Longitudinally adjustable operating unit and steer-by-wire system

Abstract

The invention relates to a longitudinally adjustable operating unit (1) comprising a telescopic pull-out device (4) with an outer guide tube (5), in which an inner pull-out tube (6) is guided in a translationally displacable manner relative to the outer guide tube (5), wherein the telescopic pull-out device (4) is coupled on the one side to a steering means (7), wherein an actuation of the steering means (7) representing a steering direction causes a rotation of the outer guide tube (5) or of the inner pull-out tube (6), and the telescopic pull-out device (4) is coupled on the other side to a motor (8) by means of which a motor torque can be applied to the outer guide tube (5) or the inner pull-out tube (6), wherein the outer guide tube (5) and the inner pull-out tube (6) are supported in a torque-transmitting manner via a roller bearing arrangement (9) so as to be translationally displacable with respect to one another, wherein the roller bearing arrangement (9) has at least one first bearing element (10) with a cup-like receptacle (11) formed in a main body (15), which cup-like receptacle has a first bearing ball (12) arranged in the cup-like receptacle (11) and projecting out of same, and has a group of second bearing balls (13) arranged within the receptacle (11).

Description

[0001]Length-adjustable control unit and steer-by-wire system The present invention relates to a length-adjustable control unit for influencing a driving direction of a motor vehicle by a user, in particular for use in a steer-by-wire system, comprising a telescopic extension device with an outer guide tube, in which an inner extension tube is guided so as to be translationally displaceable relative to the outer guide tube, wherein the telescopic extension device is coupled on the one hand to a steering means, wherein an actuation of the steering means representing a steering direction causes a rotation of the outer guide tube or the inner extension tube, and the telescopic extension device is coupled on the other hand to a motor,by means of which the outer guide tube or the inner extension tube can be subjected to a motor torque. The invention further relates to a steer-by-wire system. Electric steering devices are used, among other things, in motor vehicles to receive a driver's directional command and translate it into corresponding movements of one or more wheels. In contrast to purely mechanical steering devices, electric steering devices are divided into electrically assisted steering devices and fully electric steering devices, so-called "steer-by-wire" steering devices. These steer-by-wire steering devices in particular have the advantage that the control unit can be positioned relatively freely within the vehicle, independent of mechanical connecting components.This not only saves money when differentiating between, for example, right- and left-hand drive vehicles, but also improves accident behavior due to the absence of a steering column. Furthermore, the control unit can be moved into a stowed position, which is also used, for example, in fully automatic steering. A steer-by-wire steering system in the sense of the present invention is understood to be a steering system that essentially consists of a so-called handwheel actuator (HWA), for example, the actuator system around the commanding vehicle steering wheel, and a roadwheel actuator (RWA), i.e., the actuator system acting on the steering mechanism connected to the vehicle wheels. The steering signal is transmitted from the HWA to the RWA via a line ("by wire"). Such systems are generally known from the prior art. For example, DE 102015224602 A1 discloses an adjustable steering column for a steer-by-wire steering system of a motor vehicle.comprising an actuating unit comprising a steering spindle mounted in a casing unit so as to be rotatable about a longitudinal axis, wherein the casing unit has a first casing tube in which at least one second casing tube is arranged so as to be non-rotatable with respect to the longitudinal axis and mounted so as to be axially displaceable in a telescopic manner, wherein an actuating drive is connected to the first and the second casing tube, by which the second casing tube can be axially retracted and extended relative to the first casing tube, and which comprises a spindle drive with a threaded spindle arranged parallel to the longitudinal axis and rotatably driven by an electric actuator, which is supported on one casing tube and which is screwed into a spindle nut which is non-rotatably attached to the other casing tube, wherein the threaded spindle extends within the first casing tube,and the spindle nut is attached to the second casing tube. DE 102018212696 B3 further discloses an adjustment drive for a motor-adjustable steering column for a motor vehicle, comprising a motor drive unit and an external threaded spindle having an external thread and a coaxial internal thread into which an internal threaded spindle engages, wherein the external threaded spindle and the internal threaded spindle can be driven by the drive unit to rotate relative to one another about an axis. In order to provide an adjustment drive that requires a lower drive torque and offers an optimized free adjustment path, DE 102018 212696 B3 proposes that the external threaded spindle engages a drive nut with its external thread.wherein the drive nut or the internal threaded spindle is rotatably driven by the drive unit and is supported in the direction of the axis relative to the drive unit. The object of the invention is to provide an improved length-adjustable control unit for influencing the direction of travel of a motor vehicle by a user, in particular for use in a steer-by-wire system. It is further the object of the invention to realize an improved steer-by-wire system. This object is achieved by a length-adjustable control unit for influencing the direction of travel of a motor vehicle by a user, in particular for use in a steer-by-wire system, comprising a telescopic extension device with an outer guide tube, in which an inner extension tube is guided so as to be translationally displaceable relative to the outer guide tube, wherein the telescopic extension device is coupled on the one hand to a steering means,wherein an actuation of the steering means representing a steering direction causes a rotation of the outer guide tube or the inner extension tube, and the telescopic extension device, on the other hand, is coupled to a motor, by means of which the outer guide tube or the inner extension tube can be subjected to a motor torque, wherein the outer guide tube and the inner extension tube are mounted in a torque-transmitting manner via a rolling bearing arrangement so as to be translationally displaceable relative to one another, wherein the rolling bearing arrangement has at least one first bearing element with a dome-like receptacle formed in a base body, which has a first bearing ball arranged in the dome-like receptacle and protruding therefrom and a group of second bearing balls arranged within the receptacle, wherein the diameter of the first bearing ball is larger than the diameter of a second bearing ball of the group,The group of second bearing balls is arranged between the first bearing ball and the dome-shaped receptacle, so that the first bearing ball within the dome-shaped receptacle rolls against the group of second bearing balls, and the first bearing ball protruding from the at least first bearing element rolls into a raceway extending axially through the outer guide tube or the inner extension tube, so that the outer guide tube and the inner extension tube are circumferentially fixed to one another. This provides the advantage of realizing a telescopic steering spindle with very low frictional resistance. Furthermore, the telescopic extension device exhibits extremely low wear.which can also be adjusted, for example, via a built-in spring element. Furthermore, the telescopic extension device is acoustically particularly inconspicuous. The spring-loaded body provides additional damping at higher torques, and savings can be made in the dimensional accuracy of the raceways. Due to this arrangement, depending on the variant, a raceway is only necessary in the tube or in the shaft. The first bearing ball can, in particular, be formed from a metallic material. It is also possible for the first bearing ball to be made from a ceramic or to have a ceramic coating. The group of second bearing balls can also be formed from a metallic material. Alternatively, the second bearing balls can be made from a ceramic material. Furthermore, it is conceivable for the second bearing balls to have a ceramic coating. It is particularly preferredthat the group of second bearing balls consists of essentially identical bearing balls. The inner extension tube can be designed as a hollow shaft or a solid shaft. It is also conceivable for the inner extension tube to be configured in sections as a hollow shaft and in sections as a solid shaft. According to an advantageous embodiment of the invention, the rolling bearing arrangement can have at least one second bearing element with a dome-shaped receptacle formed in a base body, which has a first bearing ball arranged in and protruding from the dome-shaped receptacle and a group of second bearing balls arranged within the receptacle, wherein the diameter of the first bearing ball is larger than the diameter of each second bearing ball in the group, wherein the group of second bearing balls is arranged between the first bearing ball and the dome-shaped receptacle,so that the first bearing ball within the dome-shaped receptacle rolls against the group of second bearing balls, and the first bearing ball protruding from the at least second bearing element rolls into a raceway extending axially through the outer guide tube or the inner extension tube, so that the outer guide tube and the inner extension tube are circumferentially fixed to one another. The advantage of this design lies in the fact that the low-friction bearing of the telescopic extension device can be further improved. According to a further preferred development of the invention, it can also be provided that the rolling bearing arrangement has at least one third bearing element with a dome-shaped receptacle formed in a base body, which has a first bearing ball arranged in the dome-shaped receptacle and protruding therefrom, and a group of second bearing balls arranged within the receptacle.wherein the diameter of the first bearing ball is larger than the diameter of each second bearing ball of the group, wherein the group of second bearing balls is arranged between the first bearing ball and the dome-like receptacle, so that the first bearing ball within the dome-like receptacle rolls against the group of second bearing balls, and the first bearing ball protruding from the at least third bearing element rolls into a raceway extending axially through the outer guide tube or the inner extension tube, so that the outer guide tube and the inner extension tube are fixed to one another in the circumferential direction. This makes it possible to provide a statically determined rolling bearing solely by the low-friction bearing elements. Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that at least one of the raceways is designed as a groove,in which one of the bearing balls engages. The advantageous effect of this design is based on the fact that the raceways can be produced in a cost-effective manner, for example by broaching and / or rotary swaging. According to a further particularly preferred embodiment of the invention, the groove can have a trapezoidal cross-sectional contour, with the bearing ball resting on the non-parallel sides of the trapezoidal groove, which allows good torque transmission while simultaneously allowing good axial displacement. In particular, the bearing ball then only has two point contacts on the non-parallel sides, which enables particularly low-friction and acoustically quiet operation of the telescopic extension device. Furthermore, the invention can also be further developed such that the first bearing element,the second bearing element and the third bearing element are constructed essentially of the same part, thereby reducing component complexity and consequently also costs. In a likewise preferred embodiment of the invention, it can also be provided that the outer guide tube or the inner extension tube has at least one receptacle extending in the radial direction, in which one of the bearing elements is accommodated. This makes it possible to insert the bearing elements into the guide tube and / or extension tube and to couple them to it in a simple and secure manner. It can also be advantageous to further develop the invention such that at least one of the bearing elements is preloaded in the radial direction by means of a spring element, so that the bearing ball rests against the raceway under spring force. The advantage that can be realized in this way isthat the telescopic extension device can be designed without play. Furthermore, this can also provide angle compensation and tolerance compensation. It can be particularly preferred that all bearing elements are preloaded via a spring element. According to a further preferred embodiment of the subject matter of the invention, it can be provided that the spring element is supported on the one hand on the base body of the bearing element and on the other hand against the receptacle. The object of the invention is further achieved by a steer-by-wire system for a motor vehicle comprising a length-adjustable control unit according to one of claims 1-9. The invention will be explained in more detail below with reference to figures without limiting the general inventive concept. It shows: Figure 1 shows a length-adjustable control unit in an axial sectional view, Figure 2 shows a first embodiment of a length-adjustable control unit in a cross-sectional view,Figure 3 shows a second embodiment of a length-adjustable control unit in a cross-sectional view, Figure 4 shows a detailed view of a bearing element in a cross-sectional view, Figure 5 shows a detailed view of the first bearing ball of the bearing element in a perspective view, Figure 6 shows a telescopic extension device in a schematic axial sectional view, Figure 7 shows a motor vehicle with a steer-by-wire steering system in a schematic block diagram. Figure 1 shows a length-adjustable control unit 1 for influencing the direction of travel of a motor vehicle 2 by a user, in particular for use in a steer-by-wire system 3, as is also sketched by way of example in Figure 7. The control unit 1 comprises a telescopic extension device 4 with an outer guide tube 5,in which an inner extension tube 6 is guided so as to be translationally displaceable relative to the outer guide tube 5. The telescopic extension device 4 is coupled, on the one hand, to a steering means 7, wherein an actuation of the steering means 7 representing the steering direction causes a rotation of the outer guide tube 5 or the inner extension tube 6. The telescopic extension device 4, on the other hand, is coupled to a motor 8, by means of which the outer guide tube 5 or the inner extension tube 6 can be subjected to a motor torque. The motor 8 thus serves as a force feedback actuator in the illustrated embodiment. The steering means 7 is a steering wheel in the illustrated embodiment. An end angle limiter is installed axially outward in the outer guide tube 5.which is supported on the casing tubes. Thus, "only" the torque of a force feedback actuator (FFA) needs to be transmitted via the telescopic extension device 4. The outer guide tube 5 and the inner extension tube 6 are mounted in a torque-transmitting manner via a rolling bearing arrangement 9 in a translationally displaceable manner, wherein the rolling bearing arrangement 9 has at least a first bearing element 10 with a dome-shaped receptacle 11 formed in a base body 15, which has a first bearing ball 12 arranged in and protruding from the dome-shaped receptacle 11 and a group of second bearing balls 13 arranged within the receptacle 11. This can be clearly seen in Figures 2-5. The diameter of the first bearing ball 12 is larger than the diameter of each second bearing ball 13 of the group, wherein the group of second bearing balls 13 are arranged between the first bearing ball 12 and the dome-like receptacle 11,so that the first bearing ball 12 rolls against the group of second bearing balls 13 within the dome-shaped receptacle 11. The first bearing ball 12, protruding from the first bearing element 10, rolls into a raceway 14 extending axially through the outer guide tube 5 or the inner extension tube 6, so that the outer guide tube 5 and the inner extension tube 6 are circumferentially fixed to one another. The first bearing ball 12 is captively received in the first bearing element 10 by the opening diameter of the corresponding circular opening in the first bearing element 10 being smaller than the diameter of the first bearing ball 12. It can also be seen from Figures 2 and 3 that the rolling bearing arrangement 9 has a second bearing element 20 with a dome-shaped receptacle 21 formed in a base body 25.which has a first bearing ball 22 arranged in the dome-shaped receptacle 21 and protruding therefrom, and a group of second bearing balls 23 arranged within the receptacle 21. Here, too, the diameter of the first bearing ball 22 is larger than the diameter of each second bearing ball 23 of the group, the group of second bearing balls 23 being arranged between the first bearing ball 22 and the dome-shaped receptacle 21, so that the first bearing ball 22 bears rollingly against the group of second bearing balls 23 within the dome-shaped receptacle 21. The first bearing ball 22 protruding from the at least second bearing element 20 engages rollingly in a raceway 24 extending axially through the outer guide tube 5 or the inner extension tube 6, so that the outer guide tube 5 and the inner extension tube 6 are fixed to one another in the circumferential direction. The first bearing ball 22 is captively received in the second bearing element 20,by the opening diameter of the corresponding circular opening in the second bearing element 20 being smaller than the diameter of the first bearing ball 22. Figures 2-3 also clearly show that the rolling bearing arrangement 9 comprises a third bearing element 30 with a dome-shaped receptacle 31 formed in a base body 35, which has a first bearing ball 32 arranged in and protruding from the dome-shaped receptacle 31 and a group of second bearing balls 33 arranged within the receptacle 31. As with the other bearing elements 10, 20, the diameter of the first bearing ball 32 is larger than the diameter of each second bearing ball 33 of the group, with the group of second bearing balls 33 being arranged between the first bearing ball 32 and the dome-shaped receptacle 31.so that the first bearing ball 32 rolls against the group of second bearing balls 33 within the dome-like receptacle 31. The first bearing ball 32 protruding from the third bearing element 30 rolls into a raceway 34 extending axially through the outer guide tube 5 or the inner extension tube 6, so that the outer guide tube 5 and the inner extension tube 6 are fixed to one another in the circumferential direction. The first bearing ball 32 is captively received in the third bearing element 30 in that the opening diameter of the corresponding circular opening in the third bearing element 30 is smaller than the diameter of the first bearing ball 32. Figures 2-3 also show that the first bearing element 10, the second bearing element 20, and the third bearing element 30 are constructed essentially from the same parts. In the embodiments shown in Figures 2-3, the raceways 14, 24, 34 are each designed as a groove,in each of which one of the bearing balls 12, 22, 32 correspondingly engages. Figure 4 further shows that the groove has a trapezoidal cross-sectional contour, with the bearing ball 12, 22, 32 resting on the non-parallel sides 42 of the trapezoidal groove. What can also be seen from Figures 2-3 is that the outer guide tube 5 or the inner extension tube 6 has a total of three receptacles 40 extending in the radial direction, in which one of the bearing elements 10, 20, 30 is received. In the embodiment of Figure 2, the bearing elements 10, 20, 30 are arranged in the inner extension tube 6, with the bearing balls 12, 22, 32 then rolling on the raceways 14, 24, 34 of the outer guide tube 5. In the embodiment of Figure 3, the bearing elements 10, 20, 30 are arranged in the outer guide tube 5, with the bearing balls 12, 22, 32 rolling on the raceways 14, 24, 34 of the inner extension tube 6. Also shown in Figure 2,that one of the bearing elements 10 is preloaded in the radial direction by means of a spring element 41, so that the bearing ball 12 rests against the raceway 14 under spring force. The spring element 41 is supported on the one hand on the base body 15 of the bearing element 10 and on the other hand against the receptacle 40. The spring element 41 can be designed in particular as a disc spring. The bearing elements 20 and 30 can also be preloaded by means of a spring. Figure 6 shows the embodiment known from Figure 2 in an axial sectional view. The outer guide tube 5 is connected to the motor 8, which is arranged stationary with the guide tube 5 in the control unit 1. The inner extension tube 6 can then be translationally displaced in the outer guide tube 5 by the roller bearing arrangement 9.so that the steering means 7 can be extended or retracted relative to the outer guide tube 5. Finally, Figure 7 shows a steer-by-wire system 3 for a motor vehicle 2 comprising a length-adjustable control unit 1, as known, for example, from Figure 1. By means of the control unit 1, which can also be referred to as a HWA - hand-wheel actuator, an RWA - road-wheel actuator 43 is then electrically controlled, which then converts the steering movement of the HWA to the vehicle wheels. The invention is not limited to the embodiments illustrated in the figures. The above description is therefore not to be considered restrictive, but rather explanatory. The following claims are to be understood as meaning that a named feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. If the claims and the above description define 'first' and 'second' features,This designation serves to distinguish between two similar features without establishing a priority. List of reference symbols 1 Control unit 2 Motor vehicle 3 Steer-by-wire system 4 Extension device 5 Guide tube 6 Extension tube 7 Steering mechanism 8 Motor 9 Rolling bearing arrangement 10 Bearing element 11 Receptacle 12 Bearing ball 13 Bearing balls 14 Raceway 15 Base body 20 Bearing element 21 Receptacle 22 Bearing ball 23 Bearing balls 24 Raceway 25 Base body 30 Bearing element 31 Receptacle 32 Bearing ball 33 Bearing balls 34 Raceway 35 Base body 40 Receptacle 41 Spring element Pages RWA,

Claims

Claims 1. Length-adjustable operating unit (1) for influencing a driving direction of a motor vehicle (2) by a user, in particular for use in a steer-by-wire system (3), comprising a telescopic extension device (4) with an outer guide tube (5), in which an inner extension tube (6) is guided so as to be translationally displaceable relative to the outer guide tube (5), wherein the telescopic extension device (4) is coupled on the one hand to a steering means (7), wherein an actuation of the steering means (7) representing a steering direction causes a rotation of the outer guide tube (5) or the inner extension tube (6), and the telescopic extension device (4) is coupled on the other hand to a motor (8), by means of which the outer guide tube (5) or the inner extension tube (6) can be subjected to a motor torque, characterized in thatthat the outer guide tube (5) and the inner extension tube (6) are mounted in a torque-transmitting manner via a rolling bearing arrangement (9) in a translationally displaceable manner relative to one another, wherein the rolling bearing arrangement (9) has at least one first bearing element (10) with a dome-shaped receptacle (11) formed in a base body (15), which has a first bearing ball (12) arranged in the dome-shaped receptacle (11) and protruding therefrom and a group of second bearing balls (13) arranged within the receptacle (11), wherein the diameter of the first bearing ball (12) is greater than the diameter of a second bearing ball (13) of the group, wherein the group of second bearing balls (13) is arranged between the first bearing ball (12) and the dome-shaped receptacle (11),so that the first bearing ball (12) within the dome-like receptacle (11) bears rollingly against the group of second bearing balls (13) and the first bearing ball (12) projecting from the at least first bearing element (10) engages rollingly in a raceway (14) extending axially through the outer guide tube (5) or the inner extension tube (6), so that the outer, Guide tube (5) and the inner extension tube (6) are fixed to one another in the circumferential direction.

2. Length-adjustable operating unit (1) according to claim 1, characterized in that the rolling bearing arrangement (9) has at least one second bearing element (20) with a dome-shaped receptacle (21) formed in a base body (25), which has a first bearing ball (22) arranged in and protruding from the dome-shaped receptacle (21) and a group of second bearing balls (23) arranged within the receptacle (21), wherein the diameter of the first bearing ball (22) is larger than the diameter of a respective second bearing ball (23) of the group, wherein the group of second bearing balls (23) is arranged between the first bearing ball (22) and the dome-shaped receptacle (21).so that the first bearing ball (22) within the dome-like receptacle (21) rolls against the group of second bearing balls (23), and the first bearing ball (22) protruding from the at least second bearing element (20) rolls into a raceway (24) extending axially through the outer guide tube (5) or the inner extension tube (6), so that the outer guide tube (5) and the inner extension tube (6) are fixed to one another in the circumferential direction.

3. Length-adjustable operating unit (1) according to one of the preceding claims, characterized in that the rolling bearing arrangement (9) has at least one third bearing element (30) with a dome-like receptacle (31) formed in a base body (35), which has a first bearing ball (32) arranged in and protruding from the dome-like receptacle (31) and a group of second bearing balls (33) arranged within the receptacle (31).wherein the diameter of the first bearing ball (32) is larger than the diameter of a second bearing ball (33) of the group, wherein the group of second bearing balls (33) are arranged between the first bearing ball (32) and the dome-like receptacle (31), so that the first bearing ball (32) rolls within the dome-like receptacle (31) on the, Group of second bearing balls (33) and the first bearing ball (32) protruding from the at least third bearing element (30) engages in a rolling manner in a raceway (34) extending axially through the outer guide tube (5) or the inner extension tube (6), so that the outer guide tube (5) and the inner extension tube (6) are fixed to one another in the circumferential direction.

4. Length-adjustable operating unit (1) according to one of the preceding claims, characterized in that at least one of the raceways (14, 24, 34) is designed as a groove into which one of the bearing balls (12, 22, 32) engages.

5. Length-adjustable operating unit (1) according to claim 4, characterized in that the groove has a trapezoidal cross-sectional contour, wherein the bearing ball (12, 22, 32) bears against the non-parallel sides (42) of the trapezoidal groove.Length-adjustable operating unit (1) according to one of the preceding claims, characterized in that the first bearing element (10), the second bearing element (20), and the third bearing element (30) are designed essentially as identical parts.

7. Length-adjustable operating unit (1) according to one of the preceding claims, characterized in that the outer guide tube (5) or the inner extension tube (6) has at least one receptacle (40) extending in the radial direction, in which one of the bearing elements (10, 20, 30) is received.

8. Length-adjustable operating unit (1) according to one of the preceding claims, characterized in that at least one of the bearing elements (10, 20, 30) is preloaded in the radial direction by means of a spring element (41), so that the bearing ball (12, 22, 32) bears against the raceway (14, 24, 34) under spring force.

9. Length-adjustable control unit (1) according to claim 8, characterized in that the spring element (41) is supported on the one hand on the base body (15, 25, 35) of the bearing element (10, 20, 30) and on the other hand against the receptacle (40).

10. Steer-by-wire system (3) for a motor vehicle (2) comprising a length-adjustable control unit (1) according to one of the preceding claims.

Images