Steering gear for a vehicle, vehicle, method for controlling a steering gear and method for steering a vehicle

Abstract

The invention relates to a steering gear (302) for a vehicle (300). The steering gear (302) comprises a linear drive (304) with at least one sliding element (308) that is displaceable substantially along a longitudinal axis (306) of the vehicle (300) and can be attached to a steering pushrod (310) of the vehicle (300), wherein the linear drive (304) is configured to convert a rotary movement of a steering column (314) of the vehicle (300) into a movement of the sliding element (308) substantially along the longitudinal axis (306) of the vehicle.

Description

[0001] The present invention relates to a steering gear for a vehicle, to a vehicle, to a method for controlling a steering gear and to a method for steering a vehicle.

[0002] A vehicle has a steering gear via which a rotational movement of a steering column is converted into a movement of a steering rod coupled to a wheel to be steered.

[0003] DE 10 2012 213 444 A1 discloses an electrically assisted steering column servo steering system. A linear drive is installed transversely to the longitudinal direction of the vehicle.

[0004] Against this background, the approach presented here provides a steering gear for a vehicle, a vehicle, a method for controlling a steering gear for a vehicle, and a method for steering a vehicle according to the main claims. The measures listed in the dependent claims enable advantageous refinements and improvements of the device specified in the independent claim.

[0005] A steering gear for a vehicle is presented, the steering gear having the following feature: a linear drive with at least one displacement element that is displaceable substantially along a longitudinal axis of the vehicle and that can be fastened to a steering push rod of the vehicle, wherein the linear drive is designed to convert a rotational movement of a steering column of the vehicle into a movement of the displacement element substantially along the longitudinal axis of the vehicle.

[0006] A vehicle can be understood, for example, as a motor vehicle, in particular a commercial vehicle. The steering gear can, for example, be arranged on a frame of the vehicle and, depending on the embodiment, be connected thereto fixedly or so as to be movable in at least one direction. A linear drive can be understood as a drive for generating a linear movement. For example, the linear drive can be implemented as a spindle drive, in particular as a ball screw drive with a recirculating ball spindle, or as a rack and pinion drive for converting a rotary movement into a linear movement. A steering push rod can be understood as a rod for linking a wheel of the vehicle that can rotate about a steering axis. The wheel can, for example, be arranged on a rigid axle of the vehicle. The steering push rod can, for example, be movable essentially parallel to the vehicle's longitudinal axis or to a trailing arm of the vehicle.The displacement element can be, for example, a rack, a spindle, or a spindle nut that can be screwed to the spindle. The spindle nut can be designed, for example, as a recirculating ball nut. Depending on the embodiment, the steering push rod, in particular an end section of the steering push rod facing the displacement element, can be attached to the displacement element rigidly or so that it can move in at least one direction. The displacement element and the steering push rod can therefore be coupled to one another in such a way that a linear movement of the displacement element is converted directly, i.e. without further movement conversion, for example with the aid of a steering column arm, into a linear movement of the steering push rod. A steering column can be understood as a rod-shaped or tubular support for the mechanical coupling of the steering gear to a steering wheel of the vehicle. The steering column can be designed, for example, as a cardan shaft.

[0007] The approach presented here for a steering system, in particular a commercial vehicle steering system with a linear actuator, is based on the realization that a linear actuator of a vehicle steering system can be designed to generate a linear movement in the longitudinal direction of the vehicle. By directly mechanically coupling a displacement element of the linear actuator to a steering push rod of the vehicle, the linear movement generated by the linear drive can be directly converted into a linear movement of the steering push rod. Such a combination of a linear actuator, which can, for example, be installed in the vehicle frame in the longitudinal direction, with a steering push rod offers the advantage, particularly in connection with frame-fixed installation in rigid-axle vehicles, that the number of intermediate elements and gear stages in the steering gear can be significantly reduced.Furthermore, the forces and moments acting in the steering gear can be reduced, which means that the overall play in the steering gear can be reduced, the service life of parts subject to wear can be increased, friction losses in the steering gear can be minimized and the costs and weight of the steering gear can be reduced.

[0008] For example, the linear actuator can be installed longitudinally with respect to a longitudinal axis of the vehicle and connected to a steering lever of a wheel via the steering push rod. In this case, the linear actuator can be mounted on a frame member, for example. The connection via the steering push rod makes the kinematics of such a linear drive particularly suitable for rigid axles, since the steering push rod and a trailing arm of an axle suspension can form at least an approximate parallelogram, so that compression movements of the axle do not cause self-steering.

[0009] According to one embodiment, the linear drive can be implemented as a rack and pinion drive with a rack as the displacement element. Additionally or alternatively, the linear drive can be implemented as a ball screw drive with a spindle and a spindle nut. In this case, either the spindle or the spindle nut can function as the displacement element. Alternatively, both the spindle and the spindle nut can function as the displacement element. For example, the spindle can be designed to be displaced substantially along the vehicle's longitudinal axis by rotating the spindle nut, with the spindle nut being stationary. Conversely, the spindle nut can be designed to be displaced substantially along the vehicle's longitudinal axis by rotating the spindle, with the spindle being stationary. The rack and pinion can, for example, be designed to mesh with a pinion arranged on the steering column.This design allows the linear drive to be very robust and to be implemented with only a few moving parts.

[0010] The rack can be shaped to accommodate the spindle and to be displaced substantially along the vehicle's longitudinal axis by a rotational movement of the spindle. For this purpose, the rack can have a recess for receiving the spindle. The spindle can be screwed into the recess. In particular, the rack can be shaped as a recirculating ball nut so that a rotational movement of the spindle generates a linear relative movement between the rack and the spindle. The spindle can be arranged stationary in the steering gear. The spindle can, for example, be designed to be mechanically coupled to a drive unit, such as an electric motor. This embodiment enables the rack to be driven twice, once via the steering column and once via the spindle.

[0011] It is advantageous if the steering gear has a transmission gear for translating the rotational movement of the steering column into a rotational movement of the spindle and, additionally or alternatively, the spindle nut. This allows the rotation of the steering column toward the spindle or spindle nut to be increased.

[0012] Advantageously, the transmission gear can be implemented as a spur or bevel gear. The spur or bevel gear can, for example, be a single-stage gear. This design allows the transmission gear to be manufactured cost-effectively. Furthermore, friction losses can be reduced.

[0013] According to a further embodiment, the steering gear can have at least one drive unit for driving the displacement element. The drive unit can be, for example, an electric motor, such as a steering servo. This can reduce the effort required to turn the steering column.

[0014] It is advantageous if the drive unit and the displacement element are coupled to each other via at least one toothed belt, a spur gear, a ring gear, or a combination of at least two of the three elements mentioned. This design enables low-loss, low-wear power transmission between the drive unit and the displacement element.

[0015] According to a further embodiment, the steering gear can be implemented with the steering push rod. This allows the steering push rod to be subjected to the force required for steering.

[0016] According to a further embodiment, the steering push rod and the displacement element can be arranged coaxially with each other. In this case, the steering push rod and the displacement element can be rigidly connected to each other. This allows the number of moving parts in the steering gear to be reduced to a minimum. For example, the steering gear can be pivotably mounted in the vehicle.

[0017] It is advantageous if the steering push rod is pivotably connected to the sliding element via a joint. The joint can be a ball joint, for example. This allows the steering gear to be permanently installed in the vehicle.

[0018] The approach proposed here also creates a vehicle with the following features: a steering column; a steering push rod; and a steering gear coupled to the steering column and the steering push rod according to one of the preceding embodiments.

[0019] According to one embodiment, the steering gear can be arranged on a frame of the vehicle. For example, the steering gear can be attached to a frame member. Depending on the embodiment, the steering gear can be mounted fixedly or pivotably on the frame. This can simplify the installation of the steering gear.

[0020] According to a further embodiment, the steering push rod can be arranged to form a parallelogram with a trailing arm of the vehicle when the sliding element is moved. A trailing arm can be understood as a support for a rigid axle of the vehicle in the direction of the vehicle's longitudinal axis. In axles with leaf springs, the front part of the leaf spring can also serve as a trailing arm. This embodiment can prevent self-steering during compression movements of the rigid axle.

[0021] In addition, the approach described here provides a method for controlling a steering gear according to one of the preceding embodiments, the method comprising the following steps: Reading in a steering signal representing a steering movement; and Providing a control signal for controlling a drive unit for driving the displacement element using the steering signal.

[0022] The steering signal can, for example, be a signal provided by a steering torque sensor for detecting a steering torque. Accordingly, the control signal can be provided to control a speed or torque of the drive unit depending on the steering torque.

[0023] Finally, the approach proposed here provides a method for steering a vehicle having a steering column, a steering push rod, and a steering gear coupled to the steering column and the steering push rod, wherein the steering gear has a linear drive with at least one displacement element that is displaceable substantially along a longitudinal axis of the vehicle and that can be fastened to the steering push rod, the method comprising the following steps: Coupling a steering torque into the steering gear via the steering column; and Conversion of the steering torque into a movement of the sliding element essentially along the vehicle's longitudinal axis by means of the linear drive.

[0024] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. It shows: Fig. 1 a schematic representation of a steering gear; Fig. 2 a schematic representation of a vehicle with a steering gear from Fig. 1; Fig. 3 a schematic representation of a vehicle according to an embodiment; Fig. 4 is a schematic representation of a portion of a vehicle according to an embodiment; Fig. 5 is a schematic representation of a portion of a vehicle according to an embodiment; Fig. 6 is a schematic representation of a portion of a vehicle according to an embodiment; Fig. 7 a schematic representation of a transmission gear according to an embodiment; Fig. 8 a schematic representation of a linear drive according to an embodiment; Fig. 9 a schematic representation of a linear drive according to an embodiment; Fig. 10 is a schematic representation of a portion of a vehicle according to an embodiment; Fig. 11 a schematic representation of a steering gear from Fig. 10; Fig. 12 is a schematic representation of a steering gear according to an embodiment; Fig. 13 is a schematic representation of a steering gear according to an embodiment; Fig. 14 is a schematic representation of a steering gear according to an embodiment; Fig. 15 is a schematic representation of a cross section through a steering gear according to an embodiment; Fig. 16 a schematic representation of a cross section through a steering gear from Fig. 14; Fig. 17 a schematic representation of a cross-section through a steering gear; Fig. 18 is a flowchart of a method for controlling a steering gear according to an embodiment; and Fig. 19 is a flowchart of a method for steering a vehicle according to an embodiment.

[0025] In the following description of advantageous embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and having a similar effect, whereby a repeated description of these elements is omitted.

[0026] Fig. 1 shows a schematic representation of a steering gear 100. The steering gear 100 comprises an input shaft 102 partially formed as a spindle 101, a recirculating ball nut 106 arranged in the region of the spindle 101 and having an external toothing 104, a segment toothing 110 meshing with the external toothing 104 and arranged in a rotationally fixed manner on an output shaft 108, and a steering column arm 112 which is connected in a rotationally fixed manner to the output shaft 108 and is movably connected to a steering push rod 114.

[0027] Today's commercial vehicle steering systems typically incorporate recirculating ball steering gears. The kinematics of such an arrangement are particularly advantageous for commercial vehicles, as they typically have a rigid front axle. If the trailing arms of the front axle and the steering push rod are approximately the same length and arranged essentially parallel to each other, they form a parallelogram. As a result, compression movements of the front axle have little or no effect. If the steering gear is mounted integrally to the frame, length compensation in the steering column can be achieved, for example, through a corresponding relative movement between the vehicle frame and the driver's cab.

[0028] In the Fig. In the steering gear 100 shown in Figure 1, the rotation of a steering wheel is transmitted via the steering column and the input shaft 102, which may, for example, be part of the steering column, to a recirculating ball screw 101. This rotational movement is converted into a linear movement by means of the recirculating ball nut 106.

[0029] The steering gear 100 can optionally have hydraulic servo assistance. In this case, the recirculating ball nut 106 can be sealed against a housing of the steering gear 100. The recirculating ball nut 106 can thus function as a hydraulic piston. A differential pressure can be created between the two sides of the recirculating ball nut 106, for example, using a rotary valve, via the steering torque applied by the driver to the input shaft 102. The differential pressure can assist the movement of the recirculating ball nut 106.

[0030] Fig. 2 shows a schematic representation of a vehicle 200 with a steering gear 100 from Fig. 1. The recirculating ball nut, for example, has longitudinal toothing as external toothing, which in turn meshes with the segment toothing. This in turn converts the linear movement into a rotation of the pitman arm 112. At the end of the pitman arm 112, the steering push rod 114 is again moved predominantly linearly. The steering push rod 114 ultimately pivots the wheel 204 to be steered about the steering axis via a steering lever 202 attached to the wheel carrier. In this case, another wheel 206 opposite the wheel 204 can be steered via a track lever 208 and a rigid tie rod 210. Also shown is a vehicle frame 212 in the form of two frame members arranged parallel to one another. A direction of travel of the vehicle 200 is indicated by an arrow.

[0031] Since the effective radius of the segmented toothing can be approximately one-quarter to one-third smaller than the effective length of the pitman arm 112, the toothing between the recirculating ball nut and the segmented toothing should transmit a force many times greater than that required to actuate the steering push rod 114. This means that the steering gear 100 should be designed to be correspondingly solid and heavy, which can lead to high manufacturing costs and significant wear. The large number of required transmission elements can result in lower efficiency and high hysteresis due to the frictional connection points. Since the play between individual moving parts accumulates, the steering play can increase, particularly over the service life.

[0032] The spindle could, for example, be driven by an electric motor actuator. The balls and, axially, the spindle could be subjected to significant loads due to the forces acting on the ball nut, which in a conventional steering assist system are largely generated by the hydraulics, which would require a correspondingly strong design of the steering gear 100. Alternatively, the electric motor actuator could act directly on the output shaft. However, this would require a multi-stage gearbox between the actuator and the output shaft, which could lead to high costs, reduced efficiency, noise and vibration, and increased backlash.

[0033] In contrast to commercial vehicles, passenger cars usually use a linear actuator in the form of a rack and pinion steering system mounted on the axle beam transversely to the direction of travel. The rotational movement of the steering column is converted directly into longitudinal movement of the rack via a pinion. The rack is positioned transversely between the front wheels and, via tie rods, acts directly on the wheel-carrier-fixed steering arms that pivot the wheels. Due to the small number of transmission components, this arrangement is stiff, lightweight, and has little play. However, to prevent unwanted self-steering, particularly changes in toe-in or toe-out, during compression and rebound, the rack and pinion steering gear would have to be attached directly to the axle. However, since the axle in heavy commercial vehicles is a rigid, spring-loaded axle, a significant amount of length compensation for the steering column would be necessary.

[0034] In addition, the steering column would have to be routed between the wheels and the axle, which could lead to space problems in a commercial vehicle, where the engine and transmission are typically mounted between the steering wheel and the axle. Furthermore, the steering gear 100 would thus become part of the unsprung mass and be subject to correspondingly strong vibrations.

[0035] Fig. 3 shows a schematic representation of a vehicle 300 according to one embodiment. The vehicle 300 is equipped with a steering gear 302, which includes a linear drive 304 with a displacement element 308 that can be displaced along a longitudinal axis 306 of the vehicle 300. A steering push rod 310 for articulating a wheel 312 is attached to the displacement element 308. The linear drive 304 is designed to convert a rotational movement of a steering column 314 into a linear movement of the displacement element 308 along the vehicle's longitudinal axis 306, so that the steering push rod 310 is also displaced and the wheel 312 is deflected accordingly. According to one embodiment, the steering push rod 310 is directly connected to the displacement element 308.Thus, no lever element is required to translate the movement of the displacement element 308 to the steering push rod 310; instead, the movement of the displacement element 308 is directly transmitted to the steering push rod 310. A surface of the steering push rod 310 can be in direct contact with a surface of the displacement element 308.

[0036] Fig. 4 shows a schematic representation of a portion of a vehicle 300 according to an embodiment. The vehicle 300 is, for example, a vehicle previously described with reference to Fig. 3. According to this exemplary embodiment, the displacement element 308 is designed as a rack. Here, the steering column 314 is connected, for example, to a pinion 400 that meshes directly with the displacement element 308. An end section of the steering push rod 310 is connected to the displacement element 308 in the form of the rack, so that the steering push rod 310 is moved by the displacement element 308. According to one exemplary embodiment, the steering push rod 310 and the displacement element 308 are movably connected to one another via a single rigid connecting element, for example in the form of a pin or a bolt, via which a linear movement of the displacement element 308 is transmitted directly to the steering push rod 310.

[0037] Optionally, the vehicle 300 has an electric servo assistance, which, for example, according to the Fig. 4, the embodiment shown comprises an electric motor as the drive unit 402. The drive unit 402 is designed to drive at least one drive element 404, here a drive pinion, that meshes with the displacement element 308. Alternatively, the drive unit 402 is designed to engage the steering column 314 and apply an assist torque there.

[0038] According to one embodiment, the steering gear 302 is attached to a frame 406 of the vehicle 300, for example to a frame member.

[0039] Fig. 5 shows a portion of a vehicle 300 according to an embodiment. In contrast to Fig. 4 shows that Fig. The vehicle 300 shown in Figure 5 has a further drive unit 500 configured to drive the sliding element 308, implemented as a rack, via at least one further drive element 502, here also a further drive pinion, meshing with the sliding element 308. The two drive elements 404, 502 engage one and the same toothed side of the sliding element 308.

[0040] Fig. 6 shows a portion of a vehicle 300 according to an embodiment. In contrast to the Fig. In the vehicle shown in Figure 5, the displacement element 308 according to this embodiment is arranged between the drive element 404 and the further drive element 502. Here, the pinion 400 and the drive element 404 mesh with a first toothed side 600 of the displacement element 308. The further drive element 502, on the other hand, meshes with a second toothed side 602 of the displacement element 308, opposite the first toothed side 600.

[0041] According to a further embodiment, the linear drive of the steering gear is implemented as a spindle drive, in particular as a ball screw drive, for moving the steering push rod, as will be explained below with reference to the Fig. 7 to 17 are described in more detail.

[0042] Fig. 7 shows a schematic representation of a transmission gear 700 according to one exemplary embodiment. The transmission gear 700 is designed to translate a rotation of an input shaft of the steering column 314 into a rotation of a spindle 702 of the linear drive. According to this exemplary embodiment, the transmission gear 700 is designed as a single-stage bevel gear with a first bevel gear 704 fastened to one end of the steering column 314 and a second bevel gear 706 meshing with the first bevel gear 704 and fastened to one end of the spindle 702. For example, the first bevel gear 704 has a greater number of teeth than the second bevel gear 706. Thus, a rotation of the steering column 314 is increased by a transmission ratio toward the spindle 702 predetermined by the two bevel gears 704, 706.

[0043] Alternatively, the transmission gear 700 can be implemented as a single-stage spur gear.

[0044] Fig. Figure 8 shows a schematic representation of a linear drive 304 according to an embodiment. The linear drive 304 is, for example, a linear drive previously described with reference to Fig. 3 to 7. According to this exemplary embodiment, the linear drive 304 is implemented as a recirculating ball screw drive with a recirculating ball nut as the spindle nut 800 and the spindle 702 rotatably mounted in the spindle nut 800. The spindle 702 and the spindle nut 800 are arranged in a spindle drive housing 802. The spindle nut 800 is rotatably mounted in the spindle drive housing 802 by means of two spindle nut bearings 804, here rolling bearings. The spindle drive housing 802 is formed with a stop 806, which serves to fix the spindle nut 800 in the direction of a rotational axis 808 of the spindle nut 800, so that the spindle 702 moves linearly along the rotational axis 808 when the spindle nut 800 is rotated. For this purpose, the spindle nut 800 is coupled to the steering column, for example, via the transmission gear (not shown here). The spindle 702 thus functions as a displacement element.

[0045] According to the Fig. In the embodiment shown in Figure 8, the spindle 702 has, at a spindle end facing away from the transmission gear, a guide element 810, approximately in the form of a disk, which is displaceable in the spindle drive housing 802 along the rotational axis 808. One end of the steering push rod 310, which is arranged coaxially with the spindle 702, is rigidly attached to the guide element 810, for example by screwing. The steering push rod 310 is guided through a housing opening 812 in the spindle drive housing 802. The guide element 810 can also be considered a displacement element.

[0046] The steering push rod 310 is thus coaxially coupled to the steering gear in a pivotally and torsionally rigid manner. The steering gear can be pivotally connected to the vehicle frame at one point. The coaxial linkage of the steering push rod 310, combined with a pivotable mounting of the steering gear, prevents the steering gear from being subjected to any or only minimal transverse forces and bending moments, apart from weight and inertia forces. This allows for a particularly simple mounting of the linear guide.

[0047] The effective kinematics can change with the steering angle, since the length of the steering push rod 310 is supplemented by a variable distance between the linkage of the steering push rod 310 and the frame-fixed pivot point of the steering gear. Thus, the self-steering behavior during compression can depend on whether the vehicle is currently steering to the left or right.

[0048] Fig. 9 shows a schematic representation of a linear drive 304 according to an embodiment. Fig. The linear drive 304 shown in Figure 9 essentially corresponds to the one shown in Fig. 8, with the difference that the linear actuator in Fig. 9 has a spindle nut 910 which, in contrast to the one shown in Fig. 8, the spindle nut is not rotatable about the rotational axis 808, but is arranged in the spindle drive housing 802 so as to be displaceable along the rotational axis 808. The linear movement of the spindle nut 910 is effected by a rotation of the spindle 912 about the rotational axis 808. For this purpose, the spindle 912 is, for example, via the transmission gear according to Fig. 7 coupled to the steering column. According to Fig. 9 the spindle nut 910 thus acts as a sliding element.

[0049] The spindle drive housing 802 has an optional guide slot 900 for guiding the spindle nut 910 in the spindle drive housing 802. For example, the spindle nut 910 is formed with three guide pins 902, which are slidably mounted in the guide slot 900.

[0050] According to this embodiment, the steering push rod 310 is arranged outside the spindle drive housing 802 and is pivotally connected to the spindle nut 910 through the guide slot 900. The steering push rod 310 is screwed to a middle of the three guide pins 902 via a joint 904, here a ball joint.

[0051] Thus, the steering push rod 310 is pivotally coupled to the steering gear via the joint 904. The steering gear can be rigidly connected to the vehicle frame.

[0052] The advantage of such an off-center linkage of the steering push rod 310 is that a parallelogram formed by the steering push rod 310 and a trailing arm of the vehicle has the same side length at every steering angle. Furthermore, because the steering gear is rigidly connected to the frame, it is part of the sprung mass of the vehicle.

[0053] Fig. Figure 10 shows a schematic representation of a portion of a vehicle 300 according to an embodiment. The vehicle 300 is, for example, a vehicle previously described with reference to Fig. 3 to 9. According to this exemplary embodiment, the steering gear 302 has a rack 308 as the displacement element 308, wherein the rack 308 is shaped to receive the spindle 912. The rack 308 functions as a recirculating ball nut, so that the rack 308 is moved linearly, here essentially parallel to the vehicle's longitudinal axis 306, by a rotational movement of the spindle 912. The steering push rod 310 is attached to the rack 308.

[0054] According to one embodiment, the steering column input shaft drives the rack 308 via the pinion 400, which is mechanically coupled to a rotating part of a spindle drive that moves the steering push rod 310. Optionally, the rotating part is coupled to the drive unit 402, such as an electric motor, to drive the rotating part.

[0055] Fig. 11 shows a schematic representation of a steering gear 302 from Fig. 10. Shown are, among other things, the displacement element 308 in the form of the rack 308, the pinion 400 engaging a toothing of the rack 308, and the spindle 912 rotatably mounted in the rack 308. The pinion 400, the rack 308, and the spindle 912 are arranged in the spindle drive housing 802. The rack 308 is realized with a ball-filled ball return channel 1100, which is designed to cause a displacement of the rack 308, and thus of the steering push rod, along the rotational axis 808 upon rotation of the spindle 912. The rotational axis 808 can, for example, be aligned parallel to the vehicle's longitudinal axis.

[0056] According to this exemplary embodiment, the drive unit 402 is coupled to the spindle 912 via an optional spindle drive gear 1102, here a bevel gear. An end portion of the spindle 912 facing the spindle drive gear 1102 is rotatably mounted in the spindle drive housing 802.

[0057] Fig. 12 shows a schematic representation of a steering gear 302 according to an embodiment. The steering gear 302 comprises a linear drive 304, as described above with reference to Fig. 9. According to this exemplary embodiment, a ring gear 1200 is seated on the spindle 912, which is designed to drive the spindle 912. For this purpose, an internal toothing 1202 of the ring gear 1200 is coupled to the drive unit 402 via the drive element 404.

[0058] According to this embodiment, the linear drive 304 is connected to the transmission gear 700, for example a gear unit 702, which can be Fig. 7, coupled to the steering column 314.

[0059] Fig. 13 shows a schematic representation of a steering gear 302 according to an embodiment. The steering gear 302 is, for example, a steering gear previously described with reference to Fig. 3 to 12. The steering gear 302 has a linear drive 304 similar to the one described above with reference to Fig. 8, in which the steering push rod is fixed coaxially to the spindle 702.

[0060] According to the Fig. In the embodiment shown in Figure 13, the spindle 702 is arranged displaceably along the rotational axis 808 in a spindle sleeve 1300 rigidly connected to the spindle nut 800. To guide the spindle 702 in the spindle sleeve 1300, for example, an end section of the spindle 702 facing away from the steering push rod is formed with two spindle guide elements 1302, which engage in corresponding spindle guide slots in the spindle sleeve 1300 and are displaceable therein. The spindle sleeve 1300 is mounted in the spindle drive housing 802 by means of a spindle sleeve bearing 1304, for example a double-row deep groove ball bearing, for rotation about the rotational axis 808.

[0061] An output element, here, for example, the second bevel gear 706 of the transmission gear 700, is attached to an end of the spindle sleeve 1300 facing away from the steering push rod. According to this exemplary embodiment, the second bevel gear 706 is formed in two stages in order to be driven, on the one hand, by the first bevel gear 704 coupled to the steering column 314, and, on the other hand, by the drive element 404 of the drive unit 402, which is also formed as a bevel gear. For example, a stage of the second bevel gear 706 coupled to the drive element 404 has a greater number of teeth than the drive element 404.

[0062] By a rotational movement of the spindle sleeve 1300, and thus of the spindle nut 800, generated by the steering column 314 or the drive unit 402, the spindle 702, and thus the steering push rod attached to it, is displaced along the rotational axis 808 depending on the direction of rotation.

[0063] Fig. 14 shows a schematic representation of a steering gear 302 according to an embodiment. Fig. 14, the linear drive 304 essentially corresponds to a previously described linear drive Fig. 9 described linear drive with movable spindle nut 910. According to this embodiment, the spindle 912 is coupled to the drive unit 402 via a toothed belt drive as spindle drive gear 1102. Here, for example, the second bevel gear 706 is arranged coaxially with a toothed belt wheel 1400 of the spindle drive gear 1102 seated on the spindle 912.

[0064] Fig. 15 shows a schematic representation of a cross section through a steering gear 302 according to an embodiment. The steering gear 302 corresponds, for example, to a steering gear previously described with reference to Fig. 12. Shown is a cross-section of the steering gear 302 transverse to the rotation axis 808. As in Fig. As can be seen in Figure 15, the spindle drive housing 802 is cylindrical in shape. An inner wall surface of the spindle drive housing 802 has two opposing curved sections and two opposing straight sections. The spindle nut 910 has a corresponding flattened portion on each side opposite the straight sections and a corresponding rounded portion on each side opposite the curved sections. Also shown is the guide pin 902 for connecting the steering push rod.

[0065] Fig. 16 shows a schematic representation of a cross section through a steering gear 302 from Fig. 14. In contrast to Fig. 14, however, the drive is via a ring gear as in Fig. 12. Shown is a cross-section along a Fig. 15 shown section line BB. The Fig. The cross section shown in Figure 15 corresponds to a cross section along a Fig. 16 shown section line CC.

[0066] Fig. 17 shows a schematic representation of a cross section through a steering gear 302 from Fig. 16. Shown is a cross-section along a Fig. Section line AA shown in Figure 15.

[0067] In the following, embodiments of the present invention are described again by way of example with reference to the preceding figures.

[0068] According to one embodiment, the spindle drive is connected to the steering column 314 and to at least one electric motor as a drive unit 402 for servo assistance.

[0069] Depending on the embodiment, the steering push rod can be connected to the spindle 702 or the spindle nut 910.

[0070] The torque is transmitted and translated from drive unit 402 to spindle 702 or spindle nut 910, for example, using a toothed belt. This offers the advantage of low noise and minimal backlash. Multiple toothed belts can also be used for power transmission.

[0071] A coupling via a spur gear is also conceivable. Such a spur gear offers the advantages of high robustness and low manufacturing costs.

[0072] Furthermore, the coupling can be done via a ring gear, as for example in the Fig. 16 and Fig. 17. This allows for a higher gear ratio within the same installation space. Furthermore, more teeth are engaged, reducing noise and vibration and resulting in less wear compared to external gearing.

[0073] A direct drive of the spindle 702 or the spindle nut 910 is also possible. This means that no teeth are engaged, so that noise, play and wear can be reduced to a minimum, especially when the motor torque ripple is low.

[0074] Particularly favorable is an embodiment in which the steering push rod is pivotally coupled to the spindle nut 910 via the joint 904, wherein the steering column 314 drives the spindle 702 via a single-stage bevel gear and the drive unit 402 drives the spindle 702 via a single-stage ring gear.

[0075] Fig. 18 shows a flowchart of a method 1800 for controlling a steering gear according to an embodiment. The method 1800 can be used, for example, in connection with a method previously described with reference to Fig. 3 to 17. In a step 1810, a steering signal representing a steering movement is read in. In a further step 1820, a control signal for controlling a drive unit for driving the displacement element is provided using the steering signal.

[0076] Fig. 19 shows a flowchart of a method 1900 for steering a vehicle according to an embodiment. The method 1900 can be used, for example, in connection with a method previously described with reference to Fig. 3 to 18. In a step 1910, a steering torque is coupled into the vehicle's steering gear via the vehicle's steering column. In a step 1920, the steering torque is converted into a movement of the linear drive's displacement element along the vehicle's longitudinal axis by means of the steering gear's linear drive.

[0077] If an embodiment comprises an “and / or” link between a first feature and a second feature, this is to be read as meaning that the embodiment according to one embodiment has both the first feature and the second feature and according to another embodiment has either only the first feature or only the second feature. LIST OF REFERENCE SYMBOLS 100 steering gears 101 spindle 102 Input shaft 104 External gearing 106 Ball screw nut 108 Output shaft 110 Segment toothing 112 Steering column lever 114 Steering push rod 200 vehicles 202 steering lever 204 wheels 206 additional wheels 208 track lever 210 tie rod 212 vehicle frame 300 vehicles 302 steering gear 304 Linear actuator 306 Vehicle longitudinal axis 308 sliding element 310 steering push rod 312 wheels 314 Steering column 400 pinion 402 drive unit 404 drive element 406 frames 500 additional drive units 502 additional drive element 600 first gear side 602 second toothing side 700 transmission gears 702 spindle 704 first bevel gear 706 second bevel gear 800 spindle nut 802 spindle drive housing 804 spindle nut bearing 806 stop 808 axis of rotation 810 guide element 812 housing opening 900 guide slot 902 guide pin 904 joint 910 spindle nut 912 spindle 1100 ball return channel 1102 spindle drive gear 1200 ring gear 1202 internal gearing 1300 spindle sleeve 1302 spindle guide element 1304 spindle sleeve bearing 1400 timing belt pulley 1800 Method for controlling a steering gear 1810 Step of reading 1820 Step of provisioning 1900 Method of steering a vehicle 1910 Step of coupling 1920 Step of implementation

Claims

[1] Steering gear (302) for a vehicle (300), wherein the vehicle (300) has a steering column (314) and a steering push rod (310) movable in the longitudinal direction of the vehicle (300) and coupled to a rigid tie rod (210) via a steering lever (202) and a track lever (208), characterized by that the steering gear (302) has the following feature: a linear drive (304) with at least one displacement element (308) that is displaceable along the longitudinal direction of the vehicle (300) and that can be fastened to the steering push rod (310) of the vehicle (300), wherein the linear drive (304) is designed to convert a rotational movement of the steering column (314) of the vehicle (300) into a movement of the displacement element (308; 702; 910) along the longitudinal direction of the vehicle (300). [2] Steering gear (302) according to claim 1, characterized bythat the linear drive (304) is realized as a rack and pinion drive with a rack as a displacement element (308) or as a ball screw drive with a spindle (702) and / or a spindle nut (910) as a displacement element (308). [3] Steering gear (302) according to one of the preceding claims, characterized by that the linear drive (304) is realized as a rack and pinion drive with a rack as a displacement element (308) and the rack is shaped to receive a spindle (912) and to be displaced along the longitudinal direction of the vehicle (300) by a rotational movement of the spindle (912). [4] Steering gear (302) according to claim 2 or 3, characterized by a transmission gear (700) for translating the rotational movement of the steering column (314) into a rotational movement of the spindle (912) or the spindle nut (800). [5] Steering gear (302) according to claim 4, characterized bythat the transmission gear (700) is implemented as a spur or bevel gear. [6] Steering gear (302) according to one of the preceding claims, characterized by at least one drive unit (402; 500) for driving the displacement element (308; 702; 910). [7] Steering gear (302) according to claim 6, characterized by that the drive unit (402; 500) and the displacement element (308; 702; 910) are coupled to one another via at least one toothed belt and / or a spur gear and / or a ring gear (1200). [8] Steering gear (302) according to one of the preceding claims, with the steering push rod (310). [9] Steering gear (302) according to claim 8, characterized by that the steering push rod (310) and the displacement element (308; 702; 910) are arranged coaxially to one another, wherein the steering push rod (310) and the displacement element (308; 702; 910) are rigidly connected to one another. [10] Steering gear (302) according to claim 8 or 9, characterized bythat the steering push rod (310) is pivotally connected to the displacement element (308; 702; 910) via a joint (904). [11] Vehicle (300) with the following characteristics: a steering column (314); a steering push rod (310) movable in the longitudinal direction of the vehicle (300) and coupled to a rigid tie rod (210) via a steering lever (202) and a track lever (208); and a steering gear (302) coupled to the steering column (314) and the steering push rod (310) according to one of the preceding claims. [12] Vehicle (300) according to claim 11, characterized by that the steering gear (302) is arranged on a frame (406) of the vehicle (300). [13] Vehicle (300) according to claim 11 or 12, characterized by that the steering push rod (310) is arranged to form a parallelogram with a longitudinal control arm of the vehicle (300) when the displacement element (308; 702; 910) is displaced. [14] Method (1800) for controlling a steering gear (302) according to one of claims 1 to 10, wherein the method (1800) comprises the following steps: Reading (1810) a steering signal representing a steering movement; and Providing (1820) a control signal for controlling a drive unit (402; 500) for driving the displacement element (308; 702; 910) using the steering signal. [15] Method (1900) for steering a vehicle (300) according to one of claims 11 to 13, wherein the method (1900) comprises the following steps: Coupling (1920) a steering torque into the steering gear (302) via the steering column (314); and Converting (1920) the steering torque into a movement of the displacement element (308; 702; 910) along the longitudinal direction of the vehicle (300) by means of the linear drive (304).

Images