STEERING COLUMN FOR A MOTOR VEHICLE

Abstract

A steering column may include an inner casing tube in which a steering spindle is mounted rotatably about a longitudinal axis, an outer casing unit in which the inner casing tube is retained, and a motorized adjustment drive for longitudinal relative movement between the outer casing unit and the inner casing tube. The inner casing tube and the outer casing unit are coupled via an energy absorption device that has at least two energy absorption elements and a coupling device. A first energy absorption element can be coupled or uncoupled between the inner casing tube and the outer casing unit via the coupling device, which energy absorption element can be plastically deformed in the coupled state with relative displacement in the longitudinal direction of the inner casing tube and the outer casing unit. The coupling device has a coupling element that is movable between the uncoupled and the coupled state. The coupling element can be brought into operative engagement with a coupling piece that is connected to the first energy absorption element.

Claims

1.-15. (canceled)

16. A steering column for a motor vehicle, the steering column comprising: an inner casing tube in which a steering spindle is mounted rotatably about a longitudinal axis; an outer casing unit in which the inner casing tube is retained, the outer casing unit being directly or indirectly connectable to a body of the motor vehicle; a motorized adjustment drive disposed between the outer casing unit and the inner casing tube, wherein the outer casing unit and the inner casing tube are displaceable relative to one another in a direction of the longitudinal axis by way of the motorized adjustment drive; and an energy absorption device coupling the inner casing tube and the outer casing unit, the energy absorption device including at least two energy absorption elements and a coupling device, wherein a first energy absorption element of the at least two energy absorption elements is configured to be coupled or uncoupled between the inner casing tube and the outer casing unit via the coupling device, wherein the first energy absorption element is plastically deformable in a coupled state with relative displacement in the direction of the longitudinal axis of the inner casing tube and the outer casing unit, wherein the coupling device has a coupling element that is movable between an uncoupled state and the coupled state, wherein the coupling element is movable into operative engagement with a coupling piece connected to the first energy absorption element.

17. The steering column of claim 16 wherein the coupling piece is configured as an intermediate element separate from the first energy absorption element.

18. The steering column of claim 16 wherein the coupling piece has a carrier element that engages with the first energy absorption element.

19. The steering column of claim 16 wherein the coupling piece is guided in a guide means in the direction of the longitudinal axis.

20. The steering column of claim 19 wherein the coupling piece comprises a guide body that is received displaceably in the direction of the longitudinal axis in a guide groove.

21. The steering column of claim 16 wherein the coupling piece has a coupling receiving means to which the coupling element is connectable.

22. The steering column of claim 16 wherein the energy absorption element has a predetermined breaking element.

23. The steering column of claim 16 wherein a support plate is coupled to the outer casing unit.

24. The steering column of claim 23 wherein the coupling piece is guided in a guide means in the direction of the longitudinal axis, wherein the support plate comprises the guide means.

25. The steering column of claim 23 wherein a carrier connected to a second energy absorption element of the at least two energy absorption elements is fixed to the support plate.

26. The steering column of claim 23 wherein the energy absorption element has a predetermined breaking element, wherein the support plate is connected to the inner casing tube via the predetermined breaking element.

27. The steering column of claim 23 wherein the coupling device is fixed to the support plate.

28. The steering column of claim 23 wherein the motorized adjustment drive is configured to contact the support plate.

29. The steering column of claim 16 wherein the coupling device has a pyroelectric actuator.

30. The steering column of claim 16 wherein at least one of the at least two energy absorption elements is formed as a bending element that has two legs connected to one another by a bend, wherein a first of the two legs is configured to be fixed to the outer casing unit and a second of the two legs is configured to be fixed to the inner casing tube in the direction of the longitudinal axis.

Description

DESCRIPTION OF THE DRAWINGS

[0041] Advantageous embodiments of the invention are explained in greater detail below with the help of the drawings. More specifically, the drawings show:

[0042] FIG. 1 a steering column according to the invention as a perspective representation,

[0043] FIG. 2 the steering column according to FIG. 1 as a further perspective representation,

[0044] FIG. 3 a detail view of the steering column according to FIG. 1 as a perspective representation,

[0045] FIG. 4 a detail view of the steering column according to FIG. 1 as an exploded view,

[0046] FIG. 5 a detail view of an energy absorption device according to the invention in the normal running state,

[0047] FIG. 6 a side view of the energy absorption elements of the energy absorption device according to FIG. 5,

[0048] FIG. 7 an energy absorption device according to FIG. 5 in the state following a crash with the energy absorption elements coupled;

[0049] FIG. 8 the energy absorption device according to FIG. 7 in a representation similar to FIG. 6,

[0050] FIG. 9 an energy absorption device according to FIG. 5 in the state following a crash with an uncoupled energy absorption element,

[0051] FIG. 10 the energy absorption device according to FIG. 9 in a representation similar to FIG. 6,

[0052] FIG. 11 a detail view of a coupling piece according to the invention,

[0053] FIG. 12 a detail view of an inner casing tube in an alternative embodiment,

[0054] FIG. 13 a further detail view of the inner casing tube in FIG. 12,

[0055] FIG. 14 a detail view of an inner casing tube in an alternative embodiment,

[0056] FIG. 15 a detail view of an inner casing tube in a further alternative embodiment,

[0057] FIG. 16 a schematic sectional representation of the double-walled portion of the locking pot.

EMBODIMENTS OF THE INVENTION

[0058] Identical parts in the different figures are constantly provided with the same reference numbers and are therefore usually labelled or referred to only once in each case.

[0059] A steering column 1 according to the invention is schematically depicted as a perspective view obliquely from behind (in relation to the driving direction of a motor vehicle which is not shown) in FIGS. 1 and 2.

[0060] The steering column 1 can be fastened to the body of a motor vehicle which is not shown by means of a bracket 2 which has been omitted from the view in FIG. 2 for the sake of clarity. The bracket 2 comprises fastening means 21 for fastening to the vehicle body.

[0061] A steering spindle 30 is rotatably mounted in an inner casing tube 31, also referred to as an internal casing tube 31, about its longitudinal axis L which extends forwardly in the longitudinal direction. A fastening portion 32 for fastening a steering wheel which is not shown is formed at the rear on the steering spindle 30. The inner casing tube 31 is displaceably retained telescopically in the longitudinal direction in an outer casing unit 33, also referred to as an external casing unit 33 or a casing unit 33 for short.

[0062] A motorized adjustment drive 4 comprises an electrical drive unit 41 having an electric motor which is supported on the outer casing unit 33 in the longitudinal direction by means of a yoke-type supporting component 44 and can be driven rotatably by the one threaded spindle (spindle) 42 extending in a substantially longitudinal direction, which spindle is screwed into a spindle nut 43 arranged non-rotatably in relation thereto, which is supported on the inner casing tube 31 in a longitudinal direction via a support element 432.

[0063] In this way, a rotational spindle drive is achieved in which the rotating drive of the threaded spindle 42 means that the distance in the longitudinal direction between the drive unit 41 and the spindle nut 43 can be adjusted. Through activation of the drive unit 41, the inner casing tube 31 can be retracted or extended telescopically relative to the outer casing unit 33 for the length adjustment of the steering column 1, as depicted by a double arrow.

[0064] An energy absorption device 5 which is explained in greater detail below is arranged between the outer casing unit 33 and the inner casing tube 31. This can be seen in FIG. 3 in which the outer casing unit 33 is omitted in the same perspective as in FIG. 1. FIG. 6 shows an exploded view of the arrangement from FIG. 3.

[0065] The energy absorption device 5 comprises a housing 51, also referred to as a holding profile 51, in the form of a C-shaped rail with a substantially rectangular cross section which is fixedly connected to the inner casing tube 31 and extends in the longitudinal direction, wherein the open cross section is directed towards the outside of the inner casing tube 31. By means of form-fitting elements 510 which engage with corresponding receiving openings 310 in the inner casing tube 31, the housing 51 is fixedly connected to the casing tube 31, by means of laser welding for example. On its radially outwardly facing outside, the housing 51 configured as a holding profile has a slot 52 extending parallel to the longitudinal axis L.

[0066] A first energy absorption element 54 and a second energy absorption element 56 are arranged in the housing 51 spaced apart in the longitudinal direction.

[0067] The outer casing unit 33 comprises a yoke 330, wherein this yoke 330 has a free end in which a recess is formed, in which an insertion piece 331 is received non-rotatably in a force-fitting manner. The insertion piece 331 comprises an internal threaded bore, wherein said internal thread bore is configured as a blind-hole opening and has the opening on the side of the insertion piece 331 facing away from the outer casing unit 33. A covering of the steering column which is not shown, for example a plastics subshell, can therefore be easily fixed to the steering column, in that a screw is screwed into the internal threaded bore and therefore fixes the covering to the steering wheel. The insertion piece 331 has an external square cone which is pressed into the recess in the yoke 330. The angle of the cone is preferably selected in such a manner that a self-locking effect prevails between the insertion piece 331 and the yoke 330.

[0068] In the example shown, energy absorption elements 54 and 56 which have the same shape and are identical in terms of their basic function are depicted in partially different views and operating states in FIGS. 4 to 10. The energy absorption elements 54 and 56 are each configured as a U-shaped bending wire or bending strip, having a first leg 541 or 561 which is connected via a bend 542 or 562 of substantially 180 to a second leg 543 or 563. At the end of the second leg 543 or 563, a carrier hook 544 or 564 is formed in each case by a bend towards the first leg 541 or 561. Consequently, an engagement opening 545 or 565 of an energy absorption element 54 or 56 is formed in each case by the legs 541, 543, the bend 542 and the carrier hook 544 or by the legs 561, 563, the bend 562 and the carrier hook 564. The energy absorption elements 54 and 56 may be configured as stamped parts, so that cost-effective production is guaranteed.

[0069] The energy absorption elements 54 and 56 are supported with their first leg 541 or 561 contrary to the longitudinal direction (arrow in FIG. 6) against abutments 546 or 566 projecting inwardly in the cross section of the housing 51, which abutments each form a stop in the longitudinal direction.

[0070] A coupling device 6 comprises a pin-shaped or bolt-shaped coupling element 61 which is attached to a pyroelectric actuator 62, or pyroswitch 62 for short, for example by means of fastening elements 431 such as screws or the like. During the electrical triggering or actuation of the actuator 62 in a crash scenario, a pyrotechnic propellant charge is ignited, through which the coupling element 61 is moved in its axial direction transversely to the longitudinal direction of the longitudinal axis L, in the direction of the actuator 62 indicated by the arrow in FIG. 4. The actuator 62 is electrically connected to a connector 64 via an electrical line 63 in the form of a cable. The connector 64 can be connected to a second connector which is not shown wherein the second connector is connected to the vehicle electrical system.

[0071] The spindle nut 43 is fixedly held in a support element 432 in the longitudinal direction, wherein the support element 432 is connected to a support plate 7 by means of a fastening element 431, and is located on the outside, viewed from the inner casing tube 31.

[0072] On its inside, which lies against the housing 51 in the mounted state from the outside, the support plate 7 has a guide device in the form of a guide groove 71, as can be seen in FIG. 11. A coupling piece 8 according to the invention can be received displaceably in the longitudinal direction in the guide groove 71, as indicated by the arrow in FIG. 11.

[0073] The coupling piece 8 has a guide body 81 which can slide along in the guide groove 71 in the longitudinal direction. On its inside facing the inner casing tube 31, a carrier element 486 is formed on the coupling piece 8 which extends in the transverse direction through the slot 52 of the housing 51 and engages in each operating state of the energy absorption device 5 behind the carrier hooks 544 of the first energy absorption element 54, as shown in FIGS. 5, 6, 7, 8, 9 and 10. In this case, a guide piece 82 may be configured to slide along in the slot 52.

[0074] The guide groove 71 has two edge portions 711 extending parallel to one another and a groove bottom 712, wherein the edge portions 711 define the width of the guide groove 71. The guide groove 71 has a portion 710 with a reduced groove width which is formed at the closed end of the guide groove 71. In order to realize the portion 710 with the reduced groove width, a projection extends into the guide groove 71 starting from the edge portion 711. The guide body 81 of the coupling piece 8 has a width which is greater than the groove width in the portion 710 with a reduced groove width, wherein the width of the guide body 81 of the coupling piece 8 is smaller than the groove width of the guide groove outside the portion 710 with a reduced groove width. The coupling piece 8 is inserted in a force-fitting manner in the guide groove 71 in this portion 710 with the reduced groove width, wherein in a crash scenario when the energy absorption element 54 is uncoupled, the coupling piece 8 is moved out from the portion 710 of the guide groove 71 with a reduced groove width while overcoming a predefined release force and can then slide along in the guide groove 71 with play between the edge portions 711.

[0075] The coupling piece 8 also has a coupling opening 83 arranged transversely to the longitudinal axis L as the coupling receiving means, which coupling opening may be configured as a through-opening, as shown, or is at least open outwardly to the support plate 7.

[0076] The support plate 7 has an opening 72 through which the bolt-shaped coupling element 61 extends into the coupling opening 83 in the coupled state of the coupling device 6 and produces a form-fitting connection to the support plate 7 in respect of the longitudinal direction.

[0077] In the uncoupled state, the coupling element 61 is removed from the coupling opening 83 by igniting the pyroelectric actuator 62, so that the coupling piece 8 can move loosely in the guide groove 71 in the longitudinal direction in a crash scenario. The actuator 62 has an insertion portion which is inserted in the opening 72 of the support plate 7. In this way, a sufficiently tight fit of the actuator 62 can be guaranteed, as said actuator is supported with the insertion portion in the longitudinal direction in the opening 72. The guide body 81 of the coupling piece 8 lies flush against the groove bottom 712. Consequently, when the coupling element 61 is in the coupled state in the crash scenario, it is subject to shear strain which is an advantage compared with an embodiment in which the coupling element 61 is subject to bending loads. This means that operational safety can be improved.

[0078] A carrier 73 is fixed to the support plate 7 and has a carrier element 476 on its inside facing the inner casing tube 31, which carrier element extends in the transverse direction through the slot 52 in the housing 51 and engages behind the carrier hook 564 of the second absorption element 56 in each operating state of the energy absorption device 5, as shown in FIGS. 5, 6, 7, 8, 9 and 10. The carrier 73 is fixed in a form-fitted manner in an opening 741 in the support plate 7.

[0079] The support plate 7 is connected to the housing 51 via a predetermined breaking element in the form of a shear pin 75. The shear pin 75 is fixed in a form-fitting manner in a further opening 74 in the support plate 7 and in a corresponding opening 57 in the housing 51.

[0080] The support element 432 which supports the spindle nut 43 is connected to the support plate 7 by means of fastening elements 431. Consequently, the support plate 7 is supported on the outer casing unit 33 via the adjustment drive 4 in the longitudinal direction, wherein the adjustment drive 4 is fastened to the outer casing unit 33 by means of the yoke-shaped support component 44.

[0081] In the coupled state, which is depicted in the normal operating state prior to a crash in FIGS. 5 and 6, the coupling element 61 of the coupling device 6 engages with the coupling opening 83 and thereby brings about a form-fitted locking of the coupling piece 8 to the support plate 7 in the longitudinal direction. In this case, the first energy absorption element 54 is connected to the support plate 7 by the carrier element 486 of the coupling piece 8 and the second energy absorption element 56 by the carrier element 476 of the carrier 73.

[0082] In a crash scenario, the high force peak which occurs causes the shear pin 75 to break and allows the inner casing tube 33 to be pushed in forwardly telescopically in the longitudinal direction into the outer casing unit 33. The inner casing tube 31 in this case is moved relative to the support plate 7 andin the coupled statethe two carrier elements 486 and 476, as shown by the arrows in FIG. 6.

[0083] In this wayas in the end state following a crashboth energy absorption elements 54 and 56 are bent over and plastically deformed, as shown in FIGS. 7 and 8. In this case, which is referred to as a high-load crash, the greatest possible kinetic energy is absorbed.

[0084] If only a relatively small energy absorption is necessary, such as in the case of a low driver weight, for example, or a crash at low speed, the pyroswitch 62 is activated so that the coupling element 61 is removed from the coupling opening 83 and a relative movement of the coupling piece 8 is released. In this uncoupled state, only the second energy absorption element 56 permanently connected to the support plate 7 via the carrier 73 is deformed. This uncoupled state following a crash is depicted in FIGS. 9 and 10. It can be seen in FIG. 9 how the coupling piece 8 is carried along by the undeformed energy absorption element 54 and guided along in the guide groove 71 in the longitudinal direction.

[0085] During uncoupling through the removal of the coupling element 61 from the coupling opening 83, the transverse forces which occurred were held off the first energy absorption element 54 by the intermediate coupling piece 8. In a crash scenario, the disabled energy absorption element 54 which has remained undeformed is safely guided by the coupling piece 8 on the support plate 7, so that no harmful deformation can occur.

[0086] By means of a second motorized adjustment drive 9 which is likewise configured as a rotational spindle drive with a motorized drive unit 91, and a thread spindle 92 which can be driven rotatably thereby and which is screwed into a spindle nut 93, the adjustment drive 9 is supported between the bracket 2 and the outer casing unit 33 and allows motorized adjustment of the steering spindle 30 in the vertical direction H.

[0087] A perspective detail view of an inner casing tube 31 in different embodiments is shown in FIGS. 12 to 15 in each case, wherein the inner casing tube 31 in FIGS. 1 to 4, 6, 8 and 10 can be replaced by an inner casing tube 31 in FIGS. 12 to 15. The difference between the inner casing tube 31 from FIGS. 1 to 4, 6, 8 and 10 and the embodiments in FIGS. 12 to 15 is that the inner casing tubes 31 have a locking pot 311. A locking pot 311 of this kind is a coupling receiving device for coupling the inner casing tube 31 to a steering lock. A steering lock of this kind is known from DE 10 2013 112 124 A1, for example, wherein the steering lock comprises a locking pin which can be brought into engagement with the steering spindle 30 and in the engaged state locks, or at least severely restricts, the rotation of the steering spindle 30 about the longitudinal axis L. The locking pot 311 in the different embodiments shown in FIGS. 12 to 15 is attached to the opposite side of the housing 51 in each case. The locking pot 311 is configured as a hollow profile, preferably as a square hollow profile, and has a receiving opening 314 into which a portion of the steering lock which is not shown is inserted. The locking pin is received in this portion of the steering lock and displaceably guided.

[0088] FIGS. 12 to 15 show an inner casing tube 31 for a steering column of a motor vehicle for the rotatable receiving of a steering spindle 30, wherein the inner casing tube 31 comprises a locking pot 311 which has a receiving opening 314 into which a portion of a steering lock can be introduced, wherein the inner casing 31 has an opening which corresponds to the receiving opening 314, wherein the locking pot 311 has a double-walled portion 312, 313, 317, 318, wherein the double-walled portion is formed from a first wall 312, 317 and a second wall 313, 318, wherein the first wall 312, 317 has a first opening 315 and the second wall 313, 318 has a second opening 316, wherein the first opening 315 and the second opening 316 overlap at least in part, wherein the midpoint of the first opening 315 is displaced in respect of the midpoint of the second opening 316. Consequently, the openings 315, 316 are not concentric or coaxial in respect of one another.

[0089] The openings 315, 316 in the double-walled portion of the locking pot 311 form a stepped bore for receiving a fastening element, preferably a shearable screw, which is used for fastening the steering lock to the inner casing tube 31. A shearable screw of this kind comprises a shaft portion which projects through the opening 315 and a head which is received in the second opening 316. A form-fitting element is arranged in the head 330, which form-fitting element is arranged on the side of the head facing away from the shaft 331. This form-fitting element can be coupled with a screwdriver. After the shearing screw has been screwed in, the form-fitting element is separated from the head 330. Thanks to the displacement of the midpoints of the openings 315, 316 in respect of one another, it is not immediately possible for a tool to be fitted to the head 330 and the shearing screw removed and consequently for the steering lock to be removed from the locking pot 311, since the head at one point is such a small distance from the second wall 313, 318 that it does not allow the fitting of a tool. This can be particularly clearly seen from FIG. 16. FIG. 16 shows a schematic sectional depiction of the double-walled portion of the locking pot. The distance of the head 330 from the second wall 318 on the right side is smaller than on the left side. The axis A1 of the first opening 315 is arranged displaced in respect of the axis A2 of the second opening 316; they are therefore spaced apart from one another. The axes A1, A2 are arranged parallel to one another. The second opening 316 preferably has a larger diameter than the first opening 315.

[0090] In the embodiment in FIGS. 12 and 13 the locking pot is formed from a single piece of formed metal sheet, wherein the metal sheet has first and second portions which overlap and therefore provide the first wall 312 and the second wall 313 in this overlapping portion. The first and second wall 312, 313 are welded to one another. The locking pot 311 is likewise welded to the inner casing tube 31.

[0091] In the embodiment in FIG. 14 the second wall 318 is formed by a ring which is fixed on the locking pot 311. The ring has the second opening 316. The locking pot 311 is formed by a metal sheet which has been bent and the ends of which have been connected to one another by means of a form-fitted, dovetail-type frame 319 and therefore form the receiving opening 314. The frame 319 can be additionally strengthened by means of a welding process. As an alternative to a frame 319, a butt joint can also be used, wherein the ends are welded to one another.

[0092] In the embodiment shown in FIG. 15, the second wall 318 is formed by a sheet metal strip fixed onto the locking pot 311, wherein the sheet metal strip comprises the opening 316 which is offset in respect of the first opening 315. The locking pot 311 has free spaces 320 on its bending edges, so that an improved connection between the locking pot 311 and the inner casing tube 31 through a flush joint is possible. This free space 320 can also be used with the other embodiments in FIGS. 12 to 14.