Steering unit for a vehicle

Abstract

The invention relates to a steering unit (1), in particular a steer-by-wire steering unit, for a vehicle, comprising: a steering rod (2) which is configured to be coupled at each of its axial ends to a wheel of the vehicle, wherein at least portions of the steering rod (2) have a sensor toothing system (15); an adjusting actuator (3) which is coupled to the steering rod (2) in such a way that a rotational movement of the adjusting actuator (3) brings about a translational movement of the steering rod (2) for changing the position of the steering rod (2) along a predetermined steering rod movement path (VWL); a sensor toothing device (4), at least portions of which have a mating toothing system which corresponds to the sensor toothing system (15) of the steering rod (2) and is in tooth engagement with the sensor toothing system (15) of the steering rod (2) in such a way that the translational movement of the steering rod (2) brings about a change in the position of the sensor toothing device (4) along a predetermined sensor movement path, wherein relative sliding occurs in the tooth engagement between the sensor toothing device (4) and the sensor toothing system (15) of the steering rod (2), which relative sliding is greater than or equal to 80% of the translational movement of the steering rod (2); and a sensor device (5) for determining the position of the steering rod (2), which sensor device is configured to detect a position of the sensor toothing device (4) along the predetermined sensor movement path (15).

Description

[0001] Steering unit for vehicle

[0002] The present invention relates to a steering unit, in particular a steer-by-wire steering unit for a vehicle.

[0003] State of the art

[0004] Today, both mechanical steering systems or steering units and so-called steer-by-wire steering systems or steering units are known. Steering systems can be divided into two subsystems: the system of the steering shaft with a steering element, such as a steering wheel, which is also referred to as a “hand wheel actuator” (HWA) system, and the system of the steering actuator for steering the wheels, which is also referred to as the “road wheel actuator” (RWA) system. In mechanical steering systems, these two subsystems are mechanically connected via the steering column and, if applicable, a steering gear. Thus, in mechanical steering systems, the two subsystems are directly, i.e. physically, connected. In these mechanical steering systems, the position of the steering element is always uniquely linked to the position of the steering actuator, in particular a steering rod.This means that a specific position of the steering element is uniquely assigned to a specific position of the handlebar, so that each position of the handlebar is assigned to a specific position of the steering element.

[0005] In steer-by-wire steering systems, the mechanical connection between the two subsystems via the steering column is dispensed with, and the steering of the wheels in response to a movement of the steering element is controlled by transmitting corresponding signals between the two subsystems HWA and RWA. In other words, with steer-by-wire steering systems, the physical steering column, which transmits the steering movement or driver input from the steering wheel directly via the steering gear, tie rod and wheel carrier to the wheel, is replaced by electrically redundant “by wire”, i.e. signal transmission via cable. As a result, the position of the steering element is no longer physically linked to the position of the handlebar, and such a one-to-one coupling of the position of the steering element with the position of the handlebar is usually achieved with sensors that are arranged in the RWA system and serve to determine the position of the handlebar. Various sensor arrangements are possible, such as:B. from WO 2018 / 073267 A1, DE 11 2020 002 949 T5, DE 102021 212 470 A1, known.

[0006] It has now become apparent that there is a further need to improve a known device for determining the position of the steering rod for a steering unit, in particular a steer-by-wire steering unit, of a vehicle. In particular, there is a further need to provide a device for determining the position of the steering rod that allows the position of the steering rod to be determined absolutely, and in particular even after the vehicle has been switched off or de-energized.

[0007] Against this background, it is an object of the present invention to provide an improved device for determining the position of a handlebar for a steering unit, in particular a steer-by-wire steering unit, of a vehicle, which device enables in particular an absolute, and further in particular constant, determination of the handlebar position.

[0008] Disclosure of the invention

[0009] These and other objects, which will be mentioned upon reading the following description or which may be recognized by a person skilled in the art, are achieved by the subject matter of the independent claim. Advantageous embodiments and further developments can be found in the dependent claims and the following description.

[0010] The steering unit according to the invention, in particular a steer-by-wire steering unit, for a vehicle comprises a steering rod, a control actuator, a sensor gearing device, and a sensor device for determining the position of the steering rod. The steering rod is configured to be coupled to a wheel of the vehicle at each of its axial ends and has a sensor gearing at least in sections. The control actuator is coupled to the steering rod in such a way that a rotational movement of the control actuator causes a translational movement of the steering rod along its longitudinal axis to change the position of the steering rod along a predetermined steering rod travel path.The sensor gearing device has, at least in sections, a counter-toothing system corresponding to the sensor gearing of the handlebar, which meshes with the sensor gearing of the handlebar in such a way that the translational movement of the handlebar along its longitudinal axis causes a change in the position of the sensor gearing device along a predetermined sensor travel path. In the meshing between the sensor gearing device and the sensor gearing, a relative sliding occurs that is equal to or greater than 80% of the handlebar travel path. The sensor device for determining the position of the handlebar is configured to detect a position and / or a change in the position of the sensor gearing device along the predetermined sensor travel path.

[0011] The sensor gearing device and / or the sensor gearing on the handlebar each have a tooth height of less than 3 mm, more particularly less than 2 mm, wherein the tooth height is defined from a tooth tip to a tooth root. Furthermore, the tooth engagement has a tooth engagement angle of greater than 25°.

[0012] The sensor toothing is provided in particular only in local zones, i.e., in sections, on the handlebar, especially outside of other sliding and / or rolling zones provided on the handlebar. With respect to the circumference of the handlebar or a lateral surface of the handlebar, the sensor toothing can be provided in sections or completely circumferentially, in particular in a helical thread.

[0013] Relative sliding of more than 80% of the predetermined sensor travel enables tooth engagement with low frictional resistance because the contact force of the sensor gearing device is low. This can reduce frictional force, frictional energy, and / or frictional wear.

[0014] The advantage of the solution according to the invention lies in particular in the fact that the movement of the handlebar along its longitudinal axis is recorded with a high degree of accuracy. The required measuring path, in this case the maximum sensor travel path that the sensor gearing device must be able to cover in order to be able to determine the position, in particular the absolute position, of the handlebar, is smaller than the maximum travel path that the handlebar can cover. The maximum travel path is defined as the path that the handlebar covers when it is moved along its longitudinal axis from a maximum deflection position of the wheels, e.g. maximum possible inclination of the wheels to the left, to another maximum deflection position of the wheels, e.g. maximum possible inclination of the wheels to the right.This makes it possible to determine the position of the handlebar, in particular to determine the absolute position of the handlebar, with reduced installation space, especially in comparison to directly measuring linear displacement sensors.

[0015] It can therefore be said that the sensor device for determining the position of the handlebar, in particular the absolute position of the handlebar, generally works independently and can essentially determine the position of the handlebar on its own with sufficiently high accuracy, resolution and reliability and output it as an output signal.

[0016] In addition, however, it is also possible to combine the output signal of the sensor device for determining the position of the handlebar with another signal, in particular the signal from a rotor position sensor from the actuator. The rotor position sensor generally provides a highly precise signal corresponding to an electrical or mechanical angle of the rotor, which is required to control the actuator, in particular in the form of an electric motor. The angle of the rotor is highly proportional to the position of the handlebar, in particular usually around 2-5 mm / rev, but - considered on its own - does not allow the absolute position of the handlebar to be determined, since the angle of the rotor performs several complete revolutions over the entire travel path of the handlebar, which can also be referred to as the handlebar travel path, e.g., on the order of approximately 20-100 revolutions.In combination with the sensor device of the steering unit described above, in particular according to the invention, an exact determination of the position of the handlebar, in particular of the absolute position of the handlebar, is now possible, wherein the sensor device only has to have a low resolution or accuracy, since the sensor device only has to carry out a rough determination of the position of the handlebar, while the rotor position sensor has the high resolution or accuracy, so to speak.

[0017] decimal places. Such a combination can make it possible to further improve resolution and accuracy.

[0018] This allows the costs for the sensor device for determining the position of the handlebar, and thus for the steering unit, to be reduced, as the demands placed on the sensor device are lower than in a case where the sensor device alone, i.e. independently, must deliver the high accuracy or resolution. Even in a case where the rotor position sensor fails during operation, it is possible to temporarily control the actuator using the signal from the sensor device, even if the resolution or accuracy of the sensor device relative to the angle of the rotor of the actuator is rather low. Conversely, it is also possible to temporarily compensate for a failure of the sensor device for determining the position of the handlebar during operation by incrementally "counting" the signal from the rotor position sensor, in particular at least as long as power is ensured to the rotor position sensor and, if applicable, an associated control unit.

[0019] Furthermore, continuous monitoring of the signal from the rotor position sensor and the signal from the sensor device for determining the position of the steering rod can make it possible to detect implausible discrepancies in the signals, which could indicate, for example, a belt jump and / or belt wear. This allows for early detection of an incipient failure of the mechanical system.

[0020] Furthermore, it is conceivable to determine the position of the handlebar, in particular the absolute position of the handlebar, using the Vernier principle. In this case, it is conceivable to design the sensor device for position determination not to determine the absolute position of the handlebar, but rather such that it only covers a small, in particular high-resolution, measuring range on the handlebar, which is repeated periodically over the entire travel path of the handlebar. The period length should in particular be selected such that it differs only slightly from that of the rotor position sensor and the difference or phase shift between the signals allows a clear determination of the position, in particular the absolute position, of the handlebar at any time. This can reduce the requirements with regard to the detection accuracy of the sensor device, since a significantly smaller measuring range has to be covered, but this range is repeated several times in a row.Inductive sensor devices are particularly suitable for this purpose.

[0021] According to one embodiment, the sensor toothing of the steering rod has a helix angle of approximately 45° to 85°, in particular approximately 65° to 85°, and more particularly approximately 80°. Thus, the sensor toothing is oriented virtually lengthwise along the steering rod, rather than transversely to the spindle like conventional rack toothing. Such an inclined position of the teeth supports the relative sliding of the sensor toothing device relative to the sensor toothing.

[0022] According to one embodiment, the steering unit further comprises a bearing unit for radially supporting the handlebar. The bearing unit is designed to reduce or even prevent deflection of the handlebar in the radial direction and / or rotation of the handlebar about its own longitudinal axis, while still allowing linear movement of the handlebar along its longitudinal axis. In particular, the bearing unit is arranged on a flattened section of the handlebar. Arranging it on a flattened section of the handlebar enables simple and thus cost-effective implementation of the bearing unit, since a flattened section particularly simplifies the implementation of an anti-twist device.

[0023] According to one embodiment, the bearing unit comprises a pressure piece and a pressure roller, which are arranged opposite one another and guide the handlebar between them so that they can move longitudinally. The pressure piece generally serves to prevent the handlebar from rotating about its own longitudinal axis. The pressure roller is generally designed to reduce or even prevent radial deflection of the handlebar, particularly in the area of ​​the pressure piece, in order to ensure contact with the pressure piece that guides the handlebar.

[0024] According to one embodiment, the sensor toothing of the handlebar is essentially flat. This simplifies the manufacture of the sensor toothing because the handlebar does not need to be rotated during production, particularly by machining.

[0025] According to one embodiment, the sensor gearing device has at least one spur gear that is configured to rotate by a specific angle, in particular less than 360°, over the entire travel of the handlebar. The rotation of the spur gear corresponds to the sensor travel. The rotation angle of the spur gear is detected by the sensor device, e.g., by detecting a sensor target that is non-rotatably attached to the spur gear, and can be uniquely assigned to a position of the handlebar. "Unique" here means that each angular position of the spur gear is assigned to only a single position of the handlebar, so that the position of the handlebar can be easily determined from the detected angular position. A rotation of less than 360° over the entire travel of the handlebar enables the use of simple, and thus cost-effective, sensors.For rotations of equal to or more than 360° over the entire travel range of the handlebar, so-called multi-turn sensors are generally used to enable a unique assignment between the angle of rotation and the position of the handlebar.

[0026] Furthermore, it is also conceivable for the sensor gearing device to have two or more spur gears, all meshing with the same sensor gearing, or for the steering rod to have multiple sensor gearing sections, and for the two or more spur gears to each mesh with one of these multiple sensor gearing sections. The spur gears can all have the same configuration or different configurations, in particular with regard to a number of teeth and / or a helix angle.

[0027] According to one embodiment, the spur gear is mounted in a preloaded manner and / or a toothing of the spur gear has a helix angle of up to approximately 45°. Furthermore, the spur gear is mounted in particular with axial and / or radial plain or roller bearings. The spur gear is in particular preloaded against the handlebar, further in particular with a preload force greater than 100 N, in order to ensure that the tooth engagement between the spur gear and the sensor toothing of the handlebar is free of play under all operating conditions. In particular, the teeth of the toothing on the spur gear are designed with a helix angle of up to approximately 45°, furthermore conical or tapered, or with another gear helix. A rotational axis of the spur gear is oriented almost parallel, in particular substantially parallel, to the longitudinal axis of the handlebar.Alternatively, the rotational axis of the spur gear can also be oriented at an angle of up to 45°, in particular less than 45°, relative to the longitudinal axis of the steering rod, whereby a straight-toothed spur gear can be used.

[0028] According to one embodiment, the sensor gearing device is designed as a two-stage spur gear having two meshing gears, wherein a first gear of the two-stage spur gear is further meshed with the sensor gearing of the handlebar, and the spur gearing has a gear ratio such that a second gear of the spur gearing rotates by a predetermined angle, in particular less than 360°, over the entire travel of the handlebar. With such a spur gearing, it is possible to design the sensor gearing on the handlebar as a straight gear, which simplifies the manufacture of the sensor gearing.Thus, the first gear and the second gear can also be designed with straight teeth, and the rotational movement of the second gear over the entire travel path of the handlebar is essentially defined by a transmission ratio between the first gear and the second gear. This means that the rotational movement of the second gear corresponds to the sensor travel path. The rotation angle of the second gear is detected - analogous to the spur gear described above - by the sensor device, e.g. by detecting a sensor target which is rotationally attached to the second gear, and can be uniquely assigned to a position of the handlebar. Unique here means that each angular position is assigned only a single position of the handlebar, so that the position of the handlebar can be easily determined from the detected angular position.A rotation of less than 360° across the entire travel of the handlebar allows for the use of simple, and therefore cost-effective, sensors. For rotations of equal to or greater than 360° across the entire travel of the handlebar, so-called multi-turn sensors are generally used to enable a unique correlation between the rotation angle and the position of the handlebar.

[0029] According to one embodiment, the spur gear is mounted preloaded, particularly on the output side. This ensures backlash-free meshing between the spur gear and the handlebar. For example, the second spur gear can be preloaded by means of a spiral spring. Alternatively, the second gear can be designed in two parts, with the two parts of the second gear being mounted clamped against each other. The output-side preload ensures that the same flank always remains in tooth contact, even during a change of direction, making the preload less sensitive to tolerances, particularly manufacturing tolerances. In other words, the preload can be rotational, particularly via the angle of rotation of the second gear, or via the radial distance between the second gear and the handlebar.Additionally or alternatively, the teeth of the first gear may have a helix angle of up to approximately 45°.

[0030] According to one embodiment, the sensor gearing device comprises at least one internally toothed ring gear, which is arranged to rotate, in particular non-coaxially, around the handlebar, wherein an internal toothing of the ring gear meshes with the sensor toothing of the handlebar, and wherein the ring gear is configured to rotate by a predetermined angle, in particular less than 360°, over the entire handlebar travel path. Thus, in this embodiment, the rotational movement of the ring gear corresponds to the sensor travel path. The design as an internally toothed ring gear enables mounting within the housing, in particular with plain or roller bearings, and thus a particularly space-saving implementation of the sensor gearing device.Furthermore, the internally toothed ring gear can have a high number of teeth, thereby implementing a high contact ratio that enables secure contact between the sensor gearing device and the sensor gearing. Furthermore, the ring gear can be made of a plastic, such as a single-material plastic, a plastic blend, or a fiber-reinforced plastic or blend. Analogous to the spur gears described above, the ring gear has a sensor target that is non-rotatably mounted on the ring gear and is configured to be detected by the sensor device.

[0031] According to one embodiment, the sensor toothing is formed spirally on the outer surface of the handlebar. In particular, the sensor toothing is formed helically around the outer surface. The grooves of the sensor toothing are very long, as they run almost the length of the handlebar.

[0032] According to one embodiment, the sensor gearing device comprises a rack, in particular a helical-toothed rack, which meshes with the sensor gearing of the handlebar, wherein the rack is arranged substantially perpendicular or orthogonal to the handlebar. Thus, a movement of the handlebar along its longitudinal axis is converted into a longitudinal movement of the rack that is orthogonal or tangential thereto. By selecting a transmission ratio between the gearing of the rack and the sensor gearing of the handlebar, the length of the entire sensor travel path can be influenced. In this embodiment, the sensor travel path corresponds to the longitudinal movement of the rack.Purely mathematically, a rack arranged at right angles to the handlebar results in relative sliding, i.e. slippage, of more than 100%, which can be reduced to less than 100% by a slight inclination, i.e. a non-vertical, in particular skewed, orientation of the rack to the longitudinal axis of the handlebar.

[0033] According to one embodiment, the rack is arranged in or near the bearing unit for radially supporting the handlebar. The arrangement of the rack, in particular combined with the orientation of the rack substantially perpendicular to the handlebar movement, can almost completely prevent any distortion of the measured value detected by the sensor device due to deformation of the handlebar. If the rack is arranged close to, but next to, the bearing unit, such distortion can be kept to a minimum. In particular, the rack can be arranged or mounted in the pressure piece of the bearing unit, wherein the rack is in contact with the handlebar in the central region of the pressure piece. In the central region, the pressure piece, in particular a plain bearing of the pressure piece, does not bear, i.e.In this area, no load is absorbed by the steering rod, and therefore this area can be spared and used to support the steering rack. Furthermore, the pressure piece always rests against the steering rod due to spring force, thus preventing distortion of the measured value or measurement signal even in the event of external force or deflection of the steering rod.

[0034] According to one embodiment, the rack and the sensor toothing of the handlebar mesh in such a way that the total rack travel is smaller than the total travel of the handlebar. This means that a gear ratio between the rack and the sensor toothing is selected such that the total rack travel, i.e., the sensor travel, is smaller than the total travel of the handlebar along its longitudinal axis. The smaller or shorter movement of the rack simplifies the position determination of the handlebar by the sensor device, since the smaller movement is easier to measure. In particular, the rack travel is less than one-third of the travel of the handlebar.

[0035] According to one embodiment, the rack is arranged to be axially displaceable relative to the bearing unit. The axial relative movement relative to the bearing unit enables the perpendicular relative movement of the rack relative to the steering rod when the steering rod is moved along its longitudinal axis.

[0036] According to one embodiment, the sensor device comprises an inductive sensor, an xMR sensor, or a Hall sensor. The type of sensor can depend on the operating conditions, such as environmental influences, interference, etc. The type of target is generally selected depending on the type of sensor used in the sensor device. The term "xMR sensor" refers to all magnetoresistive (MR) sensors, such as GMR, TMR, AMR, etc. In other words, the "x" is a placeholder for the various types of magnetoresistive sensors.

[0037] According to one embodiment, the sensor device has at least one moving coil sensor arranged at one axial end of the rack, surrounding the rack. The moving coil sensor is an example of an inductive sensor. In particular, the sensor device has two moving coil sensors, one of which is arranged at each axial end of the rack, surrounding the rack. For this purpose, at least the axial ends of the rack comprise a metallic material, e.g., iron or steel. Furthermore, in particular, the externally arranged moving coil sensors are connected to the pressure piece of the bearing unit, such that the moving coil sensors follow every movement of the pressure piece, e.g., due to external forces on the steering rod, and thus falsification of the measured value or the measurement signal due to a shift in the relative position of the rack to the moving coil sensors is avoided.

[0038] Alternatively, as already mentioned above, other types of sensors, e.g. capacitive, magnetic, resistive, etc. sensors, are also conceivable.

[0039] In general, the rack can be formed at least predominantly from a plastic, such as a single-variety plastic, a plastic mixture or a fiber-reinforced plastic or mixture, whereby the cost and / or weight of the rack can be reduced compared to a rack made of metal.

[0040] According to one embodiment, the rack is preloaded in the axial and / or radial directions. As a result, the rack is preloaded parallel and / or orthogonally to the steering rod and thus positioned without backlash. Particularly with large gear ratios between the rack and the sensor gearing, even small deviations in the rack movement or position can lead to significant measurement errors, which can be reduced or even prevented by the backlash-free meshing between the rack and the sensor gearing of the steering rod.

[0041] Detailed description based on drawing

[0042] Further measures improving the invention are described in more detail below, together with the description of preferred embodiments of the invention, with reference to the figures. It shows:

[0043] Fig. 1 shows schematic representations of a steering unit according to an embodiment of the invention in a perspective view (a), a side view (b), a view from above (c), and a perspective enlarged detail view (d), Fig. 2 shows a schematic, enlarged representation of a partial section of a steering unit according to an embodiment of the invention in a view from the front,

[0044] Fig. 3 schematic, enlarged representations of a partial section of a steering unit according to an embodiment of the invention in a side view (a) and a view from above (b),

[0045] Fig. 4 is a schematic representation of a steering unit according to an embodiment of the invention in a side view,

[0046] Fig. 5 is a schematic representation of a steering unit according to an embodiment of the invention in a perspective view,

[0047] Fig. 6 schematic representations of a steering unit according to an embodiment of the invention in a perspective view (a) and a side view (b),

[0048] Fig. 7 is a schematic, enlarged view of a partial section of a steering unit according to an embodiment of the invention in a front view,

[0049] Fig. 8 is a schematic partial representation of a steering unit according to an embodiment of the invention in a perspective view,

[0050] Fig. 9 is a schematic cross-sectional view of a steering unit according to an embodiment of the invention,

[0051] Fig. 10 is a schematic partial representation of a steering unit according to an embodiment of the invention in a perspective view, and

[0052] Fig. 11 is a schematic longitudinal sectional view of a steering unit according to an embodiment of the invention,

[0053] The figures are merely schematic and serve only to clarify the invention. The same elements are designated by the same reference numerals.

[0054] Fig. 1 to Fig. 11 all show schematically and by way of example a steering unit 1 or partial sections of the steering unit 1 according to various embodiments of the invention. Even if not everything is always shown for every embodiment, the steering unit 1 according to all of the exemplary embodiments shown has a handlebar 2, a control actuator 3 (see Fig. 8 as an example), a sensor gearing device 4, and a sensor device 5 for determining the position of the handlebar (see Fig. 8 and Fig. 9 as examples). The embodiments shown in Fig. 1 to Fig. 11 differ essentially in the design and the measuring principle of the sensor gearing device 4. Thus, the embodiments can be roughly divided according to the measuring principle for determining the position of the handlebar 2 into a rotary measuring principle (Fig. 1 to Fig. 7) and a translatory measuring principle (Fig. 8 to Fig. 11).

[0055] 1 to 3 show a steering unit 1 according to an exemplary embodiment of the invention in different views. The steering rod 2 according to the embodiment shown in Fig. 1 has a spindle section 6 and a section 7 that is flattened on one side. The spindle section 6 has a screw contour 8 with a typical pitch of approximately 8 mm and is part of a ball screw drive (not shown) that serves to convert the rotational movement of the actuating actuator 3 into a translational movement of the steering rod 2 along its longitudinal axis L. A bearing unit 9 is arranged on the flattened section 7 and comprises a pressure piece 10 (not shown in Fig. 1(d)) and a pressure roller 11. The flattened section 7 has a plurality of functional zones distributed over the circumference. For example,a partial circle section 12 of the handlebar 2, on which the pressure piece 10 is arranged, is designed as a sliding surface, over which the handlebar 2 is arranged so as to be axially displaceable relative to the pressure piece 10 along its longitudinal axis L. A section 13 arranged opposite the sliding surface, which is flattened on one side here, serves, among other things, as a rolling surface 14 (see in particular Fig. 1(d)), on which the pressure roller 11 rolls in order to prevent rotation of the handlebar 2 about its longitudinal axis L (see also Fig. 2).

[0056] In addition, the section 13 further comprises a sensor toothing 15, which is designed as a strong helical toothing with a helix angle β of approximately 80° (see Fig. 3(b)). In particular, the sensor toothing 15 can have a helix angle β of approximately 60° to approximately 85°. Such a strong inclination of the sensor toothing 15 enables or causes the sensor toothing device 4, which engages with the sensor toothing 15 of the handlebar 2, to slide in this tooth engagement rather than roll. In particular, a relative sliding of more than 80% is possible here, and in particular, even desirable.

[0057] In the embodiment shown in Fig. 1, the pressure roller 11 is recessed in the area of ​​the sensor toothing 15, so that the sensor toothing 15 can, so to speak, dip beneath the pressure roller 11 when the handlebar 2 moves along its longitudinal axis L. The pressure roller 11 therefore does not touch the sensor toothing 15, thereby preventing wear of the sensor toothing 15 due to rolling contact with the pressure roller 11. In principle, the sensor toothing 15 can also be formed in other areas of the section 13 (see, for example, Fig. 4 or Fig. 6). As can be seen in particular in Fig. 1(b) and Fig. 1(c), it is possible for a production-related run-out zone 19 of a rolling tool required for producing the sensor toothing 15 to protrude into the spindle section 6. More precisely, a run-out zone 20 of the screw contour 8 formed on the spindle section 6 and the run-out zone 19 of the sensor toothing 15 can overlap.Furthermore, it is even conceivable that an operating zone of the sensor toothing 15 overlaps with the run-out zone 20 of the screw contour 8, provided that the spur gear 16 is designed to be correspondingly wide, e.g., 20 mm with a pitch of approximately 8 mm.

[0058] In the embodiment shown in Fig. 1 to Fig. 3, the sensor gearing device 4 is designed as a helical-toothed spur gear 16 that meshes with the sensor gearing 15 of the handlebar 2 such that it rotates about a rotation axis R (see in particular Fig. 3(a)) when the handlebar 2 moves along its longitudinal axis L. The rotation axis R is oriented almost parallel to the longitudinal axis L of the handlebar 2. A helix angle of the helical gearing of the spur gear 16, which can also be referred to as the sensor gear 17, is approximately 45° here, for example. A sensor target 18, for example a magnet, is arranged on the spur gear 16 in a rotationally fixed manner. The sensor target 18 is configured to be detected by the sensor device 5 (not shown in Fig. 1 to Fig. 3, but e.g. designed as a sensor PCB or sensor chip and arranged opposite the sensor target 18).Since the sensor target 18 rotates together with the spur gear 16, the sensor device 5 detects a rotational movement or a rotation angle of the spur gear 16 via the sensor target 18, based on which the position of the handlebar 2 can be determined. In particular, the tooth engagement between the spur gear 16 and the sensor toothing 15 is selected such that the spur gear 16 rotates by less than 360° over the entire travel path of the handlebar 2. This enables the use of simple and cost-effective sensors for the sensor device 5 to determine the position of the handlebar 2.

[0059] Fig. 4 shows an embodiment of the steering unit 1 in which the sensor toothing 15 is arranged or formed on both sides between the pitch circle section 12 designed as a sliding zone for the pressure piece 10 and the rolling surface 14 for the pressure roller 11. Since the sensor toothing 15 is not arranged on the rolling surface 14, the pressure roller 11 does not have to be recessed. Furthermore, the sensor device 5 here has several, for example three, spur gears 16, each of which serves as sensor wheels 17. This creates redundancy which enables protection in the event of a failure or defect of one of the sensor wheels 17. The plurality of sensor wheels 17 do not have to be identical, but can, for example, have different numbers of teeth.

[0060] The bearing unit 9 has, as shown here, a pressure piece 10 and a pressure roller 11, wherein the pressure piece 10 is designed here, for example, as a sliding element and the pressure roller 11 is designed, for example, as a rolling element. However, it is also conceivable for both the pressure piece 10 and the pressure roller to be designed as sliding elements, or alternatively, both as rolling elements. Furthermore, it is conceivable for the bearing unit 9 to have further, additional sliding and / or rolling elements. Furthermore, it is conceivable to implement the anti-twist device of the steering rod 2, which is implemented here by means of the pressure roller 11 rolling on the rolling surface 13, instead by means of non-circular sliding contours, so-called "V-grooves".

[0061] Fig. 5 shows an embodiment of the steering unit 1, in which the sensor gearing device 4 is designed as a two-stage spur gear 21. The two-stage spur gear 21 comprises a first gear 22 and a second gear 23, which mesh with each other at a predetermined gear ratio. The first gear 22 is also meshed with the sensor gearing 15 of the handlebar 2, and the second gear 23 functions as the sensor gear 17. Due to the gear ratio between the first gear 22 and the second gear 23, the first gear 22 can be rotated over the entire travel path VWL of the handlebar 2, i.e. from the travel path shown in Fig.5 from the very left position of the first gear 22 (marked with 22') to the very right position of the first gear (marked with 22"), in particular undergo several 360° rotations, since the gear ratio between the first gear 22 and the second gear 23 can be selected such that the entire travel path of the handlebar 2 is translated into a rotation of the second gear 23, designed as a sensor wheel 17, of less than 360°. As described above, this enables the use of simple and cost-effective sensors for the sensor device 5 for determining the position of the handlebar 2. Of course, here, as in the embodiment described with reference to Fig. 1 to Fig. 3, the use of so-called multi-turn sensors is also possible, by means of which the position of the handlebar 2 can be determined unambiguously even with a rotational movement of 360° or more on the sensor wheel 17.

[0062] Furthermore, with the sensor gearing device 4 designed as a two-stage spur gear 21, it is also possible to design the sensor gearing 15 of the handlebar 2 with straight teeth. In Fig. 5, the pressure roller 11 (schematically indicated to the right of the first gear 22) must also be partially recessed to prevent it from rolling on the sensor gearing 15 formed in the rolling surface 14. In Fig. 5, the second gear 23 is also preloaded by a spiral spring 24 to ensure backlash-free tooth engagement under all operating conditions. As indicated in Fig. 5, the two-stage spur gear 21 requires only a small opening or bulge in a housing 25 of the handlebar 2, in the contact area with the handlebar 2.

[0063] Fig. 6 and Fig. 7 show an embodiment of the steering unit 1, in which the sensor toothing 15 is designed as spiral or helical grooves 26 that essentially run around the handlebar 2, and the sensor toothing device 4 is designed as an internally toothed ring gear 27. Typically, in particular six to 20 grooves 26, here ten grooves 26 as an example, are provided and have a pitch of approximately 200-400 mm / rev, here 300 mm / rev as an example, which results in a helix angle β of approximately 60° to approximately 85°. This means that teeth of the sensor toothing 15 run parallel to the handlebar 2 up to an angle of approximately 10°. The internally toothed ring gear 27 engages with the sensor toothing 15 and, due to a comparatively high number of teeth, has a high overlap, which can improve the tooth engagement. Thus, the internally toothed ring gear 27 serves here as the sensor wheel 17.The ring gear 27 itself is received in the housing 25 of the handlebar 2 by sliding or rolling bearings and comprises in particular a plastic, such as a single-material plastic, a plastic mixture, a fiber-reinforced plastic or mixture.

[0064] In the embodiment shown in Fig. 6 and 7, the sensor target 18 is designed as a cylindrical target ring made of metal, which serves as the outer surface of the ring gear 27. Alternatively, a disk-shaped sensor target 18 is also possible. As can be seen particularly in Fig. 7, the internally toothed ring gear 27 is designed eccentrically to the handlebar 2. Alternatively, it is also conceivable to use a nut concentric to the handlebar 2 instead of the ring gear 27. The ring gear 27 can, for example, be inserted into the housing 25 of the handlebar from the right or from the left. A housing division would also be conceivable in order to simplify the assembly of the ring gear 27.

[0065] Fig. 8 to Fig. 11 show an embodiment of the steering unit 1, in which the sensor toothing device 4 is designed as a toothed rack 28 which is arranged at a right angle to the sensor toothing 15 of the handlebar 2 and is in tooth engagement with the latter. The sensor toothing 15 is designed here, for example, as a strong helical toothing in the area of ​​the bearing unit 9, more precisely, in the area of ​​the pressure piece 10. Due to the tooth engagement between the toothed rack 28 and the sensor toothing 15, the longitudinal movement of the handlebar 2 along its longitudinal axis L is converted into a longitudinal movement of the toothed rack 28 which is essentially orthogonal or tangential thereto. A transmission ratio between the sensor toothing 15 of the handlebar 2 and the toothing of the toothed rack 28 is selected such that the longitudinal movement of the toothed rack 28 is in particular less than a third of the longitudinal movement of the handlebar 2 and is thus much smaller orshorter and easier to measure.

[0066] The rack 28 is, in particular, helically toothed and, here for example, is mounted in the pressure piece 10. This means that the rack 28 is in contact with the steering rod 2 via a central region 29 of the pressure piece 10. The function of the pressure piece 10 is not impaired by this, since the pressure piece 10 is only load-bearing in the outer regions 30, but not in the central region 29. The movement of the rack 28 can, for example, as shown in Fig. 8 and Fig. 9, be measured or detected by means of moving coil sensors 31 arranged on both sides. The moving coil sensors 31 are inductive sensors, which means that the rack 28 must have a metallic material, e.g., iron or steel, at least in the region of its axial ends. Otherwise, the rack 28 can also be made predominantly from a plastic or similar material. The plunger coil sensors 31 are connected to the pressure piece 10 so that they detect any movement of the pressure piece 10, e.g.due to external forces on the handlebar 2.

[0067] The arrangement of the rack 28 within the pressure piece 10 is particularly suitable because the pressure piece is preloaded against the handlebar 2 by a spring element 32 and thus always rests against the handlebar 2. This prevents distortion of the measurement signal generated by the plunger coil sensors 31, even in the event of external force or deflection of the handlebar 2. Furthermore, by positioning the rack 28 in or near the bearing unit 9, combined with the perpendicular orientation to the handlebar 2, distortion of the measured value due to deformation of the handlebar 2 can be virtually eliminated.

[0068] In addition, the rack 28, as shown in Fig. 9, is preloaded both axially and radially in order to achieve a freedom from play of the rack 28. This means that the rack 28 is preloaded both parallel to the handlebar 2, here for example by a spring element 33 which presses the rack 28 onto the handlebar 2 via a stamp-like component 34 (see arrow P1), and perpendicular to the handlebar 2, here for example by a spring element 34. In order to reduce friction between the stamp-like component 34 and the rack 28, rolling elements, for example balls, needles, rollers, etc., can be arranged in the contact area as so-called "rollers" (not shown), which can reduce the friction and / or the resistance in the tooth engagement between the rack 28 and the handlebar 2.

[0069] List of reference symbols

[0070] 1 steering unit

[0071] 2 handlebar

[0072] 3 actuator

[0073] 4 Sensor gearing device

[0074] 5 Sensor device

[0075] 6 spindle section

[0076] 7 flattened section

[0077] 8 Screw contour

[0078] 9 Storage unit

[0079] 10 pressure piece

[0080] 11 Pressure roller

[0081] 12 partial circle section

[0082] Section 13

[0083] 14 Rolling surface

[0084] 15 Sensor gearing

[0085] 16 Spur gear

[0086] 17 Sensor wheel

[0087] 18 Sensor target

[0088] 19 Run-off area

[0089] 20 Run-off area

[0090] 21 two-stage spur gear

[0091] 22 first gear

[0092] 23 second gear

[0093] 24 spiral spring

[0094] 25 housings

[0095] 26 grooves

[0096] 27 ring gear

[0097] 28 rack

[0098] 29 middle range

[0099] 30 outer area

[0100] 31 moving coil sensor

[0101] 32 spring element

[0102] 33 spring element

[0103] 34 stamp-like component

[0104] 35 Spring element L longitudinal axis

[0105] VWL travel of the steering rod

[0106] P1 Arrow

Claims

Claims 1. Steering unit (1), in particular a steer-by-wire steering unit, for a vehicle, comprising: a handlebar (2) which is designed to be coupled at its axial ends to a wheel of the vehicle, wherein the handlebar (2) has at least in sections a sensor toothing (15), a control actuator (3) which is coupled to the handlebar (2) in such a way that a rotational movement of the control actuator (3) causes a translational movement of the handlebar (2) for changing the position of the handlebar (2) along a predetermined handlebar travel path (VWL), a sensor toothing device (4) which, at least in sections, has a counter toothing corresponding to the sensor toothing (15) of the handlebar (2), which is in tooth engagement with the sensor toothing (15) of the handlebar (2) in such a way that the translational movement of the handlebar (2) causes a change in the position of the sensor toothing device (4) along a predetermined sensor travel path,wherein in the tooth engagement between the sensor toothing device (4) and the sensor toothing (15) of the handlebar (2), a relative sliding occurs which is equal to or greater than 80% of the handlebar travel path (VWL) of the handlebar (2), and a sensor device (5) for determining the position of the handlebar (2), which is designed to detect a position of the sensor toothing device (4) along the predetermined sensor travel path (15).

2. Steering unit (1) according to claim 1, wherein the sensor toothing (15) of the handlebar (2) has a helix angle (ß) of approximately 45° to 85°, in particular of approximately 65° to 85°, further in particular of approximately 80°.

3. Steering unit (1) according to claim 1 or 2, further comprising a bearing unit (9) for radially supporting the steering rod (2).

4. Steering unit (1) according to one of claims 1 to 3, wherein the sensor toothing (15) of the handlebar (2) is substantially planar.

5. Steering unit (1) according to one of claims 1 to 4, wherein the sensor gearing device (4) is designed as a spur gear (16) which is adapted to rotate by a predetermined angle over the entire steering rod travel path (VWL).

6. Steering unit (1) according to claim 5, wherein the spur gear (16) is mounted in a prestressed manner, and / or wherein a toothing of the spur gear (16) has a helix angle of up to approximately 45°.

7. Steering unit (1) according to one of claims 1 to 3, wherein the sensor toothing device (4) has at least one internally toothed ring gear (27) which is arranged to be rotatable about the handlebar (2), wherein an internal toothing of the ring gear (27) is in tooth engagement with the sensor toothing (15) of the handlebar (2), and wherein the ring gear (27) is designed to rotate by a predetermined angle over the entire handlebar travel path (VWL).

8. Steering unit (1) according to one of claims 1 to 4, wherein the sensor toothing device (4) comprises a rack (28) which is in tooth engagement with the sensor toothing (15) of the handlebar (2), wherein the rack (28) is arranged substantially at right angles to the handlebar (2), and wherein the rack (28) and the sensor toothing (15) of the handlebar (2) are in tooth engagement such that a total rack travel path is less than one third of the total handlebar travel path (VWL) of the handlebar (2).

9. Steering unit (1) according to claim 8, wherein the rack (28) is arranged displaceably relative to the bearing unit (9).

10. Steering unit (1) according to one of claims 1 to 9, wherein the sensor device (5) comprises an inductive sensor (31), an xMR sensor or a Hall sensor.

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