionlessly prevented. Thus, the steering device also enables efficient linear displacement of the steering rod in its longitudinal direction, whereby, when the steering device is installed in a vehicle, a steering movement of the wheels can be effected via corresponding tie rods.

[0025] It is further proposed that the steering device comprise a housing and an actuator configured to drive a spindle nut of the rolling screw drive, wherein the at least one recirculating roller device is arranged within the housing. This allows for a compact and integral design. Additionally, the actuator, i.e., the electric motor, can also be arranged within the housing. The housing can be constructed either as a single piece or assembled from multiple housing parts.

[0026] It is further proposed that the steering device comprise a pressure element configured to apply a compressive force to the steering rod orthogonally to its longitudinal direction, so that the running surface is pressed against the rolling elements of the at least one recirculating roller device. This ensures play-free contact of the rolling elements with the running surface, thereby reducing wear and noise. Preferably, the pressure device and the recirculating roller device are arranged in a common housing; further preferably, a section of the steering rod, which also includes the running surface, is mounted in the housing between the pressure element and the recirculating roller device.

[0027] The application is explained below using preferred embodiments with reference to the attached figures. Herein: Fig. 1 a schematic representation of a steer-by-wire steering system of a vehicle; Fig. 2 a perspective view of a steering device with tie rods; Fig. 3 a perspective view of a steering rod with a ball screw drive; Fig. 4 a perspective view of a steering rod and a roller circulation device; Fig. 5 is a sectional view of a first embodiment of a roller conveyor device; Fig. 6 is a sectional view of a second embodiment of a roller conveyor device; Fig. 7 is a sectional view of a third embodiment of a roller conveyor device; Fig. 8 is a sectional view of a fourth embodiment of a roller conveyor device; Fig. 9 a perspective detailed view of a roller conveyor device; Fig. 10 an exploded view of a roller conveyor system; Fig. 11 a first perspective sectional view of a roller conveyor device; Fig. 12 a second perspective sectional view of a roller conveyor device; Fig. 13 a perspective view of a first outer deflection device; Fig. 14 is a side view of a handlebar in a first embodiment with a roller circulation device; Fig. 15 is a side view of a handlebar in a second embodiment with a roller circulation device; Fig. 16 a perspective detailed view of a roller conveyor device; Fig. 17 a perspective detailed view of a roller conveyor device; Fig. 18-22 Sectional views of different installation configurations of a steering rod and a roller conveyor in a housing; and Fig. 23 a further embodiment of a steering device with two separate running surfaces.

[0028] Fig. 1 shows a schematic representation of a steer-by-wire steering system 100 of a vehicle comprising a steering wheel 25 and a steering device 1, wherein the steering movements of the steering wheel 25 are transmitted electrically and / or by signaling to the steering device 1. The steering device 1 in turn comprises a steering rod 2 (see also Fig. 3), which is connected at its outer ends to a tie rod 26.

[0029] Fig. 2 shows an enlarged view of the steering device 1 from Fig. 1. The steering rod 2 is not visible because it is covered by a housing 21. Furthermore, an actuator 22 in the form of an electric motor is shown, which drives a roller screw drive 20 (see Fig. 3) in the form of a ball screw drive. Furthermore, the position shown is that in the interior of the housing 21 there is a bearing device 4, which serves for the linearly displaceable, but torsion-proof mounting of the steering rod 2 (see Fig. 3) a roller circulation device 7 in the form of a roller circulation shoe (see Fig. 4). The actuator 22 is controlled electrically and / or by signaling depending on the steering movement of the steering wheel 25. A rotational movement of the actuator 22 is converted into a linear movement of the steering rod 2 by means of the roller screw drive 20.

[0030] Fig. 3 shows the handlebar 2 and its longitudinal axis 3. It can also be seen that the handlebar 2 forms a threaded spindle 27 in a first section, which cooperates with a spindle nut 23 in such a way that the rotational movement of the spindle nut 23 is transmitted to the threaded spindle 27 via balls (not shown); this causes a linear displacement movement of the handlebar 2 along the longitudinal axis 3. The spindle nut 23 is driven by the actuator 22. Of course, the handlebar 2 can be displaced in both directions along the longitudinal axis 3 depending on the rotational movement of the spindle nut 23; the handlebar 2 can therefore be moved back and forth. Finally, in the Fig. 3 shows that the steering rod 2 has a flat flattening 16 in a second section, which has a running surface 6 for rolling elements 5 (see for example Fig. 5) of the roller circulation device 7.

[0031] Fig. Figure 4 shows a perspective view of the steering rod 2 with the running surface 6 formed by the flattened portion 16. Also shown is the recirculating roller assembly 7, which rests against the running surface 6 with a portion of its rolling elements 5 (not visible).

[0032] Fig. Figure 5 shows a sectional view of the bearing device 4 and the steering rod 2 in a sectional plane that runs orthogonal to the longitudinal axis 3. The steering rod 2 and the roller recirculating device 7 are arranged in a common housing 21, which is, for example, a road wheel actuator housing. The actuator 22 can also be arranged completely or partially in the housing 21. The rolling element 5, which is arranged in a support channel 9 and is visible in the sectional plane shown, rests against the running surface 6. During a sliding movement of the steering rod 2 relative to the roller recirculating device 7, the rolling elements 5 move by a rolling movement in a rolling element recirculating channel 8, which, in addition to the support channel 9, also has a return channel 10 as well as a first and second deflection channel 11 and 12 as further sections (see Fig. 11). The subset of rolling elements 5 that are in contact with the running surface 6 are located in the support channel 9. A support distance 19 is defined here by the contact points 17, 18 of the rolling element(s) 5 that are furthest apart from one another on the corresponding running surface 6. The support distance 19 is defined by the length of the rolling elements 5, so that a torsion-proof mounting of the steering rod 2 with respect to rotation about its longitudinal axis 3 is ensured. In this embodiment, the support distance 19 defined by the length of the rolling elements 5 is smaller than the transverse extent of the running surface 6. The rolling elements 5 are cylindrical rollers that are designed as solid bodies.

[0033] In the Fig. 6-8 are variations of the Fig. 5 shown embodiment. To avoid repetition, the following description of the Fig. 6-8 only the changes compared to the embodiment according to Fig. 5 explained.

[0034] In the embodiment according to Fig. 6, the length of the rolling element 5 in the transverse direction is greater than the transverse extent of the running surface 6. The support distance 19 thus corresponds to the transverse extent of the running surface 6.

[0035] In the embodiment according to Fig. 7, the roller recirculating device 7 comprises two rolling element recirculating channels 8 running parallel to one another; this is also referred to as a two-row roller arrangement. In principle, embodiments are also possible in which the roller recirculating device 7 comprises three, four or more rolling element recirculating channels 8. In the embodiment shown here, the two rolling element recirculating channels 8 run in such a way that the adjacent rolling elements 5 of two different rolling element recirculating channels 8 abut one another with their end faces. Thus, no central rim 28 (see Fig. 8) for spacing the rolling elements 5. The support distance 19 is defined by the sum of the lengths of the two rolling elements 5 adjacent in the transverse direction.

[0036] In the embodiment according to Fig. 8 are as in the embodiment according to Fig. 7 two parallel rolling element circulation channels 8 are provided. In contrast to the embodiment according to Fig. 7, however, the rolling elements 5 of the adjacent rolling element circulation channels 8 are spaced from each other by a central rim 28. Because the rolling elements 5 protrude beyond the running surface 6 of the steering rod 2 due to the spacing, the support distance 19 is defined by the transverse extent of the running surface 6.

[0037] In the Fig. In the embodiments illustrated in Figures 5 to 8, the support distance 19 corresponds to at least 0.2 times the maximum diameter of the handlebar 2 in the respective sectional plane shown. This allows sufficient support of the handlebar 2 to prevent rotation about its longitudinal axis 3. Furthermore, the rolling elements 5 are in contact over at least half, here at least 2 / 3, of the transverse extent of the running surface 6.

[0038] The Fig. Figure 9 shows a perspective view of an assembled roller bearing device 7 comprising a single rolling element circulation channel 8. The roller bearing device 7, which can also be referred to as a roller bearing shoe, comprises a tube 13 (see Fig. 10) made of steel, which is hardened at least in the area of ​​the support channel 9, two internal and thus not visible inner deflection devices 29, 30 (see Fig. 10) made of plastic and two visible outer deflection devices 31, 32. The two outer deflection devices 31, 32 are connected to each other by means of a positive connection means, here in the form of a snap-in connection. For this purpose, the first outer deflection device 31 comprises a snap-in lug 33, which, in the assembled state, cooperates positively with an undercut 34 on the second outer deflection device 32. At the Fig. 9 and Fig. 10 not visible side of the roller circulation device 7 there is also such a locking connection, with the locking lug 33 being provided on the second outer deflection device 32 and the undercut 34 being provided on the first outer deflection device 31 (see Fig. 10). By means of these locking connections, the roller conveyor device 7 is secured against falling apart during transport and handling. The roller conveyor device 7 is thus mounted in the housing 21 (see, for example, Fig. 5-8) such that the locking connection is secured by the housing 21. The two outer deflection devices 31 and 32, in the assembled state, form a type of housing for the roller recirculating device 7, wherein a window 48 is provided which exposes the portion of the rolling elements 5 which rest in the support channel 9 on the running surface 6 of the steering rod 2. Optionally, this window 48 can be surrounded by a partially or completely circumferential wiper 35. A wiper and / or sealing function can be realized by means of the wiper 35. The wiper 35 can, for example, be injection-molded onto the surface of the first and second outer deflection devices 31, 32. In the Fig. 9, the wipers 35 are designed as completely circumferential and closed wiper strips around the open window 48, i.e. as transverse and longitudinal wipers or seals. They can also be designed only in the area in front of and / or behind the window 48 with respect to a direction of displacement of the steering rod 2. The wipers 35 can be integrated into the injection-molded component and consist either of the same material as the base body or of a softer material, for example rubber, TPU or TPE. They can be manufactured, for example, using a 2-component injection-molding process. Alternatively, the wipers 35 can also be used as a separate component. The geometry of the wipers 35 is designed to keep the lubricating grease in the bearing as best as possible, thus achieving a long, maintenance-free service life.Sealing against external dirt is not necessary because the roller recirculating device 7 is installed in a closed system, namely within the housing 21.

[0039] Furthermore, two recesses 36 are shown on the outside of the roller conveyor 7, which serve to improve handling of the roller conveyor 7 during the assembly process, for example, using an assembly gripper of an assembly robot (not shown). The external geometry of the roller conveyor 7 is designed according to the poka-yoke method, which ensures correct installation, e.g., through a rectangular basic shape with different lengths and widths.

[0040] Furthermore, the first and second outer deflection devices 31, 32 comprise press-in ribs 37 on an outer surface for securing the mounting position within the housing 21 (see Fig. 8). These press-fit ribs 37 enable a permanent, play-free attachment in the housing 21. Alternatively, the press-fit ribs 37 can be formed from a soft, elastic material or an O-ring. This ensures the necessary flexibility to accommodate any deflection of the steering rod 2 that may occur during operation.

[0041] Fig. 10 shows the roller circulation device 7 from Fig. 9 in an exploded view. The complete rolling element set comprising a plurality of rolling elements 5, each in the form of a cylindrical roller, can be seen, wherein the rollers are designed as solid bodies. Furthermore, the first and second inner deflection devices 29 and 30 can be seen in this illustration, which partially form the radially inner boundary of the rolling element circulation channel 8 for the rolling elements. In a further section, the radially inner boundary of the rolling element circulation channel 8 is formed by an outer surface 15 of the tube 13. In the deflection area, a radially outer boundary of the rolling element circulation channel 8 is formed by the first and second outer deflection devices 31 and 32. In the interior 14 (see Fig. 5 to 8) of the tube 13, the rolling element circulation channel 8 is completely defined by the two inner deflection devices 29 and 30. The deflection devices 29, 30, 31 and 32 are designed as injection-molded plastic parts. The two inner deflection devices 29 and 30 can be pushed with their base body into the interior of the tube 13 so that the radially outer surface of the first and second inner deflection devices 29 and 30 bears against the inner surface of the tube 13 in a shape corresponding to that of the first inner deflection device 29 and 30. In order to connect the first and a second inner deflection device 29 and 30 to one another inside the tube 13, the second inner deflection device 30 comprises a pin 38 which, in the assembled state, is received by a corresponding pin receptacle (not visible) of the first inner deflection device 29.Accordingly, the first inner deflection device also includes a corresponding pin (not visible), which, when assembled, is received by a corresponding pin receptacle 39 of the second inner deflection device 30. This allows for easy assembly of the two inner deflection devices 29 and 30.

[0042] The two inner deflection devices 29 and 30 made of plastic, which are manufactured by injection molding, form the inner curvature of the rolling element circulation channel 8 for the deflection of the cylindrical rolling elements 5 and also the return channel 10 as well as a groove 65 as an inner lubricant depot 41 (see Fig. 12). The C-shaped cross-sectional profile forms an additional outer lubricant reservoir 42 between the two C-ends (see Fig. 12). All lubricant reservoirs 41 and 42 together ensure maintenance-free operation with lifetime lubrication. The rolling element circulation channel 8, which is made entirely of plastic and comprises the first deflection channel 11, the second deflection channel 12, and the return channel 10, ensures particularly quiet running of the rolling elements 5.

[0043] Fig. 11 shows a perspective sectional view of the roller conveyor 7 from the Fig. 9 and Fig. 10. It is particularly evident how the rolling element circulation channel 8 is formed by the deflection devices 29-32 and by the rectangular tube 13. The rolling element circulation channel 8 is divided into the following sections: support channel 9, in which the rolling elements 5 rest against the running surface 6 of the steering rod 2; first deflection channel 11; return channel 10; and second deflection channel 12. The rolling elements 5 absorb the torsional forces from the steering rod 2, while the opposite side of the rolling elements 5 is supported on the outer surface 15 of the tube 13. The tube 13 can thus in turn be supported with its further outer surface 40 on the housing 21 (see, for example, Fig. 5-8). Thus, the plastic deflection devices 20-32 are subjected to only minimal stress when absorbing torsional forces or torques. When the steering rod 2 moves relative to the stationary roller recirculating device 7 along the longitudinal axis 3 of the steering rod 2, the rolling elements 5 rotate in the rolling element circulation channel 8 in one direction or the other, depending on the direction of displacement. The tube 13 is designed such that it is elastically deformed under the expected moments and / or forces in a situation where anti-twist protection is required. The tube 13 thus forms a resilient raceway for the rolling elements 5.

[0044] Fig. 12 shows a further perspective sectional view of the roller conveyor device 7 from Fig. 11. From this perspective, an inner lubricant dope 41 and an outer lubricant reservoir 42 can be seen. The terms "inner" and "outer" refer to the radial arrangement relative to the rolling element circulation channel 8.

[0045] Fig. 13 shows one of the two outer deflection devices 31, 32 made of plastic, which are manufactured by injection molding and are in direct contact with one another, i.e. are connected to one another directly by means of the locking tabs 33 and undercuts 34 without an additional central part. These form the outer curvature for the deflection of the rolling elements 5. A groove 43 in the two outer deflection devices 31, 32 continues the outer lubricant reservoir 42, which is formed by the two inner deflection devices 29 and 30. This groove 43 ends shortly before the window 48, which releases the rolling elements 5 for contact with the running surface 6. In this way, it can be achieved that as little lubricant as possible, for example lubricating grease, is carried out of the roller bearing device 7 by the rolling elements 5 rotating in the rolling element circulation channel 8 during operation and that as little lubricating grease as possible escapes during the initial greasing.A distance 44 between the groove end 46 and the outlet end formed by the window edge 47 is greater than a diameter 45 (see . Fig. 12) of the rolling elements 5 formed by cylindrical rollers. The selected spacing 44 ensures that the groove 43 is closed in the direction of the window 48 at any roller position. This ensures a sufficiently long service life and freedom from maintenance.

[0046] As a further feature, at least one of the two outer deflection devices 31 and / or 32 has at least one filling channel 49, here in the form of a bore, for the initial filling of the bearing device 4 with lubricating grease, through which the lubricant reservoirs 41 and 42 can be filled. The outer lubricating grease reservoir 42 is thereby filled directly. The inner lubricant reservoir 41 is achieved, for example, by designing the total clearance between the rolling elements 5 (also referred to as pitch circle end play) of more than 0.1 mm, so that the lubricating grease can also reach the inner lubricant reservoir 41 through this gap. Alternatively, the inner lubricant reservoir 41 can be filled via its own, i.e., separate, bore (not shown).

[0047] To prevent the cylindrical rolling elements 5 from falling out during transport and handling, at least one of the two flange surfaces in the outer deflection devices 31, 32, which are in contact with the end faces of the cylindrical rolling elements 5, preferably has a rolling element securing means 50 in the form of a projection or a bead at least on one side over the entire length of the open roller area formed by the window 48, which clamps the rolling elements 5 in their axial direction and thereby prevents them from falling out. Alternatively, this can also be achieved by projections (not shown) projecting into the rolling element spaces, which then wear away during the initial functional movements. A further alternative is a rolling element retaining means by means of spacers or cage segments or cage chains.

[0048] Fig. Figure 14 shows a first embodiment of a handlebar 2 with a roller recirculating device 7. The flattened portion 16 forming the running surface 6 is tapered, i.e., the diameter of the handlebar 2 toward a free end 51 is selected such that it does not extend beyond the running surface 6. Thus, after installation of the roller recirculating device 7, the handlebar 2 can be inserted into the housing 21 with the tapered free end 51 facing forward.

[0049] Fig. Figure 15 shows a second embodiment of a handlebar 2 with a roller recirculating device 7. The flattened portion 6 forming the running surface 6 is delimited in both directions along the longitudinal axis 3 of the handlebar 2 by an elevation, i.e., by an increase in diameter. In this embodiment, the roller recirculating device 7 is installed in the housing 21 after the handlebar 2.

[0050] Fig. 16 shows an embodiment of a roller recirculating device 7 with an inclination error compensation device 52. This is provided by a point contact support or by a line contact support (not shown) transverse to the direction of displacement of the steering rod 2, for example in the form of a lens-shaped or spherical segment-shaped or wave-shaped support, between the roller recirculating device 7 and the housing 21 (see Fig. 18 to 22). For this purpose, for example, a formed sheet steel component 53 is connected, preferably integrated, to the roller conveyor 7. Alternatively, the inclination error compensation device 52 in the form of a lens cap can also be formed directly onto the steel tube 13 or provided by the connection geometry.

[0051] In order for the roller bearing device 7 to fulfil the angle compensation function, an elastic element 54 (see Fig. 17), preferably in the form of an O-ring. This allows the roller recirculating device 7 to be mounted in a receiving pocket of a housing 21 (see Fig. 18 to 22) are positioned without play and, on the other hand, the two outer deflection devices 31 and 32 tilt relative to the longitudinal axis 3 within the housing 21 and thereby follow the angular displacement of a deflecting steering rod 2, which leads to a more uniform load distribution between the rolling elements 5 located in the support channel 9 and consequently has an advantageous effect on the service life of the roller conveyor device 7.

[0052] The Fig. 18 to 22 show different installation configurations of a steering rod 2 and a roller conveyor 7 in a housing 21. This is the housing 21 of a road wheel actuator. The Fig. The sectional views shown in Figures 18 to 22 show a section in a plane that is orthogonal to the longitudinal axis 3.

[0053] In the Fig. 18, the steering rod 2 is mounted in the housing 21. The pressure element 24 is arranged between the steering rod 2 and an inner wall of the housing. This pressure element forms the radial counterbearing for the roller bearing device 7 and presses the steering rod 2 with the running surface 6 against a subset of the rolling elements 5 of the roller bearing device 7, so that these rolling elements 5 rest against the running surface 6 without play. The steering rod 2 has the flat flattened area 16 on only one side to form the running surface 6. On the side that is in contact with the pressure element 24, no flattened area 16 is required, so the steering rod 2 is rotatably and axially displaceably mounted in the pressure element 24. The pressure element 24 is inserted into the housing 21 and has sliding surfaces that allow a low-friction sliding movement of the steering rod 2 relative to the housing 21 along the longitudinal axis 3.On the side of the recirculating roller device 7 facing away from the steering rod 2, the device is radially preloaded and secured without play by means of a closure cover 55, which is a component of the housing 21. The closure cover 55 is designed to close an opening 66 in the housing 21. The closure cover 55 also has a tilting contact surface 67, with which the closure cover 55 bears against the recirculating roller device 7 and, together with the elastic element 54, enables a damped / sprung angular adjustment movement of the recirculating roller device 7. The geometry, the material or the heat treatment of the closure cover 55 makes it possible to specifically influence its axial compliance or spring characteristic. The tilting contact surface 67 is designed as a lens dome here, although other embodiments of the tilting contact surface 67 are also possible. This also applies to the tilting contact surfaces 67 of the following with reference to the . Fig. 19 to 21 described embodiments.

[0054] The Fig. The embodiments shown in Figures 19 to 22 are modifications of the embodiment shown in Fig. 18, which is why only the differences compared to the embodiment according to Fig. 18 is discussed.

[0055] Fig. 19 shows an adjusting screw 56, which is screwed into a corresponding thread 57 of the cover 55. Depending on the screwing depth, this adjusting screw 56 can be used to adjust whether the roller recirculating device 7 is mounted with play or preloaded between the cover 55 and the steering rod 2. For this purpose, a tilting contact surface 67 of the adjusting screw 56 rests against the roller recirculating device 7.

[0056] The Fig. The embodiment shown in Figure 20 also shows the adjusting screw 56 screwed into a thread 57 of the closure cover 55, which also bears against the roller recirculating device 7 with the tilting contact surface 67. Furthermore, an additional spring element 58, for example a disc spring, is provided on the side of the housing 21 opposite the closure cover 55, between the housing inner wall and the pressure element 24. In an alternative embodiment, this additional spring element 58 can also be provided on the side of the closure cover 55; in this case, the additional spring element 58 is arranged between the closure cover 55 or the adjusting screw 56 and the roller recirculating device 7.

[0057] The embodiment according to the Fig. 18 to 20 can be manufactured as follows: The roller recirculating device 7 is preferably arranged so that all anti-rotation elements and guide elements can be mounted through the opening 66 of the housing 21, ie the construction or assembly process is designed as follows: In a first process step, the pressure element 24 is joined, either resiliently or rigidly, with or without an adjusting screw. In a second process step, the steering rod 2, e.g. according to the embodiment in Fig. 15 is installed. In a third process step, the roller recirculating device 7 is inserted into a correspondingly designed receiving pocket. In a fourth process step, the receiving pocket and thus the opening 66 are closed by means of the closure cover 55; optionally, a lens-shaped contact is established between the closure cover 55 and the roller recirculating device 7 for the angle adjustment function using the inclination error compensation device 52 (this allows a deflection of the steering rod 2 of up to 5 mm).

[0058] In the Fig. In the embodiment shown in Figure 21, an adjusting screw 56 is also provided, which is screwed into a thread 57 of the closure cover 55 and also bears against the roller recirculating device 7 with the tilting contact surface 67. In this case, the pressure element 24 is formed by a plain bearing bush 59 and a spring element 60, for example in the form of a polygonal spring foil element (also referred to as a "gas foil bearing"). In an alternative embodiment, the spring element 60 can also be omitted.

[0059] The embodiments according to the Fig. 21 can be manufactured as follows: In a first process step, the pressure element 24 is replaced by the plain bearing bushing 59 and optionally also by the spring element 60, which is / are inserted into the housing 21 in the axial direction along the longitudinal axis 3. In a second process step, the steering rod 2 is installed. In a third process step, the roller bearing device 7 is installed. The spring preload can be implemented at different locations. The illustration shows a type of tolerance sleeve or corrugated foil similar to that of a radial foil bearing as the spring element 60. Shown, for example, is a spring sheet bushing shaped into a polygon. The resulting free spaces hold the plain bearing bushing 59 elastically springy. The spring travel can, for example, be defined via the side length of the polygonal sections. The sequence of the joining steps is exemplary and does not have to be adhered to.

[0060] In the embodiment according to Fig. 22, the recirculating roller assembly 7 rests against an inner wall of the housing 21 opposite the closure cover 55. The steering rod 2 is pressed against a portion of the rolling elements 5 of the recirculating roller assembly 7 by means of the pressure device 24. The pressure device 24 is preloaded by an additional spring element 58, which is supported on the closure cover 55. There are four options for mounting the recirculating roller assembly 7 in the housing 21: First, from above in the mounting direction 61, via the opening 66 of the housing 21 closed by the closure cover 55. Second, laterally in the mounting direction 62, through a mounting window (not shown). Third, from below in the mounting direction 63, via a mounting window (not shown) and secured by means of a cover (not shown). Fourth, in the mounting direction 64, which runs parallel to the longitudinal axis 3, through a non-visible opening in the housing 21.

[0061] The embodiments according to the Fig. 22 can be manufactured as follows: In a first process step, the roller conveyor 7 is installed according to one of the four variants described above. In a second process step, the steering rod 2 is installed, which for this purpose is Fig. 14, i.e., the flattened portion tapers off toward the nearest free axial end 51, i.e., it has no elevations at the free end 51 compared to the flattened portion 16. In a third method step, the (conventional) pressure element 24 is then installed. The cover 55 is designed such that a defined gap to the pressure element 24 can be set, whereby the cover 55 forms a defined fixed stop for the pressure element 24 above a certain load. The spring element 58 thus compensates for tolerances and deformations of the system without play, and the fixed stop ensures sufficient load-bearing capacity.

[0062] Fig. 23 shows a further embodiment of a steering device 1, in which the roller circulation device 7 comprises two separate rolling element circulation channels 8. In contrast to the embodiment according to the Fig. 7 and Fig.8, which also show a roller recirculating device 7 with two rolling element recirculating channels 8, two structurally separate running surfaces 6 are provided here. The running surfaces 6 are separated by a web 68 extending along the longitudinal axis 3. The web 68 can improve the stability of the steering rod 2. Furthermore, the web 68 partially projects into the roller recirculating device 7, so that the rolling elements 5 of the two rolling element recirculating channels 8 are arranged on both sides next to the web 68. Otherwise, reference can be made to the preceding explanations; in particular, the support distance 19 can be determined by the distance between the two contact points 17 and 18 that are furthest apart from one another. List of reference symbols 1 steering device 2 handlebar 3 Longitudinal axis 4 Storage facility 5 rolling elements 6 Tread 7 Roller circulation device 8 rolling element circulation channel 9 Support channel 10 Return channel 11 first deflection channel 12 second deflection channel 13 pipe 14 Inside (of the pipe) 15 Outer surface (of the pipe) 16 Flattening 17 Investment point 18 Investment point 19 Support spacing 20 roller screw drive 21 housings 22 Actuator 23 Spindle nut 24 pressure element 25 steering wheel 26 Tie rod 27 Threaded spindle 28 centerboard 29 first inner deflection device 30 second inner deflection device 31 first outer deflection device 32 second outer deflection device 33 locking lug 34 Undercut 35 scrapers 36 recess 37 press-fit ribs 38 cones 39 tenon holder 40 additional outer surface (of the pipe) 41 internal lubricant reservoir 42 external lubricant reservoir 43 groove 44 distance 45 diameter 46 groove end 47 Window edge 48 windows 49 Filling channel 50 rolling element locking agents 51 free end (of the handlebar) 52 Inclination error compensation device 53 Sheet steel component 54 elastic element 55 closure caps 56 Adjusting screw 57 threads 58 spring element 59 plain bearing bush 60 spring element 61 Mounting direction 62 Mounting direction 63 Mounting direction 64 Mounting direction 65 groove 66 Opening 67 Tilting contact surface 68 jetty 100 Steering system QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2017 103 975 A1

[0002] DE 10 2019 208 451 A1

[0002] EP 2 738 067 A1

[0002]

Claims

[1] Steering device (1) for a steer-by-wire steering system of a vehicle, comprising - a steering rod (2) which is mounted so as to be linearly displaceable along its longitudinal axis (3), and - a bearing device (4) comprising at least one rolling element (5) which is designed for the rotationally secure mounting of the steering rod (2), wherein - the steering rod (2) comprises a running surface (6) against which the at least one rolling element (5) of the bearing device (4) rests, characterized by , that - the bearing device (4) comprises at least one roller circulation device (7), wherein - the roller circulation device (7) comprises at least one rolling element circulation channel (8) with a plurality of rolling elements (5) arranged therein in the form of rollers, which rotate in the rolling element circulation channel (8) during a linear movement of the steering rod (2) along its longitudinal axis (3), wherein - a subset of the rolling elements (5) of the at least one roller circulating device rests against the running surface (6) of the steering rod (2) in such a way that the steering rod (2) is mounted in a rotationally secure manner. [2] Steering device (1) according to claim 1, characterized by , that - the at least one rolling element circulation channel (8) comprises the following sections: - a support channel (9) which is designed to guide rolling elements (5) in such a way that they come into contact with the running surface (6) of the steering rod (2), - a return channel (10) which is designed to space the rolling elements (8) guided therein from the running surface (6), - a first deflection channel (11) which is designed to guide the rolling elements (8) from the support channel (9) into the return channel (10), and - a second deflection channel (12) which is designed to guide the rolling elements (8) from the return channel (10) into the support channel (11). [3] Steering device (1) according to claim 2, characterized by , that - the roller circulation device (7) comprises a pipe (13), wherein the return channel (10) runs through the interior (14) of the pipe (13), and / or - the rolling elements (8) in the support channel (9) are supported at least in sections by an outer surface (15) of the tube (13), and / or - the first deflection channel (11) consists entirely or partially of plastic, and / or - the second deflection channel (12) consists entirely or partially of plastic, and / or - the return channel (10) is made entirely or partially of plastic. [4] Steering device (1) according to one of the preceding claims, characterized by , that - the running surface (6) is flat and - the rolling elements (8) are cylindrical rollers. [5] Steering device (1) according to claim 4, characterized by , that - the handlebar (2) has a flat flattening (16) for forming the running surface (6), which has a transverse extension orthogonal to the longitudinal axis (3) of the handlebar (2), wherein - the length of the rolling elements (8) in the transverse direction corresponds to at least 0.5 times the transverse extent of the flattening (16). [6] Steering device (1) according to one of the preceding claims characterized by , that - the at least one roller circulation device (7) comprises at least two rolling element circulation channels (8), each with a plurality of rolling elements (5) arranged therein. [7] Steering device (1) according to one of the preceding claims, characterized by , that - in a sectional plane orthogonal to the longitudinal axis (3) of the handlebar (2), a support distance (19) is defined by the furthest apart contact points (17, 18) of the rolling element(s) (5) on the corresponding running surface (6), which support distance corresponds to at least 0.2 times the maximum diameter of the handlebar (2) in this sectional plane. [8] Steering device (1) according to one of the preceding claims, characterized by , that - the steering device (1) comprises a roller screw drive (20) which is designed to displace the steering rod (2) along its longitudinal axis (3). [9] Steering device (1) according to claim 8, characterized by , that - the steering device (1) comprises a housing (21) and an actuator (22) which is designed to drive a spindle nut (23) of the rolling screw drive (20), wherein - the at least one roller circulation device (7) is arranged within the housing (21). [10] Steering device (1) according to one of the preceding claims, characterized by , that - the steering device (1) comprises a pressure element (24) which is designed to apply a pressure force to the steering rod (2) orthogonally to its longitudinal direction (3), so that the running surface (6) is pressed against the rolling elements (5) of the at least one roller circulation device (7).

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