Steering column for a motor vehicle and energy absorption element for a steering column

Abstract

The present invention relates to a steering column (1) for a motor vehicle, the steering column comprising a second component (33) which can be moved relative to a first component (31) in a longitudinal direction, wherein: an energy absorption element is mounted between the first component (31) and the second component (33), the energy absorption element comprising at least one U-shaped bending strip (6) having a first leg (61) which extends in the longitudinal direction in a first plane (B), the first leg being fastened to the first component (31) and being connected by a bend (62) to a second leg (63) which extends in the longitudinal direction in a second plane spaced from the first plane, the second leg being fastened to the second component (33); a break-loose device is provided which is designed such that, when a predefined crash force is exceeded, the break-loose device breaks loose and allows a relative movement of the first component (31) relative to the second component (33) in the longitudinal direction. In order to allow improved response behavior in the breaking loose, according to the invention the break-loose device has a connection between the second leg (63) and the first component (31), said connection being releasable in the longitudinal direction.

Description

[0001] Steering column for a motor vehicle and energy absorption element for a steering column

[0002] State of the art

[0003] The invention relates to a steering column for a motor vehicle, which has a second component which is displaceable in a longitudinal direction relative to a first component, wherein an energy absorption element is attached between the first component and the second component, which energy absorption element comprises at least one U-shaped bending strip which has a first leg which extends in the longitudinal direction in a first plane and which is fixed to the first component and is connected via a bend to a second leg which extends in the longitudinal direction in a second plane which is spaced apart from the first plane and which is fixed to the second component, wherein a breakaway device is provided which is designed such that it breaks away when a predetermined crash force is exceeded and releases a relative movement of the first component relative to the second component in the longitudinal direction.

[0004] To increase occupant safety in the event of a vehicle collision, a so-called crash, a steering column of this type has a so-called crash device or crash system. Such a crash device provides that a first component, for example the inner casing of an actuating unit to which the steering wheel is attached on the driver's side, can be displaced longitudinally, i.e. forwards in the direction of travel, relative to a second component, for example an outer casing which is supported by a support unit of the steering column fixed to the body. If a person impacts the steering wheel at high speed during a collision, a relatively large force - the so-called crash force - is exerted on the steering wheel, which exceeds a limit that only occurs in the event of a crash.

[0005] In order to reduce the risk of injury to the person hitting the steering wheel in the event of a crash, it is known to couple an energy absorption device between the support unit and the actuating unit, which enables a controlled and as even as possible braking of the body.

[0006] The energy absorption device has at least one energy absorption element which is mounted between the first and second components. The energy absorption element has, according to the generic type, at least one bending strip. This is U-shaped with a first leg which merges into a second leg via a U-shaped bend. The first leg extends longitudinally forward in a first plane in which it is fixed to the first component, for example on the radial outer side of an inner casing or inner shell. The second leg extends substantially parallel to the first leg in a second plane which is spaced perpendicular to the first plane and is fixed to the second component, likewise preferably forward as viewed from the bend.In the event of a relative movement of the components in the event of a crash, the second leg undergoes continuous plastic deformation as it bends into the first leg, whereby kinetic energy is absorbed by conversion into heat and deformation work, and a controlled, even deceleration of the body that has impacted the steering wheel occurs.

[0007] To ensure that the flexure strip is not deformed and its function is not impaired outside of a crash situation, for example, due to accidental or improper application of high force to the steering wheel, it is known to provide a breakaway device. This ensures that the components, and thus also the legs of the flexure strip, are held in position relative to one another during normal operation and even under increased stress. However, at the peak load that only occurs in a crash situation, the crash force exceeds a predetermined force threshold, causing the breakaway device to be suddenly released and allowing relative movement of the components to deform the flexure strip.

[0008] Such a breakaway device is described, for example, in US 2022 / 0126907 A1. This device has a pin-shaped predetermined breaking element that extends transversely through the first and second legs of the bending strip, so that the two legs are connected to one another and a relative movement for energy absorption can only occur when the predetermined breaking element is severed by the impact of the crash force. In principle, this can enable a force threshold. However, it is disadvantageous that both legs must have fastening means for the predetermined breaking element, for example through openings, which impairs the deformation behavior and function. The function can also be disrupted by the fragments of the predetermined breaking element remaining after it has been severed in the event of a crash.Furthermore, it is problematic that the predetermined breaking element must span the normal distance between the two legs, making uncontrolled longitudinal tilting unavoidable during a crash load. This makes maintaining a defined force threshold, which is crucial for reproducible breakaway, problematic. Given that the proper functioning of the energy absorption device is highly safety-relevant, these disadvantages are unacceptable.

[0009] In view of the problems explained above, it is an object of the present invention to enable an improved response behavior during breakaway.

[0010] Description of the invention

[0011] This object is achieved according to the invention by the steering column according to claim 1. Advantageous further developments emerge from the subclaims.

[0012] In a steering column for a motor vehicle, which has a second component which is displaceable in a longitudinal direction relative to a first component, wherein an energy absorption element is mounted between the first component and the second component, said energy absorption element comprising at least one U-shaped bending strip which has a first leg extending in a first plane in the longitudinal direction, which first leg is fixed to the first component and is connected via a bend to a second leg extending in the longitudinal direction in a second plane spaced apart from the first plane, which second leg is fixed to the second component, wherein a breakaway device is provided which is designed to break away when a predetermined crash force is exceeded and to release a relative movement of the first component relative to the second component in the longitudinal direction, the invention providesthat the breakaway device has a longitudinally detachable connection between the second leg and the first component.,

[0013] The first and second legs are hereinafter referred to collectively as the two legs or, for short, as the legs. They extend at least substantially parallel to one another in two normally spaced planes. The distance between the legs corresponds to the distance measured in the normal direction between the aforementioned first and second planes. The legs are connected to one another via the bend, which represents a curved section in longitudinal section, and, viewed from this, both extend in the longitudinal direction. Accordingly, the free ends of the legs point away from the bend in the longitudinal direction, for example, towards the rear with respect to the direction of travel.

[0014] The breakaway device is operatively arranged between the first component and the second component, with the first leg being permanently attached to the first component, and the second leg to the second component, in a known manner. According to the invention, however, the second leg is additionally fixed to the first component via a longitudinally releasable, namely breakaway, connection, so that the breakaway device is operatively incorporated between the second leg and the first component. In other words, the releasable connection between the second leg and the first component is arranged parallel to the fixed, permanent connection between the first leg and the first component with respect to the force introduced between the components in the event of a crash.This represents a significant difference to the aforementioned prior art, in which the second leg is connected exclusively to the first leg via the predetermined breaking element, so that this detachable connection is arranged in series with the fixed connection of the first leg to the first component.

[0015] The breakaway device according to the invention can be arranged outside the sections of the legs that are deformable in the event of a crash. This results in the significant advantage that the force required for breakaway, also referred to as the breakaway force, is exerted directly between the second leg and the first component on the detachable connection, and not transferred to the first leg as in the prior art. As a result, the flexural strip is not subjected to the breakaway force, and both legs can be plastically deformed unhindered in the event of a crash. Unlike in the prior art, the deformation is not impaired by fastening means of predetermined breaking elements, so that the response behavior of the breakaway device and the energy absorption characteristics of the flexural strip can be optimized independently of one another.A more reproducible breakaway behavior and thus an improved function of the energy absorption device can be realized.

[0016] It is advantageous that the connection is formed directly between the second leg and the first component. The direct connection is characterized in that both legs directly contact the first component, for example, they rest against it, the first leg via the non-detachable connection, and the second leg via the detachable connection of the breakaway device. In other words, the connections of the two legs to the first component are arranged parallel with respect to the effect of the crash force. The direct connection has the advantage that the breakaway device can be designed flexibly and structurally freely, for example by using fracture or shear elements, friction elements and / or the like, without impairing the energy absorption function of the bending strip. It is preferred that the connection is formed exclusively between the second leg and the first component.This specifically means that the breakaway device has no direct connection between the first leg and the second leg. This is advantageous with regard to independent optimization of the bending strip and the breakaway device.

[0017] It is possible for the second leg to have a connecting section that houses the breakable connection of the breakaway device. The connecting section can preferably be realized in the end region directed longitudinally away from the bend. This region is not deformed for energy absorption and allows for a structurally simple adaptation of the breakable connection to the first component.

[0018] In the aforementioned embodiment, it is advantageous that the connecting section extends at least partially in the first plane. The connecting section of the second leg can be formed flush with the first leg, i.e. the outer surface of the first leg facing the first component and the inner side of the connecting section on the same side, likewise facing the first component, preferably lie in the same plane, in which they can preferably bear directly against the outer side of the first component and are fixed thereto. The first leg is firmly and non-releasably attached to this outer side, and the connecting section is fixedly and breakably attached parallel to it via the releasable connection. The arrangement in the same plane enables simple adaptation and assembly to the first component.

[0019] The aforementioned embodiment can be implemented in a structurally simple manner by giving the second leg a stepped configuration. Due to the stepped configuration, the connecting section is arranged offset parallel to the second leg in the first plane, as seen from the second leg. This can be achieved by first bending or offsetting the free end section of the second leg, which points away from the bend in the longitudinal direction, toward the first leg, and then angled in the opposite direction, so that a step height is formed which corresponds to the normal distance of the first leg perpendicular to the second leg. As a result, the end section of the connecting section is at the same height as the first leg, normal to the first plane.

[0020] It can advantageously be provided that the breakaway device is spaced apart from the first leg in the longitudinal direction. The detachable connection of the breakaway device can be arranged at a distance from a free end of the first leg, which faces away from the bend in the longitudinal direction. In this direction, the connecting section protrudes beyond the first leg. This makes it easy to provide sufficient installation space for the breakaway device in the longitudinal direction.

[0021] It is possible, characterized in that the connecting section has a sliding block. The sliding block has a slot-shaped opening that is open on one side in the longitudinal direction and runs through in the normal direction. A fastening element, for example a rivet, a screw bolt or the like, is passed through this opening normal to the first plane and connected to the first component. As a result, the connecting section can be frictionally clamped to the first component in order to create a releasable frictional connection directly between the second leg and the first component. If, in the event of a crash, a crash force acts in the longitudinal direction between the first and second components that is greater than the frictional force acting between the sliding block and the first component, the frictional connection is released.The fastening element is moved longitudinally out of the fork opening, overcoming the frictional force, causing the sliding block to break away from the first component. This releases the movement of the second leg relative to the first leg, so that the first component is moved relative to the second component under continuous plastic deformation of the bending strip, thereby decelerating it.

[0022] One advantage of the frictionally engaged, detachable connection is that no fragments are produced when the connection breaks loose, which could impair its function. Furthermore, the response and breakaway behavior can be easily and widely adjusted by adjusting the friction force.

[0023] Alternatively, a longitudinally closed opening can be provided through which a predetermined breaking element is passed, for example a shear pin or the like.

[0024] An advantage over the state of the art is that a better shearing behavior can be achieved than with the predetermined breaking pin that is freely guided over the normal distance between the legs.

[0025] It can preferably be provided that an electromotive adjustment drive is arranged between the first component and the second component. This has a linear drive driven by an electric motor, for example a spindle drive, in which a spindle nut and a threaded spindle engaging therein can be driven in rotation relative to one another in a conventional manner. Because the adjustment drive engages the first and second components, which are adjustable relative to one another, a motorized adjustment can be achieved.

[0026] It is possible for the first component and the second component to comprise longitudinally telescopic casings. The casings can have telescopically nested casing tubes that can be extended and retracted in the longitudinal direction to form a length-adjustable casing unit. For example, an inner casing can be provided in which a steering spindle with a manual steering handle attached thereto is rotatably mounted, and which is accommodated in an outer casing so as to be telescopically adjustable in the longitudinal direction, which in turn is held on the vehicle body via a support unit. The energy absorption device according to the invention can advantageously be arranged between the casings, wherein the first leg of the bending strip can be fixed to the outside of the inner casing, and the second leg to the inside of the outer casing, and additionally with the connecting section on the inner casing.

[0027] The bending strip can preferably comprise a sheet metal part. Such a sheet metal part can preferably be efficiently manufactured as a one-piece press-stamped part, preferably from sheet steel.

[0028] In an energy absorption element for a steering column of a motor vehicle, comprising at least one U-shaped bending strip which has a first leg extending in a first plane in a longitudinal direction, which has first fastening means for connection to a first component of the steering column and is connected via a bend to a second leg extending in the longitudinal direction in a second plane spaced from the first plane, which second leg has second fastening means for connection to a second component of the steering column, it is provided according to the invention that the second leg has a connecting section which extends at least in sections in the first plane.

[0029] The fastening means on the legs are designed to create fixed, permanent connections to the components. They can, for example, have fastening openings through which rivets, screws, or the like can be passed and firmly connected to the components. Form-locking elements or the like can also be provided, which can provide positive support in the longitudinal direction. The connecting section has connecting means that can be released in the longitudinal direction under the action of a crash force above a predetermined limit, for example, by a releasable frictional connection or the like, as described above.

[0030] The connecting section is arranged at the same height as the first leg, perpendicular to the planes in the normal direction. This allows the second leg to be fixed to the first component via the detachable connection in the same plane as the first leg via the non-detachable connection.

[0031] The energy absorption element can preferably be used in a steering column according to the invention, and it can have all the features described above in connection with the steering column according to the invention.

[0032] For example, the second leg can be designed in a step-like manner and / or the connecting section can have a sliding shoe.

[0033] It is further advantageous for the connecting portion to project beyond the first leg in the longitudinal direction. This allows the breakaway device according to the invention to be arranged on the connecting portion at a distance in the longitudinal direction for securing the first leg to the first component.

[0034] Description of the drawings

[0035] Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. In detail:

[0036] Fig. 1 shows a steering column according to the invention in a schematic perspective view,

[0037] Fig. 2 is an enlarged detailed view of the energy absorption device of the steering column according to Fig.1,

[0038] Fig. 3 is a partial view of a longitudinal section through the steering column according to Fig. 1, Fig. 4 is a bending strip according to the invention of the steering column according to Fig. 1-3 in a cut-out perspective view,

[0039] Fig. 5 a side view of the bending strip according to Fig.4.

[0040] Embodiments of the invention

[0041] In the various figures, identical parts are always provided with the same reference symbols and are therefore usually named or mentioned only once.

[0042] In Figures 1, a steering column 1 according to the invention is shown schematically in a perspective view obliquely from the rear, relative to the direction of travel of a motor vehicle not shown.

[0043] The steering column 1 can be attached to the body of a motor vehicle by means of a support unit 2. The support unit 2 comprises fastening means 21 for connection to the vehicle body, which can be designed as fastening openings.

[0044] An actuating unit 3 comprises a steering spindle 30, which is rotatably mounted in an inner casing 31, also referred to as an inner casing tube or inner casing pipe, about its longitudinally extending longitudinal axis L. At the rear end portion of the steering spindle 30, a fastening portion 32 is formed for attaching a steering wheel (not shown) for manually inputting steering commands. The inner casing 31 forms a first component within the meaning of the invention.

[0045] The inner casing 31 is accommodated and held in an outer casing 33, also referred to as an outer casing tube, outer casing unit, or guide box, so as to be telescopically displaceable in the longitudinal direction, as indicated by the double arrow. The outer casing 33 forms a second component within the meaning of the invention.

[0046] To achieve height adjustment, the outer casing 33 is pivotally mounted on the support unit 2 about a horizontal pivot axis 22 extending transversely to the longitudinal axis L, so that the steering spindle 30 can be moved up and down in a height direction H, as indicated by the double arrow. An adjustment drive 4 designed as a rotary spindle drive serves for longitudinal adjustment. It has a motorized drive unit 41 attached to the outer casing 33 and supported in the longitudinal direction. This motorized drive unit has an electric motor, which drives a threaded spindle 42 to rotate about its spindle axis. The spindle axis is parallel to the longitudinal axis L.

[0047] The external thread of the threaded spindle 42 engages a spindle nut 43 that is fixed with respect to rotation about the spindle axis. The spindle nut 43 is connected to the inner casing 31 and supported longitudinally. Accordingly, a rotating drive of the threaded spindle 42 by the drive unit 41 results in an axial linear displacement of the spindle nut 45, whereby the inner casing 31 can be adjusted longitudinally relative to the outer casing 33, i.e., can be extended or retracted telescopically.

[0048] An energy absorption device 5 is incorporated between the inner shell 31 and the outer shell 33, which has a bending strip 6 designed according to the invention as an energy absorption element. The arrangement is shown in Fig. 2 in an enlarged view from Fig. 1, and in Fig. 3 in a longitudinal section AA parallel to the longitudinal axis L, seen from above with respect to Fig. 2.

[0049] Fig.4 shows the bending strip 6 separately in a perspective view, and Fig.5 in a side view as in Fig.3.

[0050] The bending strip 6 has a first leg 61 which extends in the longitudinal direction and merges into a second leg 63 via a bend 62.

[0051] The first leg 61 has fastening means 64 in the form of through-holes. Fastening elements 51, such as rivets or the like, are passed through these holes and connected to the inner casing 31. The inner leg 61, with its inner side facing radially toward the longitudinal axis L, rests directly against the outer side of the inner casing 31 in a fastening plane B (see Fig. 3) and is permanently secured thereto.

[0052] The second leg 63 lies parallel to the first leg 61 in a second plane that is normally spaced from the first plane B.

[0053] The second leg 63 has similarly designed fastening means 64 in the form of through-holes. Fastening elements 51, such as rivets or the like, are also passed through these. As a result, the second leg is firmly and permanently connected to the outer casing 33.

[0054] At its free end portion facing away from the bend 62 in the longitudinal direction, the second leg 63 has a connecting portion 65. This has a slot-shaped opening 66 extending in the normal direction and open on one side in the longitudinal direction, as indicated by the arrow in Fig. 4. A sliding shoe is formed on the connecting portion 65 through the opening 66, which is open on one side.

[0055] According to the invention, the second leg 63 is designed in a stepped manner in longitudinal section, so that the connecting portion 65 lies in the same plane as the first leg 61, i.e., is flush with it. Accordingly, the inner side of the connecting portion 65 facing the longitudinal axis L lies in the fastening plane B, as can be seen in Figs. 3 and 5.

[0056] A fastening element 52, for example a rivet, screw bolt, or the like, is passed through the opening 66 and connected to the inner casing 31. As a result, the connecting portion 65 is frictionally clamped in the fastening plane B against the outer side of the inner casing 31.

[0057] The second leg 63, with the connecting portion 65, projects longitudinally beyond the first leg 61. This allows the opening 66 to be spaced longitudinally from the fastening means 64 of the first leg.

[0058] The breakaway device is formed in the connecting section 65 by the opening 66 which is open on one side and the fastening element 52.

[0059] In the event of a crash, a crash force F, which is schematically shown in Fig. 3, is applied to the inner shell 31, causing the inner shell 31 to move longitudinally relative to the outer shell 33, to the right in Fig. 3. This overcomes the holding effect of the frictional engagement between the connecting section 65 and the inner shell 31. The fastening element 52 is moved longitudinally out of the opening 62, as indicated by the arrow in Fig. 4, thereby releasing the breakaway device. Subsequently, the first leg 61 can undergo the forming step 62 under continuous plastic deformation and energy absorption. List of Reference Symbols

[0060] 1 steering column

[0061] 2 carrying unit

[0062] 21 means of fixing

[0063] 3 Actuator

[0064] 30 steering spindle

[0065] 31 inner jacket

[0066] 32 fastening section

[0067] 33 Outer jacket

[0068] 4 Adjustment drive

[0069] 41 Drive unit

[0070] 42 threaded spindle

[0071] 43 Spindle nut

[0072] 5 Energy absorption device

[0073] 51 Fastening element

[0074] 52 Fastening element

[0075] 6 bending strips

[0076] 61 first leg

[0077] 62 bend

[0078] 63 second leg

[0079] 64 fasteners

[0080] 65 connecting section

[0081] 66 Opening

[0082] L Longitudinal axis

[0083] B Mounting level

Claims

PATENT CLAIMS 1. A steering column (1) for a motor vehicle, comprising a second component (33) displaceable in a longitudinal direction relative to a first component (31), wherein an energy absorption element is mounted between the first component (31) and the second component (33), said energy absorption element comprising at least one U-shaped bending strip (6) having a first leg (61) extending in the longitudinal direction in a first plane (B), which is fixed to the first component (31) and connected via a bend (62) to a second leg (63) extending in the longitudinal direction in a second plane spaced from the first plane, which second leg is fixed to the second component (33), wherein a breakaway device is provided which is designed to break away when a predetermined crash force is exceeded and to release a relative movement of the first component (31) relative to the second component (33) in the longitudinal direction, characterized in thatthat the breakaway device has a longitudinally detachable connection between the second leg (63) and the first component (31).

2. Steering column according to claim 1, characterized in that the connection is formed directly between the second leg (63) and the first component (31).

3. Steering column according to one of the preceding claims, characterized in that the connection is formed exclusively between the second leg (63) and the first component (31).

4. Steering column according to one of the preceding claims, characterized in that the second leg (63) has a connecting portion (65) which has the breakable connection of the breakaway device.

5. Steering column according to claim 4, characterized in that the connecting section (65) extends at least partially in the first plane (B).

6. Steering column according to one of the preceding claims 4 to 5, characterized in that the second leg (63) is designed in a step-like manner.

7. Steering column according to one of the preceding claims 4 to 6, characterized in that the breakaway device is spaced apart in the longitudinal direction from the first leg (61).

8. Steering column according to one of the preceding claims 4 to 7, characterized in that the connecting section (65) has a sliding shoe.

9. Steering column according to one of the preceding claims, characterized in that an electromotive adjustment drive (4) is arranged between the first component (31) and the second component (33).

10. Steering column according to one of the preceding claims, characterized in that the first component (31) and the second component (33) comprise longitudinally telescopic casings (31, 33).

11. Steering column according to one of the preceding claims, characterized in that the bending strip (6) comprises a sheet metal part.

12. Energy absorption element for a steering column (1) of a motor vehicle, comprising at least one U-shaped bending strip (6) which has a first leg (61) extending in a longitudinal direction in a first plane (B), which has first fastening means (64) for connection to a first component (31) of the steering column (1) and is connected via a bend (62) to a second leg (63) extending in the longitudinal direction in a second plane spaced from the first plane (B), which second leg has second fastening means (64) for connection to a second component (33) of the steering column, characterized in that the second leg (63) has a connecting section (65) which extends at least in sections in the first plane (B).

13. Energy absorption element according to claim 12, characterized in that the second leg (63) is step-shaped.

14. Energy absorption element according to one of the preceding claims 12 to 13, characterized in that the connecting section (65) has a sliding shoe.

15. Energy absorption element according to one of the preceding claims 12 to 14, characterized in that the connecting section (65) projects beyond the first leg (61) in the longitudinal direction.

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