Patent Description:
Additionally, the present disclosure is directed to a vehicle comprising such a steering column assembly.

Furthermore, the present disclosure relates to a method for operating a steering column assembly.

The primary functionality of a steering column assembly is to transform a steering activity of a driver of the associated vehicle into a steering movement of the wheels. Following the steering movement of the wheels, the vehicle may change its driving direction.

Beyond that, modern steering column assemblies are configured to provide a secondary functionality which relates to energy absorption in a case in which the vehicle is in a collision situation or a crash situation. In such a situation, the inner tube and the outer tube are allowed to move relative to each other. Thereby, energy is absorbed by the energy absorption mechanism of the steering column assembly. The energy being absorbed by the steering column assembly is withheld from the driver. This enhances the safety of the driver in the crash situation.

Steering column assemblies which allow a relative movement between the inner tube and the outer tube in order to absorb energy in a crash situation are often called collapsible steering column assemblies or steering column assemblies which allow a so-called ride-down.

<CIT> discloses a steering column assembly including an inner jacket disposed along a longitudinal axis and coupled to a host structure of a vehicle. The steering column assembly also includes an outer jacket arranged co-axially about the inner jacket and the longitudinal axis. The outer jacket is configured to translate along the longitudinal axis relatively to the inner jacket to thereby facilitate telescoping motion of the steering column assembly. The outer surface of the inner jacket and the inner surface of the outer jacket cooperate to define a telescope-inhibiting range of motion of the steering column assembly along the longitudinal axis. The steering column assembly is configured to impose telescope-resisting forces as the length of the steering column assembly decreases within the telescope-inhibiting range of motion.

<CIT> teaches a steering shaft for a motor vehicle steering system including a spindle built-up from two profiled sections of which the outer one is tubular. The inner part is secured inside the tubular part against axial and angular movements. The tubular part incorporates at least one shear strip which is made by grooves which are machined into the outside diameter of the tube. The sheared out sections are bent inward and upward and are secured to the inner spindle section. On impact, e.g. during a crash, of driver with the steering wheel and column, the sections are further sheared out and folded over.

<CIT> shows a collapsible steering column arrangement for a vehicle comprising a U-shaped deformable member connected to a fixed support for the steering column and a deforming member connected to the steering column itself. Under impact conditions caused by an accident the members move relative to one another thus allowing the steering column to collapse. This relative movement of the members enables the deforming member to contact the base of the 'U' to deform the U-shaped deformable member to reduce its overall length thus absorbing the energy of the impact and allowing the column to collapse in a controlled manner. The members can be shaped and dimensioned to give the desired energy absorption characteristics.

<CIT> discloses an adjustable steering column for a motor vehicle, comprising a rotatable steering shaft, which has a shaft part that can be moved axially along the axis of rotation of the steering shaft and that is rotatably mounted in a jacket tube, which is mounted for axial sliding in a guide box retained on a retaining part fixed to the vehicle body and which can be adjusted by means of an electric motor. Said adjustable steering column is improved with regard to a small installation space of the electrical adjustment system in conjunction with high strength of the steering column in that a gear rack is attached to the outer face of the jacket tube and that the electric motor is fastened to the guide box and drives a worm gear, which protrudes through an opening of the guide box toward the jacket tube and meshes with the gear rack.

It is additionally known to make steering column assemblies adjustable such that a position of a steering wheel being connected to an end of the steering column assembly can be chosen as a function of physical properties of a driver and/or a driving mode. In other words, the inner tube and the outer tube of the steering column assembly may have different operational positions. In a case in which the steering column assembly is adjustable and collapsible at the same time, the energy absorption characteristics of the energy absorption mechanism may not be ideal for each of these operational positions.

Consequently, it is an objective of the present disclosure to provide a steering column assembly, wherein the energy absorption characteristics in a crash situation may be adapted to different operational positions of the inner tube and the outer tube.

According to a first aspect, there is provided a steering column assembly for a vehicle. The steering column assembly comprises an inner tube and an outer tube. The inner tube and the outer tube extend along a common axis. In an operational position, a portion of the inner tube is arranged inside the outer tube. Moreover, the steering column assembly comprises an energy absorption mechanism being coupled to at least the inner tube and being configured to absorb energy in case of a relative movement of the inner tube with respect to the outer tube along the axis and out of the operational position. An energy absorption capacity per distance unit of the energy absorption mechanism is variable along the axis. Consequently, at least two different energy absorption capacities per distance unit are provided along the axis. The distance unit is for example a centimeter or a millimeter. Thus, the energy absorption capacity per distance unit relates to an amount of energy that can be absorbed by a relative movement of the inner tube with respect to the outer tube over the distance unit. In alternative terms, the energy absorption capacity per distance unit may also be called a collapsing resistance per distance unit of the steering column assembly. This has the effect that in a crash situation, in which the inner tube and the outer tube move relative to one another, different amounts of energy may be absorbed depending on the relative position of the inner tube and the outer tube that corresponds to the operational position. Put otherwise, different energy absorption characteristics may be realized for different relative positions of the inner tube and the outer tube, i.e. for different operational positions. For example, the energy absorption mechanism may absorb a different amount of energy in a situation in which the steering column assembly is in a stowed position, which may for example be used during an autonomous drive, and in a situation in which the steering column assembly is in an extended position, which may for example be used during a non-autonomous drive. The different amounts of energy may be well adapted to the corresponding driving mode. At the same time, the steering column assembly is structurally simple and compact.

Since a portion of the inner tube is arranged inside the outer tube and the inner tube and the outer tube may move relative to one another, the steering column assembly may also be called a telescopic steering column assembly.

In an example, the inner tube may be associated to a steering wheel. In more detail, a steering wheel may be connectable to the inner tube. The outer tube may be associated with a steering mechanism of the wheels. This means that the outer tube may be connectable to such a steering mechanism.

It is noted that the energy absorption mechanism is always coupled to the inner tube. Additionally, the energy absorption mechanism may be coupled to the outer tube in a direct or indirect manner. In all these alternatives, energy resulting from a relative movement between the inner tube and the outer tube may be efficiently and effectively absorbed.

According to the invention, the energy absorption mechanism comprises an inner friction surface being arranged on the inner tube and being frictionally coupled to the outer tube. Additionally or alternatively, the energy absorption mechanism comprises an outer friction surface being arranged on the outer tube and being frictionally coupled to the inner tube. Consequently, the energy absorption mechanism is configured to absorb energy resulting from a relative movement between the inner tube and the outer tube in that at least a portion of the outer tube moves over the inner friction surface and/or at least a portion of the inner tube moves over the outer friction surface. Thus, energy resulting from a crash situation may be reliably absorbed by the energy absorption mechanism.

In an example, the inner friction surface and/or the outer friction surface comprises at least two friction zones being arranged at different positions along the axis. The at least two friction zones differ in at least one of:.

Using the at least two friction zones, different energy absorption capacities per distance unit can be realized in a simple and reliable manner. Different diameters of the friction zones may lead to different normal forces acting on the friction surfaces. Thereby, the energy being absorbed by frictional engagement may be adjusted. The same applies to the surface roughness and a surface coating.

It is noted that the different positions of the at least two friction zones may be arranged along the axis such that the at least two friction zones are directly adjacent to one another. Alternatively, a distance or gap may be provided between neighboring friction zones. According to the invention, the energy absorption mechanism further comprises at least one of a deformation element, a shearing element or a sliding mechanism with a rail element.

According to an alternative of the invention, the energy absorption mechanism further comprises a deformation element being coupled to at least the inner tube and being configured to deform upon a relative movement of the inner tube with respect to the outer tube out of the operational position and along the axis. Consequently, in this example, the energy is absorbed in that the deformation element is deformed. This is a reliable manner for absorbing energy resulting from a crash situation.

It is noted that the deformation element is always coupled to the inner tube. Additionally, the deformation element may be coupled to the outer tube in a direct or indirect manner. In all these alternatives, energy resulting from a relative movement between the inner tube and the outer tube may be efficiently and effectively absorbed.

In an example, the deformation element comprises at least two deformation zones, wherein the at least two deformation zones differ in at least one of:.

The geometrical dimension may for example relate to a height, a width or a length. Of course, it is also possible that the geometrical dimension relates to a dimension of a cross-section. Based on the different geometric dimensions, also different forms of the two deformation zones may be used. Consequently, a deformation resistance of the deformation element may be adjusted, thereby creating different energy absorption capacities per distance unit. The same applies to the use of different materials and/or coatings. In the latter case, one deformation zone may be equipped with a coating while another deformation zone may not comprise a coating.

According to an alternative of the invention, the energy absorption mechanism comprises both and inner and/or outer friction surface as explained above and a deformation element as explained above.

According to an alternative of the invention, the energy absorption mechanism further comprises a shearing element being coupled to at least the inner tube and being configured to at least partially shear off upon a relative movement of the inner tube with respect to the outer tube out of the operational position and along the axis. Thus, energy resulting from a crash situation is absorbed by shearing of the shearing element. This is a reliable manner for absorbing energy.

It is noted that the shearing element is always coupled to the inner tube. Additionally, the shearing element may be coupled to the outer tube in a direct or indirect manner. In all these alternatives, energy resulting from a relative movement between the inner tube and the outer tube may be efficiently and effectively absorbed.

In an example, the shearing element comprises at least two shearing zones, wherein the at least two shearing zones differ in at least one of:.

Again, the geometrical dimension may for example relate to a height, a width or a length. Of course, it is also possible that the geometrical dimension relates to a dimension of a cross-section. Based on the different geometric dimensions, also different forms of the two shearing zones may be used. Consequently, a shearing resistance of the shearing element may be adjusted, thereby creating different energy absorption capacities per distance unit. The same applies to the use of different materials and/or coatings. In the latter case, one shearing zone may be equipped with a coating while another shearing zone may not comprise a coating.

According to an alternative of the invention, the energy absorption mechanism comprises both and inner and/or outer friction surface as explained above and a shearing element as explained above.

According to an alternative of the invention, the energy absorption mechanism further comprises a sliding mechanism with a rail element being coupled to the inner tube, and a carriage element. The carriage element is configured to slide on the rail element upon a relative movement of the inner tube with respect to the outer tube out of the operational position and along the axis. The carriage element may be connected to the outer tube in a direct or indirect manner. Thus, energy is absorbed by the carriage sliding on the rail element. This is simple and reliable.

In an example, the rail element comprises at least two sliding zones being arranged at different positions along the axis, wherein the at least two sliding zones differ in at least one of:.

In this context, sliding zones refer to zones in which the carriage and the rail interact with one another. By altering a corresponding geometrical dimension, surface structure, surface inclination, surface roughness or surface coating, a sliding resistance may be altered. Consequently, different amounts of energy per distance unit may be absorbed by sliding the carriage on the rail element.

According to an alternative of the invention, the energy absorption mechanism comprises both and inner and/or outer friction surface as explained above and a sliding mechanism as explained above.

In an example, the steering column assembly may selectively assume at least two different operational positions, wherein in each of the two different operational positions a portion of different size of the inner tube is arranged inside the outer tube, and wherein a different energy absorption capacity is associated to each of the at least two different operational positions. In other words, the steering column assembly is adjustable or has an adjustable length. Consequently, a position of a steering wheel that may be connected to an end of the steering column assembly may be adjusted. By associating different energy absorption capacities to each of the different operational positions, the energy absorption characteristic is made a function of the operational position. The above-mentioned ways for creating different energy absorption capacities per distance unit may be used. Consequently, an energy absorption capacity which is appropriate for each of the operational positions, may be chosen.

According to a second aspect, there is provided a vehicle comprising a steering column assembly according to the present disclosure. Consequently, at least two different energy absorption capacities per distance unit are provided along the axis of the steering column assembly. This has the effect that in a crash situation, in which the inner tube and the outer tube of the steering column assembly move relative to one another, different amounts of energy may be absorbed depending on the relative position of the inner tube and the outer tube that correspond to the operational position. Put otherwise, different energy absorption characteristics may be realized for different relative positions of the inner tube and the outer tube, i.e. for different operational positions. For example, the energy absorption mechanism may absorb a different amount of energy in a situation in which the steering column assembly is in a stowed position, which may for example be used during an autonomous drive, and in a situation in which the steering column assembly is in an extended position, which may for example be used during a non-autonomous drive. The different amounts of energy may be well adapted to the corresponding driving mode. At the same time, the steering column assembly is structurally simple and compact.

According to a third aspect, there is provided a method for operating a steering column assembly of the present disclosure. The method comprises:.

This method may be applied in a crash situation in which the inner tube and the outer tube of the steering column assembly move relative to one another in order to absorb energy resulting from the crash situation. Consequently, the energy absorption characteristics may vary along the axis. Moreover, the total amount of energy being absorbed during the relative movement of the inner tube with respect to the object to may be adjusted. In other words, at least two different energy absorption capacities per distance unit are provided along the axis of the steering column assembly. This has the effect that in a crash situation, in which the inner tube and the outer tube of the steering column assembly move relative to one another, different amounts of energy may be absorbed depending on the relative position of the inner tube and the outer tube that corresponds to the operational position. Put otherwise, different energy absorption characteristics may be realized for different relative positions of the inner tube and the outer tube, i.e. for different operational positions. For example, the energy absorption mechanism may absorb a different amount of energy in a situation in which the steering column assembly is in a stowed position, which may for example be used during an autonomous drive, and in a situation in which the steering column assembly is in an extended position, which may for example be used during a non-autonomous drive. The different amounts of energy may be well adapted to the corresponding driving mode. At the same time, the steering column assembly is structurally simple and compact.

It should be noted that the above examples mentioned in connection with the steering column assembly according to the first aspect of the invention may be combined with the examples mentioned in connection with the second and/or third aspect of the invention and vice versa.

The vehicle <NUM> comprises front wheels <NUM> and rear wheels <NUM>. The front wheels <NUM> are steerable.

To this end, the vehicle <NUM> comprises a steering column assembly <NUM>.

One end of the steering column assembly <NUM> is coupled to a steering mechanism <NUM> of the front wheels <NUM>. A steering wheel <NUM> is coupled to an opposite end of the steering column assembly <NUM>. The steering wheel <NUM> is arranged in an interior of the vehicle <NUM>, such that a driver of the vehicle <NUM> may manipulate the steering wheel <NUM>.

The steering column assembly <NUM> is shown in more detail in <FIG>.

The steering column assembly <NUM> comprises an inner tube <NUM> and an outer tube <NUM>.

The inner tube <NUM> and the outer tube <NUM> extend along a common axis A.

Moreover, a portion of the inner tube <NUM> is arranged inside the outer tube <NUM>.

This is the case in each operational position.

In the present example, a length of the steering column assembly <NUM> is adjustable. This means that the inner tube <NUM> and the outer tube24 may assume different relative positions.

In <FIG>, the inner tube <NUM> and the outer tube <NUM> are in a relative position to one another which may be called a middle position being indicated with the letter M.

In an outer position, the portion of the inner tube <NUM> which is received inside the outer tube <NUM> is smaller than in the middle position. This position is indicated with the letter O.

In an inner position, the portion of the inner tube <NUM> which is received inside the outer tube <NUM> is bigger than in the middle position. This position is indicated with the letter I.

The middle position M, the outer position O and the inner position I are all operational positions.

In the outer position, the steering wheel <NUM> is relatively close to a driver of the vehicle <NUM>, wherein in the inner position I, the steering wheel <NUM> is relatively distant from the driver.

The steering column assembly <NUM> also comprises an energy absorption mechanism <NUM>.

In the example of <FIG>, the energy absorption mechanism <NUM> comprises an outer friction surface <NUM> being arranged on the outer tube <NUM> and being frictionally coupled to the inner tube <NUM>.

Optionally, the inner tube <NUM> carries an inner friction surface <NUM> being arranged on an outer circumference of the inner tube <NUM>.

Thus, in this example, the energy absorption mechanism <NUM> is coupled to the inner tube <NUM> and to the outer tube <NUM>.

Furthermore, the energy absorption mechanism <NUM> is configured to absorb energy in case of a relative movement of the inner tube <NUM> with respect to the outer tube <NUM> along the axis A and out of the respective operational position, i.e. out of the inner position I, the middle position M or the outer position O.

In case of a relative movement between the inner tube <NUM> and the outer tube <NUM>, the inner tube <NUM> will slide along the outer friction surface <NUM>. This movement is subject to friction and thus transforms kinetic energy into friction energy.

An energy absorption capacity per distance unit of the energy absorption mechanism <NUM> is variable along the axis A.

In the example of <FIG> this is realized in that the outer friction surface <NUM> comprises at two friction zones 28a, 28b being arranged at different positions along the axis A.

The first friction zone 28a and the second friction zone 28b differ in respect of their diameters.

A diameter D1 of the first friction zone 28a is bigger than a diameter D2 of the second friction zone 28b.

Thus, if the inner tube <NUM> moves along a ride-down direction R with respect to the outer tube <NUM>, the inner tube <NUM> is first in frictional engagement with the first friction zone 28a. A length over which the inner tube <NUM> is in frictional engagement with the first friction zone 28a depends on the operational position, i.e. the inner position I, the middle position M or the outer position O.

Thereafter, the inner tube <NUM> enters into frictional engagement with the second friction zone 28b. This goes together with squeezing the inner tube <NUM> due to the diameter D2 which is reduced as compared to diameter D1.

Consequently, an energy absorption capacity per distance unit of the second friction zone 28b is higher than an energy absorption capacity per distance unit of the first friction zone 28a.

The steering column assembly <NUM> may be operated using a method for operating a steering column.

This method comprises absorbing a first amount of energy per distance unit during a first portion of a relative movement of the inner tube <NUM> with respect to the outer tube <NUM> along the axis A and out of the operational position. The first portion of the relative movement corresponds to a relative movement wherein the inner tube <NUM> is frictionally coupled with the first friction zone 28a.

The method further comprises absorbing a second amount of energy per distance unit during a second portion of a relative movement of the inner tube <NUM> with respect to the outer tube <NUM> along the axis A and out of the operational position, wherein the second amount of energy per distance unit is different from the first amount of energy per distance unit. The second portion of the relative movement corresponds to a movement, wherein the inner tube <NUM> is in frictional engagement with the second friction zone 28b.

The relative movement of the inner tube <NUM> with respect to the outer tube <NUM> may be limited by an abutment means.

It is noted that additionally or alternatively to providing two friction zones 28a, 28b with different diameters D1, D2, the friction zones 28a, 28b can also differ with respect to a surface roughness and/or a surface coating. The effect is the same as has been explained in connection with the different diameters D1, D2.

<FIG> show a further alternative steering column assembly <NUM>.

For the ease of explanation, the outer tube <NUM> is represented in a schematic manner.

In the example of <FIG>, the energy absorption mechanism <NUM> comprises the energy absorption mechanism <NUM> as shown in <FIG> as a first component of the energy absorption mechanism <NUM> and a sliding mechanism <NUM> with a rail element <NUM> and a carriage <NUM>. The sliding mechanism <NUM> forms a second component of the energy absorption mechanism <NUM>. In other words, the sliding mechanism <NUM> is used in addition to the friction-based mechanism of <FIG>.

The rail element <NUM> is fixedly connected to the inner tube <NUM>.

The carriage <NUM> is indirection connected to the outer tube <NUM>.

As can best be seen in <FIG>, the rail element <NUM> comprises a first sliding zone 32a having a first width W1 and a second sliding zone 32b having a second width W2.

The first sliding zone 32a and the second sliding zone 32b are arranged adjacent to one another along the axis A.

Due to the different widths W1, W2, a clamping force acting between the rail element <NUM> and the carriage <NUM> is different in the first sliding zone 32a and the second sliding zone 32b. Since in the present example, the width W2 is bigger than the width W <NUM>, an energy absorption capacity per distance unit of the second sliding zone 32b is bigger than an energy absorption capacity per distance unit of the first sliding zone 32a.

The rail element <NUM> additionally comprises two holding depressions 36a, 36b, wherein each of the holding depressions 36a, 36b may be engaged by the carriage <NUM> in a specific relative position of the carriage <NUM> with respect to the rail element <NUM>.

Also in the example of <FIG>, the steering column assembly <NUM> is adjustable. Depending on the operational position of the steering column assembly <NUM>, the carriage <NUM> is located at a different position on the rail element <NUM>. This leads to different characteristics of the energy absorption mechanism <NUM> depending on the operational position.

The steering column assembly <NUM> of <FIG> may also be operated using a method for operating a steering column.

This method comprises absorbing a first amount of energy per distance unit during a first portion of a relative movement of the inner tube <NUM> with respect to the outer tube <NUM> along the axis A and out of the operational position. In the present example, the first portion of the relative movement corresponds to a movement of the carriage <NUM> out of the holding depressions 36a, 36b.

A second amount of energy per distance unit is absorbed during a second portion of the relative movement. During this portion of the movement, the carriage <NUM> slides along the first sliding zone 32a. The second amount of energy per distance unit is different from the first amount of energy per distance unit.

The method further comprises absorbing a third amount of energy per distance unit during a third portion of a relative movement of the inner tube <NUM> with respect to the outer tube <NUM> along the axis A and out of the operational position, wherein the third amount of energy per distance unit is different from the first amount of energy per distance unit and the second amount of energy per distance unit. The third portion of the relative movement corresponds to the carriage <NUM> sliding along the second sliding zone 32b.

Additionally, during the first and second portion of the relative movement of the inner tube <NUM> with respect to the outer tube <NUM>, the inner tube <NUM> slides on first friction zone 28a of the outer friction surface <NUM>. During the third portion of the relative movement of the inner tube <NUM> with respect to the outer tube <NUM>, the inner tube <NUM> slides on second friction zone 28b of the outer friction surface <NUM>.

As before, the relative movement of the inner tube <NUM> with respect to the outer tube <NUM> may be limited by an abutment means.

It is noted that additionally or alternatively, the first sliding zone 32a and the second sliding zone 32b may differ in at least one of a respective surface structure, a respective surface inclination with respect to the axis, a respective surface roughness, and a respective surface coating. The effect is the same which has already been explained in connection with the different widths W1, W2.

For the ease of explanation, the outer tube <NUM> is represented schematically.

In the example of <FIG>, the energy absorption mechanism <NUM> comprises the energy absorption mechanism <NUM> as shown in <FIG> as a first component of the energy absorption mechanism <NUM> and a deformation element <NUM>. The deformation element <NUM> forms a second component of the energy absorption mechanism <NUM>. In other words, the deformation element <NUM> is used in addition to the friction-based mechanism of <FIG>.

One end of the deformation element <NUM> is fixedly connected to the inner tube <NUM>. The other end of the deformation element <NUM> is connectable to the outer tube <NUM>.

The deformation element <NUM> is configured to deform upon a relative movement of the inner tube <NUM> with respect to the outer tube <NUM> out of the operational position and along the axis A.

In the example of <FIG>, the deformation element <NUM> is a bending strap.

The strap has a substantially constant thickness, but comprises a total of five deformation zones being denoted 38a, 38b, 38c, 38d and 38e which differ with respect to the respective width. The width of the different deformation zones 38a, 38b, 38c, 38d and 38e are denoted B1, B2, B3, B4, and B5.

Due to the different widths B1, B2, B3, B4, and B5, each deformation zone 8a, 38b, 38c, 38d and 38e has a different bending resistance. In other words, an energy absorption capacity per distance unit of the deformation zones 38a, 38b, 38c, 38d and 38e is different.

This method comprises absorbing a first amount of energy per distance unit during a first portion of a relative movement of the inner tube <NUM> with respect to the outer tube <NUM> along the axis A and out of the operational position. During the first portion of the relative movement, the first deformation zone 38a is bent.

The method also comprises absorbing a second amount of energy per distance unit during a second portion of a relative movement of the inner tube <NUM> with respect to the outer tube <NUM> along the axis A and out of the operational position. During the second portion of the relative movement, the second deformation zone 38b is bent.

The method further comprises absorbing a third amount of energy per distance unit during a third portion of a relative movement of the inner tube <NUM> with respect to the outer tube <NUM> along the axis A and out of the operational position. During the third portion of the relative movement, the third deformation zone 38c is bent.

The method additionally comprises absorbing a fourth amount of energy per distance unit during a fourth portion of a relative movement of the inner tube <NUM> with respect to the outer tube <NUM> along the axis A and out of the operational position. During the fourth portion of the relative movement, the fourth deformation zone 38d is bent.

Furthermore, the method comprises absorbing a fifth amount of energy per distance unit during a fifth portion of a relative movement of the inner tube <NUM> with respect to the outer tube <NUM> along the axis A and out of the operational position. During the fifth portion of the relative movement, the fifth deformation zone 38e is bent.

Additionally, during the first, second, and third portion of the relative movement of the inner tube <NUM> with respect to the outer tube <NUM>, the inner tube <NUM> slides on first friction zone 28a of the outer friction surface <NUM>. During the fourth and fifth portion of the relative movement of the inner tube <NUM> with respect to the outer tube <NUM>, the inner tube <NUM> slides on second friction zone 28b of the outer friction surface <NUM>.

<FIG> shows a further alternative steering column assembly <NUM>.

In the example of <FIG>, the energy absorption mechanism <NUM> comprises the energy absorption mechanism <NUM> as shown in <FIG> as a first component of the energy absorption mechanism <NUM> and a shearing element <NUM>. The shearing element <NUM> forms a second component of the energy absorption mechanism <NUM>. In other words, the shearing element <NUM> is used in addition to the friction-based mechanism of <FIG>.

One end of the shearing element <NUM> is fixedly connected to the inner tube <NUM>. The other end of the shearing element <NUM> is connectable to the outer tube <NUM>.

The shearing element comprises two shearing zones 42a, 42b which in the example of <FIG> are formed as perforated sections of the shearing element <NUM>.

Thus, the shearing element <NUM> is configured to at least partially shear off upon a relative movement of the inner tube <NUM> with respect to the outer tube <NUM> out of the operational position and along the axis. The shearing happens in the shearing zones 42a, 42b.

It is understood that the shearing resistance may be tuned by tuning the perforations in the shearing zones 42a, 42b, e.g. by varying a distance between holes forming the perforation or by varying diameters of holes forming the perforation.

Thus, different amounts of energy per distance unit may be absorbed by the shearing element <NUM>.

It is noted that in further alternatives, the shearing zones 42a, 42b may as well differ in at least one of a respective geometrical dimension, a respective material, and a respective coating. As before, the shearing element is provided in addition to the friction-based mechanism of <FIG>.

<FIG> shows ride-down forces F of an energy absorption mechanism <NUM> comprising an outer friction surface <NUM> and an energy absorption mechanism <NUM> comprising a deformation element <NUM>.

The ride-down forces F are denoted over a ride-down distance from zero to Rmax.

In the example of <FIG>, the steering column assembly <NUM> is in an operational position corresponding to ride-down distance zero.

As can be seen from the Figure, both the outer friction surface <NUM> and the deformation element <NUM> realize different levels of energy absorption capacities per distance unit.

It is noted that the energy absorption mechanism <NUM> comprising the outer friction surface <NUM> and the energy absorption mechanism <NUM> comprising the deformation element <NUM> may be used alone or in combination. In the latter case, the ride-down forces resulting from both the friction surface <NUM> and the deformation element <NUM> need to be added.

In contrast to the example of <FIG>, now the steering column assembly <NUM> is in an operational position corresponding to a ride-down distance of roughly <NUM>%.

As can be seen from the Figure, the outer friction surface <NUM> realizes different levels of energy absorption capacities per distance unit. The ride-down force resulting from the deformation element <NUM> is roughly constant.

It is noted again that the energy absorption mechanism <NUM> comprising the outer friction surface <NUM> and the energy absorption mechanism <NUM> comprising the deformation element <NUM> may be used alone or in combination. In the latter case, the ride-down forces resulting from both the friction surface <NUM> and the deformation element <NUM> need to be added.

Claim 1:
A steering column assembly (<NUM>) for a vehicle (<NUM>), comprising an inner tube (<NUM>) and an outer tube (<NUM>), wherein the inner tube (<NUM>) and the outer tube (<NUM>) extend along a common axis (A) and wherein in an operational position a portion of the inner tube (<NUM>) is arranged inside the outer tube (<NUM>), and
an energy absorption mechanism (<NUM>) being coupled to at least the inner tube (<NUM>) and being configured to absorb energy in case of a relative movement of the inner tube (<NUM>) with respect to the outer tube (<NUM>) along the axis (A) and out of the operational position, wherein an energy absorption capacity per distance unit of the energy absorption mechanism (<NUM>) is variable along the axis (A),
wherein the energy absorption mechanism (<NUM>) comprises an inner friction surface being arranged on the inner tube (<NUM>) and being frictionally coupled to the outer tube (<NUM>) and/or wherein the energy absorption mechanism (<NUM>) comprises an outer friction surface (<NUM>) being arranged on the outer tube (<NUM>) and being frictionally coupled to the inner tube (<NUM>), and
characterized in that
the energy absorption mechanism (<NUM>) comprises at least one of:
- a deformation element (<NUM>) being coupled to at least the inner tube (<NUM>) and being configured to deform upon a relative movement of the inner tube (<NUM>) with respect to the outer tube (<NUM>) out of the operational position and along the axis (A), and
- a shearing element (<NUM>) being coupled to at least the inner tube (<NUM>) and being configured to at least partially shear off upon a relative movement of the inner tube (<NUM>) with respect to the outer tube (<NUM>) out of the operational position and along the axis (A), and
- a sliding mechanism (<NUM>) with a rail element (<NUM>) being coupled to the inner tube (<NUM>) and a carriage element (<NUM>), wherein the carriage element (<NUM>) is configured to slide on the rail element (<NUM>) upon a relative movement of the inner tube (<NUM>) with respect to the outer tube (<NUM>) out of the operational position and along the axis (A).