steering gear

Abstract

Steering gear (1) for a motor vehicle comprising a steering spindle (3) arranged in a rotationally fixed and linearly displaceable manner, which is supported at a first bearing point (4) and a second bearing point (5) spaced apart in the longitudinal extent of the steering spindle (3), wherein the steering spindle (3) engages with a rotatable gear element such that a rotation of the gear element causes a linear displacement of the steering spindle (3), wherein a bearing block (7) is fixed to the steering spindle (3) between the first bearing point (4) and the second bearing point (5), which extends radially outwards from the outer surface of the steering spindle (3) and engages in a guide element (8) that is stationary relative to the steering spindle (3),wherein a first sliding element (9) bears against a first sliding surface (10) of the guide element (8) between the bearing block (7) and the guide element (8), and a second sliding element (11) bears against a second sliding surface (12) of the guide element (8) opposite the first sliding surface (10), characterized in that the bearing block (7) has a first receiving area (17) for the first sliding element (9), wherein the first receiving area (17) has a spherically or cylindrically shaped contact section (18) against which a corresponding contact section (19) of the first sliding element (9) bears such that the first sliding element (9) is pivotable relative to the first receiving area (17) by an angle.

Description

[0001] The present invention relates to a steering gear for a motor vehicle comprising a steering spindle arranged in a rotationally fixed and linearly displaceable manner, which is mounted at a first bearing point and a second bearing point spaced apart in the longitudinal extent of the steering spindle, wherein the steering spindle engages with a rotatable gear element such that a rotation of the gear element causes a linear displacement of the steering spindle.

[0002] The present invention relates to a steering gear for vehicles, in particular to an improved steering gear that makes the transmission of steering forces more efficient and safer. A steering gear is an essential component of the steering system in vehicles. It converts the rotary motion of the steering wheel into a linear motion that then controls the wheels. In a steer-by-wire steering system, there is no mechanical connection between the steering wheel and the steering gear, since the steering commands are transmitted from the steering wheel to a road wheel actuator via an electrical signal path. The steering gear is then driven by a correspondingly controlled electric actuator.

[0003] In conventional steering gears, the steering rod is actuated by a gearbox, which often exerts an additional torque on the spindle. This torque, in turn, must be supported against the gearbox housing, which presents various challenges depending on the steering gear design. One such challenge is that the tie rods are usually at an angle to the steering rod axis, which can lead to steering rod deflection, especially when steering forces and road surface impacts are applied.

[0004] DE 10 2021 103 018 A1 discloses a linear actuator comprising a slide within a housing that is translationally displaceable by an actuator drive. A locking device is arranged on the slide to prevent rotation of the slide relative to the housing. The locking device has two opposing legs supported on the slide, with a spring element arranged on each leg that bears elastically against an inner wall of the housing. This design serves to ensure the stability and precision of the slide's movement.

[0005] DE 10 2020 105 195 A1 discloses an actuator for a rear axle steering system of a vehicle, comprising a push rod that is longitudinally displaceable within a housing. The push rod has an anti-rotation device with a cam element that is guided axially in the housing by a guide element arranged thereon. The guide element has at least one elastically deformable section that is supported on the housing transversely to the longitudinal displacement direction of the push rod. The disclosure further relates to a rear axle steering system with such an actuator and to a vehicle comprising such a rear axle steering system.

[0006] DE 10 2018 130 228 B3 discloses an actuator for a vehicle's rear axle steering system, comprising a push rod that is longitudinally displaceable within a housing. The push rod has an anti-rotation device with a guide element that is guided axially in a one- or multi-part slide rail arranged on the housing. An elastomer ring is arranged between the slide rail and the housing to support the actuator's functionality. Furthermore, a rear axle steering system with such an actuator and a vehicle comprising such a rear axle steering system are described.

[0007] The object of the invention is therefore to avoid or at least reduce these problems and to provide an improved steering gear for motor vehicles.

[0008] This problem is solved by a steering gear for a motor vehicle comprising a steering spindle arranged in a rotationally fixed and linearly displaceable manner, which is supported at a first bearing point and a second bearing point spaced apart in the longitudinal extent of the steering spindle, wherein the steering spindle engages with a rotatable gear element such that a rotation of the gear element causes a linear displacement of the steering spindle, wherein a bearing block is fixed to the steering spindle between the first bearing point and the second bearing point, which extends radially outwards from the outer surface of the steering spindle and engages in a guide element that is stationary relative to the steering spindle, wherein a first sliding element bears against a first sliding surface of the guide element between the bearing block and the guide element, and a second sliding element bears against a second sliding surface of the guide element opposite the first sliding surface.

[0009] The steering gear according to the invention achieves optimized torque support, which is provided between the two main bearing points of the spindle and steering rod. This design ensures improved transmission and distribution of forces within the steering gear, thereby increasing the safety and efficiency of the steering process in vehicles.

[0010] The steering gear does not impede the steering spindle's deflection and must be adjustable with respect to deflection amplitudes and angles so that the steering gear is not over-constrained with regard to its bearing.

[0011] In its simplest form, the torque support point of the steering gear can have a sliding guide consisting of the bearing block, which serves as a slide, and the guide element with a groove into which the bearing block engages. The two opposing sliding elements allow, in particular, for uniform torque support in both linear offset directions of the steering spindle.

[0012] The bearing block can, for example, be attached to the steering spindle using a screw connection. In principle, other fastening methods are also conceivable, such as material-bonded connections, in particular welding or gluing.

[0013] A sliding element can, for example, be made from a material from the group consisting of metals, polymer composites, fluoropolymers, in particular PTFE, ceramics and / or elastomers. Self-lubricating metals or plastics impregnated with solid lubricants such as graphite or molybdenum disulfide to ensure continuous lubrication are particularly preferred.

[0014] According to an advantageous embodiment of the invention, it can be provided that the first sliding element is subjected to spring force by a first spring element in the direction of the first sliding surface and / or that the second sliding element is subjected to spring force by a second spring element in the direction of the second sliding surface.

[0015] An additional spring element, which presses one of the sliding elements against the sliding surface of the guide element with preload, helps to ensure that the moment support is as free of play as possible and preferably spring-loaded relative to the guide element. This reliably prevents rattling and clattering noises that would otherwise occur at this point during steering operation. The preload is advantageously selected to be greater than the moment-related support forces that occur from the road surface during "normal" driving. "Normal" here refers, for example, to driving over common road irregularities, gravel roads, or cobblestones—not to increased support moments such as those that occur when driving over potholes, parking while stationary, etc. The resulting sliding friction due to the spring preload also dampens unwanted chassis resonances such as wheel flutter.The necessary magnitude of the spring preload force can also be chosen with regard to this requirement.

[0016] It is advantageous if the first spring element is supported on the bearing block on one side and on the first sliding element on the other.

[0017] It can also be advantageous for the first and second spring elements to be formed in one piece, particularly monolithically. In other words, the sliding elements are then subjected to spring force by a common spring element, for example, a coil spring. The spring element is then pre-tensioned against both the first and second sliding elements.

[0018] A spring element, as used in connection with this invention, is a mechanical component that stores and releases energy in the form of elastic deformation. It is designed such that it undergoes a specific deformation when a force is applied and returns to its original shape after the force is removed. A spring element can be selected from the group consisting of coil springs, leaf springs, disc springs, torsion springs, and / or rubber springs.

[0019] According to a further preferred embodiment of the invention, the first spring element and / or the second spring element may also be designed as a coil spring. A coil spring typically consists of an elastic material, preferably metal, wound into a spiral or helical shape. A coil spring can be selected from the group consisting of tension springs, compression springs, torsion springs, conical springs, and non-cylindrical springs.

[0020] Furthermore, according to another advantageous embodiment of the invention, the first sliding element may have a coupling section against which the first spring element rests. This coupling section may be designed to absorb the forces transmitted from the spring element to the sliding element and to transfer and distribute them into the sliding element without causing mechanical damage to the sliding element. The spring element may rest directly against the coupling section of the sliding element. It would also be conceivable to arrange a washer between the coupling section and the spring element, which could provide improved pressure distribution into the sliding element and offer a more wear-resistant contact surface, thus contributing to increased operational reliability and reduced wear of the steering gear.

[0021] In this context, it may also be preferred that the coupling section has a cylindrical receptacle into which the first spring element, designed as a coil spring, engages. This can provide improved guidance of the spring element relative to the coil spring, which helps to prevent unintentional loosening or slippage of the coil spring relative to the sliding element.

[0022] According to the invention, the bearing block can be provided with a first receiving area for the first sliding element, wherein the first receiving area has a spherically or cylindrically shaped contact section against which a corresponding contact section of the first sliding element rests such that the first sliding element can pivot relative to the first receiving area by an angle. This allows the sliding guide of the bearing block to be designed in such a way that it is able to compensate for the deflections and angular errors occurring during the operation of the steering spindle and thus ensure a consistent quality of the sliding contact.

[0023] It is particularly preferred that one contact section of the bearing block is concave and one contact section of a sliding element is convex, which leads to particularly favorable force transmission during axial displacement of the bearing block, since a sliding element edge can bear against the bearing block for support. However, it would also be conceivable to reverse the convex / concave arrangement.

[0024] Furthermore, it is advantageous if a cylindrical section extending into the interior of the bearing block is connected to the spherically shaped contact section, in which a corresponding contact section of the first sliding element engages, which can contribute to an improved bearing of the sliding element on the bearing block.

[0025] In one possible embodiment, the first sliding element and / or the second sliding element may be substantially cylindrical. The contact surface has a substantially round, preferably circular, shape. The cylindrical sliding element may have various cylindrical sections with different diameters along its longitudinal extent.

[0026] In principle, it would also be conceivable that the first sliding element and / or the second sliding element are essentially cuboid in shape. In this case, the contact surface would then have an essentially rectangular shape.

[0027] To ensure a secure connection of a spring element, the first and second sliding elements can have different spatial shapes. In principle, it would also be conceivable, for example to increase the degree of uniformity in the steering gear, to design the sliding elements identically.

[0028] According to a preferred embodiment, the bearing block can be manufactured from a metallic material using machining processes or by metal casting. In principle, it is also conceivable to mold the bearing block from a plastic, for example by injection molding.

[0029] Furthermore, the invention can also be further developed in that the bearing block is formed from a sheet metal part and the bearing block formed from a sheet metal part has a first sheet metal section and a second sheet metal section that runs substantially parallel to the first sheet metal section, wherein the first sheet metal section carries the first sliding element and the second sheet metal section carries the second sliding element. A bearing block manufactured from sheet metal by means of a forming process can offer particular cost advantages in the manufacture of the steering gear. It is also possible to achieve weight advantages within the steering gear by using a bearing block formed from sheet metal.

[0030] In a further preferred embodiment of the invention, the first and second sheet metal sections can also be designed to exert a spring force on the first and / or second sliding element, acting in the direction of the first sliding surface and / or in the direction of the second sliding surface. Integrating a spring element into the bearing block design eliminates the need for an additional spring element in the steering gear, potentially resulting in weight and cost savings. Of course, it is also conceivable that, in addition to the spring action of the sheet metal bearing block, a separate spring element could be used, which could then potentially be made smaller.

[0031] It can also be advantageous to further develop the invention by arranging a first spring cup between the first sliding element and the first spring element, which transmits the spring force of the first spring element to the first sliding element. This offers the advantage that the force of the spring element is not applied directly to the sliding element, which can contribute to a more uniform pressure distribution. Furthermore, the spring cup can also provide improved guidance of the spring element, in particular a coil spring, by having a cup-shaped projection extending into the coil spring. The spring cup is preferably made of a metallic material, most preferably of a sheet metal part.

[0032] According to a further preferred embodiment of the invention, the first sliding surface can be shaped such that it exerts a spring force in the direction of the first sliding element. It would also be conceivable, in principle, for the second sliding surface to be shaped such that it exerts a spring force in the direction of the second sliding element. Thus, one or both sliding surfaces can exert a spring force on the respective sliding element. This would, for example, eliminate the need for a spring element within the movable bearing block and shift the spring action to a static area of ​​the steering gear.

[0033] To apply the spring force, a spring element can be coupled with a sliding surface, whereby the sliding surface itself does not need to have spring elasticity.

[0034] However, it is preferred that a sheet metal plate is inserted between the guide element and a sliding element to improve friction. This is particularly advantageous when the guide element is made of an aluminum alloy and therefore has correspondingly high coefficients of friction. Since the sliding element is then in sliding contact with the sheet metal plate as a sliding surface, correspondingly lower coefficients of friction can be achieved between the sliding partners.

[0035] In this context, it is further advantageous if at least one of the intermediate plates serving as a sliding surface is resilient. For this purpose, the plate can, for example, be bent, curved, or angled to represent a resilient element.

[0036] According to one embodiment, the first sliding surface can be a first sheet metal plate and / or the second sliding surface a second sheet metal plate. It is then preferred that at least one of the sheets has a spring effect.

[0037] However, it would also be possible that the first sheet and the second sheet are made in one piece, especially monolithically.

[0038] Finally, the invention can also advantageously be implemented such that a first stop element is arranged on the bearing block, which, upon reaching a predefined offset position in a first offset direction of the bearing block, abuts a second stop element that is stationary relative to the steering spindle. This allows a mechanical end stop for the steering movement to be integrated into the steering gear.

[0039] In this context, it is further preferred if a third stop element is arranged on the bearing block, which, upon reaching a predefined offset position in a second offset direction of the bearing block, abuts a fourth stop element that is fixed relative to the steering spindle.

[0040] To reduce manufacturing and assembly costs, it may also be preferable for the first stop element and the second stop element to be made in one piece, in particular monolithically.

[0041] The invention will now be explained in more detail with reference to figures, without limiting the general concept of the invention.

[0042] It shows: Fig. 1 a first embodiment of a steering gear in a perspective view, Fig. 2 a first embodiment of a steering gear in a cross-sectional view, Fig. 3 a bearing block and two sliding elements of the first embodiment of the steering gear in an exploded view, Fig. 4 a cuboid-shaped embodiment of a sliding element in two perspective views, Fig. 5 a second embodiment of a steering gear in a guide element in a perspective view, Fig. 6 a second embodiment of a steering gear in a guide element in a perspective view, Fig. 7 a second embodiment of a steering gear in a guide element in a cross-sectional view, Fig. 8 a third embodiment of a steering gear in a guide element in a cross-sectional view, Fig. 9 a fourth embodiment of a steering gear in a guide element in a cross-sectional view.

[0043] The Fig. Figure 1 shows a first embodiment of a steering gear 1 for a motor vehicle, comprising a steering spindle 3 that is fixed against rotation and linearly displaceable, and which is supported at a first bearing point 4 and a second bearing point 5 spaced apart along the longitudinal extent of the steering spindle 3. The steering spindle 3 engages with a rotatable gear element such that a rotation of the gear element causes a linear displacement of the steering spindle 3. The gear element can, for example, be a worm gear or a spindle nut.

[0044] A bearing block 7 is attached to the steering spindle 3 between the first bearing point 4 and the second bearing point 5 by means of a screw connection 25, which extends radially outwards from the outer surface of the steering spindle 3 and engages in a guide element 8 that is stationary relative to the steering spindle 3, which can be clearly seen from the Fig. 2 can be recognized.

[0045] Between the bearing block 7 and the guide element 8, a first sliding element 9 rests against a first sliding surface 10 of the guide element 8, and a second sliding element 11 rests against a second sliding surface 12 of the guide element 8 opposite the first sliding surface 10. The sliding elements 9, 11 have a circular contact surface 31.

[0046] From the Fig. Figure 2 further shows that the first sliding element 9 is subjected to spring force by a first spring element 13, designed as a coil spring, in the direction of the first sliding surface 10. The first spring element 13 is pre-tensioned and supported on one side by the bearing block 7 and on the other side by the first sliding element 9. The second sliding element 11, on the other hand, is mounted on a projecting boss 29 of the bearing block 7 without direct spring force, as the boss 29 engages in a corresponding recess of the second sliding element 11. The second sliding element 11 is, however, indirectly pre-tensioned by the spring element 13 bearing against the bearing block 7, which in turn presses against the second sliding element 11.

[0047] The first sliding element 9 has a coupling section 15 against which the first spring element 13 rests. As can also be clearly seen from Fig. As can be seen in Figure 3, the coupling section 15 has a cylindrical receptacle 16 into which the first spring element 13, shaped as a spiral spring, engages.

[0048] The bearing block 7 further comprises a first receiving area 17 for the first sliding element 9, wherein the first receiving area 17 has a spherically shaped contact section 18 against which a corresponding contact section 19 of the first sliding element 9 rests such that the first sliding element 9 can pivot relative to the first receiving area 17 by an angle. The second sliding element 11 also has a corresponding second receiving area 28 for the second sliding element 11. This second receiving area 28 also has a spherically shaped contact section 26 against which the correspondingly shaped contact section 27 of the second sliding element 11 rests such that the second sliding element 11 can also compensate for angular misalignments.

[0049] The spherically shaped system section 18 is adjoined by a cylindrical section 30 extending into the interior of the bearing block 7, in which a corresponding system section 20 of the first sliding element 9 engages.

[0050] In the embodiment shown, the Fig. 1-3 the first sliding element 9 and the second sliding element 11 are essentially cylindrical, wherein the first sliding element 9 and the second sliding element 11 have different spatial shapes.

[0051] As in the Fig. As shown in Figure 4, it is also conceivable, in principle, to design a sliding element 9, 11 to be essentially cuboid and essentially identical. Such a sliding element 9, 11 then has a cylindrical contact section 19 instead of a spherical one, which is received in a corresponding cylindrical contact section 18 of the receiving area 17 of the bearing block 7. While spherical contact sections 18, 19 allow angular compensation in virtually all spatial directions, with a cylindrical contact section 18, 19, angular compensation is only possible about a pivot axis.

[0052] In the Fig. Figures 5-9 show further embodiments of the steering gear 1, in which the bearing block 7 is formed from a sheet 22. The bearing block 7 formed from a sheet 22 has a first sheet section 23 and a second sheet section 24 that is substantially parallel to the first sheet section 23, wherein the first sheet section 23 carries the first sliding element 9 and the second sheet section 24 carries the second sliding element 11, which is clearly shown in the Fig. 6 can be seen.

[0053] In this case, the first sheet metal section 23 and the second sheet metal section 24 can be designed such that they exert a spring force acting in the direction of the first sliding surface 10 and / or in the direction of the second sliding surface 12 on the first sliding element 9 and / or on the second sliding element 11.

[0054] In the Fig. Figure 5 shows the guide element 8, which in the illustrated embodiment is designed as a housing component of the steering gear 1. The steering spindle 3 extends through the guide element 8, which has sliding surfaces 10, 12 running parallel to this longitudinal extension of the steering spindle 3. In this embodiment, it is conceivable that the bearing block 7, together with the length of the illustrated housing guide, also serves as a mechanical steering end stop, and that the bearing block 7 can abut the end faces of the guide element 8.

[0055] In this arrangement, at least one additional stop element (not shown) made of a plastic, in particular an elastomer, can be provided, which is connected to the bearing block 7, for example by being fitted over the bearing block 7. It would also be possible for a first stop element to be arranged on the bearing block 7, which, upon reaching a predefined offset position in a first offset direction of the bearing block 7, abuts a second stop element that is fixed relative to the steering spindle 3, and for a third stop element to be arranged on the bearing block 7, which, upon reaching a predefined offset position in a second offset direction of the bearing block 7, abuts a fourth stop element that is fixed relative to the steering spindle 3. The first stop element and the second stop element can be manufactured in one piece, in particular monolithically.

[0056] In the Fig. Figure 7 shows that a first spring cup 21 is arranged between the first sliding element 9 and the first spring element 13. This spring cup transmits the spring force of the first spring element 13 to the first sliding element 9. The spring cup 21 engages with the spiral-shaped first spring element 13, which improves the guidance of the spring element 13 relative to the spring cup 21. The first spring element 13 then rests against a circumferential collar of the spring cup 21 that extends radially outwards.

[0057] In the Fig. Figures 8-9 show embodiments of the steering gear 1 in which the first sliding surface 10 is shaped to exert a spring force in the direction of the first sliding element 9. For this purpose, the first sliding surface 10 is formed on a first sheet 32, which is arranged between the guide element 8 and the first sliding element 9. The first sheet 32 ​​has a convex curvature pointing towards the first sliding element 9, which causes the spring force of the first sliding surface 10. A second sheet 33 is also arranged on the opposite side to ensure the most identical possible sliding friction between the sliding surfaces 10, 12 and the sliding elements 9, 11 on both sides. The second sheet 33 has no curvature and therefore no spring effect.

[0058] As in the Fig.As can be seen in Figure 9, the spring effect of the first sliding surface 10 can also be achieved by a sheet 32 ​​that is bent in a U-shape and has a curvature in the area of ​​the first sliding surface 10. In this case, one free leg of the U-shaped sheet 32 ​​serves as the first sliding surface 10 and the other free leg as the second sliding surface 12.

[0059] The invention is not limited to the embodiments illustrated in the figures. The foregoing description is therefore not to be considered limiting, but rather explanatory. The following claims are to be understood as meaning that a named feature is present in at least one embodiment of the invention. This does not preclude the presence of further features. Insofar as the claims and the foregoing description define 'first' and 'second' features, this designation serves to distinguish between two similar features without establishing any hierarchy. Reference symbol list 1 Steering gear 3 Steering spindle 4 storage locations 5 storage location 7 bearing block 8 Guide element 9 sliding element 10 Sliding surface 11 Sliding element 12 Sliding surface 13 Spring element 15 Coupling section 16 recording 17 Recording area 18 Plant section 19th section of the plant 20 Plant section 21 feather bowl 22 sheets 23 sheet metal sections 24 sheet metal sections 25 screw connection 26 Plant section 27th section of the plant 28 Recording area 29 Cathedral 30 Cylinder section 31 Contact area 32 sheets 33 sheet metal

Claims

[1] Steering gear (1) for a motor vehicle comprising a steering spindle (3) arranged in a rotationally fixed and linearly displaceable manner, which is supported at a first bearing point (4) and a second bearing point (5) spaced apart in the longitudinal extent of the steering spindle (3), wherein the steering spindle (3) engages with a rotatable gear element such that a rotation of the gear element causes a linear displacement of the steering spindle (3), wherein a bearing block (7) is fixed to the steering spindle (3) between the first bearing point (4) and the second bearing point (5), which extends radially outwards from the outer surface of the steering spindle (3) and engages in a guide element (8) that is stationary relative to the steering spindle (3),wherein a first sliding element (9) bears against a first sliding surface (10) of the guide element (8) between the bearing block (7) and the guide element (8), and a second sliding element (11) bears against a second sliding surface (12) of the guide element (8) opposite the first sliding surface (10), , characterized by , that the bearing block (7) has a first receiving area (17) for the first sliding element (9), wherein the first receiving area (17) has a spherically or cylindrically shaped contact section (18) on which a corresponding contact section (19) of the first sliding element (9) rests such that the first sliding element (9) can be pivoted by an angle relative to the first receiving area (17). [2] Steering gear (1) according to claim 1, characterized by, that the first sliding element (9) is subjected to spring force by a first spring element (13) in the direction of the first sliding surface (10) and / or the second sliding element (11) is subjected to spring force by a second spring element in the direction of the second sliding surface (12). [3] Steering gear (1) according to claim 2, characterized by , that the first spring element (13) and / or the second spring element is shaped as a coil spring. [4] Steering gear (1) according to any one of the preceding claims 2-3, characterized by , that the first sliding element (9) has a coupling section (15) against which the first spring element (13) rests. [5] Steering gear (1) according to any one of the preceding claims 2-4, characterized by, that the bearing block (7) is formed from a sheet (22) and the bearing block (7) formed from a sheet (22) has a first sheet section (23) and a second sheet section (24) running substantially parallel to the first sheet section (23), wherein the first sheet section (23) carries the first sliding element (9) and the second sheet section (24) carries the second sliding element (11). [6] Steering gear (1) according to claim 5, characterized by , that the first sheet metal section (23) and the second sheet metal section (24) are designed such that they exert a spring force acting in the direction of the first sliding surface (10) and / or in the direction of the second sliding surface (12) on the first sliding element (9) and / or on the second sliding element (11). [7] Steering gear (1) according to any one of the preceding claims 2-6, characterized by, that between the first sliding element (9) and the first spring element (13) a first spring cup (21) is arranged which transmits the spring force of the first spring element (13) to the first sliding element (9). [8] Steering gear (1) according to any one of the preceding claims 2-7, characterized by , that the first sliding surface (10) is shaped in such a way that it exerts a spring force in the direction of the first sliding element (9). [9] Steering gear (1) according to any one of the preceding claims 2-8, characterized by , that a first stop element is arranged on the bearing block (7) which, when a predefined offset position is reached in a first offset direction of the bearing block (7), abuts a second stop element which is fixed in position relative to the steering spindle (3).

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