MOTOR-ADJUSTABLE STEERING COLUMN FOR A MOTOR VEHICLE

Abstract

A motor-adjustable steering column for a motor vehicle has an outer casing which is held by a support unit that is attachable to a vehicle body. An actuator unit is received in the outer casing to adjust in the longitudinal direction. A steering spindle is coaxially and rotatably mounted in a casing tube in the actuator unit. An adjustment drive and an energy absorbing installation are disposed between the outer casing and the actuator unit. The adjustment drive has a spindle mechanism with a threaded spindle which is rotatably drivable by an electric servomotor engaged in a spindle nut. The energy absorbing installation has at least one energy absorbing element at least indirectly disposed between the spindle nut and the actuator unit. The spindle nut or the threaded spindle has at least one forming element which operatively engages with the energy absorbing element and is plastically deformable.

Claims

1.-8. (canceled)

9. A motor-adjustable steering column for a motor vehicle, comprising: a support unit that is attachable to a vehicle body; an outer casing held by the support unit and in which an actuator unit is received so as to be adjustable in a longitudinal direction; a steering spindle coaxially mounted in a casing tube in said actuator unit so as to be rotatable about a longitudinal axis; an adjustment drive and an energy absorbing installation disposed between the outer casing and the actuator unit; wherein the adjustment drive has a spindle mechanism with a threaded spindle which is configured to be driven in a rotating manner by an electric servomotor engaged in a spindle nut; and the energy absorbing installation comprises at least one energy absorbing element which is at least indirectly disposed between the spindle nut and the actuator unit; wherein the spindle nut or the threaded spindle has at least one forming element which operatively engages with the energy absorbing element and by way of which the energy absorbing element is plastically deformable.

10. The steering column of claim 9 wherein the forming element is configured so as to be integrated in the spindle nut or the threaded spindle.

11. The steering column of claim 9 wherein the energy absorbing element is an elongated flexural wire having a length, said flexural wire being movable relative to the forming element and being able to be formed by the forming element at least partially along the length of said flexural wire.

12. The steering column of claim 11 wherein the forming element has at least one bending anvil about which the flexural wire is bent transversely to the longitudinal axis.

13. The steering column of claim 11 wherein the flexural wire has a first end connected to the actuator unit and the has a second, free end.

14. The steering column of claim 9 wherein the spindle nut or the threaded spindle has at least one guiding element.

15. The steering column of claim 9 wherein a predetermined breaking element is disposed between the spindle nut or the threaded spindle and the actuator unit.

16. The steering column of claim 9 wherein the steering spindle is coupled to a steering gear or a feedback actuator.

Description

DESCRIPTION OF THE DRAWINGS

[0053] Advantageous embodiments of the invention will be explained in more detail hereunder by means of the drawings. In detail:

[0054] FIG. 1 shows a steering column according to the invention in a schematic perspective view;

[0055] FIG. 2 shows a further perspective view of the steering column according to FIG. 1;

[0056] FIG. 3 shows a schematic perspective partial view of the steering column according to FIG. 1;

[0057] FIG. 4 shows a partial longitudinal section through the steering column according to FIG. 1;

[0058] FIG. 5 shows a cross-section through the steering column according to FIG. 1;

[0059] FIG. 6 shows a detailed view from FIG. 5;

[0060] FIG. 7 shows a schematic perspective view of a partially sectioned actuator unit of a steering column according to FIG. 1,

[0061] FIG. 8 shows an exploded individual illustration of functional elements of the assembly according to FIG. 7;

[0062] FIG. 9 shows a further perspective view of the assembly according to FIG. 7;

[0063] FIG. 10 shows an exploded individual illustration of functional elements of the assembly according to FIG. 9;

[0064] FIG. 11 shows a schematic perspective view of a spindle nut with an energy absorbing element in a second embodiment in the non-deformed state prior to the event of a crash;

[0065] FIG. 12 shows the spindle nut according to FIG. 11 in the deformed state after the event of a crash;

[0066] FIG. 13 shows the energy absorbing element according to FIG. 11 in a stand-alone view;

[0067] FIG. 14 shows a view as in FIG. 7 of alternative embodiment of an actuator unit of a steering column;

[0068] FIG. 15 shows a schematic perspective view of a spindle nut with an energy absorption element in a third embodiment in the non-deformed state prior to the event of a crash;

[0069] FIG. 16 shows a schematic perspective view of a partially sectioned actuator unit of a steering column, in a manner analogous to that of FIG. 7, with an energy absorbing element in a fourth embodiment;

[0070] FIG. 17 shows a schematic perspective view of a spindle nut with an energy absorbing element in the fourth embodiment in a non-deformed state prior to the event of a crash;

[0071] FIG. 18 shows the energy absorbing element according to FIG. 17 in a stand-alone view; and

[0072] FIG. 19 shows the spindle nut according to FIG. 17 with an energy absorbing element in the deformed state after the event of a crash.

EMBODIMENTS OF THE INVENTION

[0073] Identical parts are at all times provided with the same reference signs in the various figures and are therefore in each case typically also referred to or mentioned only once, respectively.

[0074] FIGS. 1 and 2 show a steering column 1 according to the invention in its entirety in perspective views from the rear left and the rear right in terms of the travel direction of a motor vehicle not illustrated. The steering column 1 has an actuator unit 2 having a casing tube 21 in which a steering spindle 22 is coaxially mounted so as to be rotatable about a longitudinal axis L. The steering spindle 22 at the steering-wheel rear end thereof which in the installed state in the motor vehicle faces the driver has a fastening portion 23 for attaching a steering wheel not illustrated. The steering spindle 22, by way of the front end portion 24 which at the front protrudes from the steering column 1 at the steering gear, by way of an intermediate shaft not illustrated can be mechanically connected to a steering gear which is likewise not illustrated.

[0075] The actuator unit 2 is received in an outer casing 3 so as to be telescopic in the longitudinal direction, that is to say in the direction of the longitudinal axis L, wherein the casing tube 21 can be retracted forward into the outer casing 3 or be deployed rearward, as is indicated by a double arrow in FIG. 1.

[0076] The outer casing 3 is held in a support unit 4 which has fastening means 41 for connecting to a vehicle body not illustrated. A drive unit 51 of an adjustment drive 5 for the telescopic length adjustment of the actuator unit 2 relative to the outer casing 3 is fastened to the outer casing 3 in the front region at the steering gear, said length adjustment yet to be explained further below.

[0077] It can be derived from FIG. 2 that the outer casing 3 in the front region thereof is pivotable about a horizontal pivot axis 42, and in the rear region thereof by way of an actuator lever 43 is articulated on the support unit 4, said actuator lever 43 by a motorized height adjustment drive 6 being pivotable relative to the support unit 4 such that the rear end of the steering spindle 22 at the steering wheel for adjusting the steering wheel in terms of height is adjustable upward and downward in the height direction H relative to the support unit 4, as is indicated by the double arrow.

[0078] FIG. 3 in the same perspective as in FIG. 1 shows an exploded stand-alone view, wherein the outer casing 3 has been omitted for improved clarity. A longitudinal section along the longitudinal axis L is illustrated in a lateral view in FIG. 4. The drive unit 51 of the adjustment drive 5 is fixedly connected to the front end of the outer casing 3 and has a worm gear 52 which in bearings 53 is rotatable about a spindle axis S and in the longitudinal direction is supported on the drive unit 51, as can be seen in the longitudinal section of FIG. 4. A worm 55 which is drivable in a rotating manner by an electric servomotor 54 meshes with the worm gear 52 such that the latter by the servomotor 54 is drivable so as to rotate about the spindle axis S.

[0079] A threaded spindle 56 which extends on said spindle axis S is connected in a rotationally fixed manner to the worm gear 52. The threaded spindle 56 is screwed into a spindle nut 57 in a threaded bore 57a which so as to be secured against rotation about the spindle axis S is attached to the casing tube 21 of the actuator unit 2 so as to be supported in the longitudinal direction, as will yet be explained in detail below. The threaded spindle 56 at the free end thereof has a detent member 560 which delimits the movement of the spindle nut 57 on the threaded spindle 56.

[0080] Depending on the driving direction by the servomotor 54, the threaded spindle 56 rotates, and is either screwed into the threaded bore 57a of the spindle nut 57, the latter on account thereof retracting the casing tube 21 and thus the actuator unit 2 in a forward telescopic manner toward the drive unit 51 into the outer casing 3, to the left in FIG. 4, or the threaded spindle 56 is screwed out of the spindle nut 57 so that the actuator unit 2 is deployed rearward out of the casing tube 3, to the right in FIG. 4.

[0081] The steering spindle 22 has an upper steering spindle part 22a and a lower steering spindle part 22b which are conjointly adjustable relative to one another in a rotationally fixed and telescopic manner in the longitudinal direction, so as to be able to follow the longitudinal adjustment of the steering column 1.

[0082] The spindle axis S in the example shown is disposed substantially parallel to the longitudinal L at a spacing a, that is to say that the threaded spindle 56 has a radial spacing a from the steering spindle 22 and is according to the invention at least in portions disposed within a spindle tunnel 25 within the actuator unit 2. The spindle tunnel 25 is formed by an opening which in the longitudinal direction runs through the casing tube 21 and which is configured so as to be separate from the opening 26 which likewise runs longitudinally and in which the steering spindle 22 is coaxially mounted on the longitudinal axis L, as can be derived from the cross section B-B from FIG. 5 illustrated in FIG. 6.

[0083] When the actuator unit 2 is retracted into the outer casing 3, the threaded spindle 56 is further immersed in the spindle tunnel 25. The threaded spindle 56 is accommodated so as to be protected in the spindle tunnel 25 in each setting state of the steering column 1.

[0084] The enlarged fragment of the cross section in FIG. 6 shows that the spindle tunnel 25 has an eccentric cross-section in which the spindle nut 57 is inserted in a form-fitting manner such that said spindle nut 57 on account of the form-fit is secured against rotation relative to the casing tube 21 about the spindle axis S.

[0085] The spindle nut 57 in a forward manner in the longitudinal direction is secured by a fixing bolt 58 which transversely penetrates the spindle tunnel 25 and is fixedly inserted into the casing tube 21. In a rearward manner in the longitudinal direction, the spindle nut 57 is secured by means of a predetermined breaking element in the form of a shear pin 59 which likewise transversely penetrates the spindle tunnel 25. Consequently, the spindle nut 57 in the normal operation is established between the fixing bolt 58 and the shear pin 59 so that the movement of the spindle nut 57 for the telescopic adjustment is transmitted to the actuator unit 2.

[0086] An energy absorbing installation 7 which has an energy absorbing element 71 in the form of an elongated flexible wire 71 is disposed between the spindle nut 57 and the casing tube 21, said flexible wire 71 being shown in a first embodiment in FIGS. 6 to 10, and in a second embodiment in FIGS. 11 to 13. The flexible wire 71 can have a circular cross-section, or be configured as a flexural strip having an angular cross-section, and can be embodied, for example, as a flexural part or a flexural punched part from steel.

[0087] It can be derived from the exploded illustration in FIG. 10 that the flexural wire 71 at the first end thereof has a fastening portion 71a, the latter being joined by a first leg 71b which in the longitudinal direction runs rearward so as to be substantially parallel to the longitudinal axis L and which by way of a bend 71c of substantially 180 transitions to a second leg 71d which runs forward counter to the longitudinal direction. The fastening portion 71a is fastened to the actuator unit 2 at the front end of the casing tube 21, specifically hooked therein in a form-fitting manner, as can be seen in FIG. 9. The first leg 71b is disposed and guided in the longitudinal direction in a groove-shaped recess 57b of the spindle nut 57 that runs in the longitudinal direction and forms a guiding groove for the flexural wire 71, is rooted rearward in the spindle tunnel 25, then guided about a bending anvil 57c configured on the spindle nut 57, and by way of the second leg 57c is again guided to the front in a groove-shaped recess 57d between the spindle nut 57 and the spindle tunnel 25. The disposal of the legs 71a and 71b can be clearly seen in FIG. 6.

[0088] The second end of the flexural wire forms the free end having an exposed end portion 71i.

[0089] The groove-shaped recesses 57b and 57d conjointly with the bending anvil 57c form a guiding installation through which the flexural wire 71 is pulled in the event of a crash and on account of the plastic deformation taking place herein when being bent continuously absorbs kinetic energy. The groove-shaped recesses 57b and 57d and the bending anvil 57c are preferably configured so as to be integral to the spindle nut 57, for example by subtractive or non-subtractive forming.

[0090] FIGS. 7 and 9 show perspective views, wherein the spindle tunnel 25 is sectioned in the longitudinal direction. The casing tube 21 in FIG. 8, in the same view as in FIG. 7, is omitted for improved clarity. It can be seen therefrom how the flexural wire 71 within the spindle tunnel 25 is guided about the spindle nut 57.

[0091] The energy absorbing installation 7 in the event of a crash is activated when a high force peak on account of an impacting body is exerted in a forward manner on the actuator unit 2 by way of the steering spindle 22. On account thereof, the spindle nut 57, which in a forward manner is supported on the threaded spindle 56, by said high force is pushed rearward in the longitudinal direction against the shear pin 59 which upon exceeding a predefined nominal limit value breaks and releases the rearward movement of the spindle nut 57 within the spindle tunnel 25 relative to the casing tube 21. The movement of the spindle nut 57 relative to the casing tube 21 in the event of a crash is indicated by an arrow in FIGS. 7 and 9.

[0092] In the relative movement between the spindle nut 57 and the casing tube 21 the casing tube 21 entrains the fastening portion 71a of the flexural wire 71 such that the first leg 71b, guided in the recess 57b, is drawn forward relative to the spindle nut 57, and the second leg 57d in relation to the spindle nut 57 is consequently moved rearward and hereby is forced about the bending anvil 57c such that the bend 71c is continuously moved along the flexural wire 71, wherein kinetic energy for the absorption of energy is continuously converted to deformation work and, by virtue of the friction acting between the flexural wire 71 and the spindle nut 57, to a minor part is also converted to heat such that a controlled deceleration of the actuator unit 2 relative to the outer casing 3 is effected. The flexural wire 71 has an end portion 71i, which can also be referred to as the free end, wherein the end portion 71i is not established and in the event of a crash thus moves relative to the spindle nut 57. The fastening portion 71a thus moves conjointly with the actuator unit 2, wherein the end portion 71i moves relative to the actuator unit 2 as well as relative to the spindle nut 57.

[0093] According to the invention the threaded spindle 56 as well as the energy absorbing installation 7 is protected by the flexural wire 71 and thus accommodated in a functionally reliable manner within the actuator unit 2, in the example shown within the spindle tunnel 25.

[0094] A second embodiment of an energy absorbing installation having a flexural wire 71 is illustrated in FIGS. 11 to 13. Said flexural wire 71 in addition to the first embodiment described above has a second bend 71e of approximately 180 which adjoins the second leg 71b and which is adjoined by a third leg 71f which by way of the third bend 71g of substantially 180 transitions to a fourth leg 71h. The leg 71b and 71f have in, the legs 71d and 71h counter to the longitudinal direction. The exposed end portion 71i forms the free end of the flexural wire 71.

[0095] The spindle nut 57 has a guiding installation comprising recesses 57b, 57d, 57f, and 57h which correspond to the profile of the leg 71b, 71d, 71f, and 71h of the flexural wire 71, and a second bending anvil 57e about which the bend 71e is guided, and a third bending anvil 57g about which the bend 71g is guided. The flexural wire 71 prior to the event of a crash is disposed in the guiding installation of the spindle nut 57 as shown in FIG. 11. In the event of a crash, the flexural wire 71 is guided through the recesses 57b, 57d, 57f, 57h and while performing in each case forming work is pulled about the total of three bending anvils 57c, 57g, and 57e until said flexural wire 71 after the event of the crash is stretched in the longitudinal direction as is illustrated in FIG. 12. On account thereof, a relatively long flexural wire 71 which in the guiding installation is wound multiple times about the spindle nut 57 and in the event of a crash can absorb kinetic energy uniformly along a long deformation path can be used. The spindle nut 57 of the second embodiment has a bore 570 which is disposed so as to be orthogonal to the spindle axis S. The shear pin 59 which is coupled to the actuator unit can be inserted into said bore. A particularly compact and protected construction mode is possible on account of the spindle nut 57 being disposed within the actuator unit 2, in particular in the spindle tunnel 25. The flexural wire 71 has an end portion 71i which can also be referred to as the free end, wherein the end portion 71i is not established and in the event of a crash thus moves relative to the spindle nut 57. The fastening portion 71a in the event of a crash thus moves conjointly with the actuator unit 2, wherein the end portion 71i moves relative to the actuator unit 2 as well as relative to the spindle nut 57.

[0096] The bending anvils 57c, 57g, and 57e which act as forming elements according to the invention, and the groove-shaped recesses 57b, 57d, 57f, and 57h which serve as guiding elements for the flexural wire 71, can preferably be configured so as to be integral to the spindle nut 57, for example by subtractive or non-subtractive machining.

[0097] The casing tube 21 and/or the outer casing 3 can in each case be configured as an extruded profile, for example from an aluminum or magnesium alloy.

[0098] An alternative embodiment of the actuator unit 2 is illustrated in the same view as in FIG. 7 in FIG. 14. Said alternative embodiment differs to the extent that the casing tube 21 does not have a spindle tunnel 25, but the threaded spindle 56 is disposed so as to be exposed laterally outside the casing tube 21, and the spindle nut 57 is likewise fastened externally on the casing tube 21. The function of the adjustment drive 5 according to the invention and of the energy absorbing device 7 is otherwise identical.

[0099] In order for a smooth-running linear bearing of the actuator unit 2 to be implemented in the outer casing 3, roller element raceways 27 can be configured externally on the casing tube 21, three roller element raceways 27 which extend along the entire length and may be molded so as to be integral to the casing tube 21 being distributed across the circumference in the example shown. Corresponding roller element raceways 31 are configured internally in the outer casing 3 so as to be radially opposite said roller element raceways 27. Rollers 8 which for forming a smooth-running linear bearing are able to roll in the longitudinal direction when adjusting the steering column 1 are disposed as roller elements so as to be rotatable in a roller cage 81 between the roller elements raceways 27 and 31.

[0100] A spindle nut 57 having an energy absorbing installation is shown in a third embodiment in a view similar to that in FIG. 11 in FIG. 15. Said spindle nut 57 has a flexural wire 71 having a first leg 71b and a second leg 71d. The first leg 71b which in the longitudinal direction runs rearward at the front free end thereof has a hook-shaped fastening portion 71a, and by way of a bend 71c of substantially 180 transitions to the second leg 71d which counter to the longitudinal direction runs forward. The bend 71c in this embodiment is freely bent, that is to say that said bend 71c is not guided so as to lie on a bending anvil 57c as in FIG. 11. The second leg 71d by way of the front, free, end 71i is supported in a forward manner on a counter bearing 57i on the spindle nut 57. The flexural wire 71 has a rectangular cross section.

[0101] The flexural wire 71 by way of the fastening portion 71a is hooked into the casing tube 21, as is described in the context of the embodiment in FIGS. 10 to 12. In the event of a crash the flexural wire 71 is continuously bent, wherein the in this embodiment free bend 71c in the longitudinal direction travels relative to the spindle nut 57, as is indicated by the arrow in FIG. 15. A fourth embodiment of an energy absorbing installation 7 is shown in FIGS. 16 to 19, wherein the view of FIG. 16 corresponds to the view of FIG. 7, FIG. 17 corresponds to the view of FIG. 11 or 14, FIG. 18 corresponds to the view of FIG. 13, and FIG. 19 shows the situation after the event of a crash in a manner analogous to FIG. 12. The same reference signs are in each case used for equivalent components.

[0102] The spindle nut 57, in a manner similar to the embodiment shown in FIG. 12, has the groove-shaped recesses 57b, 57d, and 57f, the bending anvils 57c and 57e being disposed in the profile of said recesses 57b, 57d, and 57f. A guiding installation through which the flexural wire 71 is pulled in the event of a crash and by way of which the plastic deformation arising in the bending herein continuously absorbs kinetic energy is formed on account thereof.

[0103] As can be clearly seen in FIG. 18, the flexural wire 71 has a hook-shaped fastening portion 71a which is adjoined by a first leg 71b which in the longitudinal direction runs rearward and by way of a bend 71c of substantially 180 transitions to a second leg 71d which counter to the longitudinal direction runs forward. The fastening portion 71a is fastened to the front end of the casing tube 21, specifically hooked thereinto in a form-fitting manner, as in FIG. 9. The first leg 71b is disposed in the groove-shaped recess 57b of the spindle nut 57 that runs in the longitudinal direction, and in the spindle tunnel 25 is routed rearward, then in the region of the bend 71c of said first leg 71b is guided about the bending anvil 57c. The second leg 57c which adjoins the bend 71c disposed in the groove-shaped recess 57d, and by way of the bend 71e is guided about the second bending anvil 57e, and transitions to the third leg 71f. Subsequently, the flexural wire 71 for forming a reserve coil 71k, also referred to as the coil for short, is helically wound about the spindle axis S on a substantially cylindrical coiling portion 57k which is configured on the spindle nut 57 so as to be directed rearward and coaxial with the spindle axis S.

[0104] As can be seen in FIG. 18, the reserve coil 71k is embodied as a single-tier, flat, coil which preferably has a plurality of windings which are successive in the axial direction. In the event of a crash the flexural wire 71 is drawn from the reserve coil 71k in the axial direction into the recess 57 and is pulled through the recesses 57f, 57d, and 57b, and about the intervening two bending anvils 57e and 57c while in each case performing deforming work, until said flexural wire 71 after the crash is stretched in the longitudinal direction between the fastening portion 71a and the spindle nut 57, as is illustrated in FIG. 19.

[0105] A relatively long flexural wire 71 which in a plurality of windings can be stored in the reserve coil 71k can be used. When being unwound from the reserve coil in the event of a crash, the flexural strip 71 which is continuously being bent about the bending anvils 57e and 57c can absorb kinetic energy uniformly along a long deformation path.

[0106] It is a particular advantage of this assembly that the reserve coil 71k by way of the leg 71f is pulled apart and unwound substantially in the axial direction in terms of the spindle axis S. On account thereof, the reserve coil 71k in the event of a crash can be continuously unwound from the coiling portion 57k until the state shown in FIG. 19 is achieved, the latter being achieved in a manner analogous to FIG. 12. On account of the unwinding in the axial direction, the flexural wire stored on the reserve coil 71k can be unwound in a uniform manner and it is prevented that the windings tighten in the manner of loops on the coiling portion 57, on account which force required for unwinding could potentially be increased.

[0107] One advantage of the embodiment described in FIGS. 16 to 19 lies in that the bending anvils 57e and 57c are engaged with the flexural wire 71 for deformation along the entire deformation path, the latter corresponding to the length of the flexural wire 71 stored in the reserve coil 71k. On account thereof, the deformation output in the event of a crash is substantially constant and uniform deceleration takes place.

LIST OF REFERENCE SIGNS

[0108] 1 Steering column [0109] 2 Actuator unit [0110] 21 Casing tube [0111] 22 Steering spindle [0112] 22a,b Steering spindle part [0113] 23 Fastening portion [0114] 24 End portion [0115] 25 Spindle tunnel [0116] 26 Opening [0117] 27 Roller element raceways [0118] 3 Outer casing [0119] 31 Roller element raceways [0120] 4 Support unit [0121] 41 Fastening means [0122] 42 Pivot axis [0123] 43 Actuator lever [0124] 5 Adjustment drive [0125] 51 Drive unit [0126] 52 Worm gear [0127] 53 Bearing [0128] 54 Servomotor [0129] 55 Worm [0130] 56 Threaded spindle [0131] 57 Spindle nut [0132] 57a Threaded bore [0133] 57b,d,f,h Recess (guiding groove) [0134] 57c,e,g Bending anvil [0135] 57i Counter bearing [0136] 57k Coiling portion [0137] 58 Fixing bolt [0138] 59 Shear pin [0139] 6 Height adjustment drive [0140] 7 Energy absorbing installation [0141] 71 Flexural wire [0142] 71a Fastening portion [0143] 71b,d,f,h Leg [0144] 71c,e,g Bend [0145] 71i End portion [0146] 71 Reserve coil [0147] 8 Roller [0148] 81 Roller cage [0149] L Longitudinal axis [0150] S Spindle axis