STEERING COLUMN FOR A STEER-BY-WIRE STEERING SYSTEM FOR A MOTOR VEHICLE

Abstract

A steering column for a steer-by-wire steering system may include a casing unit in which a steering spindle is received such that the steering spindle is rotatable about a longitudinal axis. The casing unit may have an inner casing tube, which is rotatable and longitudinally displaceable, received coaxially in an outer casing tube. The steering spindle may have a longitudinally displaceable inner shaft that is received coaxially in an outer shaft in a torque-transmitting manner. The steering spindle may be coupled to a drive unit of a feedback actuator that has an electric motor for the generation and introduction of a feedback torque into the steering spindle. The drive unit has a recess that is arranged coaxially with respect to the longitudinal axis, is open toward the outer shaft, and has a maximum inscribed internal diameter that is greater than an external diameter of the outer shaft.

Claims

1.-15. (canceled)

16. A steering column for a steer-by-wire steering system for a motor vehicle, the steering column comprising: a casing unit in which a steering spindle is received so as to be rotatable about a longitudinal axis, the casing unit including an inner casing tube that is received coaxially in an outer casing tube such that the inner casing tube is displaceable telescopically in a direction of the longitudinal axis, wherein the steering spindle has an inner shaft that is received coaxially in an outer shaft in a torque-transmitting manner such that the inner shaft is displaceable telescopically in the direction of the longitudinal axis, wherein the steering spindle is connectable to a steering wheel; and a drive unit of a feedback actuator to which the steering spindle is coupled, wherein the feedback actuator includes an electric motor for generating and introducing a feedback torque into the steering spindle, wherein the drive unit includes a recess that is arranged coaxially with respect to the longitudinal axis, is open towards the outer shaft of the steering spindle, and has a maximum inscribed internal diameter that is greater than an external diameter of the outer shaft of the steering spindle.

17. The steering column of claim 16 wherein the internal diameter of the recess is smaller than an external diameter of the inner casing tube.

18. The steering column of claim 16 wherein a length of the inner casing tube or a length of the outer casing tube is smaller than a length of the outer shaft of the steering spindle.

19. The steering column of claim 16 comprising an intermediate casing tube that is disposed in a telescopically adjustable manner between the inner casing tube and the outer casing tube.

20. The steering column of claim 16 wherein the drive unit includes a drive wheel that coaxially surrounds the recess at least partially, is configured to be coupled to the steering spindle, and is configured to be driven rotationally by the electric motor.

21. The steering column of claim 20 wherein the drive wheel is connected to the inner shaft of the steering spindle.

22. The steering column of claim 21 wherein the drive wheel is configured as a gear mechanism wheel that is connected via a gear mechanism to the electric motor.

23. The steering column of claim 21 wherein the drive wheel is configured integrally with a rotor of the electric motor.

24. The steering column of claim 16 wherein the steering spindle is connected to the drive unit at a front end region of the steering spindle that dips axially into the recess.

25. The steering column of claim 16 wherein the drive unit is attached to an outer casing tube.

26. The steering column of claim 16 wherein the casing unit includes a bell-shaped housing of the drive unit.

27. The steering column of claim 16 comprising a motorized adjusting drive that acts between the inner casing tube and the outer casing tube, wherein the motorized adjusting drive is configured for relative displacement in the direction of the longitudinal axis.

28. The steering column of claim 16 comprising a clamping device that interacts with the casing unit, wherein the clamping device is movable into a fixing position where the clamping device fixes the inner casing tube relative to the outer casing tube and movable into a release position where the clamping device releases the inner casing tube for displacement relative to the outer casing tube.

29. The steering column of claim 16 wherein the casing unit is held in a carrying unit that is connectable to a body of the motor vehicle.

30. The steering column of claim 16 comprising an energy absorption apparatus that is attached between the inner and outer casing tubes or between the inner and outer casing tubes and a carrying unit that holds the inner and outer casing tubes.

Description

DESCRIPTION OF THE DRAWINGS

[0030] Advantageous embodiments of the invention will be described in greater detail in the following text on the basis of the drawings, in which, in detail:

[0031] FIG. 1 shows a steer-by-wire steering system in a diagrammatic illustration,

[0032] FIG. 2 shows a steering column according to the invention in a diagrammatic perspective view,

[0033] FIG. 3 shows the steering column according to FIG. 2 in a further perspective view,

[0034] FIG. 4 shows the steering column according to FIG. 2 in a partially cut-away illustration,

[0035] FIG. 5 shows a cross-sectional view of the steering column according to FIGS. 2 to 4,

[0036] FIG. 6 shows a longitudinal section through the steering column according to FIGS. 2 to 5 in the extended state,

[0037] FIG. 7 shows a longitudinal section through the steering column as in FIG. 6 in the retracted state,

[0038] FIG. 8 shows the drive unit of the steering column according to FIGS. 2 to 7 in an exposed perspective partial view,

[0039] FIG. 9 shows the drive unit according to FIG. 8 in a further perspective view,

[0040] FIG. 10 shows a steering column according to the invention in a second embodiment in a diagrammatic perspective view,

[0041] FIG. 11 shows a longitudinal section through the steering column according to FIG. 10 in the extended state,

[0042] FIG. 12 shows a longitudinal section through the steering column as in FIG. 11 in the extended state,

[0043] FIG. 13 shows a cross-sectional view of the steering column according to FIGS. 10 to 12, and

[0044] FIG. 14 shows the steering column according to FIGS. 10 to 13 in a partially cut-away illustration.

EMBODIMENTS OF THE INVENTION

[0045] In the various figures, identical parts are always provided with the same designations, and are therefore as a rule also named or mentioned in each case only once.

[0046] FIG. 1 shows a diagrammatic steer-by-wire steering system 1 for a motor vehicle, with a steering column 2 which can be mounted on the body (not shown) of the motor vehicle. In the steering column 2, a steering spindle 3 is mounted such that it can be rotated about its longitudinal axis L. A steering wheel 31 is fastened to the rear end (with regard to the driving direction) of the steering spindle 3, which rear end faces the driver.

[0047] A control unit 4 is connected via electric control lines to a rotary angle sensor 41 which, in the case of a steering command which is input by the driver by way of rotation of the steering wheel 31, detects a rotary angle of the steering spindle 3. The control unit 4 generates an electric control signal in a manner which is dependent on the measured rotary angle, and possibly further parameters such as, for example, the vehicle speed, the yaw rate and the like, and in this way actuates an electric motor steering actuator 5 via electric control lines. The steering actuator 5 brings about a steering angle of the steered wheels 53 via a steering gear 51 and track rods 52 which are connected to it.

[0048] The steering column 2 has an electric feedback actuator 6 which is coupled to the steering shaft 3 and by which feedback torque can be coupled into the steering spindle 3 in a manner which is dependent on the respective driving situation, which feedback torque simulates the feedback of the roadway on the wheels 53 and transmits it to the steering wheel 31, in order to give the driver feedback about the steering and driving behavior of the vehicle.

[0049] The steering column 2 is shown in a first embodiment in FIGS. 2 to 9.

[0050] The steering spindle 3 is mounted in a casing unit 21 such that it can be rotated about the longitudinal axis L, which casing unit 21 has an outer casing tube 22, in which an intermediate casing tube 23 is received axially and is arranged such that it can be displaced telescopically in the direction of the longitudinal axis L, in which intermediate casing tube 23 in turn an inner casing tube 24 is likewise arranged coaxially and such that it can be displaced telescopically in the direction of the longitudinal axis L. The inner casing tube 24 has an external diameter M; in the case of a non-round cross section, this is the diameter of the envelope circle. As a result, a three-piece telescope arrangement of the casing unit 21 is formed.

[0051] The steering spindle 3 has an outer shaft 32, at the rear end region of which, which prom jects on the driver's side out of the inner casing tube 24, a fastening section 33 is configured for attaching the steering wheel 31 fixedly for conjoint rotation. An inner shaft 34 dips coaxially such that it can be adjusted telescopically in the direction of the longitudinal axis L into the outer shaft 32 which is configured as a hollow shaft, with the result that a two-piece telescope arrangement is formed. The inner shaft 34 and the outer shaft 32 are connected to one another in a torque-transmitting manner for the transmission of the steering torque, for example by way of corresponding non-round cross-sectional profiles, such as polygonal profiles which are known per se from adjustable-length shafts or groove/tooth profiles which extend in the longitudinal direction or the like. The outer shaft 32 has an external diameter A; in the case of a non-round cross section, this is the diameter of the envelope circle. The inner shaft 34 extends as far as into the front end region of the casing unit 21.

[0052] The longitudinal section in FIG. 6 shows the steering column 2 in the extended state, in which the intermediate casing tube 23 is pushed rearward (to the left in FIG. 6) out of the outer casing tube 22 so as to project in the longitudinal direction, and the inner casing tube 24 is pushed out of the intermediate casing tube 23. The outer shaft 32 is mounted in steering spindle bearings 35 which are preferably configured as anti-friction bearings in the inner casing tube 24 such that it can be rotated about the longitudinal axis L, and is held in the inner casing tube 24 such that it cannot be displaced in the longitudinal direction, that is to say in the direction of the longitudinal axis L, with the result that, in the case of a longitudinal adjustment, it is moved together with said inner casing tube 24. The inner shaft 34 is mounted in the outer casing tube 22 such that it cannot be displaced in the longitudinal direction.

[0053] In the same longitudinal sectional view, FIG. 7 shows the retracted state of the steering column 2, in which state the intermediate casing tube 23 is pushed toward the front (to the right in FIG. 7) into the outer casing tube 22, and the inner casing tube 24 is pushed into the intermediate casing tube 23.

[0054] The feedback actuator 6 is attached in the front region to the outer casing tube 22 on the casing unit 21, and comprises a drive unit 61. The drive unit 61 has a bell-shaped housing 25 which is attached to the outer casing tube 22 in a manner which is open toward the front in a cup-like manner, and is preferably formed in one piece with the outer casing tube 22, for example as a shaped sheet metal part or cast metal part, or else can be manufactured from plastic material. A bearing cap 26 is flange-connected at the front on the opening of the housing 25 which has a greater diameter than the outer casing tube 22.

[0055] The drive unit 61 has a drive wheel 62 which is mounted such that it can be rotated coaxially with respect to the longitudinal axis L in bearings 27 in the housing 25. Here, the diameters of the drive wheel 62 and also of the bearings 27 can be greater than the diameter of the outer casing tube 22, as a result of which a particularly rigid bearing arrangement can be realized.

[0056] As can be seen in the exposed illustration of FIGS. 8 and 9, the drive wheel 62 has a hub 621 with a toothing system 622 which runs around on the outside. In the example which is shown, the toothing system 622 is configured as a worm toothing system, and can be molded as a plastic overmolded part on the hub 621 which is preferably manufactured from steel. The hub 621 and the inner shaft 34 are coupled to one another in a torque-transmitting manner, the inner shaft 34 being secured in the hub 621 in the direction of the longitudinal axis L by way of a calked portion 333 which is configured as a local plastic deformation. In other words, the hub 621 cannot be displaced with respect to the inner shaft 34.

[0057] The drive wheel 62 has a coaxial (cylindrical in the example) recess 63 which is open axially in relation to the steering spindle 3 toward the outer shaft 32, as can be seen in FIGS. 6, 7 and 8. The inner shaft 34 extends axially through the recess 63, and is connected in a connecting section 64 in a torque-transmitting manner to the front end region of the inner shaft 34. The annular space which remains free between the inner shaft 34 and the inner wall of the recess 63 is closed toward the front by way of the connecting section 64, with the result that a hollow-cylindrical blind opening is formed.

[0058] The recess has an internal diameter D which is greater than the external diameter A of the outer shaft 32. As a result, in the retracted state, as shown in FIG. 7, the outer shaft 32 can dip axially toward the front as far as into the drive wheel 62 of the drive unit 61. By virtue of the fact that the external diameter M of the inner casing tube 24 is greater than the internal diameter D, the inner casing tube 24 cannot dip into the recess 24, as can be seen in FIG. 7.

[0059] It can be seen from FIG. 7 that the arrangement which is formed from the inner casing tube 24, the intermediate casing tube 23 and the outer casing tube 22 is shorter in the maximum retracted state, as measured in the direction of the longitudinal axis L, than the inner shaft 34 which is pushed to a maximum extent into the outer shaft 32. The outer shaft 32 is mounted rotatably in the inner casing tube 24 which can also be called an internal casing tube, the outer shaft 32 protruding beyond both ends of the inner casing tube 24. By virtue of the fact that the outer shaft 32 can dip into the recess 63 of the drive wheel 62, a short stowage length is nevertheless realized in the retracted state.

[0060] In order to generate the feedback torque, the feedback actuator 6 has a motor 65, namely an electric motor, to the motor shaft of which a worm 651 is coupled. It can be seen from the cross-sectional view in FIG. 5 how the worm 651 meshes with the corresponding toothing system 622 of the drive wheel 62.

[0061] FIGS. 10 to 14 show a second embodiment of a steering column 2 according to the invention. As in the first embodiment, said steering column 2 has a drive wheel 62 with a hub 621 which, however, does not have a toothing system, but on which rather the rotor 66 of a motor 67 is arranged fixedly for conjoint rotation, the stator 68 of which is attached coaxially in the housing 25 fixedly for conjoint rotation. The bell-shaped housing 25 forms the motor housing. The drive wheel 62 directly has the rotor 66, that is to say forms the motor shaft as it were, with the result that a direct drive without further gear mechanism members is realized. The drive unit 61 is therefore integrated in a compact structural unit in the housing 25. The recess 63 and the associated advantages are as in the first design variant.

[0062] For longitudinal adjustment by way of telescoping extension or retraction of the casing unit 21, an adjusting drive 7 is provided which is configured as a spindle drive, with a spindle nut 71, into which the threaded spindle 72 is screwed. The spindle nut 71 can be driven rotationally relative to the threaded spindle 72 by an actuating motor 73. By virtue of the fact that the spindle nut 71 is supported on the outer casing tube 22 in the direction of the longitudinal axis L, and the threaded spindle 72 is supported on the inner casing tube 24, or vice versa, the casing unit 21 can be retracted or extended by motor depending on the rotational direction of the actuating motor 73.

[0063] For attachment to a body (not shown) of a motor vehicle, the steering column 2 has a carrying unit 8, by which the casing unit 21 is held. In order to realize a vertical adjustment, the casing unit 21 is mounted on the carrying unit 8 such that it can be pivoted about a pivot axis S which lies horizontally transversely with respect to the longitudinal axis L. The pivot axis S can preferably be arranged in the region of the housing 25 in the front region of the carrying unit 8. In the front region, the casing unit 21 is articulated on the carrying unit 8 via a movable pivoting lever 81. As a result, the steering wheel 31 which is attached to the rear end can be moved about the pivot axis S up and down in the vertical direction H.

[0064] For the vertical adjustment of the casing unit 21 relative to the carrying unit 8, an adjusting drive 9 is provided which is configured as a spindle drive, with a spindle nut 91, into which a threaded spindle 92 is screwed and which can be driven rotationally relative to the spindle nut 91 by an actuating motor 93. The threaded spindle 92 is supported in the direction of its axis on the carrying unit 21, and the spindle nut 91 is attached to the pivoting lever 81 in a stationary manner with regard to the rotation of the threaded spindle 92, and is supported in the direction of the axis of the threaded spindle 92. By way of rotational drive by means of the actuating motor 93, the pivoting lever 81 can be moved and, as a result, the casing unit 21 can be adjusted upward or downward in the vertical direction H relative to the carrying unit 8.

LIST OF DESIGNATIONS

[0065] 1 Steering system [0066] 2 Steering column [0067] 21 Casing unit [0068] 22 Outer casing tube [0069] 23 Intermediate casing tube [0070] 24 Inner casing tube [0071] 25 Housing [0072] 26 Bearing cap [0073] 27 Bearing [0074] 3 Steering spindle [0075] 31 Steering wheel [0076] 32 Outer shaft [0077] 33 Fastening section [0078] 34 Inner shaft [0079] 35 Steering spindle bearing [0080] 4 Control unit [0081] 41 Rotary angle sensor [0082] 5 Steering actuator [0083] 51 Steering gear [0084] 52 Track rod [0085] 53 Wheel [0086] 6 Feedback actuator [0087] 61 Drive unit [0088] 62 Drive wheel [0089] 621 Hub [0090] 622 Toothing system [0091] 63 Recess [0092] 64 Connecting section [0093] 65 Motor [0094] 651 Worm [0095] 66 Rotor [0096] 67 Motor [0097] 68 Stator [0098] 7, 9 Adjusting drive [0099] 71, 92 Spindle nut [0100] 72, 92 Threaded spindle [0101] 73, 93 Actuating motor [0102] 8 Carrying unit [0103] 81 Pivoting lever [0104] L Longitudinal axis [0105] A External diameter [0106] D Internal diameter [0107] S Pivot axis