ADJUSTABLE STEERING COLUMN FOR A VEHICLE

The present disclosure relates to a steering column for a vehicle, with:-an inner steering column element that is received in an outer steering column element, the inner and outer steering column element being displaceable relative to one another along a displacement axis;-at least one preload force generating element that is configured to generate a preload force to set a defined resistance against the relative displacement; where the inner steering column element has a number of side faces which form a hollow cross-section of the inner steering column element; where at least a portion of a side face of the number of side faces has a protruding shape.

TECHNICAL FIELD

The present disclosure relates to a steering column for a vehicle, such as a car or a truck.

BACKGROUND

Steering columns generally serve to support a steering wheel, e.g. by coupling it to the chassis of a vehicle.

Adjustable steering columns are generally known in the prior art. The adjustability typically allows for a changing position of the steering wheel relative to the driver. This way, the driver can position the steering wheel according to his ergonomic preferences. Further or alternatively, in a steer-by-wire arrangement in autonomous or semi-autonomous vehicles, the adjustability can allow for changing a position of the steering wheel from a retracted position (during autonomous driving) and an extended position (during manual driving).

One type of adjustability concerns moving the steering wheel back and forth in a forward driving direction relative to the driver. Put differently, a driver and/or an actuator can move the steering wheel towards the driver (extended state) and away from the driver towards a dashboard (retracted state).

For doing so, existing steering columns may comprise telescopic structures with several steering column elements that are linearly displaceable relative to one another. In order to set a defined force that needs to be overcome for achieving said linear displacement preload elements such as screws may be provided. These exert a preload force on at least one of the steering column elements which results in a frictional resistance.

One example of a known steering column can be found in JP 2008-290491 A1.

It has been determined that existing linearly displaceable steering columns are often heavy and bulky. This results from a need to make the steering column sufficiently stiff. Accordingly, the weight, costs and complexity are increased.

It is therefore an object of the present application to provide an adjustable steering column having desired mechanical characteristics, in particular in terms of stiffness, at a limited weight and at a limited volume.

This object is achieved by the subject matter of the independent claims. Other embodiments and other features are specified in the dependent claims and the following description.

SUMMARY

The present disclosure relates to a steering column for a vehicle and in particular for a steer-by-wire steering system of the vehicle.

The steering column has an inner steering column element that is received in an outer steering column element of the steering column, the inner and outer steering column elements being linearly displaceable relative to one another along a displacement axis.

The steering column has at least one preload force generating element that is configured to set a defined resistance against the relative displacement of the inner and outer steering column element, e.g. by generating resistance and/or frictional forces acting against said relative displacement.

The inner steering column element has a number of side faces, e.g. at least a first to fourth side face, which form (or, put differently, enclose, define or bound) a hollow cross-section of the inner steering column element.

At least a portion of a first side face has a protruding shape. According to an example, said at least one portion protrudes towards the preload force generating element. The preload force is introduced into said at least one protruding portion of the first side face and/or said portion is positioned opposite to said preload force generating element.

The steering column may be connected or connectable to a rigid member of the vehicle. In one example, it is at least indirectly coupled or couplable to a chassis of the vehicle.

Additionally or alternatively, the steering column may be connected or connectable to a steering wheel, in particular so that the steering wheel is rotatable relative to the steering column. In an embodiment, this is done by the steering column being connected to and/or including at least one rotational bearing that is coupled to the steering wheel. For example, the steering column and in particular an end portion of the inner steering column element facing away from the outer steering column element may rotatably support the steering wheel. This may be done at an outer circumferential surface of the steering column element.

In an embodiment, the steering column is configured to be used in a steer-by-wire steering system in which there is no direct mechanical connection between the steering wheel and steering gears and/or steerable wheels of the vehicle.

Generally, supporting the steering wheel at an outer circumference of the steering column means that the interior space of the steering column is less obstructed. Accordingly, this space can be used for different purposes. According to one embodiment it is used for receiving electronic components e.g. of the overall steering system. This helps to reduce space requirements and complexity. For example, there may not be a shaft connected to the steering wheel and by means of which rotations of the steering wheel are directly conveyed to a steering gear or the like. Instead, according to known steer-by-wire principles, rotations of the steering wheel may be sensed and an electro-mechanical actuator connected to the steering gear and/or wheels of the vehicle (but not being mechanically connected to the steering wheel) may be controlled based on these sensed rotations to execute a steering command and steer the wheels accordingly.

Therefore, according to an example, the steering column does not receive and/or is free of any components (such as the above shaft) rigidly connected to the steering wheel (i.e. that rotate jointly therewith). In particular, the steering column may be free of any rotatable supports and/or connections to the steering wheel at its inner circumferential face and/or within an interior space of the steering column.

Nonetheless, the steering column disclosed herein can also support and/or be connected to a shaft connected to the steering wheel, said shaft being at least partially inserted into or received by the steering column. For example, the shaft may be rotatably supported within a hollow cross-section of the steering column and in particular the inner steering column element. The shaft may rotate jointly with the steering wheel. It may be connected to a steering gear e.g. by an intermediate cardan shaft, thereby e.g. being mechanically coupled to steerable wheels of the vehicle.

The inner steering column element and outer steering column element may both be elongated members. They may be made from a metallic material. The may e.g. be hollow elongated profiles. They may be similarly shaped and may in particular have similarly shaped cross sections. At least those portions of the cross sections of the inner and outer steering column element that are directly opposite to one another may be similarly shaped. For example, an inner circumferential surface of the cross-section of the outer steering column element may be shaped according to an outer circumferential surface of the cross-section of the inner steering column element. By having cross-sections with matching shapes, the inner steering column element can be reliably supported and guided within the outer steering column element.

The cross-sections of the inner and outer steering column element may be formed in a plane extending orthogonally to the displacement axis.

One of the steering column elements (for example, the outer steering column element) may generally be fixed or fixable within the vehicle and/or may be non-displaceable along the displacement axis. Accordingly, only one of the steering column elements (for example, the inner steering column element) may be linearly displaceable along the displacement axis.

According to a further example, the inner steering column element and in particular the first side face may comprise at least one sliding surface. The sliding surface may be made from a different material compared to the remainder of the inner steering column element, e.g. from a softer metal or from a polymeric material. The sliding surface may be arranged at an outer surface of one of the side faces. In an embodiment, the sliding surface may be formed by an elongated piece of material that extends along the displacement axis.

The protruding portion may extend along and/or form the complete first side face. Put differently, the first side face may generally protrude, towards the preload force generating element. Alternatively, the protruding portion may be formed as a local projection within the first side face. According to an example, the first side face has angled sections that converge towards each other, thereby forming a generally outwardly protruding shape (e.g. a V-shape) of the first side face.

The preload force generating element can also be referred to as a clamping force generating element or a resistance force generating element. It may extend through and/or be inserted into an opening within the outer steering column element. It may contact said first side face and in particular a sliding surface provided thereat. It may exert a preload force onto the first side face and in particular onto a sliding surface provided thereat. As a result, a resistance force e.g. in form of a frictional force may be generated at and/or in the area of the sliding surface. This resistance force may be the force acting against the relative displacement.

Generally, the preload force generating element may be configured to variably set the force that acts against the relative displacement, e.g. by varying a degree of tightening the preload force generating element. During production or maintenance of the steering column a resistance force out of a possible range of resistance forces may be set by the tightening preload force generating element to a predetermined degree.

The first side face may generally be non-planar and/or non-straight due to its protruding shape. Its at least one protruding portion may form a local projection of and within the first side face that e.g. projects relative to further portions of the side face (e.g. relative to outer edges thereof, see below). In one example, the at least one protruding portion forms an outermost and/or lowermost portion of the first side face.

The further side faces of the inner steering column element may be differently formed compared to the first side face. For example, they may be substantially protrusion free and/or straight or flat. The side faces may be connected to one another or merge with each other at angled or rounded corner portions of the cross-section.

By providing a respectively protruding first side face, the distribution of forces and stresses within the inner steering column element is improved when being exposed to the preload force.

Specifically, it has been determined that compared to providing the first side face with a substantially planar shape, the received preload force results to a higher degree in compression stresses within the first side face. In the theoretical planar case, the first side face would experience bending as a main deformation and main load case. This would have to be compensated for by increasing a thickness of the first side face to achieve a desired stiffness. However, this would result in an increase of weight.

Although providing the protruding first side face disclosed herein may at a first glance, be perceived to complicate the design and/or increase the dimensions and thus weight of the steering column, it has been determined that its beneficial stress distribution allows for using less material. This in fact helps to reduce weight. Specifically, the outwardly protruding first side face can be made thinner compared to a theoretically alternative planar configuration thereof while still achieving a sufficient or even improved stiffness.

When, providing the outer steering column element with a hollow cross-section that is correspondingly shaped to that of the inner steering column element, a force distribution in the outer steering column element can equally be improved. For example, at least a shape of a side face of said cross section that is opposite to the first side face of the inner steering column element can be correspondingly shaped. As a result, compared to a (theoretical) planar shape of said opposite side face of the outer steering column element, a degree of bending can be reduced and e.g. tension loading can be increased. This may similarly allow for reducing the thickness of said side face, thereby reducing weight.

In one example, the thickness is less than 30 mm, e.g. between 1 mm and up to 20 mm or between 1 mm and up to 10 mm.

In an embodiment, the first side face protrudes outwardly, e.g. with respect to a geometric centre of the cross-section. Alternatively, the side face may protrude inwardly, e.g. by having an inverted V-shape. Such an inwardly extending protrusion equally helps to reduce bending of the first side face. However, an outwardly protrusion can be advantageous in view of providing interior space where to locate other elements of the system, and in view of providing a geometrically less complex structure compared to an inwardly protruding portion.

According to an embodiment, the hollow cross-section has a polygonal and/or a substantially rectangular shape. For example, the cross-section comprises at least four side faces that are connected to define a substantially rectangular shape. The latter may include that at least two side faces (e.g. left and right side faces or top and bottom side faces) are similarly shaped and/or extend substantially parallel to one another.

The first side face may form a longer side of the rectangular shape. It may e.g. be at least 1.2 times or at least 1.5 times as long as the further side faces directly connected and extending at an angle thereto. This further helps to improve stiffness. For example, the first side face may be between 30 mm and 150 mm long.

In one example, two parallel further side faces are provided that are connected to one another by the first side face. Said parallel side faces may also be connected by a further side face that is oriented similarly to the first side face, e.g. due to both extending substantially at similar angles relative to the parallel side faces.

It is noted that positional and/or directional terms such as left, right, bottom, top, horizontal and vertical used herein may generally relate to an installation orientation and installation position of the steering column in the vehicle and when viewed by a driver.

According to a further aspect, at least one of the side faces other than the first side face has a substantially planar shape and e.g. may be free of a similarly protruding portion. With respect to the cross-section of the inner steering column element, said side faces may define a straight portion and in particular a straight edge of the cross-section. In an embodiment, the majority of further side faces or even all further side faces have a respective substantially planar shape. By providing at least one planar side face the strength and compactness of the inner steering column element is improved.

According to a further aspect, the first side face has two outer edge portions (e.g. extending along the displacement axis) and which are each connected to (and/or each merge with) a further side face of the inner steering column element (e.g. a first outer edge portion of said two outer edge portions may be connected to a first further side face and a second outer edge portion of said two outer edge portions to a second further side face). The edge portions may define opposite outer edges of the first side face when viewed in the cross-sectional plane. The at least one protruding portion and/or a (for example, centre) portion of the first side face may be located in between these edges and in particular substantially in a middle between them. The edge portions may connect to and/or be part of corner portions to which the respectively adjacent further side faces are connected.

In an embodiment, at least a portion of the first side face that is opposite to the preload force generating element protrudes relative to these outer edge portions. In particular, said opposite portion and the outer edge portions may not be positioned along one common line (e.g. when viewed in the cross-sectional plane). For example, at most the outer edge portions may be located on a respective common line, while said opposite portion is at a distance to said line and e.g. displaced relative thereto towards the preload force generating element.

Put differently, the opposite portion may be arranged closer to the preload force generating element then the outer edge portions e.g. when viewed along an axis extending orthogonally to the displacement axis and/or along which the preload force is introduced. Again, the opposite portion may be a centre portion of the first side face when viewed in the cross-sectional plane.

Additionally or alternatively, the first side face may generally have V- or U-shape e.g. when viewed in the cross-sectional plane. The opposite portion may form a respective bottom of the V- or U-shape, whereas the outer edge portions may form the upper end and starting point of said V- or U-shape.

With such a shape, as well as any of the further angled shapes discussed herein, an advantageous stress distribution can be achieved within the inner steering column element that allows for reducing a material thickness while maintaining a required stiffness.

According to further embodiment, the first side face has an angled shape, e.g. when viewed in the cross-sectional plane. This may be achieved by providing any of the above relative arrangements of a centre or opposite portion and outer edge portions of the first side face and/or by providing the first side face with the above discussed V-shape. Specifically, the first side face may comprise at least two angled sections that converge, thereby providing an outwardly protruding shape of the first side face.

The generated preload force may act along a preload axis. A shape of the first side face may be angled with respect to an axis extending orthogonally to said preload axis. In particular, said axis may also extend orthogonally to the displacement axis. The preload axis may extend within the cross-sectional plane and/or orthogonally to the displacement axis. It may extend substantially orthogonally to at least one side face of the inner steering column element. In one example, the preload axis is a substantially horizontal or vertical spatial axis. The preload axis may extend along the preload force generating element and coincides with a longitudinal axis thereof.

According to an aspect, the first side face includes at least two angled sections that are mirror symmetric with respect to the preload axis. Specifically, an angle of each angled section with respect to an axis extending orthogonally to the preload axis and to the displacement axis is between 0.5° and 60°, or between 10° and up to 50° or between 20° and up to 45°. The hollow cross-section (or at least the first side face thereof) of the inner and/or outer steering column element may generally be mirror symmetric with respect to the preload axis.

The first side face may be a top or bottom side face of the inner steering column element. The term top or bottom may again relate to an installation orientation of the steering column within the vehicle. With such an orientation of the first side face, a secure preloading of the steering column is achieved while enabling a comfortable axial displacement thereof.

In one aspect, the preload force generating element is a screw or comprises a screw. The outer steering column element may comprise a threaded through hole in which the screw is received. By tightening and loosening the screw a degree by which it extends out of said through hole and towards the first side face can be varied. This degree may determine the extent of the preload force that is received by the first side face and thus the extent of generated resistance forces which counteract the axial displacement.

As mentioned above, the first side face may comprise at least one sliding surface into which the preload force is introduced and/or that is contacted by the preload force generating element.

According to a further embodiment, at least two further sliding surfaces are provided that are each positioned at a corner portion of the hollow cross-section of the inner steering column element. The first side face may extend at distance to said corner portions and/or may not be directly connected thereto due to being spaced apart therefrom by at least one intermediate further side face. The corner portions may be formed by two side faces joining one another and/or may form a connecting portion between such two side faces. These side faces may extend angle to one another that is e.g. larger than 45°. In one example, said side faces extend substantially orthogonally to one another. The corner portions may be rounded or angled. They may comprise or be connected to a sliding surface that is in contact with the outer steering column element.

The sliding surfaces may form the only areas of contact between the inner steering column element and the outer steering column element and/or the preload force generating element. By means of the optional further sliding surfaces provided at the corner portions, the inner steering column element can be reliably centred within the outer steering column element.

As indicated above, at least portions of the inner and outer steering column element may be similarly shaped. For example, the outer steering column element may have a number of side faces which form a hollow cross-section of the outer steering column element, said cross-section receiving the inner steering column element. A side face of the outer steering column element that is adjacent to the first side face of the inner steering column element may be correspondingly shaped to said first side face. In particular, an inner surface facing the inner steering column element of said side face may be shaped correspondingly to an outer surface of the first side face of the inner steering column element. For example, said side face of the outer steering column element may be similarly angled.

Additionally or alternatively, the protruding portion of the first side face of the inner steering column element may at least partially be received within said similarly shaped side face of the outer steering column element, in particular wherein said similarly shaped side face forms a recess and/or a dent or indentation due to its corresponding (e.g. angled) shape.

Providing respective corresponding shapes increases compactness. Further, when said similarly shaped side face of the outer steering column element receives the preload force generating element, an advantageous stress distribution and in particular a predominant tension loading can be achieved. This allows for reducing a material thickness (e.g. compared to planar shape and predominantly bent load case) while maintaining a sufficient stiffness. Again, the thickness may be less than 30 mm, e.g. between 1 mm and up to 20 mm or between 1 mm and up to 10 mm.

The present disclosure also relates to a steering system for a vehicle, the steering system is a steer-by-wire steering system and comprises:a steering column according to any of the previous claims;a steering wheel coupled to the inner steering column element (e.g. at an outer circumferential surface of the inner steering column element) and being rotatable relative thereto.

DESCRIPTION OF THE EMBODIMENTS

FIG.1shows a schematic sectional view of a steering system10for a road vehicle according to an embodiment of the present disclosure. The steering system10is a steer-by-wire steering system that has no direct mechanical connection for transferring a driver's steering commands from a steering wheel12of the steering system10to the wheels (not shown) of the vehicle. Instead, the mechanical connections are replaced by an electro-mechanical arrangement which, together with the steering system10, is part of the steer-by-wire steering system.

In addition to the steering wheel12, the steering system10comprises a steering wheel hub14mechanically connected with the steering wheel12. The steering wheel hub14and the steering wheel12are non-rotatable relative to each other, but can be rotated together about an axis of rotation A. The steering wheel12is removably attached to the steering wheel hub14in a non-rotatable manner by fixing elements16in form of screws. More precisely, the steering wheel12is provided with an internal armature18, wherein the fixing elements16extend through through bores20of the internal armature18into internally threaded blind holes22provided in the steering wheel hub14.

The steering wheel hub14is rotatably supported on a rigid steering column24of the steering system10, more precisely on an aligned section26of the steering column24. The steering column24may also be referred to as a steering system support column.

Besides the aligned section26, the steering column24comprises an off-axis section28formed integrally with the aligned section26or formed separately and mechanically connected thereto. The off-axis section28is axially spaced from the aligned section26and from the steering wheel hub14, while the steering wheel hub14overlaps and is located coaxial to the aligned section26. The off-axis section28has a first longitudinal axis L1that is off-set and parallel to the axis of rotation A. The aligned section26has a second longitudinal axis L2. The aligned section26of the steering system support column24is aligned with or coaxial to the steering wheel hub14and to the steering wheel12, i.e. the second longitudinal axis L2corresponds to the axis of rotation A.

The off-axis section28and the aligned section26are connected by a connection portion30extending transversally to both the first longitudinal axis L1and the second longitudinal axis L2. The off-axis section28and the aligned section26are comprised by an inner steering column element100.

The depicted angled configuration of the inner steering column element100provided by the off-axis section28and the aligned section26is merely optional. The inner steering column element100can equally configured as a non-angled straight member.

The steering wheel hub14is rotatably mounted on the aligned section26of the steering column24by a first bearing arrangement32and a second bearing arrangement34, the second bearing arrangement34being axially spaced from the first bearing arrangement32. For example, the first bearing arrangement32and/or the second bearing arrangement34can be a ball bearing or a roller bearing.

The first bearing arrangement32is supported on a protruding flange portion36of the aligned section26of the steering column24, which protrudes radially outward from the outer circumferential surface of the aligned section26. The protruding flange portion36provides a circular ring-shaped first bearing surface for supporting the first bearing arrangement32. The protruding flange portion36is arranged in the vicinity of the connection portion30, i.e. in a transition region between the aligned section26and the connection portion30.

Consequently, the first bearing arrangement32is axially located at a first end portion of the aligned section26oriented towards the connection portion30.

The second bearing arrangement34is supported on a circular ring-shaped portion38of the aligned section26of the steering24. The circular ring-shaped portion38is formed in an area of the aligned section26following the steering wheel12and extending towards the protruding flange portion36. The circular ring-shaped portion38provides a second bearing surface for the second bearing arrangement34. Thus, the second bearing arrangement34is axially located at a second end portion of the aligned section26opposing the first end portion.

The first bearing arrangement32is mounted between the protruding flange portion36of the aligned section26and the steering wheel hub14via a support bushing40arranged between the first bearing arrangement32and the inner circumferential surface of the steering wheel hub14.

The second bearing arrangement34is mounted directly between the circular ring-shaped portion38of the aligned section26and the steering wheel hub14. To this, the steering wheel hub14is provided with an inwardly protruding flange portion42that provides a counter bearing surface for the second bearing arrangement34. At the same time, the inwardly protruding flange portion42covers components located inside the steering wheel hub14. As can be seen inFIG.1, the blind holes22for receiving the fixing elements16extend into or through the inwardly protruding flange portion42.

Generally, the inner steering column element100thus rotatably supports the steering wheel12at an outer circumferential surface of the inner steering column element100. Unlike in various prior art solutions, the inner steering column element100does not rotatably support the steering wheel at its inner circumferential surface and generally does not receive any shaft or any member mechanically connected to the steering wheel12and/or to steered wheels of the vehicle on its inside.

The steering system10further comprises a torque feedback device44including an electric machine having a rotor46and a stator48with stator windings50. The torque feedback device44can be operated to produce resistance torque to the rotation of the steering wheel12so as to simulate the resistance torque present in conventional steering systems. In other words, the torque produced by the torque feedback device44can counteract the rotational force applied to the steering wheel12by a driver.

In the shown embodiment, the electric machine is an outer rotor electric machine comprising an outer rotor46and an inner stator48. The rotor46is fixed to an inner circumferential surface of the steering wheel hub14. Thus, the rotor46is rotatable together with the steering wheel hub14about the axis of rotation A. The rotor46is non-rotatable relative to the steering wheel hub14. The stator48is fixed to the rotatably stationary (i.e. non-rotatable) aligned section26of the steering system support column24. Thus, the steering wheel hub14and the rotor46can rotate together around the stator48and the aligned section26.

The electric machine of the torque feedback device44is arranged inside the steering wheel hub14. The torque feedback device44is radially enclosed and thus covered by the steering wheel hub14(the inner circumferential surface of the steering wheel hub14) and the aligned section26of the steering system support column24(the outer circumferential surface of the aligned section26). The torque feedback device44is axially located between the protruding flange portion36of the aligned section26and the circular ring-shaped portion38of the aligned section26. The torque feedback device44is axially enclosed and thus covered by the protruding flange portion36of the aligned section26, the first bearing arrangement32and the support bushing40on one side and by the inwardly protruding flange portion42of the steering wheel hub14and the second bearing arrangement34on the other side.

The arrangement, configuration and support of the steering wheel hub14, the steering wheel12, the torque feedback device44and the steering column24provides a very compact structure. More precisely, as shown inFIG.1, various components are arranged at least partially parallel to each other, with respect to their radial and/or axial arrangement.

The steering system10further comprises a steering wheel rotation limiting device52for limiting rotation of the steering wheel hub14and the steering wheel12. The steering wheel rotation limiting device52is fixed to the steering system support column24and is arranged radially offset to the steering wheel hub14, more precisely adjacent to the outer circumferential surface of the steering wheel hub14. The steering wheel rotation limiting device52is non-rotatable relative to the steering system support column24.

The steering wheel rotation limiting device52comprises a base54and a sliding element56arranged inside a compartment58formed in the base54. The sliding element56is axially slidable relative to the base54and relative to the steering wheel hub14. The sliding element56can slide between the two opposing end stop surfaces of the steering wheel rotation limiting device52. The sliding element56comprises a projection64that engages a spiral groove66formed on the outer circumferential surface of the steering wheel hub14. By the interaction of the projection64and the spiral groove66, rotation of the steering wheel hub14causes axial movement of the sliding element56.

Likewise, abutment of the sliding element56with one of the two end stop surfaces blocks further movement of the sliding element56in a certain direction and thus blocks further rotation of the steering wheel hub14in a certain direction of rotation. Hence, the steering wheel rotation limiting device52is configured to restrict rotation of the steering wheel hub14and of the steering wheel12connected therewith.

The base54of the steering wheel rotation limiting device52is fixed to the off-axis section28of the steering system support column24by screws (not shown). The steering wheel rotation limiting device52, more precisely the base54, extends in the axial direction from the off-axis section28of the steering system support column24to the steering wheel hub14so that the compartment58is arranged between and enclosed by the base54and the outer circumferential surface of the steering wheel hub14.

The base54of the steering wheel rotation limiting device52covers an opening70configured in the off-axis section28of the steering system support column24. More precisely, the opening70is arranged in another transition region between the off-axis section28and the connection portion30. The opening70provides access to electric machine phase connections72and to electric steering wheel angle sensor connections74for service and maintenance purposes. The electric machine phase connections72connect the electric machine of the torque feedback device44with a control unit/control electronics76. The electric steering wheel angle sensor connections74connect a steering wheel angle sensor78with the control unit/control electronics76.

The control unit76is arranged inside the hollow tubular off-axis section28of the steering system support column24. More precisely, the control unit76is arranged in a portion of the off-axis section28close to the connection portion30so as to locate the control unit76and the electric machine close to each other.

The steering wheel angle sensor78is configured to measure a present steering angle and thus to detect the driver's steering command that is to be transmitted electronically to actuator/s for actuating/steering the wheels in line with this command. The steering wheel angle sensor78is arranged adjacent or lateral to the first bearing arrangement32.

The steering column24is formed as a tubular (i.e., hollow) telescope arrangement80that comprises the inner steering column element100and an outer steering column member82. The inner steering column element100may also be referred to as a steering wheel support element and the outer steering column member82may also be referred to as a vehicle support element. A portion of the inner steering column element100facing away from the steering wheel12is inserted into and received by the outer steering column member82.

The inner steering column element100is axially displaceable relative to the stillstanding outer steering column member82along the displacement axis L1and relative to a vehicle body, but is non-rotatable and non-pivotable relative to the outer steering column member82.

In the shown example, the optional off-axis section28is mounted axially slidable inside the outer steering column member82of the tubular telescope arrangement80.

In an implementation mode, the steering column24is connected to the vehicle body (not shown) by brackets102formed at the outer steering column member82and connected to axial adjustment elements84(see lower bracket102inFIG.1) and vertical adjustment elements (see upper bracket102inFIG.1). Consequently, the inner steering column element100and all components supported thereon are only translationally displaceable with respect to and along the first longitudinal axis L1independent of the vehicle support column82. Further, the inner steering column element100and all components supported thereon are radially displaceable/pivotable relative to the vehicle body dependent on the outer steering column member82, i.e. the adjustability/displaceability of the outer steering column member82.

Still further, inFIG.1a position of a preload force generating element104is indicated. The preload force generating element104is a screw received in and extending through a threaded hole in the outer steering column member82. Thus, the preload force generating element104contacts a sliding surface106of the inner steering column element100to generate frictional forces. These set a defined resistance against the sliding displacement of the inner steering column element100relative to the outer steering column member82.

FIG.2is a cross-sectional view of the steering column24with the cross-sectional plane extending through the preload force generating element104and orthogonally to the displacement axis L1.

It again becomes apparent that the inner steering column element100and the outer steering column member82are both shaped as hollow tube-like members and in particular as hollow elongated metallic profiles.

The cross-section of the inner steering column element100has a substantially rectangular shape. It comprises four side faces110,112,114,116that are connected to each other at corner portions118. A left and right side face112,116extent upright and/or vertically as well as in parallel to one another. A top and bottom side face114,110, the bottom side face110being a first side face of the inner steering column element100, extend substantially horizontally and connect the left and right side faces112,116.

The left and right side faces112,116and the top side face114are straight. The first side face110, on the other hand, has an angled configuration and is generally outwardly bulging and/or convexly shaped. The first side face110defines a width of the inner steering column element e.g. has a length (in the horizontal direction) of between 50 mm and 150 mm.

Specifically, the first side face110comprises two outer edge portions120at opposite outer ends thereof which connect to and/or are comprised by the corner portions118. In between (or starting from) these two edge portions120, two angled sections122converge towards a centre portion124of the first side face110. The centre portion124is positioned opposite to the preload force generating element104and forms a lowermost or outermost portion of the first side face110. The angled sections122extend downwards or outwards relative to the outer edge portions120, so that the first side face110generally protrudes towards the preload force generating element104. Put differently, a protruding portion of the first side face110generally covers the complete first side face110and/or contains the complete outer surface of said first side face110. This, however, is not mandatory and the first side face may alternatively have non-angled horizontally portions which are connected to a locally protruding centre portion124.

In an implementation mode, the shape of an inner surface of the first side face110slightly deviates from the shape of the outer surface in that it is provided with a horizontal section126that spans across the centre portion124.

The cross-section of the outer steering column element82is shaped substantially similar to that of the inner steering column element, except for the optional and only locally provided brackets102. In particular, a shape of in inner circumferential surface of the outer steering column element82matches the shape of an outer circumferential surface of the inner steering column element100.

In consequence, the cross-section of the outer steering column element82likewise comprises a number of side faces130,132,134,136forming a rectangular (in particular inner) cross-section. Each side face extends along a directly adjacent similarly shaped and/or similarly oriented side faces110,112,114,116of the inner steering column element100. Also, the side faces130,132,134,136are connected to one another at corner portions138of the outer steering column element82.

A lower side face130of the outer steering column element82that extends along the first side face110of the inner steering column element100has a similarly angled and outwardly protruding shape (e.g. outwardly relative to a geometric centre of the inner and/or outer steering column element100,82at which the displacement axis L1is positioned inFIG.2). A threaded through hole105is provided in a centre portion of said lower side face130in which the preload force generating element104is received. In the sectional view ofFIG.2, an internal hexagon profile or socket of the preload force generating element104is visible which is configured to receive a correspondingly shaped tightening tool.

An end portion of the preload force generating element104reaches into the outer steering column element82and contacts a sliding surface106comprised by the first side face110of the inner steering column element100.

In an implementation mode, two further sliding surfaces106are shown. These are comprised by two corner portions118of the inner steering column element100to which the first side face110is not connected, i.e. that are positioned opposite to said first side face110.

Each of the sliding surfaces106contact the inner surface of the outer steering column element82. In an implementation mode, they form the only points of contact between the inner and outer steering column element100,82. The inner steering column element100is thus reliably supported at at least three points of contact by the outer steering column element82which enables a secure axial displacement.

When tightening the preload force generating element104, a preload force is exerted onto the sliding surface106comprised by the first side face110. The preload force acts along a preload axis P towards the interior of the steering column24. The preload axis P extends in parallel to the left and right side faces112,116and/or orthogonally to the upper side face114. It may be a vertical axis.

InFIG.2, an angle α of the angled sections122with respect to an axis B extending orthogonally to the preload axis P and to the displacement axis L1is indicated. The angle α may be between 0.5° and up to and including 60°, e.g. between 10° and 50°. It is noted that the side face130of the outer steering column element82opposite the first side face110has similar angled sections131whose respective angles are, however, not specifically indicated.

As a result of the outwardly protruding shape of the inner steering column element100, the preload force does not cause a substantial bending of the non-planar first side face110and/or side face130. Instead, the first side face110mainly experiences compression loading as indicated by respective arrows C. These compression forces may be compensated for with a reduced material thickness of the first side face110compared to a case where said first side face110would experience a substantial bending.

Further, the upper sliding surfaces106experience pressure reaction forces indicated by arrows R. These are introduced in the planar sliding surfaces106without causing substantial deformation of the inner steering column element100.

The outer steering column element82and in particular the angled portions131of its lower side face130mainly experience tension loading as indicated by arrows T. Again, however, they are not significantly bent which allows for reducing the material thickness of said side face130.

While the embodiment shows an outwardly protruding first side face110, an inwardly protruding shape is also possible and can provide similar advantages in view of stiffness. This may e.g. be achieved by mirroring the angled sections122,131at the axis B or at an axis parallel thereto, thereby providing an inverted V-shape.

List of Reference Signs