Steering column for a motor vehicle

Abstract

Steering column (1) for a motor vehicle, comprising a shell unit (2) in which a steering spindle (3) is rotatably mounted about its longitudinal axis (L), and which has a shell tube (5) with a tube body (52) which is connected at its front end to an externally circumferential flange (51), and which is telescopically connected at its rear end in the longitudinal direction of the longitudinal axis (L) to a shell element, characterized in that the tube body (52) is designed as a one-piece molded part on which a radially outwardly projecting channel (57) is formed, which extends over its entire length.

Description

State of the art

[0001] The invention relates to a steering column for a motor vehicle, comprising a shell unit in which a steering spindle is rotatably mounted about its longitudinal axis, and which has a shell tube with a tube body which is connected at its front end to an externally circumferential flange, and which is connected at its rear end in a telescopic manner in the longitudinal direction of the longitudinal axis to a shell element.

[0002] The steering column of a motor vehicle serves to input manual steering commands via a steering handle, such as a steering wheel. This is typically attached to the rear end, facing the driver's position and relative to the direction of travel, of a steering spindle, which is rotatably mounted in a sleeve about its longitudinal axis. This sleeve is held by a support unit connected to the vehicle body.

[0003] To achieve longitudinal adjustment, the jacket unit has a jacket tube that can be adjusted telescopically in the direction of the longitudinal axis, which can have an outer jacket in which an inner jacket is adjustable, or conversely, an inner jacket on which an outer jacket is adjustable.

[0004] The outer casing is held to the vehicle body by means of a support unit. In a steering column of this type, such as that described in DE 10 2022 204 566 B3, the outer casing is supported longitudinally against the body by a retaining element. This retaining element can, for example, include a feedback actuator for a steer-by-wire steering system and can preferably be pivoted about a height adjustment axis located horizontally transverse to the longitudinal axis to achieve height adjustment. In this design, the outer casing, which is supported longitudinally against the body, extends into an outer casing that is telescopically adjustable relative to it in the longitudinal direction.

[0005] Alternatively, the steering column may have an outer outer tube, also known as a box-section or guide box. This outer tube can accommodate an inner sleeve in a telescopically adjustable manner. This inner sleeve can be clamped in place by a clamping device, either for fixed positioning or for adjustment. Such a steering column is known, for example, from DE 10 2019 200 150 A1.

[0006] The generic casing tube always has a tube body coaxial to the longitudinal axis, which is telescopically connected to a casing element in a rearward-facing direction of travel. A radially projecting flange, preferably circumferential, is attached to the front end of the tube body, and a flange connection to the mounting element, for example, the feedback actuator, is formed via this flange.

[0007] The outer tube can be reliably fixed relative to the body via the flange and supported longitudinally. This requires the highest possible stiffness and natural frequency with a compact design and functional adaptation. While this can be achieved in the prior art using a welded sheet metal construction, this increases manufacturing costs and weight. The outer tube can be slotted longitudinally for bracing, but this reduces its stiffness.

[0008] In view of the problems explained above, one objective of the present invention is to enable efficient manufacturing with optimized mechanical properties. Description of the invention

[0009] This problem is solved according to the invention by the steering column with the features of claim 1. Advantageous further developments result from the dependent claims.

[0010] In a steering column for a motor vehicle, comprising a shell unit in which a steering spindle is rotatably mounted about its longitudinal axis, and which has a shell tube with a tube body which is connected at its front end to an externally circumferential flange, and which is telescopically connected at its rear end in the longitudinal direction of the longitudinal axis to a shell element, it is provided according to the invention that the tube body is designed as a one-piece molded part on which a radially outwardly projecting channel is formed, extending over its entire length.

[0011] The pipe body comprises a pipe profile section, for example, a cylindrical pipe section. The channel extends over the entire axial length of the single-piece pipe body, measured from its edge at the rear end to the flange at the front end. It projects outwards from the pipe section in a convex radial direction.

[0012] Preferably, the pipe body is continuously closed over its entire circumference, i.e., over the pipe profile section including the channel molded onto it, in the circumferential direction, at least over the majority of its length.

[0013] The channel forms a kind of groove-shaped bead extending radially outwards from the pipe profile section and running lengthwise along the length of the pipe, i.e., a kind of longitudinal bead.

[0014] The channel creates a defined elastic deformability of the pipe body in the circumferential direction. This means that the longitudinal edges of the pipe profile section adjacent to the channel can be moved elastically towards each other in the circumferential direction by a clamping force acting on the pipe body. This controlled elastic deformation radially reduces the cross-section of the pipe body, both the open through-section and the outer cross-section of the pipe profile section. This allows an actuating unit, such as a cylindrical inner sleeve of such an actuating unit, which can be telescopically inserted into the through-section, to be detachably clamped within the pipe body, for example, to fix an adjustment position of the steering column.Inside the open channel cross-section, radially protruding functional elements, such as stop or bearing elements, energy absorption elements or the like, can be axially displaceable on a telescopically immersible actuating unit.

[0015] Alternatively, it is possible for the pipe body to be telescopically adjustable within an outer shell and to be clamped in place.

[0016] The channel, which according to the invention runs axially along the length of the tube body, ensures in every case improved elastic deformation behavior.

[0017] Another advantage is that the continuous channel simplifies the manufacturing of the pipe body as a single-piece component. A single-stage forming process in the axial direction can be achieved using a plastic forming process, thus enabling efficient production.

[0018] The molded part, which according to the invention is formed entirely in one piece, comprises at least the pipe body and the flange. These together consist of a single, one-piece formed material section.

[0019] The basic form of the pipe body is a hollow profile section, which can be, for example, a cylindrical pipe profile. Alternatively, a polygonal pipe profile can be used.

[0020] At the end furthest forward in the direction of travel, which faces away from the steering spindle or the steering input attached thereto in the longitudinal direction, the tubular body, according to the invention, merges integrally into the flange projecting radially outwards from its outer circumference. This flange extends in a ring- or plate-like shape perpendicular to the longitudinal axis and may include fastening means, such as longitudinally through flange bores or the like, which are known per se.

[0021] In contrast to designs where the flange and the pipe body are provided separately and then joined together, for example by welding, the plastic forming process according to the invention reduces manufacturing effort. Furthermore, the one-piece integrated channel according to the invention allows for advantageous functional properties, such as defined stiffness at a relatively lower weight, and the integration of safety devices.

[0022] It is advantageous that the formed part is a cold-formed part. This can preferably be made of steel. The cold-formed part is produced by plastically deforming a blank below the recrystallization temperature of a metallic material, preferably steel. It can, for example, be a flow-formed part.

[0023] Advantages of cold forming include efficient production in high volumes, even with complex shapes, and the ability to achieve beneficial material hardening and high surface finishes. The combination of optimized material properties with optimized shaping enables increased steering column stiffness at a relatively low weight.

[0024] It is possible that the part is designed as a deep-drawn part. Deep drawing is a proven cold forming process for sheet metal, in which a sheet metal part with a constant or essentially constant material thickness, i.e., a uniform wall thickness, can be efficiently produced from a sheet metal blank.

[0025] In an inner shell designed as a sheet metal part according to the invention, the axial thickness of the flange and the radial wall thickness of the pipe body, including the channel, can be essentially the same. This allows the stiffness to be optimized with the lowest possible mass.

[0026] Preferably, the pipe body is made of steel.

[0027] It is preferred that the channel has a rectangular, open cross-section. This cross-section is open radially inwards towards the through-section of the – preferably cylindrical – pipe profile and bounded radially outwards by a cylindrical or flat outer wall. The two side walls are parallel to each other, spaced apart by the channel width measured circumferentially, and extend parallel to the longitudinal axis. In other words, the channel forms a kind of elongated, narrow box that extends along the outside of the pipe profile.

[0028] It is advantageous that a clamping force for bracing the pipe body can simply be applied from the outside to the parallel side walls in order to press them together in the circumferential direction.

[0029] In the aforementioned embodiment, it is advantageous that a clamping opening extends through both side walls of the channel. The clamping opening passes circumferentially through both side walls. Clamping can be easily achieved by means of a clamping bolt of a releasable clamping device, which passes through the clamping opening and engages the two side walls from the outside. The clamping device can generate a clamping stroke to compress the side walls, preferably by means of a known lifting device that converts a rotation of the clamping bolt about its axis into an axial clamping stroke, for example, by means of wedge discs, ball ramps, toggles, or the like.

[0030] The clamping opening can be easily created during manufacturing, for example by punching or similar methods.

[0031] In the aforementioned design, a clamping element can be attached to the pipe body. The clamping element can be a sheet metal construction, which, for example, is slipped onto the pipe body and fixed by welding. The clamping bolt can be mounted in the clamping element, and the clamping force exerted by the clamping device can be transmitted to the pipe body via the clamping element in a defined manner.

[0032] It is preferred that the flange be plate-shaped. The flange comprises a flat flange ring which has plate-shaped sections that are at least partially perpendicular to the longitudinal axis. The pipe profile of the pipe body is integrally connected to the flange. The channel opens into the flange with its open cross-section.

[0033] The flat flange ring can be manufactured cost-effectively as an integral part of the pipe body, using plastic forming as a sheet metal component.

[0034] It is possible for the fitting to have at least one reinforcing element arranged between the pipe body and the flange. One or more reinforcing elements can be provided, thereby increasing the stiffness of the inner shell. A reinforcing element is preferably arranged in the area of ​​the connection between the pipe body and the flange. It can be realized by a plastic forming integrally with the fitting. It can be plastically molded into the fitting, for example by deep drawing or the like. The advantage is that the manufacturing effort is lower compared to welded-in separate gusset plates or the like. In principle, the reinforcing element can also be realized by the channel according to the invention, which is integrally connected radially to the flange outside the pipe profile.

[0035] An advantageous further development is that the molded part has an energy absorption element. An energy absorption element can be integrally integrated with the pipe body and / or the flange by means of the plastic shaping of the molded part according to the invention. It can preferably be plastically molded into the molded part.

[0036] One or more energy absorption elements may be provided.

[0037] Telescopic longitudinal adjustment can be achieved by having the inner shell's tubular body have a section that extends axially (i.e., longitudinally) into the open passage of the outer shell; this section can be called the adjustment section. Its outer cross-section is smaller than the inner cross-section of the outer shell over its entire circumference, allowing radial play and enabling relative axial adjustment. Alternatively, the tubular body can form an outer shell into which an inner shell extends in a telescopically adjustable manner.

[0038] An energy absorption element can be implemented by a convex outward projection extending from the tube body, which lengthwise over a section of the tube body, also known as the energy absorption section. In this area, the outer cross-section of the inner sleeve is larger than the inner cross-section of the outer sleeve, i.e., it has an excess relative to the open passage, through which the inner sleeve is telescopically adjustable for longitudinal adjustment of the steering column.

[0039] The energy absorption section can preferably be connected to the adjustment section in the longitudinal direction.

[0040] In a crash, a high axial force, the so-called crash force, is exerted on the steering wheel and steering spindle via the steering column, causing the tubular body and the inner or outer sleeve to be telescoped together longitudinally. Initially, a frictional relative movement occurs in the adjustment section, followed by plastic deformation of the energy absorption section. An excess of material can cause plastic deformation in the area of ​​the energy absorption element; specifically, the inner sleeve can be plastically compressed radially inwards, or the tubular body can be continuously compressed radially. Alternatively or additionally, the outer sleeve can be plastically deformed. In each case, kinetic energy is continuously converted into deformation work and heat, resulting in controlled deceleration of the inner sleeve relative to the outer sleeve.

[0041] It is preferable to provide that a radial expansion is formed between the pipe body and the flange. The radial expansion is formed by an end section of the pipe body that has a larger diameter, in particular a larger outer diameter, than the rest of the pipe body. The pipe body transitions into the flange at this larger diameter. The channel according to the invention can extend longitudinally across the expansion.

[0042] The radial expansion increases the rigidity of the pipe body. This also allows for an optimized connection to the flange, thus creating a reinforcing element.

[0043] It is also possible that the expansion provides an energy absorption section with an outer cross-section larger than the open inner cross-section of the outer shell. If the expansion is forced into the outer shell by the high axial crash force acting in a crash, energy absorption occurs through friction and plastic deformation.

[0044] The expansion can preferably be conical. The diameter increases from the pipe body towards the flange. This allows for high bending stiffness. Furthermore, in the event of a crash, increasing energy absorption can be achieved by axially pressing or compressing the conical expansion into the outer shell under increasing friction and plastic deformation. The energy absorption characteristic can be easily determined by the cone angle.

[0045] An advantageous embodiment provides that the pipe body has at least one outwardly projecting bead that transitions into the flange. A bead is plastically formed radially from the inside into the pipe body as a channel-shaped depression, so that a radially outwardly projecting bulge in the wall is formed in cross-section. In cross-section, the bead extends over a portion of the circumference. Preferably, a plurality of beads can be arranged distributed around the circumference.

[0046] The channel-shaped corrugation cross-section can be formed at an angle to the longitudinal axis, particularly at the end of the pipe body in the area of ​​the circumferential connection edge with the flange. This creates a type of oblique or diagonal corrugation, whose convex outward projection extends from the inner end face of the flange, which faces axially towards the pipe body, and radially inward at an angle to the longitudinal axis into the outer circumference of the pipe body. The wall sections of this oblique or diagonal corrugation thus form a kind of integrally formed gusset plate between the pipe body and the flange projecting perpendicularly from it. This enables a more efficient design and optimized stiffening of the connection between the pipe body and the flange, thereby saving material and weight.

[0047] A further advantage can be achieved by extending the bead(s) longitudinally over the section of the tube body that defines the energy absorption area. They form radially outward-projecting energy absorption elements, which, due to the axial pressure exerted on the outer shell during a crash, are plastically molded or squeezed radially inward, thereby absorbing energy.

[0048] The amount and course of energy absorption can be determined practically without additional effort simply by the number, shape and dimensions of the corrugations.

[0049] In the aforementioned embodiment, it is preferred that the bead runs longitudinally. An advantageous further development can be achieved by having the bead rise in a wedge shape longitudinally towards the flange. In this embodiment, it is preferably provided that the bead or beads extend longitudinally over a section of the pipe body, namely over the energy absorption section. An advantageous further development is that they rise radially outwards from the outside of the pipe section in a ramp-like fashion until they merge into the flange.

[0050] The advantage is that in the event of a crash, when the energy absorption section is pressed into the outer shell, the energy absorption can be designed to gradually and continuously increase according to the wedge angle as the beads are plunged into the surface.

[0051] The wedge angle, which corresponds to the inclination angle of the ribs relative to the longitudinal axis, can be easily adjusted to optimize energy absorption and stiffness. For example, the wedge angle can be constant, at least in certain sections, or it can increase or decrease towards the end.

[0052] It is possible that the retaining element is connected to a height-adjustable bearing. The height-adjustable bearing forms a bearing arrangement connectable to the vehicle body, in which the outer shell unit is pivotably mounted at its front end (in the direction of travel) about a horizontal height-adjustment axis. Simultaneously, the inner shell is supported by the retaining element with respect to longitudinal adjustment relative to the outer shell. This outer shell can be moved forwards and backwards within the adjustment range of the inner shell according to the invention to adjust the steering column. In the event of a crash, the outer shell is telescopically pushed onto the inner shell in the direction of the flange, whereby an energy absorption device designed according to the embodiments described above can absorb the impact energy.

[0053] The flange may be connected to a feedback actuator. The steering column can be designed as a steer-by-wire column, in which the steering spindle is not mechanically connected to the wheels to be steered, but rather a manual rotation of the steering spindle is detected by means of rotary sensors to input steering commands. A motorized feedback actuator is provided to simulate the missing mechanical feedback from the wheels via the steering system.

[0054] The feedback actuator serves, in a manner known per se, to couple a motor-generated feedback torque into the steering spindle. The flange of the inner casing can be connected to a mating flange on the feedback actuator, with its drive shaft being coupled to the steering spindle. The feedback actuator is supported longitudinally against the vehicle body and can have, or be connected to, a height-adjustable bearing.

[0055] The inner sheath according to the invention enables a safe, lightweight and cost-effective design of a steer-by-wire steering column. Description of the drawings

[0056] Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. Specifically, they show: Fig. 1 a schematic perspective representation of a steering column according to the invention, Fig. 2 a schematic isolated representation of an inner lining of the steering column designed according to the invention Fig. 1 in a first version, Fig. 3 a second embodiment of a pipe body according to the invention in a view as in Fig. 2, Fig. 4 a third embodiment of a pipe body according to the invention in a view as in Fig. 2, Fig. 5 a fourth embodiment of a pipe body according to the invention. Embodiments of the invention

[0057] In the various figures, identical parts are always marked with the same reference symbols and are therefore usually only named or mentioned once.

[0058] The steering column 1 comprises a casing unit 2 in which a steering spindle 3 is rotatably mounted about its longitudinal axis L. A mounting section 31 is formed at the rear end section, facing the driver's position and in relation to the direction of travel. A steering wheel (not shown) can be attached to this mounting section for inputting manual steering commands by rotating the steering spindle 3.

[0059] The steering column 1 is designed as a steer-by-wire steering column. The steering spindle 3 is not mechanically connected to the wheels to be steered. It interacts with rotation sensors (not shown) to detect rotations of the steering spindle 3, which are converted into electrical control signals for controlling steering actuators.

[0060] The casing unit 2 has an outer casing 21, which is designed as an outer casing tube in which the steering spindle 3 is mounted. The outer casing 21 is held in a support unit 4, which can be attached to the vehicle body.

[0061] A casing tube, which in a first embodiment is designed as an inner casing 5, is shown separately in a perspective view in Fig. Figure 2 shows this. It has a disc-shaped flange 51, perpendicular to the longitudinal axis, which is integrally connected to a cylindrical tube body 52, coaxial with the longitudinal axis L. The flange 51 is located at the front end of the tube body 52 with respect to the direction of travel. It has a plurality of flange bores 510.

[0062] The flange 51 is flanged to the housing of a feedback actuator 6 by means of bolts (not shown) which are passed through the flange bores 510 in a manner known per se.

[0063] The feedback actuator has a pivot bearing in which it is mounted so that it can pivot about a horizontal height adjustment axis 61, which lies transversely to the longitudinal axis, relative to the vehicle body. This allows a steering wheel attached to the steering spindle 3 to be adjusted in the vertical direction H, as shown in Fig. 1 is indicated by the double arrow.

[0064] To achieve longitudinal adjustment of the steering wheel position, the tubular body 52, pointing rearward relative to the direction of travel, extends telescopically into the outer shell 21 in the direction of the longitudinal axis L. This allows the outer shell 31 to be adjusted longitudinally relative to the support unit 4 and the feedback actuator 6. A clamping device 41 attached to the support unit enables the outer shell 21 to be releasably clamped relative to the support unit 4, and thus relative to the vehicle body.

[0065] In the event of a crash, when a high longitudinal impact force is exerted on the steering spindle 3 by a body striking the steering wheel, the support unit 4, together with the outer sleeve 21 clamped within it, can move forward in the crash direction C along the longitudinal axis L, as indicated by the arrow. In doing so, the outer sleeve 21 is pushed forward onto the tube body 52 in the direction of the flange 51.

[0066] In the first version according to Fig. 2 it can be seen that the pipe body 62 has a circumferential, conical widening 53 in the transition area to the flange 53.

[0067] Furthermore, a plurality of diagonal beads 54, which can also be referred to as diagonal beads, are plastically formed at an angle to the longitudinal axis L in the edge region, i.e., the connection area between the wall of the pipe body 62 and the flange 51. This is indicated by dashed lines. This creates integrally formed reinforcing elements, similar to a gusset plate, which stiffen the inner shell 5.

[0068] Fig. Figure 4 shows a modified version with a plurality of diagonal beads 54.

[0069] In the third embodiment according to Fig. 4 Several longitudinally extending beads 55 are arranged around the circumference. They extend longitudinally over the length of an energy absorption section 56, which extends forward over a front section of the tube body 52 to the flange 51, and merge into the flange 51.

[0070] The beads 55 rise forward, towards the flange 51, from the outer surface of the pipe body 52 in a wedge shape. They form a wedge angle α (alpha) with the outer surface parallel to the longitudinal axis L, as shown in Fig. 4 is shown with a dashed line. This can preferably be relatively shallow, with α preferably < 30°. The corrugations 55 project with their outer cross-section beyond the open inner cross-section of the outer shell 21. This allows the cylindrical adjustment section located outside the energy absorption section 56 to be extended and retracted telescopically for longitudinal adjustment. However, the energy absorption cross-section 56 can only be compressed into the outer shell 21 in the event of a crash, with plastic deformation of the corrugations 55 and at least partially also of the inclined corrugations 54. It is also possible to design the widening 53 for energy absorption with a relatively shallow conical angle over an energy absorption section.

[0071] In all versions according to Fig. 2, Fig. 3 and Fig. 4 The inner shell 5, including the flange 51, the tube body 52, the expansion 53, and the beads 54 and 55, is formed as a single-piece component. This component is preferably made of steel by cold forming, for example, by deep drawing. It is preferably provided that the wall thickness is substantially the same in all sections of the component.

[0072] The in Fig. The casing pipe shown in Figure 5 has a pipe body 52, which has a hollow cylindrical shape and, as in the preceding examples, merges seamlessly into a flange 51. The pipe body 52 has a radially outwardly projecting channel 57, which has a substantially rectangular cross-section and is formed in one piece. The channel 57 extends over the entire axial length of the pipe body 52, namely from its free end, which is rearward with respect to the direction of travel, as shown in Figure 5. Fig. 5 points to the right, up to the flange 51 at the front end. The channel 57 transitions axially into the flange 51.

[0073] The channel 57 has side walls 571 on both sides in the circumferential direction, which lie parallel to each other and to the longitudinal axis L.

[0074] In the example shown, a conical expansion is provided at the transition between the pipe body 52 and the flange 51, but this expansion can also be omitted. It can be seen that the channel 57 extends over this expansion 53.

[0075] The channel 57 has a through both clamping openings 58, which passes through both side walls 571 in the direction of a clamping axis S perpendicular to the longitudinal axis L.

[0076] A clamping element 6 is attached to the pipe body 52. ​​This element is designed like a clamp that grips the pipe body 52. ​​It has two openings 61 aligned with the clamping axis S, through which a clamping bolt (not shown) of a clamping device can be passed. This clamping device can exert a clamping stroke to compress the pipe body 52 and releasably clamp it to an inner surface. The clamping openings 58 ensure secure relative positioning with the channel 57, and allow interaction with energy absorption devices and the like, which may be arranged inside the channel 57. Reference symbol list 1 Steering column 2 sheathed unit 21 Outer shell 3 Steering spindle 31 Fastening section 4 carrying unit 41 Clamping device 5 inner mantle 51 flange 510 holes (flange holes) 53 Expansion 54 Diagonal bead (slant bead) 55 groove 56 Energy absorption section Channel 57 571 Side wall 58 clamping opening 6 Feedback actuator 61 Height adjustment axis 7 clamping bodies 71 Opening L Longitudinal axis C Crash direction S clamping axis QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 10 2022 204 566 B3

[0004] DE 10 2019 200 150 A1

[0005]

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