Steering shaft for a vehicle and a method for manufacturing the same.

Description

[0001] The invention relates to a steering shaft for a vehicle according to the preamble of patent claim 1 and to a method for producing a steering shaft for a vehicle according to the preamble of patent claim 9.

[0002] Steering shafts are used in vehicles, particularly motor vehicles, to transmit torque between the steering wheel and the steering gear. Steering shafts are connected at their ends to the steering wheel or steering gear. In the event of a vehicle crash, i.e., a collision, the steering shaft may inadvertently penetrate further into the vehicle's passenger compartment if the steering gear is displaced by the crash or collision. This can result in injury to the driver.

[0003] Steering shafts with a corrugated section (corrugated tubes) are known from the prior art. In the event of a vehicle crash, the steering shaft deforms, particularly compresses or bends, in the corrugated area. By compressing or bending, the penetration of the steering shaft into the passenger compartment can be prevented or at least mitigated.

[0004] EP 0 661 117 A1 discloses a method for producing a corrugated tube or a metal bellows for steering systems in motor vehicles. In this method, a plurality of similar annular concavities are formed on the outer circumference of a cylindrical metal tube to form a uniform structure, thereby obtaining an intermediate product. In a second step, a cylindrical core iron is inserted into the intermediate product, and the intermediate product is compressed in the axial direction, whereby the annular concavities deform radially outward.

[0005] DE 10 2009 024 847 A1 shows a device for producing helical corrugated tubes for adjusting the pitch of the corrugation of the corrugated tube.

[0006] From US 5,503,431 A, a steering system for motor vehicles is known with an intermediate shaft having a cylindrical bellows made of metal which contracts or bends in the event of a collision of the vehicle in order to absorb the displacement of the steering gear due to the impact.

[0007] From US 3,699,624 A a method for producing tubular blanks, for example for steering shafts, is known, wherein each tubular blank is designed to collapse axially under a predetermined axial compressive load, for which purpose a series of depressions and elevations are introduced into a section.

[0008] US 4,050,326 A describes a steering column comprising an axially compressible steering shaft with an energy-absorbing wave-shaped deformation element surrounding the steering shaft.

[0009] A steering shaft with a shaft tube part which is flexible under compression load can be manufactured more cost-effectively using the outer jacket tube disclosed in DE 24 59 246 A1.

[0010] Another steering shaft, which is designed to be compressible under pressure load due to a wave-shaped section, is known from US 3,508,633 A, wherein the steering shaft is also designed to be flexurally stable.

[0011] Furthermore, GB 1 262 913 A discloses a method for introducing a corrugation into a tube which can be used as a compressible steering column.

[0012] A method for producing annular grooves on thin-walled pipes is also known from DE 800 480 C.

[0013] The steering shafts known from the state of the art and the processes for their production have the disadvantage that they are complex to manufacture and the bending characteristics of the steering shafts are subject to high fluctuations.

[0014] Based on this prior art, the object of the present invention is to provide a steering shaft with improved bending behavior, in particular a bending characteristic that can be adjusted as precisely as possible. Furthermore, a method for manufacturing such a steering shaft is to be provided that is, in particular, as simple as possible.

[0015] This object is achieved by a steering shaft according to claim 1 and a method according to claim 9. Advantageous further developments emerge from the respective subclaims.

[0016] To achieve the object, a steering shaft for a vehicle is proposed, comprising a tubular shaft body which extends along a longitudinal axis and has a first shaft end and a second shaft end, wherein a bending section is arranged between the first shaft end and the second shaft end, wherein the bending section has a plurality of grooves running in the circumferential direction of the shaft body to form a groove structure, characterized in that the groove structure is formed unevenly in the direction of the longitudinal axis.

[0017] Thanks to the uneven groove structure in the direction of the longitudinal axis, a steering shaft with improved bending behavior, in particular a bending characteristic that can be adjusted as precisely as possible, can be provided.

[0018] The groove structure is formed by a plurality of grooves extending in the circumferential direction, wherein the groove structure is irregularly formed. The irregular groove structure can be characterized by a heterogeneous arrangement and / or heterogeneous formation of the individual grooves relative to one another.

[0019] Preferably, the irregular groove structure can be characterized in that the grooves are asymmetrical with respect to any plane within the bending section, wherein the arbitrary plane is oriented orthogonally to the longitudinal axis. The arbitrary plane is a plane orthogonal to the longitudinal axis in any position or location of the bending section. In other words, there is no plane within the bending section that is oriented orthogonally to the longitudinal axis and to which the grooves are symmetrical.

[0020] The groove structure is uneven before a crash occurs, i.e., during normal operation, before a crash has occurred. Thus, the groove structure is uneven before the plastic deformation of the bending section in a crash. Thus, at least two grooves and / or at least two sections between the grooves can have different properties against compression (upsetting) and / or bending.

[0021] According to the invention, a groove can be understood as a recess, in particular a bead, which is formed to extend at least over part of the circumference of the shaft body or the steering shaft (circumferential groove or annular groove). In particular, the groove lies in a plane perpendicular to the longitudinal axis of the steering shaft, preferably having no gradient in the longitudinal direction.

[0022] In an advantageous development, the geometry of a first groove can differ from the geometry of a second groove. Thus, the first groove is designed differently from the second groove, creating an irregular groove structure.

[0023] The geometry of the grooves preferably differs in terms of shape and / or depth and / or width. The geometry of a groove is defined in particular by its shape (cross-sectional or recess shape), depth, width, and radial extent (inner diameter or outer diameter of a groove area). Grooves can generally be formed in various shapes, for example, groove-shaped with a rounded, circular segment-shaped, rectangular, trapezoidal, or triangular recess shape.

[0024] Thus, it can be provided that the grooves have a different cross-section in a longitudinal section along the longitudinal axis in order to form an uneven groove structure.

[0025] Alternatively or additionally, the distance between a first groove and a second groove and the distance between the second groove and a third groove may differ from each other.

[0026] According to the invention, the distance between two grooves can be the axial distance between the center lines of the respective groove, which in particular run along the greatest depth of the respective groove. The depth of a groove can be understood as the maximum radial extent of the groove, in particular starting from a circumferential surface of the shaft body or the steering shaft. The width of a groove can be understood as the maximum axial extent of the groove (axial groove area), in particular the width of the recess in a circumferential surface of the shaft body or the steering shaft. The bending section comprises a plurality of grooves, in particular between two and ten grooves.

[0027] The shaft body is made of a preferably circular-cylindrical tube, preferably made of a metallic material such as steel or aluminum, or of a fiber composite material, and is particularly designed as a hollow body. The connection to a steering wheel or steering gear of a vehicle can be provided directly or indirectly, in particular via additional intermediate shafts, preferably via shaft end sections of the shaft body that can be connected to joints.

[0028] The invention encompasses, inter alia, embodiments that have grooves with different geometries (shapes, depths or widths) or grooves that are spaced differently from one another, as well as embodiments that combine different geometries and different spacings.

[0029] In an advantageous further development, it can be provided that the grooves are locally hardened to varying degrees, for example, by a corresponding forming operation and / or by local laser hardening. A first groove and a second groove can have different hardness and / or strength and / or rigidity.

[0030] A steering shaft according to the invention is particularly designed to deform, in particular to bend, in the event of a vehicle crash in which in particular a steering gear is displaced in the direction of the steering wheel in order to prevent the steering shaft from penetrating, or more precisely from penetrating further than intended during normal operation, into the passenger area / passenger cell. One idea of ​​the invention is that the mechanical bending behavior (bending deformation) of the steering shaft can be adjusted as precisely as possible, i.e. matched to the desired behavior in the event of a vehicle crash, by a suitable design of a bending section of the steering shaft with a plurality of grooves to provide an uneven groove structure. In particular, the profile of the section modulus in the longitudinal direction, i.e. in the direction of the longitudinal axis of the steering shaft, can be structurally determined.In particular, a steering shaft can be constructed by suitably shaping grooves in a bending section to form an uneven groove structure so that a desired bending characteristic of the steering shaft is achieved. The bending characteristic can be understood as the (plastic) deformation or displacement due to bending as a function of the forces acting on the steering shaft. In addition to the choice of material and diameter of the steering shaft, the bending behavior can be influenced according to the invention by a suitable positioning of the bending section or the grooves in the longitudinal direction as well as by choosing the number of grooves, their geometry and their distances from one another. In particular, the bending region is designed so that, due to the uneven groove structure, the steering shaft according to the invention begins to deform (bend) in the region of a first groove under lower loads than in the region of a second groove.A steering shaft according to the invention has the advantage that its bending behavior can be precisely adjusted. Furthermore, the steering shaft is easy to manufacture.

[0031] In a further development of the invention, the depth of the grooves, the width of the grooves, and / or the distance between two grooves increase or decrease, preferably continuously, from a side of the bending section facing the first shaft end to a side of the bending section facing the second shaft end. In particular, the geometry of the grooves or the distances between (axially adjacent) grooves change gradually (uniformly) from one side of the bending section to the other, so that an irregular groove structure is formed in the direction of the longitudinal axis.

[0032] Preferably, grooves are deeper and / or wider on a side of the bending section facing the steering gear than on the side of the bending section facing the steering wheel. Preferably, the distances between the grooves decrease from a side of the bending section facing the steering gear to the side of the bending section facing the steering wheel. In this way, the most precise adjustment of the bending behavior of the steering shaft can be achieved, in particular a continuous progression of the section modulus or the (plastic) bending in the longitudinal direction, in order to achieve a desired deformation of the steering shaft in the event of a vehicle crash.

[0033] In an advantageous development of the invention, the wall thickness of the shaft body differs in a groove region of a first groove and in a groove region of a second groove to form an irregular groove structure in the direction of the longitudinal axis. In particular, each groove extends over an associated (axial) groove region, which is each an (axial) partial region of the bent section of the shaft body and thus forms the groove structure in sections. The wall thickness can be understood as half the difference between the outer diameter and the inner diameter of the shaft body in the respective groove region, in particular at the center line of the respective groove. In particular, the wall thickness between adjacent grooves increases or decreases gradually (uniformly) from one side of the bent section to the other side of the bent section.Preferably, the wall thickness on a side facing the steering gear is smaller than a side of the bent section facing the steering wheel. A variation in the wall thickness is particularly easy to achieve by varying the degree of deformation of a tube serving as the shaft body during production of the steering shaft. The groove area of ​​an individual groove can have different wall thicknesses; preferably, the wall thickness is thinnest at the deepest point of the groove. The deepest point of the groove is the point where the groove has the smallest outer diameter. The wall thickness of the groove preferably refers to the thinnest wall thickness of the corresponding groove.

[0034] Preferably, the wall thickness of each groove in the bending section is less than the wall thickness of the shaft body outside the bending section.

[0035] In an advantageous development of the invention, at least one groove, preferably all of the grooves, are recessed inwardly in an outer circumferential surface of the shaft body, in particular curved into an inner cavity of the shaft body. In particular, the outer diameters of the grooves are smaller than the outer diameter of the steering shaft, wherein the inner diameters of the grooves are preferably smaller than the inner diameter of the steering shaft. The outer or inner diameter of the steering shaft can be determined outside the bending section, in particular in a shaft side section. The grooves are formed (pressed or pressed in) into the wall of the shaft body, in particular on the outer circumferential surface of the shaft body, by (local) forming. As a result, the outer diameter of the steering shaft does not increase compared to a tube before forming during the manufacturing process.

[0036] In an advantageous development, the tubular shaft body has an enveloping circle diameter and a wall thickness outside the bending section, wherein an enveloping circle diameter of the bending section is less than or equal to the sum of the enveloping circle diameter of the tubular shaft body and twice the wall thickness of the tubular shaft body. The sum is thus the enveloping circle diameter of the tubular shaft body outside the bending section plus twice (double) the wall thickness of the tubular shaft body outside the bending section. The enveloping circle diameter of the tubular shaft body preferably corresponds to the outer diameter of the tubular shaft body.

[0037] Particularly preferably, the enveloping circle diameter of the bending section is less than or equal to the enveloping circle diameter of the tubular shaft body. This allows the irregular groove structure according to the invention to be realized in a compact installation space, while the advantages of the structural adaptation of the bending behavior in the event of a crash can be realized in a confined space. The wall thickness of the tubular shaft body can be understood as half the difference between the outer diameter and the inner diameter of the shaft body outside the bending section.

[0038] In an advantageous development of the invention, the bending section has at least three, preferably at least four, grooves of different depths and / or different spacings from one another. More than four grooves can also be provided, in particular up to ten grooves. Three or four grooves designed according to the invention enable, on the one hand, improved, in particular sufficiently continuous, bending behavior and, on the other hand, are simple and cost-effective to produce. However, it is already possible to provide corresponding bending behavior with just two grooves to form an irregular groove structure.

[0039] In an advantageous development of the invention, the depth of a groove is between 0.1 and 3 times, preferably between 0.2 and 2 times, more preferably between 0.3 and 1.5 times, more preferably between 0.4 and 1 times, the wall thickness of the shaft body outside the bending section. The wall thickness can be understood as half the difference between the shaft outer diameter and the shaft inner diameter. Such groove depths result in a sufficient change in the section modulus against bending compared to a shaft body without a bending section to suitably influence the bending behavior of the steering shaft.

[0040] In addition, the object is achieved in particular by a method for

[0041] Production of a steering shaft according to the invention, comprising the following steps: a) Providing a tube extending along a longitudinal axis; b) Forming the tube to form a tubular shaft body of a steering shaft with a bent section arranged between a first and a second shaft end of the shaft body, wherein in the circumferential surface of the tube at least two grooves running in the circumferential direction of the shaft body are formed by at least one roller, the rolling axis of which runs at least substantially parallel to the longitudinal axis, in such a way that the geometries of a first and a second groove differ from one another, in particular with regard to the shape, the depth and / or the width of the groove, and / or the distance between a first and a second groove and the distance between the second and a third groove differ from one another.

[0042] Furthermore, the object is achieved in particular by a method for producing a steering shaft for a vehicle, comprising the following steps: Providing a tube extending along a longitudinal axis with an enveloping circle diameter and a wall thickness; forming the tube to form a tubular shaft body of a steering shaft with a bending section arranged between a first shaft end and a second shaft end of the shaft body, wherein at least one groove extending in the circumferential direction of the shaft body is formed into a circumferential surface of the tube by rolling at least one roller, characterized in that the envelope diameter of the bending section is less than or equal to the sum of the envelope diameter of the pipe and twice the wall thickness.

[0043] Thus, before forming, the tube has an enveloping diameter and a wall thickness, with this enveloping diameter and the wall thickness corresponding to that outside the bent section of the tube after forming, with the enveloping diameter of the bent section being less than or equal to the sum of the enveloping diameter of the tube and twice the wall thickness of the tube. The sum is thus the enveloping diameter of the tube either before forming or outside the bent section plus twice the wall thickness of the tube before forming or outside the bent section.

[0044] Particularly preferably, the enveloping circle diameter of the bending section is less than or equal to the enveloping circle diameter of the tube. This allows the irregular groove structure according to the invention to be realized in a compact installation space, while the advantages of the structural adaptation of the bending behavior in the event of a crash can be realized in a confined space.

[0045] Preferably, the at least one groove is formed by rolling a roller along the circumferential surface of the pipe in such a way that the pipe is partially, i.e., locally, plastically deformed. After forming, i.e., when all grooves for forming the bending section have been introduced, areas exist within and / or outside the bending section that are undeformed.

[0046] The bent section is formed, in particular, by cold forming the tube, whereby forming a groove can be understood, in particular, as the pressing or pressing of a roller into the tube, in particular into its wall material. In particular, during forming, the roller exerts a forming force (pressing force) on the circumferential surface of the tube in order to locally plastically deform the wall material to form a groove. In particular, the tube and the at least one roller roll against each other, with the tube and the roller preferably rotating in opposite directions. However, the tube or the roller can also be stationary while only the roller or the tube rotates.

[0047] Preferably, the bending section has a plurality of grooves extending in the circumferential direction of the shaft body to form a groove structure, wherein the groove structure is non-uniform in the direction of the longitudinal axis.

[0048] The method according to the invention can implement some or all of the process-related features described in connection with the steering shaft according to the invention and has similar advantages. In particular, the method allows a bending section to be formed in a simple manner, preferably in such a way that a desired bending behavior of the steering shaft is achieved.

[0049] In an advantageous development of the invention, the grooves are formed by a roller, wherein at least a first groove is formed in a first longitudinal position of the roller and a second groove is formed in a second longitudinal position of the roller that is axially spaced therefrom, wherein the roller is in particular advanced to different distances towards the circumferential surface of the pipe in the first and second longitudinal positions and / or the longitudinal positions of the roller are spaced apart from one another by different distances. In particular, a single roller is provided for forming multiple grooves. The roller can be moved, preferably shifted or displaced, from the first to the second longitudinal position relative to the pipe, or vice versa. The shape of a groove corresponds in particular to the surface shape of a rolling surface of the roller. A manufacturing device corresponding to the method and having an (axially displaceable) roller is simple in design and control.Grooves at different spacings are easily formed. To form grooves of varying depths, the roller can be moved radially along the steering shaft. The roller is preferably moved motor-driven, pneumatically, or hydraulically for infeed. The roller can be further advanced during the forming process, and the forming process can involve multiple revolutions of the roller.

[0050] In an alternative advantageous development of the invention, the grooves are formed by at least two axially spaced rollers, in particular arranged along a common rolling axis, with different roller geometries, in particular different roller diameters, and / or different distances between a first and a second roller and between the second and the third roller. The rollers are in particular mounted on a common roller axis at predetermined distances from one another. Preferably, a roller is assigned to each groove to be formed. The rollers can have the same or different rolling surface shapes or roller widths.

[0051] In an advantageous development of the invention, the length of the tube is essentially the same before and after forming. "Essentially the same" is understood to mean a deviation of ±5% of the original length of the tube. Particularly preferably, the length of the tube is essentially the same before and after forming. In particular, the tube can be axially clamped on both sides during forming to prevent elongation or compression of the tube. In this way, a prefabricated tube blank can be installed in a vehicle's steering assembly as a finished steering shaft with the intended length dimensions even after forming. Thus, no mechanical processing is required to adjust the length after the forming operation. The steering shaft produced by the method according to the invention is preferably a steering shaft according to the teachings of the invention.

[0052] Embodiments of the invention are explained in more detail below with reference to the drawings. Herein: Figure 1A: a schematic representation of a first embodiment of a steering shaft according to the invention with grooves of different geometries to provide an uneven groove structure in a half-sectional view; Figure 1B: schematic representation of the embodiment according to Figure 1Awith the outer diameters of the respective groove areas indicated; Figure 2: a schematic representation of a second embodiment of a steering shaft according to the invention with differently spaced grooves to provide an uneven groove structure in a half-sectional view; Figure 3: a schematic representation of a third embodiment of a steering shaft according to the invention with three differently spaced grooves to provide an uneven groove structure in a half-sectional view; Figure 4: a schematic representation of a first embodiment of the manufacturing method according to the invention for a steering shaft with an adjustable roller in a half-sectional view; Figure 5: a schematic representation of a second embodiment of the manufacturing method according to the invention for a steering shaft with multiple rollers in a half-sectional view;Figure 6: a schematic representation of a steering arrangement with a steering shaft according to the invention in a perspective view; Figure 7: a schematic representation of a fourth embodiment of a steering shaft according to the invention in a half-sectional view; Figure 8: a schematic representation of a steering shaft according to the invention in the unbent state during normal operation; Figure 9: a schematic representation of the steering shaft according to; Figure 8 in a bent state after a crash.

[0053] In the following description of the invention, the same reference numerals are used for identical and identically acting elements.

[0054] The Figures 1A and 1Bshow an embodiment of a steering shaft 1 according to the invention with a shaft body 10 having a first shaft end 11 and a second shaft end 12, which are provided for articulated coupling to a steering gear or a steering wheel of a vehicle. The tubular shaft body 10 is designed as a hollow shaft with a longitudinal axis L, an inner diameter d, an outer diameter D, which can also be referred to as the enveloping circle diameter of the tubular shaft body 10 outside the bending section 13, and an inner cavity 15. The enveloping circle diameter is the diameter of the enveloping circle by which the cross-section, which is oriented orthogonal to the longitudinal axis, of the shaft body 10 is circumscribed. Furthermore, the shaft body 10 has a wall thickness s that corresponds to half the difference between the outer diameter and the inner diameter.In a bending section 13 of the shaft body 10, four grooves 21, 22, 23, 24 are formed at equal distances a1, a2, a3 from one another in the outer circumferential surface 14 of the shaft body 10. The bending section 13 comprises four grooves 21, 22, 23, 24, each having a different geometry, so that a non-uniform groove structure according to the invention is formed in the direction of the longitudinal axis L. The bending section 13 is delimited by the outer edges 211, 241 of the outer grooves 21, 24. The enveloping circle diameter HK of the bending section 13 is the diameter of the enveloping circle that circumscribes the maximum cross-section of the bending section 13, which is oriented orthogonally to the longitudinal axis. In other words, the enveloping circle diameter HK of the bending section 13 is the maximum outer diameter in the bending section 13.The grooves 21, 22, 23, 24 are designed as annular grooves running circumferentially around the shaft body 10 and, in cross-section, form circular segment-shaped depressions relative to the circumferential surface 14. The depth T of the axially adjacent grooves decreases from the first groove 21 on a side facing the steering gear (left in the figures) to a side facing the steering wheel (right in the figures) up to the fourth groove 24. Accordingly, the depths shown in . Figure 1Bmarked outer diameters D1, D2, D3, D4 of the corresponding grooves 21, 22, 23, 24 from left to right (D1 <D2<D3<D4). Die Innendurchmesser d1, d2, d3, d4 der zugehörigen Nuten 21, 22, 23, 24 nehmen von links nach rechts ebenfalls zu (d1<d2<d3<d4). Die Wandstärken, z.B. definiert durch die halbe Differenz zwischen dem jeweiligen Außendurchmesser D1, D2, D3, D4 und dem Innendurchmesser d1, d2. d3, d4, d.h. z.B. (D1-d1) / 2, in den jeweiligen Nutbereichen nehmen von links nach rechts zu. Die Durchmesser sind jeweils entlang einer Mittellinie der Nut, d.h. in der Mitte des axialen Nutbereichs bzw. an der tiefsten Stelle der Nut, bestimmt. Der Wellenkörper 10 wölbt sich im Biegeabschnitt 13 in den Nutbereichen in den Innenhohlraum 15 hinein nach innen aus. Die Außendurchmesser D1, D2, D3, D4 in den Nutbereichen sind kleiner als der Außendurchmesser D des Wellenkörpers 10 und die Innendurchmesser d1, d2, d3, d4 sind kleiner ist der Innendurchmesser d des Wellenkörpers 10.The tubular shaft body 10 thus has an enveloping circle diameter D and a wall thickness s outside the bending section 13, wherein the enveloping circle diameter HK of the bending section 13 is smaller than the sum of the enveloping circle diameter D of the tubular shaft body 10 and twice the wall thickness (2s) of the tubular shaft body 10. In the shaft side sections, i.e., outside the bending section 13, the shaft body 10 has an essentially constant cross-section, or a constant outer diameter D and inner diameter d. The diameter and wall thickness of the shaft body 10 can vary in the longitudinal direction L but also outside the region 13, for example to provide a coupling section for coupling the shaft body 10 to a fork of a universal joint.

[0055] Figure 2 shows a second embodiment of a steering shaft 1 according to the invention, which differs from the one shown in the Figures 1A and 1BThe steering shaft 1 shown differs in that the distances a1, a2, a3 between each two adjacent grooves 21, 22, 23, and 24 are different, thereby providing an inventive, non-uniform groove structure in the direction of the longitudinal axis L. The distances a1, a2, a3 shorten from left to right. The first distance a1 between the first groove 21 and the second groove 22 is greater than the second distance a2 between the second groove 22 and the third groove 23, which in turn is greater than the third distance a3 between the third groove 23 and the fourth groove 24.

[0056] Figure 3 shows a third embodiment of a steering shaft according to the invention, which is similar to Figure 2 wherein the bending section 13 comprises only three grooves 21, 22, 23 with different distances a1 and a2 to form an uneven groove structure.

[0057] The Figures 1A to 3The steering shafts 1 shown have bending sections 13 with an uneven groove structure, which cause a specific bending behavior of the steering shaft 1 when it is deformed in the installed state by the acting forces in the event of a vehicle crash. The uneven groove structure, such as the number, the geometry (depth T, width B) of the grooves and / or the distances between the grooves, allows the section modulus of the shaft body 10 against deformation to be locally adjusted, from which the bending behavior of the entire steering shaft 1 can be influenced according to a desired shape in the event of a vehicle crash (see Figs. 8 and 9 ).

[0058] The Figures 4 and 5 illustrate two alternative embodiments of a manufacturing method according to the invention for a steering shaft 1, comprising the following steps: Providing a tube extending along a longitudinal axis L with an enveloping circle diameter D and a wall thickness s; forming the tube to form a tubular shaft body 10 of a steering shaft 1 with a bending section 13 arranged between a first shaft end 11 and a second shaft end 12 of the shaft body 10, wherein at least one groove 21, 22, 23, 24 extending in the circumferential direction of the shaft body 10 is formed into a circumferential surface 14 of the tube by rolling at least one roller 30, 31, 32, 33, 34. According to the invention, the enveloping circle diameter HK of the bending section 13 is less than or equal to the sum of the enveloping circle diameter D of the tube and twice the wall thickness.

[0059] This can be done as in the versions of the Figures 4 and 5a bending section 13 with four grooves 21, 22, 23, 24 of different geometries, in particular different depths T and widths B, in order to achieve a specific bending behavior. In the methods described, at least one roller 30 (see Fig. 4 ) or rollers 31, 32, 33, 34 (see Fig.5 ) is advanced in a radial direction (see radial double arrow) toward the circumferential surface 14 of a tube forming the shaft body 10 in order to exert a forming force on the tube. In this embodiment, the rolling axis R and the longitudinal axis L are aligned essentially parallel to one another. The rollers 30, 31, 32, 33, 34 and the shaft body 10 rotate counter to one another (see arrows for directions of rotation), preferably rolling or rolling against one another.

[0060] In the Figure 4In the manufacturing process illustrated, a single roller 30 is provided, which is axially displaceable in the longitudinal direction L (see axial double arrow) in order to form one of the grooves 21, 22, 23, 24 in the tube at different longitudinal positions. Accordingly, the grooves 21, 22, 23, 24 are formed one after the other. The tube could also be moved relative to the roller 30 (in Figure 4 to the left). Thus, the bending section 13 has a plurality of grooves 21, 22, 23, 24 extending in the circumferential direction of the shaft body 10 to form a groove structure, wherein the groove structure is irregularly formed in the direction of the longitudinal axis L.

[0061] In the Figure 5In the manufacturing method illustrated, four rollers 31, 32, 33, 34 are provided, which are mounted rotatably about a common rolling axis R, wherein all grooves 21, 22, 23, 24 are formed simultaneously. The distances between the rollers 31, 32, 33, 34 can be varied in order to produce different distances a1, a2, a3 between the grooves 21, 22, 23, 24. Thus, the bending section 13 has a plurality of grooves 21, 22, 23, 24 running in the circumferential direction of the shaft body 10 to form a groove structure, wherein the groove structure is irregularly formed in the direction of the longitudinal axis L.

[0062] The methods according to the invention have the advantage that a steering shaft 1 with a bent section 13 can be easily manufactured and requires only a small amount of installation space.

[0063] In Figure 61 shows a steering arrangement 100 known per se, which comprises a steering shaft 1 according to the invention with a bent section 13, wherein the bent section 13 has a plurality of grooves 21, 22, 23, 24 running in the circumferential direction of the shaft body 10 to form a groove structure, wherein the groove structure is irregularly formed in the direction of the longitudinal axis L. The steering shaft 1 is coupled to a joint 5 facing a steering gear and to a joint 6 facing a steering wheel. The steering shaft 1 projects through a bulkhead feedthrough 4 in a bulkhead 2. The bulkhead feedthrough 4 is sealed against splash water with a sealing sleeve 3. Between the joint 6 and the steering wheel (not shown), the steering shaft is rotatably mounted in a steering column 600, wherein the steering column is designed as a manually adjustable steering column 600.Alternatively, other types of steering columns can be used, such as rigid steering columns or electrically adjustable steering columns.

[0064] In Figure 7 An embodiment of a steering shaft 1 according to the invention is shown, comprising a sliding shaft section 16 having longitudinally aligned form-locking elements 17. An inner shaft 111 can be inserted into the sliding shaft section 16, said inner shaft having complementary form-locking elements that can be engaged with the form-locking elements 17 to transmit torque. The inner shaft 111 and the shaft body 10 can be designed to be telescopic relative to one another.

[0065] In the Figure 8 is an embodiment of a steering shaft 1 according to the invention in the undeformed (unbent) state during normal operation with an uneven groove structure before the occurrence of a crash. In the Figure 9 the steering shaft 1 is out of the Figure 8in the deformed (bent) state after the occurrence of a crash. The steering shaft 1 bends particularly in the bending section 13, while the shaft side sections 18a and 18b arranged on either side thereof are not bent or are only slightly bent. Due to the uneven groove structure according to the invention (see Fig. 1 to 5 ), the bending section 13 is overall less rigid than the two shaft side sections 18a, 18b, whereby a specific bending behavior (bending characteristic) or a resulting bending deformation and / or compression of the steering shaft 1 is determined by the design. The bending behavior can be predetermined by the uneven groove structure, for example by a suitable choice of the geometry and / or the distances a1, a2, a3 of the grooves 21, 22, 23, 24, so that in the event of a vehicle crash, the steering shaft 1 does not penetrate the passenger compartment of the vehicle 1. This reduces the risk of injury to the driver.

Claims

1. A steering shaft (1) for a vehicle, comprising a tubular shaft body (10) which extends along a longitudinal axis (L) and has a first shaft end (11) and a second shaft end (12), a bending section (13) being arranged between the first shaft end (11) and the second shaft end (12), the bending section (13) having a plurality of grooves (21, 22, 23, 24) which run in the circumferential direction of the shaft body (10) for the formation of a groove structure, and wherein the groove structure is of non-uniform configuration in the direction of the longitudinal axis (L), characterized in that a number of grooves (21, 22, 23, 24) are configured so as to be recessed inward in an outer circumferential face (14) of the shaft body (10), wherein the external diameters (D1, D2, D3, D4) of said grooves (21, 22, 23, 24) are smaller than the external diameter (D) of the steering shaft (1), and the internal diameters (d1, d2, d3, d4) of said grooves (21, 22, 23, 24) being smaller than the internal diameter (d) of the steering shaft (1).

2. The steering shaft as claimed in claim 1, characterized in that the geometry of a first groove (21) differs from the geometry of a second groove (22).

3. The steering shaft as claimed in either of the preceding claims, characterized in that a first groove (21) is at a first spacing (a1) from a second groove (22), the second groove (22) being at a second spacing (a2) from a third groove (23), the first spacing (a1) differing from the second spacing (a2).

4. The steering shaft as claimed in one of the preceding claims, characterized in that a depth of the grooves (21, 22, 23, 24), a width of the grooves (21, 22, 23, 24) and / or the spacing of two grooves (21, 22, 23, 24) increases or decreases from a side of the bending section (13), which side faces the first shaft end (11), toward a side of the bending section (13), which side faces the second shaft end (12).

5. The steering shaft as claimed in one of the preceding claims, characterized in that the wall thickness of the shaft body (10) in a groove region of a first groove (21) and that in a groove region of a second groove (22) differ from one another.

6. The steering shaft as claimed in one of the preceding claims, characterized in that the bending section (13) has at least three grooves (21, 22, 23, 24) which are in each case of different depth and / or are at a different spacing from one another in each case.

7. The steering shaft as claimed in one of the preceding claims, characterized in that the depth of a groove (21, 22, 23, 24) is between 0.1 and 3 times a wall thickness of the shaft body (10) outside the bending section (13).

8. The steering shaft as claimed in one of the preceding claims, characterized in that the tubular shaft body (10) has an enveloping circle diameter (D) and a wall thickness (s) outside the bending section (13), an enveloping circle diameter (HK) of the bending section (13) being smaller than or equal to the sum of the enveloping circle diameter (D) of the tubular shaft body (10) and twice the wall thickness (s) of the tubular shaft body (10).

9. A method for producing a steering shaft according to one of claims 1 to 8 for a vehicle, comprising the following steps: - providing of a tube which extends along a longitudinal axis (L) with an enveloping circle diameter (D) and a wall thickness (s); - forming of the tube in order to configure a tubular shaft body (10) of a steering shaft (1) with a bending section (13) which is arranged between a first shaft end (11) and a second shaft end (12) of the shaft body (10), a plurality of grooves (21, 22, 23, 24) which run in the circumferential direction of the shaft body (10) being formed into a circumferential face (14) of the tube by way of rolling of at least one roller (30, 31, 32, 33, 34), wherein the enveloping circle diameter (HK) of the bending section (13) is smaller than or equal to the sum of the enveloping circle diameter (D) of the tube and twice the wall thickness (s).

10. The method as claimed in claim 9, characterized in that the bending section (13) has a plurality of grooves (21, 22, 23, 24) which run in the circumferential direction of the shaft body (10) for the formation of a groove structure, the groove structure being of non-uniform configuration in the direction of the longitudinal axis (L).

11. The method as claimed in claim 9 or 10, characterized in that the grooves (21, 22, 23, 24) are formed by way of a roller (30), at least one first groove (21) being formed in a first longitudinal position of the roller (30), and one second groove (22) being formed in a second longitudinal position of the roller (30), which second longitudinal position is spaced apart axially from said first longitudinal position, - the roller (30) being advanced to a different extent onto the circumferential face (14) of the tube in the first and second longitudinal position, and / or - the longitudinal positions of the roller (30) being spaced apart from one another to a different extent.

12. The method as claimed in claim 11, characterized in that the grooves (21, 22, 23, 24) are formed by way of at least two rollers (31, 32, 33, 34) which are spaced apart axially from one another, are arranged, in particular, along a common rolling axis (R), and have - a different roller geometry, and / or - different spacings (a1, a2) between a first roller (31) and a second roller (32) and between the second roller (32) and a third roller (33).

13. The method as claimed in one of claims 9 to 12, characterized in that the length of the tube is identical before and after the forming.